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Finite Element Analysis of Disk brake assembly.

The standard disc brake of a 4-wheeler model was done using Autodesk Mechanical Simulation through which the properties like deflection, heat flux and temperature of disc brake model were calculated. It is important to understand action force and friction force on the disc brake new material, how disc brake works more efficiently, which can help to reduce the accident that may happen at anytime.

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Finite Element Analysis of Disk brake assembly.

  1. 1. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 1 Disc Brake Assembly Analysis INSTRUCTOR: Dr. Gonca Altuger-Genc MET-300 Mridul Mohta Pragadeesh Ravichandran Aditya Kaliappan Velayutham 04/29/2015
  2. 2. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 2 TABLE OF CONTENTS 1. Abstract……………………………………………………………….3 2. Parameters Involved………………………………………………….5 3. Parts of Braking System……………………………………………...5 4. Geometry of ContactArea…………………………………………...6 5. Objective……………………………………………………………..8 6. Procedure…………………………………………………………….8 7. Selection of Materials……………………………………………….10 8. Mechanical Properties……………………………………………....10 9. Outcomes 1) Analysis Type 1 – Mechanical Event Simulation……………….14 Material A 2) Analysis Type 1 – Mechanical Event Simulation……………….20 Material B 3) Analysis Type 2 – Non-Linear Static Stress Simulation………...24 Material A 4) Analysis Type 2 – Non-Linear Static Stress Simulation………...29 Material B 10.Challenges Faced……………………………………………………34 11.Formulae…………………………………………………………….35 12.Computational Problem……………………………………………..36 13.Design for Manufacturing of Disc Brakes…………………………..38 14.Conclusion…………………………………………………………..39 15.References…………………………………………………………...40
  3. 3. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 3 Abstract Disc Brakes are the type of the brakes, which uses the pair of calipers attached with the brake pads to rub against the disc. This creates friction between the brake pads and the disc, which in turn reduces the rotatory motion of the axle/wheel or brings it to stationary. Braking systems rely on friction to bring the vehicle to a halt – hydraulic pressure pushes brake pads against a cast iron disc. It consists of a disc made up of cast iron, which is bolted, to the wheel hub and a caliper (stationary mount housing). The caliper is linked to the vehicle’s stationary part like the axle casing and holding pistons in each part. In between each piston and the disc there is a friction pad held in position by retaining pins, spring plates etc. Passages are drilled in the caliper for the fluid to enter or leave each housing. Failure of disc brakes - If brake pads are not changed promptly, scarring occurs. This happens once they reach the end of their service life. Cracking takes place only for drilled discs that may develop small cracks around edges of holes drilled near the edge of the disc because of the disc's non-uniform rate of expansion. The discs have a certain amount of "surface rust". Sometimes when the brakes are applied, a high-pitched squeal occurs. Most brake squeal is produced by vibration (resonance instability) of the brake components, especially the pads and discs (known as force-coupled excitation). The standard disc brake of a 4-wheeler model was done using Autodesk Mechanical Simulation through which the properties like deflection, heat flux and temperature of disc brake model were calculated. It is important to understand action force and friction force on the disc brake new material, how disc brake works more efficiently, which can help to reduce the accident that may happen at anytime.
