Identification Method Study For Degradation Mechanism Consistency Of Springs In Accelerated Storage Testing

Accelerated testing is an efficient and feasible technical approach to predict the storage life of springs.However,the conditions of accelerated testing are different from the actual storage condition of the spring.Therefore,the life prediction obtained by the accelerated testing may be inaccurate.To avoid this problem,it is necessary to ensure that the degradation mechanism of the spring in the accelerated storage testing is consistent with the actual storage degradation mechanism.Thus,it is of great significance to study the identification method for degradation mechanism consistency of springs in accelerated storage testing.This paper studied the degradation mechanism consistency of spring stress relaxation from the theoretical research,modeling and simulation,data analysis,testing verification.From the two aspects which are microstructure analysis and accelerated testing data separately,the identification method for degradation mechanism consistency was proposed.It can provide the foundation for profile design of the spring accelerated storage testing.This paper includes the following parts:1.An identification method based on the microstructure analysis for degradation mechanism consistency was proposed.The method and steps based on the microstructure for judging the degradation mechanism consistency were established.The stress relaxation mechanism of austenite stainless steel springs was preliminarily analyzed.The main technical methods of qualitative and quantitative analysis for microstructure were provided.2.An identification method based on the accelerated testing data for degradation mechanism consistency was proposed.The widely used accelerated testing models were analyzed deeply,and the spring stress relaxation model and spring acceleration model was established.Based on the activation energy constant principle,the Weibull distribution and the spring acceleration model,the constraint conditions for judging the spring degradation mechanism consistency were proposed.According to the constraint conditions,the identification algorithm of degradation mechanism consistency for the spring accelerated storage testing was provided.The identification algorithm was simulated and analyzed,which was proved to be effective.3.The austenite AISI 304 stainless steel helical compression spring was taken as the object,and the spring accelerated storage testing was designed and implemented.The application of the degradation mechanism consistency identification method based on accelerated testing data was verified.The results showed that the method can effectively determine whether the degradation mechanism of the accelerated storage testing changed,and determine the critical stress level and effective testing data for ensuring the consistent degradation mechanism.Thus the spring storage lifetime could be predicted accurately.4.The degraded spring samples under different conditions were taken as the object,and the spring microscopic analysis testing was designed and implemented.The application of the degradation mechanism consistency identification method based on microstructure analysis was verified.The results showed that the method can effectively determine the spring stress relaxation mechanism under different conditions,analyze the variation rule of stress relaxation mechanism under different conditions,and realize the qualitative identification and quantitative detection of the degradation physical characteristics.