Choose two scenes from Shakespeares Macbeth Essay Example for Free

Choose two scenes from Shakespeares Macbeth Essay At the outset of this scene, we are able to ascertain due to the careful sculpturing of Shakespeares, that Lady Macbeth is a practical kind of women from what is emanated from her soliloquy, who is imbued with an aura of insecurity full of consternation for her husbands dangerous ploy. She is ever weary of the fatal bellman who would signal the demise of her husband with the sternst goodnight however here we can see the interwoven theme of death occurring with the allusion to the toll of the bell rung outside the cell of those condemned at Newgate Prison. This would also appeal to those in Jacobean times due to the current fixation with treason and the Gunpowder plot to eradicate the king, serving as a focusing device to grab the audiences attention. As Lady Macbeth waits, the dramatic tension builds even once Macbeth enters the chamber, as he cries whos there? At this point, she could be pacing the room, looking apprehensive also in the dark, which would further contribute to the effect when Macbeth enters trying to establish where she is. This would also serve in the general panic of the scene, as Lady Macbeth is held in suspense for the outcome of the murder, the audience focusing solely on her. Also in order to eliminate the need of special effects, this scene could be off stage until Lady Macbeth bursts in and meets Macbeth. The language used would add to the general confusion and tantalising suspense with Lady Macbeth and Macbeth trying to affirm what happened as succinctly as possible using words such as when and how, adding to the further dramatic tension caused from Macbeths return. Macbeth here is depicted as frightened, for case of arousing those who would sound the alarm, hark he cries. However as Macbeth tries to denigrate himself by saying this is a sorry sight reflecting on his hands we can see the bolstering of spirit by Lady Macbeth who dismisses it as a foolish thought. Here again as at the outset of the scene we can see Lady Macbeths practical character being manifested, which is also seen further on when she returns the daggers, the determination, which she exemplifies, is also seen in Act 1. Scene 5, where she pacifies Macbeth saying leave all to me. Macbeth by contrast is asphyxiated with the thought of sleep another theme invoked thought a characters actions, seen in this scene, as Macbeths feels due to his actions, he wont be able to sleep the innocent sleep. This theme is further emphasised by the repetition of sleep no more. Also religious issues are aroused disallowing him to say Amen which under the Divine Right Of Kings should be uttered freely. Due to his contravention of the Right, he is despised of the reverential features. These two features culminate to show the slow disarray of the psychological state in Macbeth in a gradual downward spiral in mental degradation as he tries to control his ways however is adamant to look on murder again I dare not. Lady Macbeth is then faced with returning the daggers, with residual feelings of vexation for Macbeth. She dismisses his excuse using a metaphor are but as pictures pertaining to the fact that his fears are figments of the imagination like someone in childhood really trying to humiliate Macbeth for who he is. Lady Macbeth uses words such as gilt and grooms which would infer a marital sense being eluded to in the breakdown of relationship and the overlaying of something new, however the words are used here in a negative sense. Despite Lady Macbeths plausible efforts to banish all evidence from their presence in taking the daggers back, she in fact relinquished herself with the killing of Duncan with the blood on her hands. We can see the effects later on in the play when she is sleep walking she cries out damned spot this could only point back to this scene, which is a turning point from which she never escapes, and Macbeth and Lady Macbeth almost amalgamate into one. Again we have in the latter part of this scene a knocking which not only is used as a dramatic device in a quiet scene but also as a knell to show from now on they must suffer the consequences for their actions. The stage would be dark and quiet with a loud muffled pounding on the door resonating throughout the stage, the audience being caught up in this climatic suspense, trying to emulate what the two were feeling. Not only do we have this dramatic device used but also the theme of blood further intimated to wash this blood would further magnify the overall tension. We can see further allusion to blood in Act 2. Scene 3, badged with blood which is a predominate theme running through this scene. As the knocking grows ever closer Lady Macbeth keeps her composure and is not shaken by the knocking she seeks to disembalm them from the murder she says a little water which would usually signify purity. This is an example of dramatic irony, in water being used to cleanse them from their part in this deed, despite the abhorrence of such sin in the sight of purity. She is a stark contrast in character portrayal to Macbeth who is fretting for fear of being found out along with the settling apprehension of what hes done as he says of Duncan he would wake him would thou couldst portraying to the audience a change of mind within Macbeth who seeks to resurrect King Duncan however has to face the solemn fact he cant. At the outset of this next scene I wish to look at we see Lady Macbeth and Macbeth for the first time depicted with their elevated social circle enjoying those with whom they associate with in a banquet to commemorate their regal status. Macbeth tries to paint this false faà ¯Ã‚ ¿Ã‚ ½ade in an attempt to stop any animosity from being portrayed but then jeopardises his ploy at being the humble host a subtle use of alliteration, by using the word play. This would infer a temporal state pertaining to a change as we can see in the latter part of the scene. A theme of appearance and reality is intimated here due to Macbeths appearance being a complete inverse to his inner thoughts, in seeking to veto Banquos life yet trying to proclaim himself in an unostentatious way. Which also could be perceived as dramatic irony. Macbeth at this early stage in the scene is fairly composed, however we can observe a gradual change as he meets with the murders, he then asks if Banquo has been Dispatched. Shakespeares ingenious use of the word could allude to two things, which is also linked with Act 1. Scene 5. In this instance it is used ostensibly to discern whether Banquo has been killed, however it is used earlier in the play in the sense of being efficacious in the ploy of Lady Macbeth, as regards to the demise of Banquo. This initial part of the scene could be staged with Macbeth consulting with the murders, behind an opaque screen which the audience could see, but not those at table, alluring to the secrecy of the situation contrasting with the revelry going on round the table. This would also draw the audiences attention away from the table focusing them on Macbeth who is the pivotal one in this scene. Macbeths innate fears are seen in his speech saying: Im cabined, cribbed, confined bound in to saucy doubts and fears Macbeth has no consolation, he is alone in his distress without the help of his wife on whom he so heavily relied, floundering for what to do next. The use of alliteration would make it even more emphatic, like a caged animal who has no hope, and it is here we are able to discern the pressure amounting infused with a weakness of mind, heralding the decline in mental degradation. It is then we have the entrance of Banquos ghost, a dramatic device building up tension even before Macbeth notices. In a modern day theatre to resemble a ghost would be a lot easier than in the Jacobean times, due to exquisite special effects which would captivate a modern audience, than those in afore times. Due to the lack of equipment to super impose, a ghost possibly couldnt have been staged save for some one dressing up, however todays sophisticated lighting could produce a realistic effect which would further add to the aura of tension emanating from this scene. Whilst Macbeth is in a quandary about where to sit, he is trying to banish this horrific sight from his mind he cannot abstain from saying; Never shake they gory locks at me, he simply cant tolerate the image any longer, whether this arose from the heat oppressed brain it is ambiguous, however Macbeth is firmly convicted of this terrible apparition which has come to taunt him. It is here Lady Macbeth steps in dismissing his accusations as very paintings of your fear; we can see again the practical side co-insiding with the portrayal in Act 2. Scene 2, alluring to the fact she is the dominant one in their relationship trying to bolster Macbeth amidst such breakdown Another theme of blood is made manifest in Macbeths speech here and later on when Banquos ghost reappears blood hath been shed, however he is bemused using metaphorical language there is a ghost saying The brains were outthen man would diean end. Macbeth fails to grasp the concept of raising an apparition once a person has died. This however is an allusion to the further submergence in mental ruination as Macbeth elapses further into an irreparable state of mind. The ghost then makes a second appearance, more dramatic tension, filling the audience with a further sense of fear building up to a crescendo when Macbeth confronts the ghost. However we also see some dramatic irony emanating from his speech as he uses animal imagery, armed rhinoceroses. This is quite strange, as animals would symbolise a harmonic state of things, where as the thing Macbeth is describing is of a total contrast, used to emphasis the detrimental sight of Banquos ghost. The scene then draws to a close, alluring to the Divine Right Of Kings, along with religious issues invoked blood will have blood. This would also link back to the old Hebraic saying Man who lives by the word will die by the sword Macbeth has slighted the ways of the universe, the equilibrium has been altered, Stones have been known to move the hierachery of the heavens has been changed by false means in the demise of Duncan. Macbeth will have to reap what is sowed linking back to Act 2. Scene 2. Also mystics are pertained to in Macbeths speech Understood relations by maggot-pies, who had premonitions for the future beholding it in birds. Also reference to biblical saying dust to dust could be pertained to by reference of maggots referring to earthen things and ultimately death, which Macbeth will have to face. This would really captivate the attention of those in Jacobean times more effectively than those of the modern day, as they believed the supernatural, Shakespeare integrating it to focus the audience on Macbeth. The scene culminates in a theme of sleep linking back to Act 2 Scene 2, in Macbeth thinking this is the root of this self abuse however he says young in deed would reflect his mentality that he has further obstacles to clear to stop them hampering his seemingly aspiring progress, despite such denigration.