  4. 4. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 4 Figure 1 Figure 2
  5. 5. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 5 Parameters involved Clamping Force Braking Force Braking Torque Load torque Inertia torque Rubbing speed Power dissipation Kinetic energy Friction torque Braking time Maximum disc speed Deceleration during braking Delay time for brake signal External load acting on the brake Parts of Braking System  Brake Pedal—force input to system from driver  Design gives a Mechanical Advantage  Master Cylinder—converts force to pressure  Pressure is used to move brake pads into place  Brake Pads—provide friction force when in contact with rotor  Works to slow or stop vehicle  Caliper—holds pads and squeezes them against rotor  Rotor—spins with wheel
  6. 6. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 6  When used in conjunction with brake pads, slows vehicle  Vents—help provide cooling to brake ► Different materials have different coefficients of friction ► Pad material can be chosen for performance or to create a balance between performance and durability Table 1 Geometry of Contact Area Figure 3 F = Force on pads θ1, θ2, r1, r0 = Dimensions of brake pad
  7. 7. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 7 Figure 4 ► Step 1: Force is applied to by driver to the master cylinder ► Step 2: Pressure from the master cylinder causes one brake pad to contact rotor ► Step 3: The caliper then self-centers, causing second pad to contact rotor
  8. 8. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 8 Objective To develop a technical report by showing the simulation results of the disc brake assembly for different materials by providing the necessary tables/figures/graphs and to examine whether the part fails or not based on the safety factor requirements. The disc brake assembly (Figure 5) on which the analysis has to be done – Figure 5 Procedure 1. The disc brake assembly file was downloaded as an Autodesk Inventor file. 2. The unnecessary parts of the assembly were removed so as to reduce the complexity of the project. 3. The entire assembly was cut into half in two different planes. This was done to reduce the simulation time. 4. The final assembly had three parts – one caliper, brake pad and the rotor. 5. The assembly was then opened in the Autodesk Simulation software. 6. The assembly was meshed by selecting the appropriate 3D Mesh settings and by clicking “Generate 3D Mesh” command. 7. Once meshing has been done, both the element definition and element type were defined. 8. The analysis was carried with two different sets of materials for caliper, brake pad and rotor. (Details mentioned later in this report)
  9. 9. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 9 9. The analysis was carried with three different simulation types. (Details mentioned later in this report) 10. The next step was to define the constraints as follows: - For rotor’s inner side face - fixed constraint, For calipers – fixed constraint and For brake pad – fixed except translational in z-axis Constraints remained the same for Linear and Non - Linear Static Analysis. In addition, rotation of the rotor along the z-direction was set free for MES Type. 11. Linear Static Analysis –  The surface of the brake pad, which faces the rotor, was simulated so that it moves a certain distance by providing the option of prescribed displacement.  This was done by Selecting the surface  Right click, select sub entities and then the vertices were chosen.  Then one of the nodes was right clicked and prescribed nodal displacements were selected.  The translational motion magnitude was given as 10.666 mm in negative z - direction and then the load curve was selected for an addition of the return cycle.  On the same surface, by following the steps mentioned above, nodal forces were applied for 1000 N along the same direction as that of the prescribed displacement.  The simulation was then made to run. 12. Non – Linear Static Analysis – The same procedures were followed as that of the Linear Static Analysis. In addition, Surface-to-Surface contact was defined between the meeting faces of the brake pad and the rotor. Although, the outcomes were observed to be different. 13. Mechanical Event Simulation type – The same procedures were followed as that of the Non – Linear Analysis. In addition, two more steps were added i.e.  Nodal Prescribed Displacement on the rotor - the inner hollow surfaces of the rotor was selected by drawing a circle over it. In the option mesh, the joint option was selected to create a joint. For making the rotation possible, the rotor’s element definition was changed from truss to beam, which has rotational degree of freedom. The selection type was changed to rectangle and dragged over the created joint. The nodes been selected was then right clicked to choose nodal prescribed displacements and the value of rotation in terms of number of revolutions was provided.
