16018_Nemesis _CAD/CAE Report Author’s Name :
Aditya Vikram Agarwal
Co-Author’s
Name:
Jai Kumar Ramrakhyani
1. INTRODUCTION Computer-aided drafting (CAD) is the use of computer systems to aid in the creation, modification, analysis, or optimization of a design. Computer-aided engineering (CAE) is the broad usage of computer software to aid in engineering analysis tasks. Firstly, we selected the type of steering, suspension and transmission system to be used and according to that made the design. The seatback angle was kept such that it is most ergonomic. Considering the safety of driver, the sitting space, ground clearance and height of driver was kept in accordance with the rulebook. 3D CAD design was made in Solidworks 2015 SP0 x64 edition. Meshing and analysis of frame fr ame for front, side and roll over impact was performed in Altair Hyperworks 13.0 (64 bit) edition. The other CAE analysis such as fairing supports and seatback member supports was performed in Ansys Workbench 15.0.
2.
FRAME MATERIAL OPTIONS
Material
Weight (kg)
Price (₹)
Yield Strength
Ultimate Strength
I
45
7200
365 MPa
440 MPa
II
44
7040
365 MPa
440 MPa
3. CALCULATION OF BENDING STRENGTH AND BENDING STIFFNESS
AISI 1018 Properties:
Material 1: steel 1018 Circular; 31.75x28.55x1.6 (mm)
Table: Table: Chemical Composition
Outer diameter d2= 31.75mm Inner diameter d1= 28.55mm Yield strength sy = 365 Mpa C=
Distance from neutral axis to extreme fiber = 15.875 mm
Table: Physical Properties
Moment of inertia I = pi/4(d24-d14) = 17268.84 x 10-12 m4 Bending Strength, M= (sy x I)/c = (365 x 106 x 17268.84 x 10-12)/15.875x10-3 M= 397.05 N m
Options of Different Cross section:
Bending stiffness = EI (we assume proportionality constant to be 1 for comparative purpose)
1. STEEL (1018) Circular; 31.75 x 28.55 x 1.6 (mm)
= 205 x 109 x 17268.84 x 10-12 = 3540.11 N m2
2. STEEL (1018) Circular; 25.4 x 21.4 x 2 (mm)
Material 2: Steel 1018 Circular; 25.4x21.4x2 (mm) (Reference) Outer diameter d2= 25.4mm
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Inner diameter d1= 21.4mm Yield strength sy = 365 MPa C=
Distance from neutral axis to extreme fiber = 12.7
mm Moment of inertia I = pi/4(d24-d14) = 10136.74 x 10-12 m4 Bending Strength, M= (sy x I)/c = (365 x 106 x 10136.74 x 10-12)/12.7x10-3 M= 291.33 N m
As the roll cage was developed by plotting lines, so every member of roll cage is considered to be properly constrained at every joint. Altair Hypermesh 13.0 is used to create 1-D meshing of the frame. For boundary conditions for front impact test, the frame is fixed from the rear side and the front members will come across the applied load. To properly analyze the impact force, we need to find the deceleration of the vehicle after impact. To approximate the worst case scenario that the vehicle will undergo, momentum equations were used to determine the deceleration of the vehicle. The vehicle was considered to be at maximum speed of 36km/hr having total weight of 355 kg and according to different scenarios the conditions of head on impacts were employed with a crash pulse consideration of 0.2s. b) Calculation of Impact Forces:
Bending stiffness = EI (we assume proportionality proport ionality constant to be 1 for comparative purpose)
Weight of the Vehicle, M = 355kg (Including two driver each of weight 115kg). Initial Velocity before impact, u = 10 m/s Final Velocity after impact, v = 0 m/s Impact time, t = 0.2 seconds.
= 205 x 109 x 10136.74 x 10-12 =2078.03 N m2
Work done = Change in kinetic energy W = 0.5 x M x ( 2 - 2 ) = 0.5 x 355 x 100 = 17750 N-m MATERIAL
BENDING STRENGTH
BENDING STIFFNESS
I
397.05 N m
3540.11 N m2
II (Reference)
291.33 N m
2078.03 N m2
Work done = Force x displacement = F x s
(1)
Also, s = u x t + (0.5 x deceleration x t x t) Thus, v = u + (a x t) s = 1m From (1) we get, F = W/s F = 17750/1 = 17750N
4. CAE ANALYSIS OF VEHICLE/FRAME A frame of the vehicle plays the most important role in safety of passenger. The frame contains the operator, motor, brake system, steering mechanism and must be of adequate strength to protect the operator in the event of impact or rollover. Finite Element Analysis is a mathematical modeling technique used to determine the response of real structures to external and internal loads. CAE Analysis on the frame is performed to evaluate the safety offered by the frame to drivers in case of any accident including Frontal Impact, Side Impact and Rollover.
