Effect of hydroforming on structural fatigue life of multilayer reinforced S-shaped bellows in liquid rocket engine
It is one of important issues in the development of reusable liquid rocket engine that refining the fatigue life assessment methods for reinforced S-shaped bellows in the gas swing system of liquid rock-et engines and enhancing the prediction accuracy of its fatigue life.In order to acquire the actual life data after hydroforming and assess the impact of the forming process,a comprehensive fatigue life analysis method is proposed for multilayer reinforced S-shaped bellows.This method accounts for the disparate effects of the forming and preparation procedures on the geometrical configurations and mechanical prop-erties of different structural regions.Based on the forming simulations and tensile test results,a finite ele-ment model of the actual bellows has been developed for three-dimensional simulation analysis to obtain the cyclic load information at the structural danger points under various high internal pressure and differ-ent oscillating operating conditions.In addition,based on the low cycle fatigue characteristics of bellows,the cycle life of bellows is estimated and compared by using the meridional stress-strain data and the Man-son-Coffin(M-C)formula corrected by the average stress and strain.The results indicate that the loca-tion and size of the weak point of the bellows fatigue life are related to the cyclic swing angle.The fatigue predictive analyses considering hydroforming effects are more consistent with actual conditions,and show deviations from theoretical model predictions,highlighting the importance of considering these differences in structural design,optimization and health monitoring.
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维普