  10. 10. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 10  Capture rate – It analyzes the component in several steps and increments. More is the value of the capture rate, better is the simulation result. Under the parameters section, the capture rate was selected and defined as 5 for 1-second forward cycle. So, for a total of 2 seconds, the total time of 10 seconds was made as a capture rate. SelectionofMaterials • The brake disc or rotor is usually made up of cast iron, but in some cases it is made up of composites such as reinforced carbon–carbon or ceramic matrix composites. • We have used two different sets of material type. They are: - a. Caliper: Aluminum 6061 - O Brake Pad: ASTM Steel A36 Rotor: Cast Iron ASTM A48 Grade 50 b. Caliper: Aluminum 6061 - O Brake Pad: Steel AISI 4130 Rotor: Titanium Carbide (TiC) Mechanical Properties Aluminum 6061– O [CaliperMaterial] Metric English Hardness, Brinell 30 30 Ultimate Tensile Strength 124 MPa 18000 psi Tensile Yield Strength 55.2 MPa 8000 psi Elongation at Break 25 % 25 % Elongation at Break 30 % 30 % Modulus of Elasticity 68.9 GPa 10000 ksi Ultimate Bearing Strength 228 MPa 33100 psi Bearing Yield Strength 103 MPa 14900 psi
  11. 11. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 11 Poisson's Ratio 0.33 0.33 Fatigue Strength 62.1 MPa 9000 psi Machinability 30 % 30 % Shear Modulus 26 GPa 3770 ksi Shear Strength 82.7 MPa 12000 psi ASTM A36 Steel [Brake Pad Set - 1] Tensile Strength, Ultimate 400 - 550 MPa 58000 - 79800 psi Tensile Strength, Yield 250 MPa 36300 psi Elongation at Break 20 % 20 % Modulus of Elasticity 200 GPa 29000 ksi Bulk Modulus 160 GPa 23200 ksi Poisson’s Ratio 0.26 0.26 Shear Modulus 79.3 GPa 11500 ksi AISI 4130 Steel, normalized at1600°F[BrakePad - Set 2] Hardness, Brinell 197 197 Hardness, Knoop 219 219 Hardness, Rockwell B 92 92 Hardness, Rockwell C 13 13 Hardness, Vickers 207 207 Tensile Strength, Ultimate 670 MPa 97200 psi Tensile Strength, Yield 435 MPa 63100 psi
  12. 12. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 12 Elongation at Break 25.5 % 25.5 % Reduction of Area 60 % 60 % Modulus of Elasticity 205 GPa 29700 ksi Bulk Modulus 140 GPa 20300 ksi Poisson's Ratio 0.29 0.29 Izod Impact 87 J 64.2 ft-lb Machinability 70 % 70 % Shear Modulus 80 GPa 11600 ksi Gray Cast Iron Grade50 [Rotor Set - 1] Compressive (Crushing) Strength 1130 MPa (164 x 103 psi) Density 7.2 g/cm3 (450 lb./ft3) Elastic (Young's, Tensile) Modulus 130 to 160 GPa (19 to 23 x 106 psi) Elongation at Break 1 % Fatigue Strength (Endurance Limit) 148 MPa (21 x 103 psi) Fracture Toughness 650 MPa-m1/2 Melting Onset (Solidus) 1090 °C (1990 °F) Shear Strength 503 MPa (73 x 103 psi) Specific Heat Capacity 450 J/kg-K Strength to Weight Ratio 48 to 57 kN-m/kg Tensile Strength: Ultimate (UTS) 345 to 410 MPa (50 to 59 x 103 psi) Tensile Strength: Yield (Proof) 228 MPa (33 x 103 psi) Thermal Conductivity 46 W/m-K Thermal Diffusivity 14
  13. 13. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 13 Thermal Expansion 10.5 µm/m-K Titanium Carbide[Rotor Set - 2] Knoop Micro hardness 2400 2000 – 2400 Hardness, Rockwell A 93 93 Vickers Micro hardness 3200 3200 Tensile Strength, Ultimate 258 MPa 37400 psi Modulus of Elasticity 448 - 451 GPa 65000 - 65400 ksi Poisson’s Ratio 0.18 - 0.19 0.18 - 0.19 Shear Modulus 110 - 193 GPa 16000 - 28000 ksi Shear Strength 89.0MPa @Temperature 1925 °C 12900psi @Temperature 3497 °F The assembly (Figure 6) looked like the following upon meshing– Figure 6
  14. 14. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 14 Outcomes 1. Analysis Type 1 – Mechanical Event Simulation Material A - Caliper: Aluminum 6061 - O Brake Pad: ASTM Steel A36 Rotor: Cast Iron ASTM A48 Grade 50 Prescribed Displacement – 10.666 mm in the negative z-direction Force – 1000 N in the negative z-direction Load Curve - Gradual Surface-to-Surface Contact – Rotor’s outer surface & brake pad’s inner surface Capture Rate – 10 seconds The assembly (Figure 1.1) looked like the following before the analysis was done- Figure 1.1
  15. 15. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 15 Maximum Displacement – 10.67 mm Figure 1.2 Maximum Stress – 3207.31 N/mm2 Figure 1.3
  16. 16. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 16 Maximum Strain – 0.0298476 mm/mm Figure 1.4 Graph (Figure 1.5) shows maximum stress that the disc brake can handle under the applied load and the given material conditions - Figure 1.5
  17. 17. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 17 Factor of Safety – 0.1142 Figure 1.6 The pictures listed above reveal that when the disc brake assembly is at the 5th step, the stress induced by the brake pad is more than the disc brake assembly at 10th step i.e. rotor at 5th step has maximum stress of 3207 N/mm2 than at 10th step. This is because when the rotor undergoes maximum deflection due to the force applied by the brake pad (5th step) while being fixed at one end, it bends to the extent, which induces more stress in it. Thus, at the maximum limit (5th step) stress concentration is higher than when it reaches the 10th step. This disturbs the original configuration of the rotor and it can never return back to its initial position after continuous and/or repeated use.
