| As an essential basic component of model equipment,electrical connector is mainly used to realize the electric energy and signal transmission of model equipment,which is widely used in model equipment.If an electrical connector fails,it may cause the failure of the whole model equipment,so that it can not complete the task according to the specified requirements,resulting in huge losses.Therefore,it is of great significance to evaluate the life of electrical connector accurately for the reliability design and evaluation of model equipment.The storage life of the electrical connector improves with the improve of the model equipment design life.Accelerated degradation test should be used to evaluate its life.In the accelerated degradation test of electrical connector,due to the immature on-line monitoring technology,the performance degradation data is usually obtained by timing test,which makes the actual test profile of electrical connector turn into the temperature cycle stress profile.The existing accelerated degradation test methods such as constant stress and step stress can not effectively evaluate its life.Therefore,this paper starts from the core problem of accelerated degradation test technology of temperature cycle,which is the establishment of product performance degradation model.Combined with the characteristics of randomness of performance degradation process of electrical connector,the research on Modeling and verification of random process of electrical connector under temperature cycle stress is carried out from the level of failure mechanism.This article takes the Y11P-1419 electrical connector as the research object.The stress profile of Y11P-1419 electrical connector in the test state is determined as cyclic stress.The environmental effect,failure mode and failure mechanism of Y11P-1419 electrical connector under the temperature cycling profile are analyzed.Starting from the formation of oxide film and fretting wear on the surface of electrical connector under the temperature cycling test,the micro mechanism of random fluctuation of contact resistance of electrical connector during the increase process is analyzed,and the performance degradation model based on Wiener process is established.Based on the chemical reaction theory,the accelerated degradation equation of electrical connector is established.The temperature cycling accelerated degradation test was carried out on the electrical connector,and the corresponding performance degradation data were obtained.Finally,on the basis of the data obtained,autocorrelation method and D’Agostino D method are used to verify the performance degradation model of electrical connector,and linear regression analysis method is used to verify the accelerated degradation equation of electrical connector under temperature cyclic stress,the theoretical derivation of failure mechanism and the correctness of the model built from the failure mechanism level are verified by the comparative analysis of the test pieces before and after the test with SEM and EDS.This paper is divided into six chapters,as follows:Chapter one:firstly,the research background and significance of this paper are introduced.Secondly,aiming at the accelerated degradation test technology,reliability modeling of products under cyclic stress and reliability of electrical connectors,the research status and existing problems at domestic and foreign are comprehensively described.Finally,the research objectives and relevant contents of this paper are given in view of the deficiencies.Chapter two:it is determined that the stress profile in the test state is cyclic stress.According to the structure and function of the electrical connector,the environmental effect analysis of the electrical connector under cyclic stress is analyzed,and the contact failure is defined as the main failure mode.Finally,from the micro level,the failure mechanism is determined to be the growth of the oxide film on the surface under the temperature stress and fretting wear of contact surface during temperature cycling leads to accumulation of oxide wear debris;The fluctuating growth of contact resistance is mainly caused by the random distribution and different shapes of micro holes on the contact surface,the random change of contact spot position caused by fretting wear and the random entry and exit of oxide film from the contact area.Chapter three:based on the analysis of the failure mechanism of the electrical connector under the temperature cyclic stress,and considering the micro reasons of the random fluctuation of the contact resistance growth,the performance degradation model,acceleration degradation equation and life distribution model of electrical connector based on Wiener process under temperature cycling stress are established.Chapter four:the specific accelerated degradation test plan of Y11P-1419 electrical connector is given firstly,which includes the maximum temperature,cycle period,sample quantity,temperature rise slope,temperature fall slope and specific test method under each cycle stress.Then the accelerated degradation test is carried out on the electrical connector,and the performance degradation data in the test process are obtained.Through Kruskal Wallis test method,all the performance degradation data can be considered from the same distribution.Finally,based on the performance degradation data obtained during the test,the unknown parameters in the model are estimated by two-step estimation method.Chapter five:based on the test data of electrical connector under temperature cycling stress,the performance degradation model of electrical connector is verified by autocorrelation method and D’Agostino D test method,and the accelerated degradation equation of electrical connector is verified by linear regression analysis method,the theoretical derivation of failure mechanism are verified by the comparative analysis of the test pieces before and after the test with SEM and EDS.Chapter six:the research work of this paper is summarized and the future research content is prospected. |
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