fatigue simulation of automobile antiroll bars

Presented ByAmol Bhanage1 & Dr. K. Padmanabhan2

1Research Scholar & 2 Professor, SMBS, VIT University, Vellore

Paper ID : ICDMM2015-058

Static and Fatigue Simulation of Automotive

Anti Roll Bar Before DBTT

ISET 2015International Conference on “Design,

Manufacturing and Mechatronics”ICDMM 2015

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

05/01/23 2International Conference on “Design, Manufacturing and Mechatronics” ICDMM 2015

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.


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


Background

Author ConclusionMichael 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


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.


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


Specification and Material Properties of Anti Roll BarTable .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 9262Young’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


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


For Bar with round profile

• 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


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


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


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]


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]

05/01/23 14

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 05/01/23 15

International Conference on “Design, Manufacturing and Mechatronics” ICDMM 2015

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 state05/01/23 16

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


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.


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.


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


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


Thank you…