Fatigue simulation of automobile antiroll bars

1. Presented By
Amol Bhanage1
& Dr. K. Padmanabhan2
1
Research Scholar & 2
Professor, SMBS,
VIT University, Vellore
Paper ID : ICDMM2015-058
Static and Fatigue Simulation of Automotive
Anti Roll Bar Before DBTT
ISET 2015
International Conference on “Design, Manufacturing and
Mechatronics”
ICDMM 2015

2. Contents
• Objective & Background
• Specification & Material properties of Anti Roll Bar
• FE Modelling of Anti Roll Bar
• Static analysis & Ride Comfort
• Finite Element Based Fatigue Analysis
• Results and Discussion
• Conclusion & Future scope
• References
01/25/16 2International Conference on “Design, Manufacturing and Mechatronics” ICDMM 2015

3. Objective
• In the present work, Anti roll bar (ARB) used in SUV’s which reduced the
amount of ‘body roll of automotive’ during turning studied . The primary
objective is to compare fatigue characteristics of ARB for AISI 1020, SAE
4340, SAE 5160 and SAE 9262 materials before DBTT.
• Factors like fatigue life, fatigue damage, biaxiality indication etc. are plotted
for AISI 1020, SAE 4340, SAE 5160 and SAE 9262 materials and predict the
fatigue performance using ANSYS Workbench and ANSYS n Code Designlife
software.
• Therefore the objective of this paper is to present a design and simulation
study on the fatigue performance of a AISI and SAE steel materials under
constant amplitude loading before ductile to brittle transition temperature,
which leads to failure through design and finite element method and prove
the reliability of the validation methods based only on simulation, thereby
saving time, material and production costs for a complete product
realization.
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4. Anti Roll Bar - Introduction
• Anti roll bar (ARB) - reduce the amount of ‘body roll’
• Body roll is defined as the angle through which the vehicle’s body
rotates about its longitudinal axis; this motion is not only uncomfortable
for passengers, but detrimental to vehicle traction and handling due to
the non-linear response of pneumatic automotive tires
Anti Roll Bar Fig. 2 Effect of an anti-roll bar on vehicle body roll
Fig. 1 Anti-roll bar that connects with left and right wheel
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5. Background
Author Conclusion
Michael Doody, [1] ARB is an automotive suspension component that elastically couples
the suspension on one side of a vehicle to the adjacent side. If the
suspension on one side of the vehicle is compressed, a reactive force
will be generated by the ARB tending to compress the suspension on
the adjacent side of the vehicle. This coupling serves to reduce the
amount of ‘body roll’ a vehicle will experience during cornering
Preetam Shinde, M.M.Patnaik
[2]
A stabilizer bar used in suspension of the vehicles is redesigned to
minimize the stress concentration at the corner bends for given
structural limits. Locating the bushings closer to the centre of the
bar increases the stresses at the bushing locations. Also the weight
of the hollow anti-roll bar is less than the solid bar but the stresses
on the hollow bar are higher
Padmanabhan K. [3] The stabilizer bars were fabricated from the materials through the
various processes involved in the manufacturing such as induction
hardening, tempering, sizing and cutting, bending and orbital TIG
welding of end lugs. The bars were then shot peened and tested for
fatigue at various stress levels
01/25/16 5International Conference on “Design, Manufacturing and Mechatronics” ICDMM 2015

6. Background
Author Conclusion
Adam-Markus WITTEK, Hans-
Christian RICHTER [4]
The important parameter which affects on design of anti roll bar is
stabilizer bar rate, bending radii and planes should be chosen
correctly. Stress concentration, in particular in radii or critical areas
should remain under permitted limits.
J. Marzbanrad, A. Yadollahi
[5]
Tresca and Von Mises criteria are suitable for proportional fully
reversed loadings. The effect of the mean shear stress is often
neglected in High Cycle fatigue (HCF) analysis.
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7. Specification and Material Properties of Anti Roll Bar
Table No.1 Specification of Existing Anti Roll Bar
Fig. 3 Isometric view & Dimension of Anti Roll Bar
Parameters Value
Cross-section type Solid round cross-section
Total length of bar 1150 mm
Bushing locations ± 200 mm
Section diameter 25.4 mm
Loading ± 2111 N on both sides
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8. Specification and Material Properties of Anti Roll Bar
Table .2: Mechanical and Cyclic Properties of AISI 1020 , SAE 4340_434_QT, SAE 5160 & SAE 9262
Material Properties AISI 1020 SAE 4340 SAE 5160 SAE 9262
Young’s Modulus (E),
GPa
207 207 207 207
Poisson’s ratio, (υ) 0.3 0.32 0.3 0.3
Tensile Yield Strength ,
MPa
280 1102 1487 455
Tensile Ultimate Strength, MPa 416 1171 1584 923
Fatigue Strength Coefficient (Sf) 834 1649 2063 1178
Fatigue Strength Exponent
(b)
-0.114 -0.09 -0.08 -0.08
Fatigue Ductility Exponent
(c )
-0.453 -0.72 -1.05 -0.68
Fatigue Ductility Coefficient (Ef) 0.169 1.39 9.56 0.83
Cyclic Strength Coefficient (K’) 1482 1603 2432 1206
Cyclic Strain Hardening Exponent
(n’)
0.29 0.13 0.13 0.12
01/25/16 8International Conference on “Design, Manufacturing and Mechatronics” ICDMM 2015

