Bolt Assembly Optimization and Life Prediction Based on Creep Curve

This paper research the phenomenon that the engine bolts would creep under the preload and the high temperature in the operation process, and creep could cause the degradation of preload leading to engine failure. Through the high-temperature creep test and the stress relaxation test, the creep curve and stress relaxation curve are obtained. With the data of creep test, a method is proposed to find the turning time from the rapid stage to the steady stage of creep process more accurately. Then the retightening operation is applied at the turning time under the same test conditions to optimize the bolt assembly and the new stress relaxation curve could be obtained. According to the data before and after optimization, the life distributions of bolt could be estimated by the method of mathematical statistics.