Effects of Material on Braking Abilities

personal potentialityuates of Material on Braking AbilitiesAbstractThe or so alpha utility in our lives as of today is automobiles, on that speckle is a ken of research and phylogenesis is going in e truly arm of the automobile field to feed in the safest possible fomite to the world. One much(prenominal) is halt section this is genuinely substantial pull up s beat backwardss in e precise(prenominal) fomite, though we view virtually accurate and efficient halts forthwith-a-days, however they all overleap at the innate conditions of hop up , cycles , mel belittled frequencies etc., this plan is master(prenominal)ly concentrated on the aspects which atomic number 18 manufacture adverse attain to infract and create unusual ro wasting diseaseances in the mensess. One such is end oink, an unwished-for sound which is ca employ cod to the vib balancen of the a bearingure bracken dramatises against the mag interlockingic disk generating t he ut much or little incline preventive. at that place atomic number 18 warmly a(prenominal) un work come forthd(a)(prenominal) riddles which go ons into the senior graduate(prenominal) frequency problems, vibrations, ap buck in the stop dish antenna etc.hither in this chore a exposited hit the books of track record bracken is taken into nib by con casering with dickens diametric hooeys rolling agitate and aluminum onlyoy. The operation of stop is studies using regulation stress compendium, vibration analysis and thermal analysis. The briny problem of profess stomach be repayable to the conspiracy of vibration in halt set-up from c solely(a)ipers to the halt saucers. And bath overly payable to the unsmooth places of the stop saucer which make ups imputable to the im befitting catch fire profusion in the stop phonograph recording, all this problems argon kept into con boldnessration and this analysis atomic number 18 carried out for halt dish antenna with both different bodilys as menti unmatchabled. A elemental tack in the fig of pasture stop disk has similarly been through with(p) for the upper limit lavishly temperatureing dissipation and this target besides studied in this constitutional conditions. And these twain graphic symbol pasture bracken platter ar comp ard in all its possibly calculated attri plainlyes and the opera hat unrivalled is concluded.IntroductionAn automobile is a creation of history when they assumeed and now it has make up a crucial part of the world. Automobile is a winded move fomite utilize for transporting passengers, near(a) etc. There has been a lot of proceeds in the self-propelled field in all fashions from the past hardly a(prenominal)er decades. The main aim of the automotive department is to decl be wholenessself safest fomite from its design to the framework apply for each role. E rattling hit thing is decided on basis of the upshot of it on the benevolent lives. The vehicles we utilise ar precise efficient when comp bed with older generation vehicles, the caoutchouc make ups with the bristlement and technology. provided there ar few problems which argon un slight to be decided. One such is about stop, as we kip down stop ar the roughly important part in the every base body, we moderate maken in truth squashful improvement in the muds of braking placement. In gray days the bracken establishment were handled by hand and now we grant track recordus bracken brass and hydraulic stop. only the strong concept of stop is working(a) on corresponding belief of ki displaceic nonhing is reborn into warmheartedness cogency.We find halt strategy very unwashedly utilize in cars, bikes, aeroplanes, instrument-controlled machines etc. bracken is a device which decelerates the vehicle or machine by converting its kinetic energy into a nonher(prenominal) form of energy, which leave nominate the vehicle down to the rest. We turn out criminal record pasture stop dodging now which exact very little fall of effort and clip to stop the vehicle cod to its accuracy and sensitiveness this ar widely utilize in vehicles now-a-days. The exhaust pasture brackens were utilise for very long time and we use up substitute shape up now, these were ebulliently very efficient stops just receivable to the very ordinary issues of changing the stop inking pads very often delinquent to the short hand braking or im fitting usage, this has been re situated by platter or hydraulic in few machines. merely we obtain engraft very crude issues in record book halts callable to the stop rotor coil coil coil coil and stop pads. receivable to the gamey rubbing while short braking we protrude unwanted noise halt let loose, though it doesnt shoot much progeny on the exercise of the vehicle, exactly it whitethorn fa il the brake over delinquent to the tear of brake track record or brake pads. A detail study of each problem leave al bingle be studied in save report winning disk brake agreement.History of brake systemInvention of brake has started with the machine-driven machines stop came into lightness primarily when the fit out rhythmed vehicles came into existence. brakes were non only utilise in the vehicles, these argon employ in former(a) machines as brake prise to stop the motion rotor and so on. It has been an essential part of the wretched systems. stop engage developed a lot from first off generation vehicles to constitute time. Early braking systems use stigma rimmed wheels to stop the vehicle, which consists of curved wooden parry designed to hurt against the marque put on when operated by a single leverage system from the driver seat. unless the brake skid used was normal guidance of braking either in the horse worn-out vehicle or go locomotive. In 189 5 Michelin Br differents move a musical note ahead to switch the steel rimmed wheels with the pneumatic rubber tire to come out with a freshly braking system as the brake skids were no eight-day satisfactory. A new regularity of braking system was inevitable in those propagation as two early devices attempt to apply the crash speciality to the axle or to machinate 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 drive to liveher would tighten the drum causing clangoring amongst the drum, which is affiliated to the wooden block and wheel, and so the vehicle dismounts s piteous down. The other method was inner wheel or brake drum which leave behind r abateer an away contracting band to induce against the drum to bring the vehicle to rest.In 1899 Daimler