9. Design Calculations
• A force applied on the bar ends of a U-shaped bent solid stabilizer bar causes
bending stress as well as torsional stress at the bar.
• While torsional stresses prevail at the back of the bar, the bending stresses are
particularly great in the area of the arms
• Permitted Equivalent Stress
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For Bar with round profile

10. • Boundary Condition and Loading:
Finite Element Modelling
Fig. 4 Boundary condition – Anti Roll Bar
D.O.F. Constrained At the bar ends Centre
Translation
Constrained
UX, UZ Constrained
Rotation
Constrained
ROTY & ROTZ No Constrained
Allowing Free Y direction Free to Rotate
Force ± 2111 N on both
ends
------
Table. 3 : Boundary condition – Anti Roll Bar
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11. Static Analysis and Ride Comfort
Figure 5. Anti Roll Bar: Von - Mises Stress
Static Results :
From static analysis, maximum value of von-mises stress is 767.46 MPa and maximum
Principal stress is 581.35 MPa.
For AISI 1020 material, anti roll bar deformation upto 117.21 mm on applied maximum
load of 2111.1 N.
Figure 6. Anti Roll Bar: Absolute Principal stress
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12. Static Analysis and Ride Comfort
Modes Frequency in Hz
1
0
2
19.29
3
73.39
4
93.82
5
99.77
6
102.36
Table 4 : Natural frequencies of anti roll bar
Ride Comfort :
This analysis has great importance in ride comfort of
automobile. The vibration and noise should be kept within
certain limits. All selected anti roll bar materials predict same
natural frequencies and the corresponding mode shape.
In modal analysis only boundary conditions are applied and no
load is acted on the anti roll bar.
Figure 7. Mode Shape of third and fifth of Anti Roll Bar
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International Conference on “Design, Manufacturing and Mechatronics” ICDMM 2015

13. Finite Element Based Fatigue Analysis
• Main purpose of Finite Element Based Fatigue tool using for Anti Roll Bar
simulation – during the design stage of development process to enable
reliable fatigue life calculations.
• Input Parameter and Fatigue Analysis Cycle
Fig. 5 Fatigue Analysis Prediction Strategies
Fig. 6 FEM Based Fatigue Analysis Cycle [11]
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14. Finite Element Based Fatigue Analysis
• The life data analysis is a tool to be used here to predict the fatigue life of Anti Roll Bar.
• Fatigue life results are based on analytical result and resulting S-N graph
Fig. 7 S-N curves for E-Glass/epoxy composite [2]
AISI 1020 SAE 4340
SAE 5160 SAE 9262
Fig. 9 S-N Curve for Selected Materials [9]
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15. Results and Discussion
• Fatigue Life
Fig. 9 Fatigue Life of AISI 1020 Anti Roll Bar Fig. 9 Fatigue Life of SAE 4340 Anti Roll Bar
Fig. 9 Fatigue Life of SAE 5160 Anti Roll Bar Fig. 9 Fatigue Life of SAE 9262 Anti Roll Bar
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International Conference on “Design, Manufacturing and Mechatronics” ICDMM 2015

16. Results and Discussion
• Fatigue Damage
• Mean Biaxiality Ratio
Fig. 13 Plot of Fatigue Damage – SAE 4340
Fatigue damage is defined as the design life divided
by the available life. Fig. 13 shows Fatigue Damage
plot for SAE 4340 material
Fig. 14 Mean biaxiality ratio for SAE 9262 anti roll bar
Biaxiality indication is defined as the smaller
principal stress divided by the larger principal stress
with the principal stress nearest zero ignored.
Minimum value of -1 mean biaxiality ratio obtained
at node of 1006, whereas maximum value of 0.64
obtained at node of 686.
• Biaxiality of zero corresponds to uniaxial stress
• Biaxiality of –1 corresponds to pure shear
• Biaxiality of 1 corresponds to a pure biaxial state01/25/16 16

