Stability Analysis Of Ultrasonic Vibration System Based On Reliability Theory

Ultrasonic vibration systems are widely used in special processing fields.It is a complex mechanical coupling system with high reliability and stability.However,in the working process,due to the heterogeneity of the material,the cutting force may change,thus affecting the stability of the system..In the process of system operation,there are not only two states of normal and fault,but also the main performance indexes of the system gradually decline with the passage of time,reaching the fault threshold of the system;finally,it will cause the loss of system working stability,the process of system property degradation has information closely related to system stability,the failure probability of ultrasonic vibration system under working condition is calculated by using the method of reliability theory,The idea of probability is used to study its stability,the reason is that the properties degradation of system is uncertain.So study the system's working stability is great important.The main contents of this paper are as follows:1.The failure mechanism of ultrasonic vibration system is analyzed.Firstly,the working characteristics of ultrasonic machining system are analyzed from its structure and function,and then the failure mechanism of ultrasonic vibration system is analyzed,and the failure type is judged as degradation type;the main characteristic vectors of working stability of ultrasonic vibration system are proposed,including frequency and amplitude;Accelerating stress is selected as cutting force,analyze whether the system can be accelerated and the results show that it is feasible.2.The working stability modeling and analysis method of ultrasonic vibration system are studied.The degradation model,distribution model and acceleration model involved in one-dimensional accelerated degradation modeling of ultrasonic vibration system are described in detail.On this basis,Copula function is introduced as the connection function of binary accelerated degradation modeling,and a method for evaluating the working stability of ultrasonic vibration system including acceleration information,degradation information and double index information is proposed.3.The working performance of ultrasonic vibration system is studied experimentally.According to the failure mechanism and working characteristics of ultrasonic vibration system,the accelerated degradation experiment scheme under constant stress is adopted;the y-direction cutting force load of ultrasonic vibration system is analyzed;the accelerated degradation experiment scheme of ultrasonic vibration system is designed and tested.4.The performance degradation model of ultrasonic vibration system was established to evaluate the working stability.The amplitude and frequency of the ultrasonic vibration system are modeled by one-dimensional working stability.Then,by calculating and comparing AIC,BIC and DIC values,the best Copula function is selected to establish the two-dimensional accelerated degradation model of ultrasonic vibration system.The working stability of ultrasonic vibration system considering only one degradation quantity and considering the independence and correlation of two degradation quantities is analyzed and compared the stability of the system is evaluated.