Effects of Material on Braking Abilities

Effects of Material on Braking Abilities Abstract: The most important utility in our lives as of today is automobiles, there is a lot of research and development is going in every section of the automobile field to give the safest possible vehicle to the world. One such is Brakes section; this is very important part in every vehicle, though we have most accurate and efficient brakes now-a-days, but they fail at the extreme conditions of heat , vibrations , high frequencies etc., this project is mainly concentrated on the aspects which are causing adverse affect to fail and create unusual   disturbances in the brakes. One such is brake squeal, an unwanted sound which is caused due to the vibration of the brake pads against the disc generating the high pitch noise. There are few other problems which leads into the high frequency problems, vibrations, tear in the brake disc etc. Here in this project a detailed study of disc brake is taken into account by considering with two different materials cast iron and aluminium alloy. The performance of brake is studies using normal stress analysis, vibration analysis and thermal analysis. The main problem of squeal can be due to the combination of vibration in brake set-up from callipers to the brake discs. And can also due to the uneven surfaces of the brake disc which causes due to the improper heat dissipation in the brake disc, all this problems are kept into consideration and this analysis are carried out for brake disc with two different materials as mentioned. A simple change in the design of brake disc has also been done for the maximum heat dissipation and this design also studied in this extreme conditions. And these two type brake disc are compared in all its possibly calculated attributes and the best one is concluded. Introduction: An automobile is a creation of history when they started and now it has become a crucial part of the world. Automobile is a wheeled motor vehicle used for transporting passengers, good etc. There has been a lot of improvement in the automotive field in all ways from the past few decades. The main aim of the automotive department is to provide safest vehicle from its design to the material used for each component. Every single thing is decided on basis of the effect of it on the human lives. The vehicles we use are very efficient when compared with older generation vehicles, the safety increases with the development and technology. But there are few problems which are yet to be solved. One such is about brakes, as we know BRAKES are the most important part in the every moving body, we have seen very drastic improvement in the methods of braking system. In olden days the brakes were handled by hand and now we have disc brakes and hydraulic brakes.   But the whole concept of brakes is working on same principle of kinetic energy is converted into heat energy. We find brakes very commonly used in cars, bikes, aeroplanes, automated machines etc. Brake is a device which decelerates the vehicle or machine by converting its kinetic energy into other form of energy, which will bring the vehicle down to the rest. We have disc brakes now which require very less amount of effort and time to stop the vehicle due to its accuracy and sensitivity; this are widely used in vehicles now-a-days. The drum brakes were used for very long time and we use even now, these were also very efficient brakes but due to the very common issues of changing the brake pads very often due to the short hand braking or improper usage, this has been replaced by disc or hydraulic in few machines. But we have found very common issues in disc brakes due to the brake rotor and brake pads. Due to the high friction while short braking we get unwanted noise brake squeal, though it doesnt have much effect on the performance of the vehicle, but it may fail the brake due to the tear o f brake disc or brake pads. A detailed study of each problem will be studied in further report taking disc brake system. History of Brakes: Invention of brake has started with the automated machines; brakes came into light mainly when the motorised wheeled vehicles came into existence. Brakes were not only used in the vehicles, these are used in other machines as brake lever to stop the motion rotor and so on. It has been an essential part of the moving systems. Brakes have developed a lot from first generation vehicles to present time. Early braking systems used steel rimmed wheels to stop the vehicle, which consists of curved wooden block designed to bear against the steel tire when operated by a single leverage system from the driver seat. But the brake shoe used was normal way of braking either in the horse drawn vehicle or steam locomotive. In 1895 Michelin Brothers move a step ahead to replace the steel rimmed wheels with the pneumatic rubber tire to come out with a new braking system as the brake shoes were no longer satisfactory.   A new method of braking system was required in those times as two early devices attempted to apply the friction force to the axle or to drum on axle or transmission shaft were not efficient as wanted. One method was use of wooden block inside a flexible contracting metal band which when pressed together would tighten the drum causing friction between the drum, which is connected to the wooden block and w heel, then the vehicle gets slow down. The other method was inner wheel or brake drum which will add an external contracting band to bear against the drum to bring the vehicle to rest. In 1899 Daimler started cable operated braking system; a cable was wound around a drum and attached to the chassis, so that when the cable is tightened when car was moving forward, the rotation of drum will increase the tightness and grip of cable, so that it will reduce the amount of force required to pull the cable-lever on the pedal to stop the moving vehicle. This brake system worked well but still the braking efficiency was less, the added efficiency called servo assistance is still an important factor in drum brakes even today. The external brake was vulnerable to the atmospheric conditions like weathering and to un-even roads which caused a rapid loss of efficiency and wear of the brake shoe lining and on few times automatic brake use to happen due to the drum expansion. To overcome all these problems an internal shoe brake was developed were the expanding the brake shoes were placed the inside the brake drum, mainly to protect from the dust and weather. Originally early brakes were operated by mechanically, i.e. the transformation by mechanical system was used to expand the brake shoes against drum by the drivers effort applied on the brake pedal. It works by pressing the brake pedal, which make cam to rotate by a lever connected to pedal, which forces the shoes to come on contact with the brake drum. And springs attached to both of the brake shoes to retain the original position when brakes are released. As the early brakes use to operate on lever supported cables and linkage system of fixed rods, equalising the same amount of brake pressure on the wheels has presented many problems , which were solved when hydraulic system was introduced, which used fluid to transfer the force applied to the brake pedal. In hydraulic braking system the set-up of cylinders and pipe lines forms a closed system which is filled with fluid. The pressure generated in master cylinder will transmit equal force to the each wheel cylinder and then equal pressure is applied to all brake shoes. This hydraulic system is used with the disc brake as well. Disc brake is more efficient braking system which was used mostly sports car when introduced but now it has been a very common system in passenger vehicles. It has a disc and a calliper is attached to it which can be operated mechanically, hydraulically, pneumatically, electromagnetically. Types of brakes: The brakes are broadly explained as using friction, pumping or electromagnetism. But one brake system can also use more than one principle. As the project is based on the disc brake we will look forward only to discuss about the frictional brake. Frictional brakes: These types of brakes are mostly rotating devices with a stationary pad attached with a rotating surface. These types of brakes are widely used even now in modern automotive braking system. Basically this are developed from band brakes to drum brakes then to the disc brakes. Band brakes: A simple type of brake, works on a principle that a band is wrapped round the rotating drum. When a force is applied on the lever, the restraining torque is found from the difference in tension between the two ends of the belt. The principle of operation of the band brake is same as for belt drives. This is external type braking system, as we see in picture the brake shoe are mounted on the drum. Ref: http://school.mech.uwa.edu.au/~dwright/DANotes/brakes/intro/intro.html Drum shoe brakes: This type of brake usually mean the brake shoe is mounted to press the inside surface of the drum. Two brake shoes are connected with a calliper set-up; it has lining on it which will create a frictional force when pressed towards the moving surface of the vehicle. These types of drum brakes are still used in modern cars due to the some cost and engineering benefits. These are applied to the rear wheels of today cars. Ref: http://school.mech.uwa.edu.au/~dwright/DANotes/brakes/intro/intro.html Disc Brake: these most widely used brake of these days, A disc is mounted on the wheel or axle and brake pads are placed within the jaws of the calliper, this is give the necessary friction when it will grip on the brake disc. Ref: http://static.howstuffworks.com/gif/disc-brake3.jpg Characteristics of brakes: Brakes are described on basis of several characteristics as Peak force: The maximum force obtained to decelerate the vehicle is called peak force. Few times this can be more than the traction limit of tires, then the wheel gets skid Continuous Power dissipation: As we know that the brakes get hot in use and get fail when the temperature gets too high, the maximum amount of power that dissipates through the brake without failure is the continuous power dissipation. Fade: Due to the over heat of the brakes the surface of the brake pads or disc get fade which will cause decrease in the effectiveness of brakes. Few times even cooling will have big effect on to fade. Power: when a very less force leads to the braking force, which is higher than the other brakes in similar class then its stated as powerful brake, which is due to the sensitivity of the brake system. Durability: Friction brakes have the lining which has wear surfaces, these to be renewed periodically.   