c) Analysis Results: Maximum Stress = 26.1 MPa Minimum Stress = -58.6 MPa
4.1. FRONTAL IMPACT ANALYSIS It is the impact wherein there is a possibility of vehicle crashing into another vehicle head on during the race. Material-1 (AISI 1018, Outer diameter - 1.25 inch, Thickness – 1.6mm) a) Assumption & Considerations Considerations::
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Weight of the Vehicle, M = 354 kg (Including two driver each of weight 115kg). Initial Velocity before impact, u = 10 m/s Final Velocity after impact, v = 0 m/s Impact time, t = 0.2 seconds. Work done = Change in kinetic energy W = 0.5 x M x ( 2 - 2 ) = 0.5 x 354 x 100 = 17700 N-m Work done = Force x displacement = F x s
(1)
Also, s = u x t + (0.5 x deceleration x t x t) Thus, v = u + (a x t) s = 1m
Total deformation = 76.6mm
From (1) we get, F = W/s F = 17700 N-m
Factor of safety = Yield Strength/ Max Stress = 365/58.6 = 6.22
c) Analysis Results:
d) Optimizations: No optimization required as factor of safety is large enough to sustain front impact.
Material-2 (AISI 1018, Outer diameter Thickness – 2mm)
–
Maximum Stress = 26.9 MPa Minimum Stress = -60.23 MPa
1 inch,
a) Assumption & Considerations: Considerations: As the roll cage was developed by b y plotting lines, so every member of roll cage is considered to be properly constrained at every joint. Altair Hypermesh 13.0 is used to create 1-D meshing of the frame. For boundary conditions for front impact test, the frame is fixed from the rear side and the front members will come across the applied load. To properly analyze the impact force, we need to find the deceleration of the vehicle after impact. To approximate the worst case scenario that the vehicle will undergo, momentum equations were used to determine the deceleration of the vehicle. The vehicle was considered to be at maximum speed of 36km/hr having total weight of 354 kg and according to different scenarios the conditions of head on impacts were employed with a crash pulse consideration of 0.2s.
Maximum Deformation = 127mm
b) Calculation of Impact Forces: effi.saenis.org
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Also, s = u x t + (0.5 x deceleration x t x t) Thus, v = u + (a x t) s = 1.25m From (1) we get, F = W/s F = 17750/1.25 = 14200N
Factor of safety = 6.06 d) Optimizations: No Optimization necessary as maximum stress is less than yield stress.
4.2. SIDE IMPACT ANALYSIS The side impact analysis is carried out as there is a possibility of collision with another vehicle from either direction.
c) Analysis Results: Maximum Stress = 42.7 MPa Minimum Stress = -44.1 MPa
Material-1 (AISI 1018, Outer diameter - 1.25 inch, Thickness – 1.6mm) a) Assumption & Considerations: Considerations: As the roll cage was developed by b y plotting lines, so every member of roll cage is considered to be properly constrained at every joint. Altair Hypermesh 13.0 is used to create 1-D meshing of the frame. For boundary conditions for side impact test, one side of the roll cage elements are fixed while the other side will be applied with load. Thus, the stresses acting on the side members mem bers of the roll cage are analyzed. To properly analyze the impact force, we need to find the deceleration of the vehicle after impact. To approximate the worst case scenario that the vehicle will undergo, momentum equations were used to determine the deceleration of the vehicle. The vehicle was considered to be at maximum speed of 36km/hr having total weight of 355 kg and according to different scenarios the conditions of head on impacts were employed with a crash pulse consideration of 0.25s.
Maximum deformation = 36.5mm
b) Calculation of Impact Forces: Weight of the Vehicle, M = 355kg 355k g (Including two driver each of weight 115kg). Initial Velocity before impact, u = 10 m/s Final Velocity after impact, v = 0 m/s Impact time, t = 0.25 seconds. Work done = Change in kinetic energy W = 0.5 x M x ( 2 - 2 ) = 0.5 x 355 x 100 = 17750 N-m Work done done = Force x displacement = F x s
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(1)
Factor of safety = 365/44.1 = 8.27 d) Optimizations: Since factor of safety is large enough, no optimization of vehicle is required.
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Material-2 (AISI 1018, Outer diameter - 1 inch, Thickness – 2 mm) a) Assumption & Considerations: Considerations: As the roll cage was developed by b y plotting lines, so every member of roll cage is considered to be properly constrained at every joint. Altair Hypermesh 13.0 is used to create 1-D meshing of the frame. For boundary conditions for side impact test, one side of the roll cage elements are fixed while the other side will be applied with load. Thus, the stresses acting on the side members mem bers of the roll cage are analyzed. To properly analyze the impact force, we need to find the deceleration of the vehicle after impact. To approximate the worst case scenario that the vehicle will undergo, momentum equations were used to determine the deceleration of the vehicle. The vehicle was considered to be at maximum speed of 36km/hr having total weight of 354 kg and according to different scenarios the conditions of head on impacts were employed with a crash pulse consideration of 0.25s.