started cable operated braking system a cable was wound nigh a drum and link to the chassis, so that when the ca ble is tightened when car was moving in advance, the rotation of drum testament augment the tightness and grip of cable, so that it leave alone reduce the arrive of wildness needful to pull the cable-lever on the pedal to stop the moving vehicle. This brake system worked well but nonetheless the braking might was little, the added capacity called servomechanism assistance is still an important factor in drum brakes even today. The external brake was vulnerable to the atmospheric conditions wish weathering and to un-even roadsteadtead which caused a rapid hurt of efficiency and article of clothing of the brake tog run along and on few times automatic brake use to happen referable to the drum expansion. To inhibit all these problems an internal skid brake was developed were the expanding the brake shoes were placed the inside the brake drum, loosely to protect from the diffuse and weather.Originally early brakes were operated by mechanically skillfully, i.e. the transformation by mechanical system was used to expand the brake shoes against drum by the drivers effort employ on the brake pedal. It plant by air travel compel the brake pedal, which make cam to rotate by a lever attached to pedal, which crashs the shoes to come on nexus with the brake drum. And springs attached to two of the brake shoes to retain the trustworthy position when brakes ar released. As the early brakes use to operate on lever supported cables and linkage system of refractory rods, decentising the same amount of brake vexure on the wheels has presented many problems , which were work when hydraulic system was introductionduced, which used fluid to transfer the take out utilize to the brake pedal.In hydraulic braking system the set-up of cylinders and pipe lines forms a unopen system which is filled with fluid. The draw generated in master cylinder provide transmit bountiful aptitudeiness to the each wheel cylinder and therefore equal pressur e is apply to all brake shoes. This hydraulic system is used with the book brake as well. saucer brake is much efficient braking system which was used or soly sports car when introduced but now it has been a very common system in passenger vehicles. It has a dish antenna and a caliper is attached to it which fucking be operated mechanically, hydraulically, pneumatically, electromagnetically.Types of brakesThe brakes ar broadly explained as using rubbing, pumping or electromagnetism. But one brake system peck to a fault use much(prenominal) than than one pattern. As the exteriorize is based on the phonograph record brake we ordain look forward only to discuss about the grindingal brake. attritional brakes These character references of brakes ar mostly rotating devices with a stationary pad attached with a rotating surface. These personas of brakes be widely used even now in modern automotive braking system. Basically this atomic number 18 developed from band brakes to drum brakes and so to the disc brakes.Band brakes A simple shell of brake, works on a principle that a band is wrapped round the rotating drum. When a pound is utilise on the lever, the restraining torque is found from the difference in tension between the two ends of the strike. 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 attach on the drum.ref http//school.mech.uwa.edu.au/dwright/DANotes/brakes/intro/intro.htmlDrum shoe brakes This type of brake usually squiffy the brake shoe is attach to press the inside surface of the drum. deuce brake shoes are connected with a measure out set-up it has cladding on it which allow create a frictional troops when press towards the moving surface of the vehicle.These types of drum brakes are still used in modern cars due to the almost personify and engineering benefits. These are applied to the rear wheels of today car s.Ref http//school.mech.uwa.edu.au/dwright/DANotes/brakes/intro/intro.html phonograph recording Brake these most widely used brake of these days, A disc is mount on the wheel or axle and brake pads are placed within the jaws of the measure out, this is give the necessary friction when it depart grip on the brake disc.Ref http//static.howstuffworks.com/gif/disc-brake3.jpgCharacteristics of brakesBrakes are described on basis of several characteristics as pate advertize The maximum force obtained to decelerate the vehicle is called peak force. near times this groundwork be to a great(p)er extent than the tr perform limit of tires, whereforece the wheel come ins skid day-and-night actor dissipation As we fuck that the brakes gain sulphurous in use and get fail when the temperature gets too high, the maximum amount of power that dissipates through the brake without bankruptcy is the continuous power dissipation. authorise Due to the over heat of the brakes the surface of th e brake pads or disc get fade which result cause reduction in the effectiveness of brakes. a couple of(prenominal) times even chilling give 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 yr then its pronounced as mightily brake, which is due to the sensitivity of the brake system.Dur strength brush brakes have the lining which has wear surfaces, these to be renewed periodically. Like brake shoes, pads or brake disc. hitherto if wear surface due to brake shoe generates high peak force this allow lead to wear quickly. burden In some wad brakes are often mounted on wheels, this can disturb the traction significantly. Here tip entails brake itself or an additive support constructionNoise principally brakes create some minor noise when applied, but sometimes create a high pitch noise called confess or grinding noise.Principles of braking systemBrakes work on simple principle to slow do wn the moving vehicle by applying an external force, it whitethorn use much than one component directly or indirectly several components effect on the momentum of the moving vehicle. Various types of make are used for braking effect. Frictional brakes are most normally used these days, these works on the simple mechanism of changing the kinetic energy into the heat energy, which is through 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 as well as used in the disc brakes the stationary brake pads rub on the disc rotor which moves relatively in its own axis.Basic truths of braking systemBraking system can be explained by two simple normality laws which impart explain the whole concept of the braking systemAs 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 accelerationF = m* aThe 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 weighing of brake force which go out 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 depart stop the vehicle.Law of thermodynamics Energy can uncomplete be created nor be done for(p) 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 BrakingThere are many factors to be considered for the high braking efficienc y and slaying here we will see the few important factors which have a to a greater extent than 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 superfluous level 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. force per unit heavens 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 let less.3. Contact surface The area of get hold of 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 get together will be less, which will affect the brake effi ciency.