Like brake shoes, pads or brake disc. Even if wear surface due to brake shoe generates high peak force this will lead to wear quickly. Weight: In some circumstances brakes are often mounted on wheels, this can disturb the traction significantly. Here weight means brake itself or an additional support structure Noise: generally brakes create some minor noise when applied, but sometimes create a high pitch noise called squeal or grinding noise. Principles of braking system: Brakes work on simple principle to slow down the moving vehicle by applying an external force, it may use more than one component; directly or indirectly several components effect on the momentum of the moving vehicle. Various types of process are used for braking effect. Frictional brakes are most commonly used these days, these works on the simple mechanism of changing the kinetic energy into the heat energy, which is done by only factor friction. Friction is created when a stationary brake pad grips on the moving brake disc with a force applied. This type of braking system is also used in the disc brakes; the stationary brake pads rub on the disc rotor which moves relatively in its own axis. Basic laws of braking system: Braking system can be explained by two simple Newton laws; which will explain the whole concept of the braking system As we know that the Newtons second law The net force on an object is equal to the its mass times its acceleration and points in the direction of the acceleration F = m* a The law is used to find out the net force required by brake pads to bring the moving vehicle to rest, tough there are many other factors to be considered for calculation of brake force which will be discussed further. It can also be explained through Newton first law Every object remains at rest or in motion in a straight line at constant speed unless it is forced to change its state by an external force if we check this law, an external force (brake force) is required to change the state of the vehicle (motion to rest). As this law explained the evaluation of the brake force and system of braking, a further law explains how the brake force will stop the vehicle. Law of thermodynamics: Energy can neither be created nor be destroyed; it will be converted from one form of energy to other form. This explained the frictional force (brake force) is converted into the heat energy. Factors considered while Braking: There are many factors to be considered for the high braking efficiency and performance; here we will see the few important factors which have a more effect on braking efficiency. 1. Condition of disc rotor: An uneven disc or ruffed disc rotor will decrease the braking effect; it has to be very well maintained as few a times due to dust and weather a extra layer is formed on the disc surface which will have a negative effect on the braking concept. Or wear of disc rotor due to overheat. 2. Pressure on brake rotor: A sufficient amount of brake pressure is to be maintained to get enough frictional force to stop the vehicle. If less pressure is applied it will directly affect the brake efficiency as force acting on the two rubbing surface will become less. 3. Contact surface: The area of contact between the brake pads and disc rotor should be more then the high friction is obtained. If lining of brake pads or surface of disc rotor is uneven then area of contact will be less, which will affect the brake efficiency. 4. Tyres: The design of tyre also have a normal affect on the brake efficiency, the more the contact of tyre to the road surface the good will be the braking system. Worn tyres will have less braking action and will not allow vehicle to stop the required point and may also skid, braking action is found high in new tyres due to its more contact with the road surface. There are other factors which also play an crucial part in brake efficiency like aerodynamics, heat dissipation, weight of body etc., Causes of failure: The most commonly found causes for the brake failure are 1. Oil or grease on the brakes will cause failure as it interferes with the friction. If we found oil in brakes mean the oil seal has failed and is why oil is leaking. 2. Overheat of brakes to great degree, which will develop a hot spot on the rotor and drums. This spots will resist the friction from brake shoe and pads, therefore braking power is lost and brake fails. 3. Brake squeal which indicates the tear in the brake pads, by the time the brakes start making a grinding sound, they would have worn out past the pads to rotors. This will require to change more than just brake pads for new one, which will increase replacement cost as well. 4. Improper wheel alignment or disturbance in the steering system will also lead into the failure of brakes. Even if the mass of vehicle will get out of its range due to extra load will cause a brake failure due to the uneven load distribution. DISC BRAKE Introduction: Disc brakes came into existence in 1890s in England. But due to the poor state of roads and dusty conditions the disc and pads use to get rust and get wear, so the system got non-viable at that time. But later it was fully adopted in 1950s with new innovations in the previous design. Many companies started using it in their cars as it was better when to compared with drum brakes, the main reason as it has overcome the brake fade problem by providing the resistance to the brake components and overall performance is better when compared with drum brakes.   Disc brakes become popular in sports cars due to its braking performance. Now it has been common in commercial vehicles as well, as its used at front of the vehicles, as the front brakes perform most of the braking effort. Components: A disc brake assembly consists of a 1. Cast-iron disc (disc rotor) that rotates with the wheel. 2. Calliper assembly attached to the steering knuckle (operated mechanically or hydraulically). 3. Friction materials (disc pads) that are mounted to the calliper assembly. Operation: (Hydraulically powered) Disc brakes prove to be efficient when compared with drum brakes even the working principle is same for both systems. The basic principle of braking system The kinetic energy is converted into heat energy   When brake pedal is pressed, the hydraulic pressure is applied on the piston; it pushes the brake pad to get in contact with the disc. As the pressure increases the calliper pushes the outside pad to get in contact with the disc. Due the friction generated between pads and disc will create the braking force as the pads gets in contact fully with the disc rotor. But if we study the disc brakes widely, it shows that it does not use the much of the friction between the lining and rotor to increase the braking power as drum brakes does, they likely cause a pull between them. Disc brakes have constrained self-energizing action, there has to be sufficient hydraulic pressure to get the required braking force. The braking force can be increased by changing the size of calliper piston. Even less heat dissipation occurs as the friction surface is exposed to the air, which also reduces the braking fade.   Design of disc rotor: generally disc rotors are either solid or ventilated. The ventilated type disc rotor has cooling fins in the middle of the disc to ensure good cooling. Proper cooling ensures longer pad life and it also prevents fading. Some ventilated rotors have spiral fins which allow more air flow and better cooling. These fins are mounted on side of the vehicle and directional. Spiral fins are used in the front of the vehicles as front brakes take most of the braking action as more heat generates. Ref: https://pontiworld.com.au Design of calliper: The calliper are used as floating calliper or fixed calliper design, and these are mounted on the axle or attached to the wheel. Floating calliper type: The calliper are used as floating calliper or fixed calliper design, and these are mounted on the axle or attached to the wheel. this type of calliper requires less parts than the other type and its also less in weight and economical. Based on requirement it consists of one or two pistons. The piston is either side of the calliper. Hydraulic pressure from the main cylinder is generated and the piston thus press the brake pad towards the disc, then instantly an equal hydraulic pressure is generated at the other side and right brake pad pushed towards disc rotor and vehicle stops due to the braking force. Fixed calliper type: The calliper are used as floating calliper or fixed calliper design, and these are mounted on the axle or attached to the wheel. This type of calliper design has piston on both sides of the calliper, which provides the equal force to each brake pad. These fixed calliper types can set-up either one or two pistons on each side. The two pistons can generate a more braking force and a compact design, as these absorb and dissipate more heat, due to its size and weight. This design is capable for greater number of hard stops of short brakes without the effect of brake fade. Materials used for component: The material used for disc rotor plays an important role in braking force. The material should be tuff enough to stand on high pressures and high friction forces. Generally cast iron is used for disc rotor commercially, but ceramic discs are used for high-performance vehicles and heavy automobiles. Recent study shows that aluminium alloys also do a great job as disc. Now we will discuss in detail about the commonly used materials cast iron and aluminium alloys. Cast iron: Grey cast iron alloy is used for the manufacturing of disc rotor; it has superior properties and various advantages over other materials, as it best suitable for manufacturing and machining when compared with other materials which lead to the graphite lubricating the cut and breaking the chips. It contains 2.5%-4% of carbon and greater than 2% of silicon.   This material has good wear resistance and galling which leads to self lubricating due to the graphite flakes. The graphite microstructure of grey cast iron allows less shrinkage. The silicon percentage in the grey cast iron makes the material corrosion resistance and increases its fluidity when casting which also makes material easy to weld. Compared with other alloys of the cast iron, grey cast iron has low tensile strength , the good point about this material is the shock and impact resistance is almost doesnt exist. Here we will see the properties of the grey cast iron for ASTM 60, Tensile strength 62.5 Kpsi Compressive strength 187.5 Kpsi Shear modulus of rupture 88.5 Kpsi Modulus of elasticity ( Tension ) 20.4 - 23.5 Mpsi Modulus of elasticity ( Torsion ) 7.8 - 8.5 Mpsi Endurance Limit 24.5 Kpsi Brinerll Hardness 302 H_b Specific heat 447 j/kg deg Ref: http://www.engineershandbook.com Characteristics of Grey cast iron: Wear resistance: Grey cast iron works as excellent resistance to sliding friction wear, it is widely used for manufacturing of sliding components, most of the automobile components are made up of this item, its all because of the low coefficient of friction, resistance to the galling it has which is due to the effect of graphite flakes . This will help the disc rotor to withstand for high friction forces. Thermal conductivity: The important merit of grey cast iron is its high thermal conductivity, due to its flake graphite structure, heat dissipates occurs in material with good rate. This will increase the cooling of the disc rotor Machinability: Due to the ferrite graphite structure, grey cast iron is simplest and easiest alloys for machining and casting. This will make easy to get the typical designs of the disc rotor with spiral and fins Damping capacity: Grey cast iron has high ability to absorb vibration energy and also damping vibrations, which is due to the high percentage of the graphite flakes it has in it. It also has great property to resist high frequency vibrations. This will help disc rotor Aluminium Alloys: Aluminium is the important alloy of aluminium alloys, were the other metals are copper, silicon and magnesium. It has less tensile strength and low melting pointing. It has good casting characteristics due to its great levels of silicon (4-13%) in it. It is widely used as disc rotor due to its corrosion resistance.   