Maximum Deformation: 65mm
b) Calculation of Impact Forces: Weight of the Vehicle, M = 354kg 354k g (Including two driver each of weight 115kg). Initial Velocity before impact, u = 10 m/s Final Velocity after impact, v = 0 m/s Impact time, t = 0.25 seconds. Work done = Change in kinetic energy W = 0.5 x M x ( 2 - 2 ) = 0.5 x 354 x 100 = 17700 N-m Work done done = Force x displacement = F x s Also, s = u x t + (0.5 x deceleration x t x t) Thus, v = u + (a x t) s = 1.25m From (1) we get, F = W/s F = 17700/1.25 = 14160N
(1)
Factor of safety = 8.11
d) Optimizations: No optimization required.
4.3. ROLLOVER ANALYSIS The rollover impact analysis is carried out by considering the stresses induced on the members of the roll cage when the vehicle topples down from a slope with an angle of 45° 45 °. Material-1 (AISI 1018, Outer diameter - 1.25 inch, Thickness – 1.6mm) a) Assumption & Considerations: Considerations:
c) Analysis Results: Maximum Stress = 45 MPa Minimum Stress = -43.6 MPa
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As the roll cage was developed by b y plotting lines, so every member of roll cage is considered to be properly constrained at every joint. Altair Hypermesh 13.0 is used to create 1-D meshing of the frame. For boundary conditions for rollover impact test, the lower elements of the roll cage are fixed. In this impact, the upper and rear members of the vehicle will bear the force. To properly analyze the impact force, we need to find the deceleration of the vehicle after impact. To approximate the worst case scenario that the vehicle will undergo, momentum equations were used to determine the deceleration of the vehicle. The vehicle was considered to be at maximum speed of 36km/h having total weight EFFI-CYCLE 2016
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of 355 kg and according to different scenarios the conditions of head on impacts were employed with a crash pulse consideration of 0.3s. b) Calculation of Impact Forces: Weight of the Vehicle, M = 355kg (Including two driver each of weight 115kg). Initial Velocity before impact, u = 10 m/s Final Velocity after impact, v = 0 m/s Impact time, t = 0.3seconds. Work done = Change in kinetic energy W = 0.5 x M x ( 2 - 2 ) = 0.5 x 355 x 100 = 17750 N-m Work done done = Force x displacement = F x s Also, s = u x t + (0.5 x deceleration x t x t) Thus, v = u + (a x t) s = 1.5m From (1) we get, F = W/s F = 17750/1.5 = 11834 N.
(1)
Factor of safety = 365/47.6 = 7.67 d) Optimizations: Factor of safety is large enough to easily sustain the rollover impact force.
Material-2 (AISI 1018, Outer diameter - 1 inch, Thickness – 2mm) a) Assumption & Considerations Considerations::
c) Analysis Results: Maximum Stress = 17.4 MPa Minimum Stress = -47.6 MPa
As the roll cage was developed by plotting lines, so every member of roll cage is considered to be properly constrained at every joint. Altair Hypermesh 13.0 is used to create 1-D meshing of the frame. For boundary conditions for rollover impact test, the lower elements of the roll cage are fixed. In this impact, the upper and rear members of the vehicle will bear the force. To properly analyze the impact force, we need to find the deceleration of the vehicle after impact. To approximate the worst case scenario that the vehicle will undergo, momentum equations were used to determine the deceleration of the vehicle. The vehicle was considered to be at maximum speed of 36km/h having total weight of 355 kg and according to different scenarios the conditions of head on impacts were employed with a crash pulse consideration of 0.3s. b) Calculation of Impact Forces: Weight of the Vehicle, M = 354kg (Including two driver each of weight 115kg). Initial Velocity before impact, u = 10 m/s Final Velocity after impact, v = 0 m/s Impact time, t = 0.3seconds.
Maximum Deformation = 38mm
Work done = Change in kinetic energy W = 0.5 x M x ( 2 - 2 ) = 0.5 x 355 x 100 = 17700 N-m Work done = Force x displacement = F x s
(1)
Also, s = u x t + (0.5 x deceleration x t x t) Thus, v = u + (a x t) s = 1.5m effi.saenis.org
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From (1) we get, F = W/s F = 17700/1.5 = 10800 N.
