FAILURE ANALYSIS OF REAR AXLE (BANJO BEAM) HOUSING OF A UTILITY VEHICLE

This paper describes the failure analysis of a rear axle housing used in a utility vehicle. This vehicle had been involved in an accident. The rear axle shaft housing was found broken into two pieces. In present study utility vehicle rear axle housing was selected to study the failure analysis experimentally and numerically. The failed rear axle housing was undertaken to check its integrity which includes visual examination, chemical analysis, photo documentation, micro hardness test, and metallographic tests to evaluate the failure. Failure analysis of a rear axle housing used in a utility vehicle was studied to determine stress concentration area. Based on field study strain gauges are mounted on failed parts to determine stress intensity and joint analysis were validated with Finite Element Analysis results. SEM (scanning electron microscope was used to examine the failure zones. The analysis showed that the rear axle housing suffered a fatigue induced fracture. The fracture initiated at the weld joint between back plate and rear axle housing, where a stress concentration was created. This stress concentration was higher than the stress concentration considered at the time of design which results into the breakage of the housing into two parts. Also stress concentration was found more on left side as compared with right side. Hence, all the reported failures were broken on the left side only. So, the causes of the failure of the rear axle housing was due to defective geometric design of the rear axle housing. To avoid this failure in future the axle housing thickness is changed from 3.5 mm to 4 mm. This design change sustained the high stress concentration which was analysed with the help of finite element analysis.