But this is quite expensive when compared with cast iron. Though is in light in weight, has good electrical and thermal conductivity. It does also can be recyclable. All these properties brought a change in many industries to change their traditional materials i.e., aluminium alloys. Characteristics of aluminium alloys: Light weight: The best part of this material is its light in weight, actually its one third of steel in weight, due to its specific weight of 2.7 g/cm3. The more the energy consumed by aluminium the high will be the load capacity of the vehicle.   This will decrease the vibrations and also increases the brake efficiency due to its light weight. Properties of the aluminium alloys: Density 2600-2800 kg/m3 Melting point 660 deg Elastic modulus 70-79 Gpa Poisson's ratio 0.33 Tensile Strength 230-570 Mpa Yield Strength 215-505 Mpa Percent Elongation 10-25% Thermal expansion coefficient 20.4 -25.0 10-6 /k Thermal conductivity: its used in most of the high conductivity line like power transmission, it has twice of the copper in the properties, and its a good conductor of heat and electricity. This will increase the heat dissipation of the disc rotor. Ductility and recyclability: Due to the lower density and melting point, the material is considered as ductile, this will help to the complicated design, as we need in the disc rotor with spiral fins and groves for the air dissipation. Recyclability is also one great factor of aluminium as it consumes only 5% of the energy to melt it, and it doesnt affect its original quality of aluminium. Corrosion resistance: This is the main factor which made it to select for disc rotor manufacturing. It has a natural property of corrosion resistant as it surfaces form an oxide coating on it. While using as disc rotor further surface treatments like lacquering and anodising are done to increase its resistance towards corrosion. Major problems with Disc Brakes: The disc rotor of Disc Brakes is more exposed to the air, due to which there are very frequent chances of getting damaged. Usually this damage of disc rotor is explained in four common ways warping, cracking, rusting and scarring. Few a times the damage takes the disc into the unsafe area then the new disc is replaced with damaged ones. But sometimes using simple machining and other process this damages can be overcome. As scratches or damage on disc rotor can be removed by removing the thin layer on the disc on lathe machine if after that the thickness of the disc falls in the safe dimensions for the braking force. Warping: This is caused due to the excessive heat of the friction area of the disc rotor, due to excessive shorthand braking, uneven cooling of disc may also causes warping. If braking pads get into contact of disc excessively this will lead to warping after certain times, this warping is most commonly found in the racing cars as brakes are used very frequently due to speed and used at high gear times. There are few methods which can avoid the warping, braking at lower gear which will help to reduce the braking load on the brakes, and less heat is generated. The more the braking load, the more the heat generated and more the chances of improper cooling to take place. Changing the disc design with more fins can few times avoids warping. Improper installation of disc rotor may also leads to the warping as only the overwhelmed disc will come in contact with the brake pads. Cracking: This is found mainly in the drilled disc. Cracking occurs mostly around the edges and holes of the disc, due to the uneven expansion in severe environments. As the uneven expansion take place and the braking load varies every time the brake is applied which will lead to the cracking. And in several situations the disc will fail and no possible repair can be done. Even cracking can be overcome by maintaining proper the cooling of the disc and proper heat dissipation. If cracking is become severe then there might be a chance to replace the disc rotor. Rusting: This is found in the vehicle which are not used for period of time, the regular use keeps the friction area clean, but when not in use the friction area and slots get rusted and it reduces the braking power, due to which the strength of the disc also falls down and at this conditions disc should replace with new one. Scarring: Scarring occurs if something hard gets in contact with the disc while moving, which forms a hard spot on the disc, which reduces the braking power and weakens the brake. Generally this happens when the brake pad service life come to end and still its attached to the brake set-up then the steel support of the brake pad get in contact with the disc which creates a hard scratch. These scratches will form black slots when a vehicle come in use, and reduces the structure strength. This can be avoided by regular checking of brake pads checking life of the friction layer, machining the disc to remove the layer on surface of disc which removes the scratches. There are few phenomenal problems which has been a challenging task in braking department like brake squeal, brake judder and brake dust. These problems can be dangerous when they get on excessively. Change of design, material, brake assembly setup all these have been checked extensively to find out the perfect solution for these problems, this project is undertaken based on this problems. Lets discuss in detail about these problems and what are the methods being simplified to overcome it. Brake Squeal: squeal mean noise, this brake noise is a vehicle system problem due to the regularity and severity. The noise generated is mainly because of brake and suspension components together. This is not considered as the main problem to the vehicle were performance is the initial objective, but its not so proper for the road use. This noise is mainly between the pad and disc during the braking. But squeal can also be combination of disc, calliper and brake pads. To avoid squeal under the braking condition is not so possible, if we are assuming brake to absorb very high energy inputs. Actually this brake squeal came into account when front wheel drive and metallic brakes arrived. These metallic pads are harder than asbestos counterparts, and thus more squeal is observed if there are more irregularities and roughness on the rotor surface or if you found looseness between the pads and callipers. Few types of calliper designs are more noisier, if the pads of this callipers are not fitted so tightly and the calliper itself move around when brakes are applied. The more the brakes play the more are the chances of noise. Fixing the squeal problems in wrong way can lead to the squeal more worse. Brake squeal also occurs due to vibration of brake pads towards the disc rotor when vehicle is moving at low speed, this may not affect the braking performance much but will lead to the replacement of brake pads, this is very common problem which most of the vehicles are facing now.   Lot of methods are used to reduce the level of noise,   simple methods like having chamfers to the linings, applying grease between the pads and calliper, adding the brake shim between   the brake back plate and brake pads etc., these may help in some way to reduce the noise. Ref: http://www.aa1car.com/library/bsqueal.htm While using the methods to reduce the brake noise, have to assume the vehicle suspension system which acts more on the braking system, but at the end the squeal is avoided by trial and error method. Although we see an efficient improvement in understanding the actual reason for the brake squeal, it has been difficult to solve it. It was easily verified through the design and study to overcome the squeal, but it was different case practically. The failure was mainly caused because of the dynamic behaviour of the braking system and due to the gap between braking components. The easiest way was using high temperature Effects of Material on Braking Abilities Effects of Material on Braking Abilities Abstract: The most important utility in our lives as of today is automobiles, there is a lot of research and development is going in every section of the automobile field to give the safest possible vehicle to the world. One such is Brakes section; this is very important part in every vehicle, though we have most accurate and efficient brakes now-a-days, but they fail at the extreme conditions of heat , vibrations , high frequencies etc., this project is mainly concentrated on the aspects which are causing adverse affect to fail and create unusual   disturbances in the brakes. One such is brake squeal, an unwanted sound which is caused due to the vibration of the brake pads against the disc generating the high pitch noise. There are few other problems which leads into the high frequency problems, vibrations, tear in the brake disc etc. Here in this project a detailed study of disc brake is taken into account by considering with two different materials cast iron and aluminium alloy. The performance of brake is studies using normal stress analysis, vibration analysis and thermal analysis. The main problem of squeal can be due to the combination of vibration in brake set-up from callipers to the brake discs. And can also due to the uneven surfaces of the brake disc which causes due to the improper heat dissipation in the brake disc, all this problems are kept into consideration and this analysis are carried out for brake disc with two different materials as mentioned. A simple change in the design of brake disc has also been done for the maximum heat dissipation and this design also studied in this extreme conditions. And these two type brake disc are compared in all its possibly calculated attributes and the best one is concluded. Introduction: An automobile is a creation of history when they started and now it has become a crucial part of the world. Automobile is a wheeled motor vehicle used for transporting passengers, good etc. There has been a lot of improvement in the automotive field in all ways from the past few decades. The main aim of the automotive department is to provide safest vehicle from its design to the material used for each component. Every single thing is decided on basis of the effect of it on the human lives. The vehicles we use are very efficient when compared with older generation vehicles, the safety increases with the development and technology. But there are few problems which are yet to be solved. One such is about brakes, as we know BRAKES are the most important part in the every moving body, we have seen very drastic improvement in the methods of braking system. In olden days the brakes were handled by hand and now we have disc brakes and hydraulic brakes.   But the whole concept of brakes is working on same principle of kinetic energy is converted into heat energy. We find brakes very commonly used in cars, bikes, aeroplanes, automated machines etc. Brake is a device which decelerates the vehicle or machine by converting its kinetic energy into other form of energy, which will bring the vehicle down to the rest. We have disc brakes now which require very less amount of effort and time to stop the vehicle due to its accuracy and sensitivity; this are widely used in vehicles now-a-days. The drum brakes were used for very long time and we use even now, these were also very efficient brakes but due to the very common issues of changing the brake pads very often due to the short hand braking or improper usage, this has been replaced by disc or hydraulic in few machines. But we have found very common issues in disc brakes due to the brake rotor and brake pads. Due to the high friction while short braking we get unwanted noise brake squeal, though it doesnt have much effect on the performance of the vehicle, but it may fail the brake due to the tear o f brake disc or brake pads. A detailed study of each problem will be studied in further report taking disc brake system. History of Brakes: Invention of brake has started with the automated machines; brakes came into light mainly when the motorised wheeled vehicles came into existence. Brakes were not only used in the vehicles, these are used in other machines as brake lever to stop the motion rotor and so on. It has been an essential part of the moving systems. Brakes have developed a lot from first generation vehicles to present time. Early braking systems used steel rimmed wheels to stop the vehicle, which consists of curved wooden block designed to bear against the steel tire when operated by a single leverage system from the driver seat. But the brake shoe used was normal way of braking either in the horse drawn vehicle or steam locomotive. In 1895 Michelin Brothers move a step ahead to replace the steel rimmed wheels with the pneumatic rubber tire to come out with a new braking system as the brake shoes were no longer satisfactory.   