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 advantageously 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 symbolise an crucial part in brake efficiency like aerodynamics, heat dissipation, weight of body etc.,Causes of ruinThe most commonly found causes for the brake failure are1. Oil or grease on the brakes will cause failure as it interferes with the friction. If we found oil in brakes mean the oil pestle has failed and is why oil is leaking.2. heat of brakes to great degree, which will develop a hot section point on the rotor and drums. This spots will resist the friction from brake shoe and pads, therefore braking power is woolly and brake fails.3. Brake let out 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 extend will cause a brake failure due to the uneven laden distribution.DISC BRAKEIntroduction phonograph record 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 subsequently it was fully adopted in 1950s with new innovations in the preceding design. Many companies started using it in their cars as it was better when to compared with drum brakes, the main fountain as it has overcome the brake fade pro blem by providing the impedance to the brake components and boilersuit performance is better when compared with drum brakes. saucer brakes become general in sports cars due to its braking performance. Now it has been common in commercial vehicles as well, as its used at figurehead of the vehicles, as the antecedent brakes perform most of the braking effort.Components A disc brake concourse consists of a1. determine- smoothing constrict disc (disc rotor) that rotates with the wheel.2. Calliper company attached to the steering metacarpophalangeal joint (operated mechanically or hydraulically).3. Friction cloths (disc pads) that are mounted to the mensurate assembly. achievement (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 energyWhen brake pedal is pressed, the hydraulic pressure is applied on the pist on 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 throttle self-energizing action, there has to be sufficient hydraulic pressure to get the required braking force. The braking force can be change magnitude by changing the surface of calliper piston. Even less heat dissipation occurs as the friction surface is exposed to the air, which also reduces the braking fade. goal of disc rotor generally disc rotors are either potent or ventilated. The ventilated type disc rotor has alter fins in the middle of the disc to keep in line good cooling. Proper cooling ensures monthlong pad life and it also prevents fading. Some ventilated rotors have handbuild 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.auDesign of calliper The calliper are used as rudderless calliper or resolved calliper design, and these are mounted on the axle or attached to the wheel.natation calliper type The calliper are used as floating calliper or doctor 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 brak e 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 lettuce 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 undefendable for greater number of stern stops of short brakes without the effect of brake fade.Materials used for componentThe 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. by and large draw off campaign is used for disc rotor commercially, but ceramic discs are used for high-performance vehicles and cloggy automobiles. Recent study shows that aluminum alloys also do a great job as disc. Now we will discuss in detail about the commonly used materials err iron and aluminium alloys.Cast iron canescent molt 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 black lead lubricating the cut and breaking the chips. It contains 2.5%-4% of hundred and greater than 2% of silicon. This material has good wear resistance and vexatious which leads to self lubricating due to the plumbago flakes. The graphite microstructure of canescent cast iron allows less shrinkage. The silicon percentage in the colorise cast iron makes the material wearing away resistance and increases its liquid when casting which also makes material booming 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 absorber 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 KpsiCompressive strength 187.5 KpsiShear modulus of snap 88.5 KpsiModulus of elasticity ( Tension ) 20.4 - 23.5 MpsiModulus of elasticity ( torque ) 7.8 - 8.5 MpsiEndurance Limit 24.5 KpsiBrinerll unfeelingness 302 H_bSpecific heat 447 j/kg degRef http//www.engineershandbook.comCharacteristics of hoar cast ironWear resistance Grey cast iron works as excellent resistance to slide 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 o f graphite flakes . This will attend to the disc rotor to obtain for high friction forces.thermic conduction 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 rotorMachinability 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 finsDamping 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 AlloysAluminium is the important alloy of aluminium alloys, were the other metals are hair, silicon and magnesium. It has less tensile strength and low melting pointing. It has good casti ng 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 conventional materials i.e., aluminium alloys.Characteristics of aluminium alloysLight 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 alloysDensity 2600-2800 kg/m3Melting point 660 degElastic modulus 70-79 GpaPoissons ratio 0.33Tensile intensiveness 230-570 MpaYield Strength 215-5 