17. Results and Discussion
Fixed amplitude deflection value is +/- 123. 33 mm predicted from simulation result.
Material Fatigue Life in
Cycles
Damage Mean
biaxiality
ratio
AISI 1020 1.03 E+03 2.87E-02 0.64
SAE 4340 5.39 E+04 1.85 E-05 0.65
SAE 5160 3.77 E+06 2.64 E-02 0.64
SAE 9262 3.42 E+03 2.91 E-04 0.64
Table 5 : Fatigue simulation results of anti roll bar
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18. Conclusion & Future Scope
• In application to ANSYS Workbench, Finite element based static analysis
predicted maximum value of von-mises stress of 767.46 MPa and
maximum principal stress 581.35 MPa. These calculations were done for
fatigue simulation of constant amplitude loading.
• Fatigue simulation were calculated using ANSYS n code Designlife
software shows higher fatigue life for SAE 5160 with comparison to AISI
1020, SAE 4340 and SAE 9262 under same loading conditions above
ductile to brittle transition temperature.
• Using ANSYS n code Designlife, fatigue simulation comparison also done in
terms of Fatigue life, Fatigue Damage and Mean biaxiality ratio.
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19. Conclusion & Future Scope
• Finite element analysis can be used directly to calculate fatigue damage and
the damage contour shows that the highest damage value.
• Finite element method using CAE tool like ANSYS n Code Design Life prove
the reliability of the validation methods based only on simulation, thereby
saving time, material and production costs for a complete product
realization.
• It is proposed to conduct the fatigue analysis after DBTT for AISI 1020, SAE
4340, SAE 5160 and SAE 9262 materials in order to evaluate its real
environment fatigue life for extreme conditions.
01/25/16 19International Conference on “Design, Manufacturing and Mechatronics” ICDMM 2015

20. References
[1] Michael Doody, 2013, “ Design And Development Of A Composite Automotive Anti-Roll bar”, Master
Thesis, University of Windsor ,Ontario, Canada, pp. 1-103
[2] Preetam Shinde, M.M.M. Patnaik, 2013, “Parametric Optimization to Reduce Stress Concentration at
Corner Bends of Solid and Hollow Stabilizer Bar, ” International Journal of Research in Aeronautical and
Mechanical Engineering, 1(4), pp. 1-15
[3] Padmanabhan K, 2009, “Design and Optimization of Automobile Axle Stabilizer Bars for Fatigue Strength,
Journal of Manufacturing Technology and Management (IIPE Society Journal), 3(1), pp. 23-28
[4] Adam-Markus WITTEK, Hans-Christian RICHTER, 2010, “Stabilizer Bars: Part 1. Calculations And
Construction”, 5(4), pp. 135- 143
[5] J. Marzbanrad, A. Yadollahi, 2012, “Fatigue Life of an Anti-Roll Bar of a Passenger Vehicle,” World
Academy of Science, Engineering and Technology, 6, pp. 204 – 210
[6] N. Zulkarnain, H. Zamzuri, Y. M. Sam, S. A. Mazlan and S. M. H. F. Zainal, 2014, “Improving Vehicle Ride
and Handling Using LQG CNF Fusion Control Strategy For An Active Anti-Roll Bar System,” Abstract and
Applied Analysis, Hindawi, 2014 (2014), pp. 1– 14
01/25/16 20International Conference on “Design, Manufacturing and Mechatronics” ICDMM 2015

21. References
[7] Mr. Sahadev Shivaji Sutar, Mr. Gorakshanath Shivaji Kale and Mr. Hrishikesh Sharad vaste, 2014,
“Analysis of Ductile-to-Brittle Transition Temperature of Stainless steel of 304 grades International
Journal of Innovations in Engineering Research and Technology,” 1(1), pp. 1-10
[8] Orkun Umur Önem, 2003, “Effect Of Temperature On Fatigue Properties of DIN 35 NiCrMoV 12 5
Steel,” Master Thesis, The Middle East Technical University, pp. 1-73
[9] ANSYS Workbench Engineering Data
[10] ANSYS n Code Designlife Material library
01/25/16 21International Conference on “Design, Manufacturing and Mechatronics” ICDMM 2015

22. Thank you…