A new method of braking system was required in those times as two early devices attempted to apply the friction force to the axle or to drum on axle or transmission shaft were not efficient as wanted. One method was use of wooden block inside a flexible contracting metal band which when pressed together would tighten the drum causing friction between the drum, which is connected to the wooden block and w heel, then the vehicle gets slow down. The other method was inner wheel or brake drum which will add an external contracting band to bear against the drum to bring the vehicle to rest. In 1899 Daimler started cable operated braking system; a cable was wound around a drum and attached to the chassis, so that when the cable is tightened when car was moving forward, the rotation of drum will increase the tightness and grip of cable, so that it will reduce the amount of force required to pull the cable-lever on the pedal to stop the moving vehicle. This brake system worked well but still the braking efficiency was less, the added efficiency called servo assistance is still an important factor in drum brakes even today. The external brake was vulnerable to the atmospheric conditions like weathering and to un-even roads which caused a rapid loss of efficiency and wear of the brake shoe lining and on few times automatic brake use to happen due to the drum expansion. To overcome all these problems an internal shoe brake was developed were the expanding the brake shoes were placed the inside the brake drum, mainly to protect from the dust and weather. Originally early brakes were operated by mechanically, i.e. the transformation by mechanical system was used to expand the brake shoes against drum by the drivers effort applied on the brake pedal. It works by pressing the brake pedal, which make cam to rotate by a lever connected to pedal, which forces the shoes to come on contact with the brake drum. And springs attached to both of the brake shoes to retain the original position when brakes are released. As the early brakes use to operate on lever supported cables and linkage system of fixed rods, equalising the same amount of brake pressure on the wheels has presented many problems , which were solved when hydraulic system was introduced, which used fluid to transfer the force applied to the brake pedal. In hydraulic braking system the set-up of cylinders and pipe lines forms a closed system which is filled with fluid. The pressure generated in master cylinder will transmit equal force to the each wheel cylinder and then equal pressure is applied to all brake shoes. This hydraulic system is used with the disc brake as well. Disc brake is more efficient braking system which was used mostly sports car when introduced but now it has been a very common system in passenger vehicles. It has a disc and a calliper is attached to it which can be operated mechanically, hydraulically, pneumatically, electromagnetically. Types of brakes: The brakes are broadly explained as using friction, pumping or electromagnetism. But one brake system can also use more than one principle. As the project is based on the disc brake we will look forward only to discuss about the frictional brake. Frictional brakes: These types of brakes are mostly rotating devices with a stationary pad attached with a rotating surface. These types of brakes are widely used even now in modern automotive braking system. Basically this are developed from band brakes to drum brakes then to the disc brakes. Band brakes: A simple type of brake, works on a principle that a band is wrapped round the rotating drum. When a force is applied on the lever, the restraining torque is found from the difference in tension between the two ends of the belt. The principle of operation of the band brake is same as for belt drives. This is external type braking system, as we see in picture the brake shoe are mounted on the drum. Ref: http://school.mech.uwa.edu.au/~dwright/DANotes/brakes/intro/intro.html Drum shoe brakes: This type of brake usually mean the brake shoe is mounted to press the inside surface of the drum. Two brake shoes are connected with a calliper set-up; it has lining on it which will create a frictional force when pressed towards the moving surface of the vehicle. These types of drum brakes are still used in modern cars due to the some cost and engineering benefits. These are applied to the rear wheels of today cars. Ref: http://school.mech.uwa.edu.au/~dwright/DANotes/brakes/intro/intro.html Disc Brake: these most widely used brake of these days, A disc is mounted on the wheel or axle and brake pads are placed within the jaws of the calliper, this is give the necessary friction when it will grip on the brake disc. Ref: http://static.howstuffworks.com/gif/disc-brake3.jpg Characteristics of brakes: Brakes are described on basis of several characteristics as Peak force: The maximum force obtained to decelerate the vehicle is called peak force. Few times this can be more than the traction limit of tires, then the wheel gets skid Continuous Power dissipation: As we know that the brakes get hot in use and get fail when the temperature gets too high, the maximum amount of power that dissipates through the brake without failure is the continuous power dissipation. Fade: Due to the over heat of the brakes the surface of the brake pads or disc get fade which will cause decrease in the effectiveness of brakes. Few times even cooling will have big effect on to fade. Power: when a very less force leads to the braking force, which is higher than the other brakes in similar class then its stated as powerful brake, which is due to the sensitivity of the brake system. Durability: Friction brakes have the lining which has wear surfaces, these to be renewed periodically.   Like brake shoes, pads or brake disc. Even if wear surface due to brake shoe generates high peak force this will lead to wear quickly. Weight: In some circumstances brakes are often mounted on wheels, this can disturb the traction significantly. Here weight means brake itself or an additional support structure Noise: generally brakes create some minor noise when applied, but sometimes create a high pitch noise called squeal or grinding noise. Principles of braking system: Brakes work on simple principle to slow down the moving vehicle by applying an external force, it may use more than one component; directly or indirectly several components effect on the momentum of the moving vehicle. Various types of process are used for braking effect. Frictional brakes are most commonly used these days, these works on the simple mechanism of changing the kinetic energy into the heat energy, which is done by only factor friction. Friction is created when a stationary brake pad grips on the moving brake disc with a force applied. This type of braking system is also used in the disc brakes; the stationary brake pads rub on the disc rotor which moves relatively in its own axis. Basic laws of braking system: Braking system can be explained by two simple Newton laws; which will explain the whole concept of the braking system As we know that the Newtons second law The net force on an object is equal to the its mass times its acceleration and points in the direction of the acceleration F = m* a The law is used to find out the net force required by brake pads to bring the moving vehicle to rest, tough there are many other factors to be considered for calculation of brake force which will be discussed further. It can also be explained through Newton first law Every object remains at rest or in motion in a straight line at constant speed unless it is forced to change its state by an external force if we check this law, an external force (brake force) is required to change the state of the vehicle (motion to rest). As this law explained the evaluation of the brake force and system of braking, a further law explains how the brake force will stop the vehicle. Law of thermodynamics: Energy can neither be created nor be destroyed; it will be converted from one form of energy to other form. This explained the frictional force (brake force) is converted into the heat energy. Factors considered while Braking: There are many factors to be considered for the high braking efficiency and performance; here we will see the few important factors which have a more effect on braking efficiency. 1. Condition of disc rotor: An uneven disc or ruffed disc rotor will decrease the braking effect; it has to be very well maintained as few a times due to dust and weather a extra layer is formed on the disc surface which will have a negative effect on the braking concept. Or wear of disc rotor due to overheat. 2. Pressure on brake rotor: A sufficient amount of brake pressure is to be maintained to get enough frictional force to stop the vehicle. If less pressure is applied it will directly affect the brake efficiency as force acting on the two rubbing surface will become less. 3. Contact surface: The area of contact between the brake pads and disc rotor should be more then the high friction is obtained. If lining of brake pads or surface of disc rotor is uneven then area of contact will be less, which will affect the brake efficiency. 4. Tyres: The design of tyre also have a normal affect on the brake efficiency, the more the contact of tyre to the road surface the good will be the braking system. Worn tyres will have less braking action and will not allow vehicle to stop the required point and may also skid, braking action is found high in new tyres due to its more contact with the road surface. There are other factors which also play an crucial part in brake efficiency like aerodynamics, heat dissipation, weight of body etc., Causes of failure: The most commonly found causes for the brake failure are 1. Oil or grease on the brakes will cause failure as it interferes with the friction. If we found oil in brakes mean the oil seal has failed and is why oil is leaking. 2. Overheat of brakes to great degree, which will develop a hot spot on the rotor and drums. This spots will resist the friction from brake shoe and pads, therefore braking power is lost and brake fails. 