AISI 1018 mild/low carbon steel has excellent weldability and produces a uniform and harder case and it is considered as the best steel for carburized parts. AISI 1018 mild/low carbon steel offers a good balance of toughness, strength and ductility. Provided with higher mechanical properties, AISI 1018 hot rolled steel also includes improved machining characteristics and Brinell hardness. Machinability: Machinability: The machinability of AISI 1018 mild/low carbon steel is graded at 78% of B1112. Weldability: Weldability: AISI 1018 mild/low carbon steel can be instantly welded by all the conventional welding processes. Welding is not recommended for AISI 1018 mild/low carbon steel when it is carbo-nitrided and carburized.
c) Analysis Results:
Low carbon welding electrodes are to be used in the welding procedure, and post-heating and pre-heating are not necessary. Pre-heating can be performed for sections over 50 mm. Post-weld stress relieving also has its own beneficial aspects like the pre-heating process.
Maximum Stress = 16.38 MPa Minimum Stress = -33.2 MPa
Material
Factor of Safety
Maximum Deformation (mm)
FI
SI
ROI
FI
SI
ROI
I
6.22
8.27
7.67
76.6
36.5
38
II
6.06
8.11
11
127
65
58
Where, F I – Front Impact, S I – Side Impact, R O I – Roll Over Impact.
Maximum Deformation: 58mm
Factor of Safety is more and Maximum Deformation is less in case of Material I even though weight is comparable. Weight of Material I – 45 Kg Weight of Material II – 44 Kg Material Selected for Frame: STEEL (1018) Circular; 31.75 x 28.55 x 1.6 (mm) (mm)
Factor of safety: 11
6. CAE ANALYSIS OF OTHER PARTS d) Optimizations: No optimization required as factor of safety is large enough to sustain roll over impact.
CAE Analysis of other fabricated parts such as overhead support, side protection members, and seatback support members was performed.
5. FINAL MATERIAL SELECTION Material selected is AISI 1018. effi.saenis.org
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Maximum stress = 121 MPa
6.1.
SIDE SUPPORT MEMBERS
a) Assumption and Consideration: Side protection members are placed such that the drivers’ bodies must be com pletely inside the periphery made by vehicle frame. It is rigidly attached to the frame and made of same material as that of the frame. A load is applied to the side protection member and the node where it attaches the frame is kept fixed till the member yields. b) Calculations : An arbitrary force of 1000N was applied on one side support member and rear suspension and right front suspension points were kept stationary.
6.2.
OVERHEAD SUPPORT MEMBERS
a) Assumption & Considerations: Considerations: The overhead protection members are extended horizontally at least 12 inches (304.8mm) forward from the center of each driver’s heads. They are rigidly fixed such that they provide enough support from anything falling from above and also in case of rollover. The overhead support members are assumed to be rigidly fixed and force is applied to them from above vertically till they yield. b) Calculations : Arbitrary forces were applied ranging from 1000N to 600 N till the required result was obtained which gives the factor of safety above 1.
c) Analysis Results: A safety factor of 2.08 was obtained obta ined which shows that the side protection members can hold up to 2000N of impact force on them directed upon them.
c) Analysis Result : A safety factor of 1.03 was obtained on application of 600 N of force (200 N on each of three faces) which shows that overhead support member can bear a total force of 600 N impacted upon it.
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c) Analysis Results :
Maximum Stress corresponding to 600 N force = 354 MPa
6.3.
Maximum Equivalent Stress = 336 MPa
SEATBACK SUPPORT MEMBERS
Maximum Deformation = 8mm
a) Assumption and Considerations: The purpose of providing a seatback support member is to provide a rigid support to seatback and to restrict its movement in case of failure of seatback adjustment or locking system. It should be placed close to the seatback such that minimal gap exists in between. The Vehicle is considered to be in dynamic condition and made to halt suddenly such that the maximum force is applicable to the seatback support members by the drivers during impact. b) Calculation of force: Total impact force that driver can apply because of his shoulders to the seatback support members: 50 percent of total body weight of both drivers = 115kg. Let us assume 1G force is applied by drivers, thus Force = mg = 1150 N
Factor of Safety = 1.1 Thus even on application of force of 1150 N by the drivers, the seatback support members won’t yield and the drivers will be safe. 7.
VEHICLE VIEWS
Appendix – 1 includes all the vehicle views.
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APPENDIX-1: Vehicle Views
Figure-1 (Isometric View of Vehicle)
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APPENDIX-1: Vehicle Views (contd...)
Figure-2 (Front View of Vehicle)
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APPENDIX-1: Vehicle Views (contd...)
Figure-3 (Side View of Vehicle)
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A APPENDIX-1: Vehicle Views (contd...)
Figure-4 (Top View of Vehicle)
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APPENDIX-1: Vehicle Views (contd...)
Figure-5 (CAD Model of Frame)
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