  18. 18. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 18 The picture (Figure 1.7) to show that the load curve is gradual loading – Figure 1.7 Table 1.1 The brake pad’s material is ASTM A36 Steel, which is a ductile material and the rotor’s material is Cast Iron ASTM A48 Grade 50, which is also a ductile material. As it is clearly seen from the safety factor plot that the Factor of Safety (FOS) is 0.1142 < 1.0. This shows that the disc brake fails and cannot bear the stress. Also, it can be seen from the above table (Table 1.1) that the minimum factor of safety for ductile material under static load condition is 2.0. So, any value below 2.0 shows that, the disc brake is not in par with the industrial standards. The failure is unavoidable hence; it is not safe and unacceptable. The analysis was also done by providing the load curve as repeated and impact loading. However, this did not affect the outcome of the analysis and the results were the same as that of the gradual loading. The factor of safety requirements for ductile material is more for repeated and impact loading i.e. 8 and 12 respectively.
  19. 19. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 19 Load Curve – Repeated Loading (Figure 1.8) Load Curve – Impact Loading (Figure 1.9)
  20. 20. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 20 2. Analysis Type 1 – Mechanical Event Simulation Material B - Caliper: Aluminum 6061 - O Brake Pad: Steel AISI 4130 Rotor: Titanium Carbide (TiC) Prescribed Displacement – 10.666 mm in the negative z-direction Force – 1000 N in the negative z-direction Load Curve - Gradual Surface-to-Surface Contact – Rotor’s outer surface & brake pad’s inner surface Capture Rate – 10 seconds The assembly (Figure 7) looked like the following before the analysis was done – (Figure 7)
  21. 21. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 21 Maximum Displacement – 10.67 mm Figure 2.1 Maximum Stress – 4832.57 N/mm2 Figure 2.2
  22. 22. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 22 Maximum Strain – 0.0297653 mm/mm Figure 2.3 Graph (Figure 2.4) shows maximum stress that the disc brake can handle under the applied load and the given material conditions - Figure 2.4
  23. 23. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 23 Factor of safety – 0.245508 Figure 2.5 The pictures listed above reveal that when the disc brake assembly is at the 5th step, the stress induced by the brake pad is more than the disc brake assembly at 10th step i.e. rotor at 5th step has maximum stress of 4832.57 N/mm2 than at 10th step. This is because when the rotor undergoes maximum deflection due to the force applied by the brake pad (5th step) while being fixed at one end, it bends to the extent, which induces more stress in it. Thus, at the maximum limit (5th step) stress concentration is higher than when it reaches the 10th step. This disturbs the original configuration of the rotor and it can never return back to its initial position after continuous and/or repeated use.