3. Brake squeal which indicates the tear in the brake pads, by the time the brakes start making a grinding sound, they would have worn out past the pads to rotors. This will require to change more than just brake pads for new one, which will increase replacement cost as well. 4. Improper wheel alignment or disturbance in the steering system will also lead into the failure of brakes. Even if the mass of vehicle will get out of its range due to extra load will cause a brake failure due to the uneven load distribution. DISC BRAKE Introduction: Disc brakes came into existence in 1890s in England. But due to the poor state of roads and dusty conditions the disc and pads use to get rust and get wear, so the system got non-viable at that time. But later it was fully adopted in 1950s with new innovations in the previous design. Many companies started using it in their cars as it was better when to compared with drum brakes, the main reason as it has overcome the brake fade problem by providing the resistance to the brake components and overall performance is better when compared with drum brakes.   Disc brakes become popular in sports cars due to its braking performance. Now it has been common in commercial vehicles as well, as its used at front of the vehicles, as the front brakes perform most of the braking effort. Components: A disc brake assembly consists of a 1. Cast-iron disc (disc rotor) that rotates with the wheel. 2. Calliper assembly attached to the steering knuckle (operated mechanically or hydraulically). 3. Friction materials (disc pads) that are mounted to the calliper assembly. Operation: (Hydraulically powered) Disc brakes prove to be efficient when compared with drum brakes even the working principle is same for both systems. The basic principle of braking system The kinetic energy is converted into heat energy   When brake pedal is pressed, the hydraulic pressure is applied on the piston; it pushes the brake pad to get in contact with the disc. As the pressure increases the calliper pushes the outside pad to get in contact with the disc. Due the friction generated between pads and disc will create the braking force as the pads gets in contact fully with the disc rotor. But if we study the disc brakes widely, it shows that it does not use the much of the friction between the lining and rotor to increase the braking power as drum brakes does, they likely cause a pull between them. Disc brakes have constrained self-energizing action, there has to be sufficient hydraulic pressure to get the required braking force. The braking force can be increased by changing the size of calliper piston. Even less heat dissipation occurs as the friction surface is exposed to the air, which also reduces the braking fade.   Design of disc rotor: generally disc rotors are either solid or ventilated. The ventilated type disc rotor has cooling fins in the middle of the disc to ensure good cooling. Proper cooling ensures longer pad life and it also prevents fading. Some ventilated rotors have spiral fins which allow more air flow and better cooling. These fins are mounted on side of the vehicle and directional. Spiral fins are used in the front of the vehicles as front brakes take most of the braking action as more heat generates. Ref: https://pontiworld.com.au Design of calliper: The calliper are used as floating calliper or fixed calliper design, and these are mounted on the axle or attached to the wheel. Floating calliper type: The calliper are used as floating calliper or fixed calliper design, and these are mounted on the axle or attached to the wheel. this type of calliper requires less parts than the other type and its also less in weight and economical. Based on requirement it consists of one or two pistons. The piston is either side of the calliper. Hydraulic pressure from the main cylinder is generated and the piston thus press the brake pad towards the disc, then instantly an equal hydraulic pressure is generated at the other side and right brake pad pushed towards disc rotor and vehicle stops due to the braking force. Fixed calliper type: The calliper are used as floating calliper or fixed calliper design, and these are mounted on the axle or attached to the wheel. This type of calliper design has piston on both sides of the calliper, which provides the equal force to each brake pad. These fixed calliper types can set-up either one or two pistons on each side. The two pistons can generate a more braking force and a compact design, as these absorb and dissipate more heat, due to its size and weight. This design is capable for greater number of hard stops of short brakes without the effect of brake fade. Materials used for component: The material used for disc rotor plays an important role in braking force. The material should be tuff enough to stand on high pressures and high friction forces. Generally cast iron is used for disc rotor commercially, but ceramic discs are used for high-performance vehicles and heavy automobiles. Recent study shows that aluminium alloys also do a great job as disc. Now we will discuss in detail about the commonly used materials cast iron and aluminium alloys. Cast iron: Grey cast iron alloy is used for the manufacturing of disc rotor; it has superior properties and various advantages over other materials, as it best suitable for manufacturing and machining when compared with other materials which lead to the graphite lubricating the cut and breaking the chips. It contains 2.5%-4% of carbon and greater than 2% of silicon.   This material has good wear resistance and galling which leads to self lubricating due to the graphite flakes. The graphite microstructure of grey cast iron allows less shrinkage. The silicon percentage in the grey cast iron makes the material corrosion resistance and increases its fluidity when casting which also makes material easy to weld. Compared with other alloys of the cast iron, grey cast iron has low tensile strength , the good point about this material is the shock and impact resistance is almost doesnt exist. Here we will see the properties of the grey cast iron for ASTM 60, Tensile strength 62.5 Kpsi Compressive strength 187.5 Kpsi Shear modulus of rupture 88.5 Kpsi Modulus of elasticity ( Tension ) 20.4 - 23.5 Mpsi Modulus of elasticity ( Torsion ) 7.8 - 8.5 Mpsi Endurance Limit 24.5 Kpsi Brinerll Hardness 302 H_b Specific heat 447 j/kg deg Ref: http://www.engineershandbook.com Characteristics of Grey cast iron: Wear resistance: Grey cast iron works as excellent resistance to sliding friction wear, it is widely used for manufacturing of sliding components, most of the automobile components are made up of this item, its all because of the low coefficient of friction, resistance to the galling it has which is due to the effect of graphite flakes . This will help the disc rotor to withstand for high friction forces. Thermal conductivity: The important merit of grey cast iron is its high thermal conductivity, due to its flake graphite structure, heat dissipates occurs in material with good rate. This will increase the cooling of the disc rotor Machinability: Due to the ferrite graphite structure, grey cast iron is simplest and easiest alloys for machining and casting. This will make easy to get the typical designs of the disc rotor with spiral and fins Damping capacity: Grey cast iron has high ability to absorb vibration energy and also damping vibrations, which is due to the high percentage of the graphite flakes it has in it. It also has great property to resist high frequency vibrations. This will help disc rotor Aluminium Alloys: Aluminium is the important alloy of aluminium alloys, were the other metals are copper, silicon and magnesium. It has less tensile strength and low melting pointing. It has good casting characteristics due to its great levels of silicon (4-13%) in it. It is widely used as disc rotor due to its corrosion resistance.   But this is quite expensive when compared with cast iron. Though is in light in weight, has good electrical and thermal conductivity. It does also can be recyclable. All these properties brought a change in many industries to change their traditional materials i.e., aluminium alloys. Characteristics of aluminium alloys: Light weight: The best part of this material is its light in weight, actually its one third of steel in weight, due to its specific weight of 2.7 g/cm3. The more the energy consumed by aluminium the high will be the load capacity of the vehicle.   This will decrease the vibrations and also increases the brake efficiency due to its light weight. Properties of the aluminium alloys: Density 2600-2800 kg/m3 Melting point 660 deg Elastic modulus 70-79 Gpa Poisson's ratio 0.33 Tensile Strength 230-570 Mpa Yield Strength 215-505 Mpa Percent Elongation 10-25% Thermal expansion coefficient 20.4 -25.0 10-6 /k Thermal conductivity: its used in most of the high conductivity line like power transmission, it has twice of the copper in the properties, and its a good conductor of heat and electricity. This will increase the heat dissipation of the disc rotor. Ductility and recyclability: Due to the lower density and melting point, the material is considered as ductile, this will help to the complicated design, as we need in the disc rotor with spiral fins and groves for the air dissipation. Recyclability is also one great factor of aluminium as it consumes only 5% of the energy to melt it, and it doesnt affect its original quality of aluminium. Corrosion resistance: This is the main factor which made it to select for disc rotor manufacturing. It has a natural property of corrosion resistant as it surfaces form an oxide coating on it. While using as disc rotor further surface treatments like lacquering and anodising are done to increase its resistance towards corrosion. Major problems with Disc Brakes: The disc rotor of Disc Brakes is more exposed to the air, due to which there are very frequent chances of getting damaged. Usually this damage of disc rotor is explained in four common ways warping, cracking, rusting and scarring. Few a times the damage takes the disc into the unsafe area then the new disc is replaced with damaged ones. But sometimes using simple machining and other process this damages can be overcome. As scratches or damage on disc rotor can be removed by removing the thin layer on the disc on lathe machine if after that the thickness of the disc falls in the safe dimensions for the braking force. Warping: This is caused due to the excessive heat of the friction area of the disc rotor, due to excessive shorthand braking, uneven cooling of disc may also causes warping. If braking pads get into contact of disc excessively this will lead to warping after certain times, this warping is most commonly found in the racing cars as brakes are used very frequently due to speed and used at high gear times. There are few methods which can avoid the warping, braking at lower gear which will help to reduce the braking load on the brakes, and less heat is generated. The more the braking load, the more the heat generated and more the chances of improper cooling to take place. Changing the disc design with more fins can few times avoids warping. Improper installation of disc rotor may also leads to the warping as only the overwhelmed disc will come in contact with the brake pads. Cracking: This is found mainly in the drilled disc. Cracking occurs mostly around the edges and holes of the disc, due to the uneven expansion in severe environments. As the uneven expansion take place and the braking load varies every time the brake is applied which will lead to the cracking. And in several situations the disc will fail and no possible repair can be done. Even cracking can be overcome by maintaining proper the cooling of the disc and proper heat dissipation. If cracking is become severe then there might be a chance to replace the disc rotor. Rusting: This is found in the vehicle which are not used for period of time, the regular use keeps the friction area clean, but when not