Abstract

In this work, a population of fractured joint bolts have been collected from automotive and tire plants, and an analysis of each bolt is performed to determine the cause of failure, and crack initiation site location on the bolt.  The bolts are then grouped by failure cause and location to investigate the probability of failures and probability of failure location.  The results show that low-cycle and high-cycle fatigue account for 70% of bolt failures, and that 80% of bolt failures occur deep in the threaded region in the bolt.  Failure locations that were closer to the intersection of the head and the shank were only found in samples that were determined to have failed due to low-cycle fatigue. Still then, only 40% of bolt failures that result from low cycle fatigue take place closer to the head, and 60% of the failures occur in the threaded region away from the head. The results of this study can help predict the failure location on the bolt, and thus help guide preventive maintenance procedures on joint bolts.