Design optimization focused on failures during developmental testing of the fabricated rear-axle housing

Abstract

In the development of fabricated rear axle housing for heavy-duty off-road applications, engineering against failures was challenging due to budget and timeline limitations. Rear-axle housing failure on the road is a threat to other road users and hence zero failures targeted in the design verification phase. The analysis of rear axle housing beam failures had been well established. Failure in Torture-Track (TT) was resolved by engineering against the stress concentration at the notch, by adding inner side weld at the central section of the axle. This optimized design got verified in FEA and Rig testing for maximum stress concentration reduction and fatigue life improvement, respectively. The optimized design completed the target mileage in TT successfully. Further strengthening of the central section resulted in the failure mode shift from the central section to the beam section (proved in Rig testing). Hence, reestimated the life of rear-axles based on new strain measurement in severe operation. The strain measurement data from off-road testing of the design prototype closer to real-world application gave more accurate stress concentration results. It became the critical influencer to reduce further design iterations based on failures observed during design verifications in the new product development process.