  24. 24. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 24 The picture (Figure 2.6) to show that the load curve is gradual loading – Figure 2.6 Table 2.1 The brake pad’s material is Steel AISI 4130, which is a ductile material and the rotor’s material is Titanium Carbide (TiC), which is also a ductile material. As it is clearly seen from the safety factor plot that the Factor of Safety (FOS) is 0.245508 < 1.0. This shows that the disc brake fails and cannot bear the stress. Also, it can be seen from the above table (Table 2.1) that the minimum factor of safety for ductile material under static load condition is 2.0. So, any value below 2.0 shows that, the disc brake is not in par with the industrial standards. The failure is unavoidable hence; it is not safe and unacceptable. The analysis was also done by providing the load curve as repeated and impact loading. However, this did not affect the outcome of the analysis and the results were the same as that of the gradual loading. The factor of safety requirements for ductile material is more for repeated and impact loading i.e. 8 and 12 respectively.
  25. 25. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 25 3. Analysis Type 2 – Non-Linear Static Stress Simulation Material A - Caliper: Aluminum 6061 - O Brake Pad: ASTM Steel A36 Rotor: Cast Iron ASTM A48 Grade 50 Force – 1000 N in the negative z-direction Load Curve – Gradual The assembly (Figure 8) looked like the following before the analysis was done – Figure 8 Maximum Displacement – 0.006 mm Figure 3.1
  26. 26. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 26 Maximum Stress – 21.7096 N/mm2 Figure 3.2 Maximum Strain – 0.000207 mm/mm Figure 3.3
  27. 27. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 27 Graph (Figure 3.4) shows maximum stress that the disc brake can handle under the applied load and the given material conditions – Figure 3.4 Factor of Safety – 14.7624 Figure 3.5
  28. 28. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 28 The pictures listed above reveal that when the disc brake assembly is at the 5th step, the stress induced by the brake pad is more than the disc brake assembly at 10th step i.e. rotor at 5th step has maximum stress of 21.7096 N/mm2 than at 10th step. This is because when the rotor undergoes maximum deflection due to the force applied by the brake pad (5th step) while being fixed at one end, it bends to the extent, which induces more stress in it. Thus, at the maximum limit (5th step) stress concentration is higher than when it reaches the 10th step. This disturbs the original configuration of the rotor and it can never return back to its initial position after continuous and/or repeated use. The picture (Figure 3.6) to show that the load curve is gradual loading – Figure 3.6 Table 3.1 The brake pad’s material is ASTM A36 Steel, which is a ductile material and the rotor’s material is Cast Iron ASTM A48 Grade 50, which is also a ductile material. As it is clearly seen from the safety factor plot that, the Factor of Safety (FOS) is 14.7624 > 1.0. This shows that the disc brake do not fail and can bear the stress. Also, it
  29. 29. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 29 can be seen from the above table (Table 3.1) that the minimum factor of safety for ductile material under static load condition is 2.0. So, any value above 2.0 shows that, the disc brake is in par with the industrial standards. The failure is avoidable hence; it is safe and acceptable. The analysis was also done by providing the load curve as repeated and impact loading. However, this did not affect the outcome of the analysis and the results were the same as that of the gradual loading. The factor of safety requirements for ductile material is more for repeated and impact loading i.e. 8 and 12 respectively. 4. Analysis Type 2 – Non-Linear Static Stress Simulation Material B - Caliper: Aluminum 6061 - O Brake Pad: Steel AISI 4130 Rotor: Titanium Carbide (TiC) Force – 1000 N in the negative z-direction Load Curve – Gradual The assembly (Figure 9) looked like the following before the analysis was done – Figure 9
  30. 30. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 30 Maximum Displacement – 0.0072978 mm Figure 4.1 Maximum Stress – 23.7365 N/mm2 Figure 4.2
  31. 31. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 31 Maximum Strain – 0.000282 mm/mm Figure 4.3 Graph (Figure 4.4) shows maximum stress that the disc brake can handle under the applied load and the given material conditions – Figure 4.4
  32. 32. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 32 Factor of Safety – 47.5378 Figure 4.5 The pictures listed above reveal that when the disc brake assembly is at the 5th step, the stress induced by the brake pad is more than the disc brake assembly at 10th step i.e. rotor at 5th step has maximum stress of 23.7365 N/mm2 than at 10th step. This is because when the rotor undergoes maximum deflection due to the force applied by the brake pad (5th step) while being fixed at one end, it bends to the extent, which induces more stress in it. Thus, at the maximum limit (5th step) stress concentration is higher than when it reaches the 10th step. This disturbs the original configuration of the rotor and it can never return back to its initial position after continuous and/or use.