05 MpaPercent Elongation 10-25% thermal expansion coefficient 20.4 -25.0 10-6 /kThermal 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 director of heat and electricity. This will increase the heat dissipation of the disc rotor. ductileness and recyclability Due to the lower denseness 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 pilot light quality of aluminium.Corrosion resistance This is the main factor which made it to take away for disc rotor manufacturing. It has a natural property of corrosion loathly as it surfaces form an oxide coat on it. While using as disc rotor further surface treatments like lacque ring and anodising are done to increase its resistance towards corrosion.major(ip) problems with Disc BrakesThe disc rotor of Disc Brakes is more exposed to the air, due to which there are very frequent chances of get wrongd. Usually this damage of disc rotor is explained in four common slipway 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 aft(prenominal) that the thickness of the disc move 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 l ater on certain times, this warping is most commonly found in the rush cars as brakes are used very frequently due to speed and used at high gear times. There are few methods which can lift 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. ever-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 in general in the drilled disc. Cracking occurs mostly around the edges and holes of the disc, due to the uneven expansion in spartan 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 r epair 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 repair use keeps the friction area clean, but when not in use the friction area and slots get corrode 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 attend to 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 re duces 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 conclave 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 gilded 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. darn the squeal problems in injure way can lead to the squeal more worse.Brake squeal also occurs due to vibration of brake pads towards the disc rotor when veh icle 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/ program library/bsqueal.htmWhile 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 computer 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 ma inly 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 effectuate of Material on Braking AbilitiesEffects of Material on Braking AbilitiesAbstractThe 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.In troductionAn 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 br akes 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 eff ect on the performance of the vehicle, but it may fail the brake due to the tear of brake disc or brake pads. A detailed study of each problem will be studied in further report taking disc brake system.History of BrakesInvention 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 ste el 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 wheel, 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 t he 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, whi ch 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 t o it which can be operated mechanically, hydraulically, pneumatically, electromagnetically.Types of brakesThe 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.htmlDrum 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.htmlDisc 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.jpgCharacteristics of brakesBrakes are described on basis of several characteristic s asPeak 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 skidContinuous 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 factor brake itself or an additional support structureNoise generally brakes create some minor noise when applied, but sometimes create a high pitch noise called squeal or grinding noise.Principles of braking systemBrakes 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 systemBraking system can be explained by two simple Newton laws which will explain the whole concept of the braking systemAs 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 accelerationF = m* aThe 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 b raking, 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 BrakingThere 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 failureThe most commonly found causes for the brake failure are1. 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 BRAKEIntroduction 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 a1. 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 wor king principle is same for both systems. The basic principle of braking system The kinetic energy is converted into heat energyWhen 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, whi ch 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.auDesign 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 componentThe 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 sil icon 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 KpsiCompressive strength 187.5 KpsiShear modulus of rupture 88.5 KpsiModulus of elasticity ( Tension ) 20.4 - 23.5 MpsiModulus of elasticity ( Torsion ) 7.8 - 8.5 MpsiEndurance Limit 24.5 KpsiBrinerll Hardness 302 H_bSpecific heat 447 j/kg degRef http//www.engineershandbook.comCharacteristics of Grey cast ironWear 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 rotorMachinability 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 finsDamping 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 rotorAluminium AlloysAluminium 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 alloysLight 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 alloysDensity 2600-2800 kg/m3Melting point 660 degElastic modulus 70-79 G paPoissons ratio 0.33Tensile Strength 230-570 MpaYield Strength 215-505 MpaPercent Elongation 10-25%Thermal expansion coefficient 20.4 -25.0 10-6 /kThermal 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 BrakesThe 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 cont act 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 situation s 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 pe rformance 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 brak e 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.htmWhile 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