Investigation into effect of rubber bushing on stress distribution and fatigue behaviour of anti-roll bar

Anti-roll bars used in ground vehicle to reduce body roll by resisting any uneven vertical motion between the pair of wheels suffer from fatigue failure. In this study, several structural analyses of an anti-roll bar made of SAE 9262 were carried out by means of finite element (FE) technique to determine stress distributions. The result of FE analyses indicated that equivalent stress in the inner surface of the corner bend was the maximum; wherein the shear stress dominates. Fatigue tests that were carried out under 7° rotational loading also confirmed the failure location. In addition, the effects of hardness and wall thickness of rubber used in bushing on stress distribution were investigated for various polyurethane rubbers (75, 85, 90 and 95 Shore A) and bush wall thickness (5.25, 7 and 8.75 mm), systematically. It was found that both soft rubber and thick wall thickness tend to reduce stress in the critical region. Based on the results of FE analyses, several proof tests of anti-roll bars with specific bushing were planned. It was concluded that the reduction of equivalent stress in anti-roll bar accomplished by modifying the bushing provided a significant improvement in the fatigue life. Approximately 9% improvement in the fatigue life with respect to base bushing could be obtained by selecting relatively soft rubber materials. For the rubber hardness 75 Shore A, changing in wall thickness from 7 mm to 8.75 provided 11% improvement. Total improvement from the proof tests reached up to approximately 21% in the fatigue life.