  33. 33. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 33 The picture (Figure 4.6) to show that the load curve is gradual loading – Figure 4.6 Table 4.1 The brake pad’s material is Steel AISI 4130, which is a ductile material and the rotor’s material is Titanium Carbide (TiC), which is also a ductile material. As it is clearly seen from the safety factor plot that the Factor of Safety (FOS) is 47.5378 > 1.0. This shows that the disc brake do not fail and can bear the stress. Also, it can be seen from the above table (Table 4.1) that the minimum factor of safety for ductile material under static load condition is 2.0. So, any value above 2.0 shows that, the disc brake is in par with the industrial standards. The failure is avoidable hence; it is safe and acceptable. The analysis was also done by providing the load curve as repeated and impact loading. However, this did not affect the outcome of the analysis and the results were the same as that of the gradual loading. The factor of safety requirements for ductile material is more for repeated and impact loading i.e. 8 and 12 respectively.
  34. 34. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 34 Challenges Faced  In order to reduce the simulation’s complexity, most of the parts, which play no and/or less role, were removed from the actual assembly (Figure 10). Figure 10 - Actual Assembly  To avoid simulating symmetrical parts and reduce simulation time, the assembly is further divided into half in two different planes (Figure 11). This helped in bringing down the size of the actual assembly. Figure 11 - Assembly after removing the parts  In spite of providing all the necessary requirements for the simulation, the rotor was unable to rotate in the desired way.  Certain analyses under particular conditions were not functioning properly (Figure 7).
  35. 35. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 35 Figure 12  Applying different commands and options like remote force, remote loads and constraints, which we haven’t been acquainted before was one of the major issues. Formulae Stress = Force/Area = F/A Strain = Change in length/original length = dl/l Young’s Modulus, E = Stress/Strain Poisson’s Ratio = Lateral Stain /Longitudinal Strain Factor of Safety = Ultimate Tensile Strength/ Maximum Stress Computational Problem Standard Brake Design Rotor disc dimension = 240 mm (240×10-3 m) Rotor disc material = Carbon Ceramic Matrix Pad brake area = 2000 sq.mm (2000E-6 m) Pad brake material = Asbestos Coefficient of friction (Wet Condition) = Ranges between 0.07-0.13 Coefficient of friction (Dry Condition) = Ranges between 0.3-0.5
  36. 36. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 36 Maximum temperature subjected to = 350°C Maximum pressure subjected to = 1MPa (E6 Pa) Forces Acting On Rotor Due To Contact with Brake Pads Tangential force between pad and rotor (Inner face) FTRI = µ1.FRI Where, FTRI = Normal force between pad brake and Rotor (Inner) µ1 = Coefficient of friction = 0.5 FRI = Pmax / 2 × A pad brake area So, FTRI = µ1.FRI FTRI = (0.5)(0.5)(E6 N/sq.m) (2000E6 sq.m) FTRI = 500 N Tangential force between pad and rotor (outer face), FTRO. In this FTRO equal FTRI because same normal force and same material Brake Torque (TB): With the assumption of equal coefficients of friction and normal forces FR on the inner and outer faces: TB = FT.R Where TB = Brake torque µ = Coefficient of friction FT = Total normal forces on disc brake, [FTRI + FTRO] FT = 1000 N R = Radius of rotor disc So, TB = (1000) (120E-3) TB = 120 N.m Brake Distance (x) – We know that tangential braking force acting at the point of contact of the brake, and Work done = FT. x (Equation A) Where FT = FTRI + FTRO X = Distance travelled (in meter) by the vehicle before it come to rest. We know kinetic energy of the vehicle. Kinetic energy = (m.v^2) / 2 (Equation B) Where m = Mass of vehicle v = Velocity of vehicle In order to bring the vehicle to rest, the work done against friction must be equal to kinetic energy of the vehicle.
