Time-varying Reliability Analysis On Large Scale Morphing Wing Mechanism

As a major part of the aircraft in safe service,the reliability of the morphing wing directly affects the life of the aircraft.There are many uncertainty parameters in the whole life time of the morphing wing mechanism,and the accumulation of these uncertainty factors causes its performance degradation and reliability reduction.Therefore,taking into consideration the uncertainties in the morphing wing mechanism can effectively improve its reliability and safety.The traditional reliability does not consider the time factor,however,the reliability of the mechanism always shows the time-varying characteristics due to the influence of the material performance degradation and dimensional decay during the long service time.Therefore,this research develops an efficient and high-precision time-varying reliability analysis method of uncertain mechanisms,and applies it to the reliability analysis of large scale deformed wing mechanisms.The main research contents of this thesis are as follows:A time-varying reliability analysis method for uncertain mechanisms is proposed to address the phenomenon of performance degradation caused by corrosion,wear and aging of the components during the mechanism motion with the extension of service time.Firstly,a mechanism motion error model is established based on the error between the actual motion and the desired motion.Secondly,a mechanism strength reliability model is established based on the stress-strength interference model.Again,the time-varying functional function is discretized into several static functional functions and approximated as several normal variables,and the correlation coefficient matrix and probability density function are calculated and the time-varying reliability of the mechanism is obtained by one high-dimensional Gaussian integration.Finally,the validity of the method is verified by two numerical examples.2.For the time-varying uncertainty problem in the morphing wing mechanism,the time-varying reliability analysis method of the mechanism motion based on process discretization is applied to the large scale morphing wing mechanism.Firstly,the motion time variation reliability of the morphing wing mechanism is analyzed based on its motion analysis.Secondly,the finite element model of the morphing wing is established according to its material properties and boundary conditions.According to the external load of the morphing wing and the dimensional parameters of the morphing wing,the stress and strain simulation analysis of the morphing wing is performed by using the finite element analysis software to obtain the maximum stress distribution of the morphing wing.Again,based on the quadratic response surface proxy model technique,the functional functions are fitted.Finally,the time-varying reliability of the mechanism is calculated by using the time-varying reliability analysis method functional function to obtain its time-varying reliability.In this work,the time-varying reliability analysis method of mechanism motion is studied to provide a new idea for the design of mechanism in the whole life service period,and the method is applied to the large scale deformed wing mechanism to provide theoretical guidance for the whole life reliability design of morphing wing.