in use the friction area and slots get rusted and it reduces the braking power, due to which the strength of the disc also falls down and at this conditions disc should replace with new one. Scarring: Scarring occurs if something hard gets in contact with the disc while moving, which forms a hard spot on the disc, which reduces the braking power and weakens the brake. Generally this happens when the brake pad service life come to end and still its attached to the brake set-up then the steel support of the brake pad get in contact with the disc which creates a hard scratch. These scratches will form black slots when a vehicle come in use, and reduces the structure strength. This can be avoided by regular checking of brake pads checking life of the friction layer, machining the disc to remove the layer on surface of disc which removes the scratches. There are few phenomenal problems which has been a challenging task in braking department like brake squeal, brake judder and brake dust. These problems can be dangerous when they get on excessively. Change of design, material, brake assembly setup all these have been checked extensively to find out the perfect solution for these problems, this project is undertaken based on this problems. Lets discuss in detail about these problems and what are the methods being simplified to overcome it. Brake Squeal: squeal mean noise, this brake noise is a vehicle system problem due to the regularity and severity. The noise generated is mainly because of brake and suspension components together. This is not considered as the main problem to the vehicle were performance is the initial objective, but its not so proper for the road use. This noise is mainly between the pad and disc during the braking. But squeal can also be combination of disc, calliper and brake pads. To avoid squeal under the braking condition is not so possible, if we are assuming brake to absorb very high energy inputs. Actually this brake squeal came into account when front wheel drive and metallic brakes arrived. These metallic pads are harder than asbestos counterparts, and thus more squeal is observed if there are more irregularities and roughness on the rotor surface or if you found looseness between the pads and callipers. Few types of calliper designs are more noisier, if the pads of this callipers are not fitted so tightly and the calliper itself move around when brakes are applied. The more the brakes play the more are the chances of noise. Fixing the squeal problems in wrong way can lead to the squeal more worse. Brake squeal also occurs due to vibration of brake pads towards the disc rotor when vehicle is moving at low speed, this may not affect the braking performance much but will lead to the replacement of brake pads, this is very common problem which most of the vehicles are facing now.   Lot of methods are used to reduce the level of noise,   simple methods like having chamfers to the linings, applying grease between the pads and calliper, adding the brake shim between   the brake back plate and brake pads etc., these may help in some way to reduce the noise. Ref: http://www.aa1car.com/library/bsqueal.htm While using the methods to reduce the brake noise, have to assume the vehicle suspension system which acts more on the braking system, but at the end the squeal is avoided by trial and error method. Although we see an efficient improvement in understanding the actual reason for the brake squeal, it has been difficult to solve it. It was easily verified through the design and study to overcome the squeal, but it was different case practically. The failure was mainly caused because of the dynamic behaviour of the braking system and due to the gap between braking components. The easiest way was using high temperature

We Must Regain Our Lost Civil Liberties Essay -- Privacy Act, Patriot

With our nation’s tragedy of September 11, 2001, arose a deeply shaken America, shocked by the extent of the cruelty. An act of terrorism of that magnitude had never been seen before in our country. Patriots quickly came together, supporting the president to pass legislation, known as the USA Patriot Act, to tackle internal and external threats to this nation. The debate ensued, focused on which types of surveillance technology should or shouldn't be allowed for arresting terrorists. However, the question remains as to how these devices are going to be used, and how personally are those who use them held accountable. The purpose of this paper is to confirm that the proposed monitoring and archiving of users’ information on social networking sites would represent yet another erosion of our civil liberties for only a minor gain to our national security. The USA Patriot Act or simply the Patriot Act sanctions the use of wiretaps, additional surveillance of technology, such as voice mail and e-mail, trap and trace devices, and demands for educational and business records. The Department of Justice justifies that such actions in criminal investigations, have been used for years. However, this action comes under intense scrutiny by critics such as the ACLU who maintain that the secrecy surrounding the use of such tools as well as lower criteria for attaining the authority to use them â€Å"represents a broad expansion of power without building in a necessary privacy protection† (The USA PATRIOT Act: Myth vs. Reality, n.d.). The Patriot Act was signed into law on October 26, 2001, 45 days after the terrorist attacks on September 11th. The debate over what the Patriot Act actually allows law enforcement officia... ...om http://www.guardian.co.uk/usa/story/0,12271,1669540,00.html National Security. (n.d.). American Civil Liberties Union. Retrieved from http://www.aclu.org/National-Security Presidential Powers, NSA Spying, and the War on Terrorism: Americans’ Attitudes on Recent Events – Overview. (2006). American Civil Liberties Union. Retrieved from http://www.aclu.org/safefree/nsaspying/24262res20060224.html The New York Times (2009, December 12). Twitter Tapping. [Editorial]. Retrieved from http://www.nytimes.com/2009/12/13/opinion/13sun2.html The USA Patriot Act. (2005). Retrieved from http://www.epic.org/privacy/terrorism/usapatriot The USA Patriot Act: Myth vs. Reality. (n.d.). Retrieved from http://www.justice.gov/archive/ll/subs/add_myths.htm

Personal Narrative: Why Trust is Important to Me Essay -- Trust Charac

Personal Narrative: Why Trust is Important to Me Trust can take on many meanings in today’s society. It can exist in all aspects of our lives, and can have a dramatic impact on one’s personality. Trust, as a noun, is an assured reliance on the character, strength, or truth of someone or something; or a property interest held by one person for the benefit of another. Trust, as a verb, is to permit to stay or go or to do something without fear or misgiving. Trust is very important to me. I, myself, have had numerous experiences with trust, many helpless and some hopeful. It has affected my life in every way. I must place my trust in my family, my friends, and most importantly, in myself. I deal with it every day of my life in the most unexpected of situations. Many a time, I can hold it accountable for my moods and emotions, and it can sometimes lead to arguments. I feel that trust is very powerful and significant because of its ability to alter a society in such a substantial way. Trust is never ending; being dealt with on a day-to-day basis of belief and confidence. Once your self-trust is gone, so is your soul. In the book Breath, Eyes, Memory by Edwidge Danticat, trust is a main theme in the book. Sophie and Martine are never trusted by their mothers, thus leading to the testing. A mother could not trust her daughter to keep her purity, so it was a mother’s responsibility to keep her whole. The effects were traumatizing, leading to nightmares. It also led to Sophie’s phobia of the night. When she was with her husband, the testing gave her such nightmares; she had to bite her tongue to do it again. She had no desire and thought it was an evil thing to do. The testing also made Sophie hate her body an... ... trust own mental strength. She didn’t have the confidence to stand up to her boyfriend for fear of a less than rewarding outcome. My experiences, Sophie’s, as well as this 19 year old’s are all relevant to each other since we all have given in to lies at one point in our lives for the mere short-lived happiness they bring. Trust can shape one’s identity dramatically. People who are trusted tend to be more self-confident and outgoing. Those who are not trusted tend to not believe in themselves, do not speak up as much, and tend to excel at lies. Depending on your trustworthiness, you can also be judged on other aspects of your personality. It can tell a lot about your personal life as well. Trust accounts for a vast part of one’s actions and decisions. Trust has come to play an important role in today’s society and it will forever take its toll upon us.

Essay --

The Life of Mother Teresa India is a country of great poverty. The poor of India wanted help but no one seemed to listen to their cries. About 29.8% of the people of India live below the national poverty line in 2010. One person has changed the way people act today. Even now people still strive to do what she did. Mother Teresa is one of the people who shaped the world. Mother Teresa was brought into the the world on August 26, 1910. Mother Teresa was baptized the day after she was born which is August 27 1910. Her nickname was gonkha which means little bud or flower bud. Agnes Gonxha bojaxhiyIs was Mother Teresa’s real name. Mother Teresa was born in Skopje Macedonia. Skopje is the capital of the republic of Macedonia. Skopje is also the largest city in the republic of Macedonia. Skopje is a humid subtropical climate.In Skopje 10% of the population is Catholic Mother Teresa attended a public school as well as a private school. Later in life she attended a medical mission sisters school. Mother Teresa played mandolin as a young child and she also song with her sister in her church’s choir. Mother Teresa’s biggest hobby was to carry out the will of God. Mother Teresa grew up in a generous family and the family was extremely involved in the church. When mother Teresa was a child she would bring food and medicine to people who needed it. She saw that as a religious duty. When she was eight her father passed away and mother Teresa became close to her mother. When she was on a trip to the chapel of the Madonna of Lentince on a black mountain was when she felt her first calling from God. â€Å"I want Indian Nuns, Missionaries of charity, who would be my fire of love amongst the poor, the sick, the dying, and the little children† sh... ...st mother Teresa. They thought they weren’t sanitary and didn’t have good medical training to care for the poor people. Also people said the only reson people thought she helped people was because she was converting people to christianity. In 1989 she had a herat attack which was followed by surgery and then she was hooked up to a machine to regulate her heartbeat. After a couple years of heart lung and kidney problems she died at age 87 on september 5 1997. Mother teresa is the Saint of Gutters Mother teresa has helped so many poor,unhealthy,homeless,healthy,wealthy, people. She has helped people by curing there sickness, telling us that we can change the world, and that if we just help one person it will make a difference. This paper talked about the life of mother teresa. Mother teresa had a unforgettable life. She had a life that we all would want to have.