  37. 37. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 37 Therefore equating (Equation A) and (Equation B) FT. x = (m.v^2) / 2 Assumption v = 100 km/hr = 27.77 m/s M = 132 kg. (Dry weight of Vehicle) So we get x = (m.v^2) / 2 FT x = (132×27.772) / (2×1000) m. x = 50.89 m Heat Generated (Q) = M.Cр.ΔT J/s Flux (q) = Q/A W/m² Thermal Gradient (K) = q / k K/m Carbon Ceramic Matrix – Heat generated Q= m*cp*∆T Mass of disc = 0.5 kg Specific Heat Capacity = 800 J/kg°C Time taken Stopping the Vehicle = 5 sec Developed Temperature difference = 15°C Q = 0.5 * 800 * 15= 6000 J Area of Disc = Π * (R^2 – r^2) = Π * (0.120^2 – 0.055^2) = 0.03573 sq.m Heat Flux = Heat Generated /Second /area = 6000 / 5 / 0.0357 = 33.585 kw/sq.m Thermal Gradient = Heat Flux / Thermal Conductivity = 33.582E3/40 = 839.63 K/m
  38. 38. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 38 Designfor Manufacturing of Disc Brakes Figure 13
  39. 39. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 39 Conclusion From the results of the simulation and the shown computations, it was found that the braking force and the number of times the brake has been applied, has a direct relationship on the life and efficiency of the disc brake assembly. More is the load applied on the brake pad; more is the force transmitted onto the rotor and enables it to quickly come to rest. The area where the brake pad rubs the rotor generates more stress and displacement. As the brake pad is comparatively smaller than the rotor, it has less factor of safety while being simulated. As the braking force is not directly applied to the rotor, and passed on through the brake pad in between, it is essential to know about the amount of force applied on the brake pad rather than knowing about the rotor’s factor of safety. Non-Linear Static Stress analysis is preferred over Linear Static Stress analysis because it is a complex approach, which analyses the stress and strain more quickly and effectively. It is more accurate than the linear analysis because in linear analysis the basic assumptions are taken into consideration while the same assumptions are being violated in the non-linear analysis. The conditions, which are being taken into account when non-linear analysis is considered, are dynamic loading or time dependent loading and large deformations of the component, which give the engineers an efficient way to analyze the part or component more properly and appropriately than the linear analysis.
  40. 40. Computer Aided Engineering MET-300 Project – Technical Report Farmingdale State College 04/29/2015 40 References Abhang, Swapnil R., & Bhaskar, D.P. (2014, February). Design and Analysis of Disc Brake, International Journal of Engineering Trends and Technology (IJETT), Volume 8 Number 4 (ISSN: 2231-5381). Retrieved from https://www.ijettjournal.org Aluminum 6061 – O (n.d.). In ASM Aerospace Specification Metals Inc. online. Retrieved from http://asm.matweb.com/search/SpecificMaterial.asp?bassnum=MA6061O ASTM Grade 50 (ISO Grade 350, EN-JL 1060) Grey Cast Iron (n.d.). In Makeitfrom.com online. Retrieved from http://www.makeitfrom.com/material-properties/ASTM-Grade-50-ISO- Grade-350-EN-JL-1060-Grey-Cast-Iron/ Bobo (2013, January 15). Hydraulic Disc Brake. GrabCAD. Retrieved from https://grabcad.com/library/hydraulic-disc-brake Strength of Materials Basics and Equations | Mechanics of Materials Equations (n.d.). In Engineers Edge online. Retrieved from http://www.engineersedge.com/strength_of_materials.htm Titanium Carbide (TiC) (n.d.). In MATWEB Material Property Data online. Retrieved from http://www.matweb.com/search/datasheet.aspx?matguid=058d1b70edbd4b2293f2 98c52bbf9818&ckck=1

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