Research On The Constant-stress Accelerated Degradation Modeling And Validation Of Electrical Connector

As a fundamental electromechanical component in many types of equipment,the electrical connector could quickly realize connection and separation of the equipment with ground or the interstage.It is consequently numerous in electrical and control system of many types.In other word,it is an indispensable interface element in electrical energy transmission as well as signal transmission and has a great influence on the lifetime of type systems.Therefore,it is significant to accurately evaluate the storage life of electrical connector for life determination and extension of some equipment.During storage period,electrical connector,following the equipment,will experience a series of status such as inventory,testing,transportation,training,alert and so on.In each status,electrical connector is respectively affected by temperature,humidity,vibration,electricity insertion-extraction and other factors.Moreover,it is necessary to control the time interval and the duration ratio of different stresses accurately in the storage life accelerated test of electrical connector in consideration of various factors in storage profile,whose premise is that the degradation model of electrical connector considered temperature only under storage condition has been obtained.However,existing mixed effect models can't meet the accuracy requirement of degradation path in accelerated test in view of stresses of the whole storage profile.Simultaneously,in terms of contact pairs' surface microtopography and the micro-mechanism of its' electrochemical corrosion,some Markov process seems more practical.Hence,it is essential to study models which can accurately describe the performance degradation process of electrical connector under temperature stress.This dissertation,taking the widely-used model Y11P-1419 electrical connector as the object,firstly confirms the microscopic mechanism of the growth and extension of contact pairs' surface oxidation film.Secondly,the thesis,according to the microscopic mechanism,builds a new degradation model for electrical connector's contact performance based on Brownian motion and correlates correlates temperature stress with the degradation rate as well as the diffusion coefficient which is namely accelerated degradation equation.Lastly,the paper applies White testing and Breusch-Pagan testing to check the electrical connector's contact performance degradation model and the accelerated degradation equation from mechanism levels.The result proved the model's correctness and provides a theories foundation for controlling time points and time-periods accurately when stresses are applied in accelerated tests for evaluation of electrical connector' storage life in the future.The dissertation is composed of five chapters whose specific contexts are as follow:Chapter 1: Firstly,the research background,purpose and significance are clarified.Secondly,research status and existed problems in related fields are analyzed from following three aspects: performance degradation model,statistical analysis of test data and methods for model checking.Finally,the main idea and contexts are proposed.Chapter 2: this chapter mainly analyzes the failure modes and failure mechanism of electrical connector in storage environment and draws a conclusion that the oxide film growth is the main reason for the increasing of contact resistance is presented.Meanwhile,from aspect of contact pairs' surface holes,contact spots' sizes and distribution,the chapter studies the randomness of the growth and extension of contact pairs' surface oxidation film and reveals the basic reason why contact resistance increase presents a undulatory trend.Chapter 3: This chapter,taking the analysis of the failure mode and failure mechanism of electrical connector in storage environment and the micro-mechanism of contact performance degradation amounts of electrical connector presenting a trend of fluctuation into consideration,describes the random process of contact performance degradation amounts of electrical connector by use of Brownian motion and builds a model for contact performance degradation of electrical connector based on Wiener process.Moreover,the chapter also studies the relationship between coefficient of deviation and temperature stress as well as diffusion coefficient and temperature stress based on the central limit theorem and the theory of chemical reaction and builds the accelerated degradation equation.Chapter 4:This chapter proposes an accelerated degradation test plan for electrical connector under temperature stress which mainly consists of sample size,test interval and censored times at each test stress.Then the performance degradation date of electrical connector at each stress is collected,based on which,the K-W method is applied to electrical connector's homogeneity test as well as least square method and two-step maximum likelihood method to statistical analysis.Finally,the chapter gives out parameters evaluation of performance degradation model and accelerated degradation equation.Chapter 5:This part provides methods to check the degradation model of electrical connector's contact performance and the accelerated degradation equation.And more especially,the chapter,using map analysis method,White Testing and Breusch-Pagan Testing,utilizes four groups of ADT data under constant temperature stresses to achieve the model checking of electrical connector performance degradation.Then from the statistical test of test data,the accelerated equation of electrical connector is checked in linear regression method.The result shows that the model does meet the random process of electrical connector's contact performance degradation and the change law of performance degradation with temperature.Therefore,it proves that the model built from aspect of failure mechanism is correct.Chapter 6:The works of this dissertation are summarized and suggestions for further Research are proposed.