War: Effect on the Economy

Shomoi Francis Mr. Joseph English 12 26 November 2012 War: Effect on Economy War has influenced economic history profoundly across time and space. Winners of wars have shaped economic institutions and trade patterns. Wars have influenced technological developments. Above all, recurring war has drained wealth, disrupted markets, and depressed economical growth. Wars are expensive (in money and other resources), destructive (of capital and human capital), and disruptive (of trade, resource availability, labor management). Large wars make up severe shocks to the economies of participating countries.Despite some positive aspects of short-term stimulation and long-term destruction and rebuilding, war generally impedes economic development and undermines wealth. Several specific economic effects of war recur across historical eras and locales. Next inflation, the most consistent short-term economic effect of war is to push up prices, and consequently to reduce living standards. This war-in duced inflation was described in ancient China by the strategist Sun Tzu: â€Å"Where the army is, prices are high; when prices raise the wealth of the people is exhausted† (Tzu Sun, c. 00 BCE) His advice was to keep wars short and have the money in hand before assembling an army. Paying for wars is a central problem for states (see War Finance). This was especially true in early modern Europe (fifteenth to eighteenth centuries), when war relied heavily on mercenary forces. The king of Spain was advised that waging war required three things – money, money, and more money. Spain and Portugal imported silver and gold from America to pay for armies, but in such large quantities that the value of these metals eventually eroded.One way governments pay for war is to raise taxes (which in turn reduces civilian spending and investment). U. S. revolutionary Thomas Paine warned in 1787 that â€Å"war †¦ has but one thing certain, and that is to increase taxes. † Anot her way to pay for war is to borrow money, which increases government debt, but war-related debts can drive states into bankruptcy as they did to Spain in 1557 and 1596. A third way to fund war is to print more currency, which fuels inflation. Inflation thus often acts as an indirect ax on a national economy to finance war. Industrial warfare, and especially the two World Wars, created inflationary pressures across large economies. Increasingly, governments mobilized entire societies for war – conscripting labor, bidding up prices in markets for natural resources and industrial goods, and diverting capital and technology from civilian to military applications. World War I caused ruinous inflation as participants broke from the gold standard and issued currency freely. Inflation also accompanied the U. S.Civil War, World War II, and the Vietnam War, among others. War-induced inflation, although strongest in war zones, extends to distant belligerents, such as the United States in the World Wars, and, in major wars, even to neutral countries, owing to trade disruption and scarcities. Present-day wars continue to fuel inflation and drive currencies towards worthlessness. In Angola's civil war (1975-2002), for example, the government currency became so useless that an alternative â€Å"hard† currency – bottles of beer – came to replace it in many daily transactions.In addition to draining money and resources from participants' economies, most wars create zones of intense destruction of capital such as farms, factories, and cities. These effects severely depress economic output. The famine and plague that accompanied the Thirty Years' War (1618-48) killed as much as one-third of Germany's population, as mercenaries plundered civilians and civilians became mercenaries to try to survive. World War I reduced French production by nearly half, starved hundreds of thousands of Germans to death, and led to more than a decade of lower Soviet outp ut.One estimate put World War I's total cost at $400 billion – five times the value of everything in France and Belgium at the time. Battle casualties, war-induced epidemics, and other demographic disruptions have far-reaching effects. World War I contributed to the 1918 influenza epidemic that killed millions. Military forces in East Africa may have sparked the outbreak of what became a global AIDS epidemic. Quincy Wright estimates that â€Å"at least 10 percent of deaths in modern civilization can be attributed directly or indirectly to war† (Wright, 1942).The U. S. â€Å"baby boom† after World War II continues decades later to shape economic policy debates ranging from school budgets to social security. Wars also temporarily shake up gender relations (among other demographic variables), as when men leave home and women take war jobs to replenish the labor force, as in the Soviet Union, Britain, and the United States during World War II. Countries that can fig ht wars beyond their borders avoid the most costly destruction (though not the other costs of war).For example, the Dutch towards the end of the Thirty Years' War, the British during the Napoleonic Wars, the Japanese in World War I, and the Americans in both World Wars enjoyed this relative insulation from war's destruction, which meanwhile weakened their economic rivals. Also, just as wars' costs and outcomes affect economic conditions and evolution, so too do economic conditions and evolution affect war. Causality runs in both directions. For example, Dutch economic strengths in the early 17th century allowed fast and cheap production of ships, including warships.The resulting naval military advantage in turn supported Dutch long-distance trade. The wealth derived from that trade, in turn, let the Netherlands pay and train a professional standing army, which successfully sheltered the Netherlands from the ruinous Thirty Years' War. This protection in turn let the Dutch expand thei r share of world trade at the expense of war-scarred rivals. Thus the evolutions of warfare and of world economic history are intertwined. War is the proximal cause of the recurring inflationary spikes that demarcate 50-year â€Å"Kondratieff waves† in the world economy.Those waves themselves continue to be controversial. However, they may have some predictive value to the extent they clarify the historical relationships between war and military spending on the one hand, and inflation and economic growth on the other. The 1990s mainly followed a predicted long-wave phase of sustained low inflation, renewed growth, and reduced great-power military conflict. If this pattern were to continue, the coming decade would see continued strong growth but new upward pressures on military spending and conflict, eventually leading to a new bout of inflation in the great-power economies.Since scholars do not agree on the mechanism or even the existence of long economic waves, however, such projections are of more academic than practical interest. The relationship between military spending and economic growth has also generated controversy. Despite its pump-priming potential in specific circumstances, as during the 1930s, military spending generally acts to slow economic growth, since it diverts capital and labor from more productive investment (such as in roads, schools, or basic research). During the Cold War, high ilitary spending contributed (among other causes) to the economic stagnation of the Soviet Union and the collapse of North Korea, whereas low military spending relative to GDP contributed to Japan's growth and innovation. During the 1990s, as real military spending worldwide fell by about one-third, the United States and others reaped a â€Å"peace dividend† in sustained expansion. However, effects of military spending are long-term, and sharp reductions do not bring quick relief, as Russia's experience since 1991 demonstrates. The global North-Sou th divide – a stark feature of the world economy – is exacerbated by war.The dozens of wars currently in progress worldwide form an arc from the Andes through Africa to the Middle East and Caucasus, to South and Southeast Asia. In some of the world's poorest countries, such as Sudan and Afghanistan, endemic warfare impedes economic development and produces grinding poverty, which in turn intensifies conflicts and fuels warfare. To conclude, you have read about the good and bad things of war effects on the economy. War has drained wealth, disrupted markets, and depressed economical growth. But, the winners of these wars often were rewarded from these wars.War is bad overall; I feel that war should be the last option for any country. Works Cited Washigntonsblog. â€Å"Proof that war is bad for the economy. † 24 Feb. 2012. < http://www. washingtonsblog. com/2012/02/debunking-the-myth-that-war-is-good-for-the-economy-once-and-for-all. html>. Symonds, Peter. â€Å"U S wages over war†. 7 Oct. 2012. < http://www. globalresearch. ca/us-wages-economic-war-on-iran/5307485. > < http://www. joshuagoldstein. com/jgeconhi. htm. >

Lab Report on TLC analisys of Analgestic Drugs Essay

In this experiment, thin-layer chromatography (TLC) was used to determine the composition of various over-the-counter (OTC) analgesics: Anacin, Bufferin, Excedrin, and Tylenol. The TLC plates were first viewed under ultraviolet (UV) light and then treated with iodine vapor in order to visualize the spotting. Experiment Scheme Initially, sixteen capillary micropipets were created in order to spot the TLC plates. Two TLC plates were then obtained and marked with pencil for spotting. A line was drawn 1 cm from the bottom of each plate, and five small, evenly spaced marks were made along those lines (see Figure 1). Each mark indicated where a substance would be spotted. All compounds used were in solutions of 1g of each dissolved in 20 ml of a 50:50 mixture of methylene chloride and ethanol. The first plate made was the reference plate. Capillary micropipets were used to spot the first four marks with acetaminophen, aspirin, caffeine, and salicylamide (in that order). (See figures 2-5 for chemical structures.) The last mark was spotted with a reference solution of all four chemicals. The second plate made was the sample plate. The first four marks were spotted with Anacin, Bufferin, Excedrin, and Tylenol. The fifth mark was spotted with a reference solution of all four drugs. Figure 1. Prepared TLC plates Figure 2. AcetaminophenFigure 3. Aspirin Figure 4. CaffeineFigure 5. Salicylamide A development container was created with a wide-mouthed screwcap jar. It was filled with the development solvent, which was .5% glacial acetic acid in ethyl acetate, so that the solvent was approximately . 5 cm deep.The first TLC plate was then carefully placed into the development container. Great care was taken to ensure that the plate went in evenly so that the solvent could rise evenly up the plate. Once the solvent front had reached approximately 1cm from the top of the plate, the plate was removed, the solvent front was marked with a pencil, and the plate was allowed to dry. The second plate was then placed in the development chamber in the same manner as the first. Once the solvent front reached approximately 1cm from the top of the plate, the plate was removed, the solvent front was marked with a pencil, and the plate was allowed to dry. Each plate was then viewed under the UV light. Any spots that were seen were lightly circled with a pencil, and their color was noted. The orders of elution (Rf values) were calculated by dividing the distance from the baseline to the center of the spot by the distance from the baseline to the solvent front. After all observations and calculations were made, the plates were placed in a jar containing iodine. The jar was warmed with hands so that the iodine vaporized. The plates were then removed from the jar and observed. The reference and sample plates were then compared to determine which compounds the drugs on the sample plate contained. Data