Reliability Design Method Of The Locking Mechanism For Electrical Connectors

As a key component to achieve electrical signal connection and separation for the type and system,the separation electrical connector has high coverage on type system.In recent years,the model or system cannot be emitted on time sometimes due to its reliability problems.It does not only cause significant economic losses,but also leads to serious consequences.The locking mechanism is the key component to realize the reliable connection and separation of the electrical connector,and also it's the weak link for the reliability of the separation electrical connector.According to the statistics,the problem related to separation performance problem takes up about 66.7% in the reliability issue for separating the electrical connectors,for example,the JF2 electrical connectors have repeatedly encountered the dis-separation after receiving the electrical separation signals.The reason lies that the locking separation mechanism of the electrical connector of China is imitated from foreign products and the dynamic characteristics of mechanism separation,including the influencing disciplinarian of factors,and the modes of failure and the associated mechanism is not well identified.Meanwhile,there is a lack of corresponding reliability modeling and design techniques for the connectors.Therefore,the JF2 locking mechanism of the electrical connector is chosen as the study object of this paper.The dynamic characteristics of the concerning collision is carried out,the impact law of the separation performance is studied,the reliability modeling and evaluation methods and the reliability optimization design method are studied too.It is of great importance to improve the reliability of the locking mechanism and to ensure the success rate of the model launch.The background and significance of this paper is expounded in Chapter 1,the developing history and current situation of reliability,the development and existing problems of mechanical reliability,reliability studying status and existing problem of separation electrical connectors are analyzed and summarized,and then the research objectives and research contents of this paper are presents based on above discussion.In Chapter 2,the dynamic characteristics of locking mechanism are analyzed.According to the structure and working principle of the locking mechanism,the unlocking process for the mechanism is then divided into four stages: the first stage unlocking,the collision,the second stage unlocking and the connector separation.Based on the Lagrange equation and Hertz contact theory,the mechanism dynamics theoretical model concerning collision is established,which has laid a foundation for the reliability analysis,modeling and evaluation,as well as for the reliability optimization design of the locking mechanism.In Chapter 3,the dynamic simulation analysis and experimental verification of locking and separating mechanism are performed.By using the ANSYS Maxwell and ADAMS,two kinds of software,the parameterized dynamics simulation model of the locking mechanism is established.Comparing the solution results of the simulation with the ones from the dynamic theoretical model,it shows that the theoretical model and simulation model can be verified preliminarily.The kinematical characteristic curve for the separation process of the locking mechanism is obtained by the electromagnet dynamic displacement characteristic test and the high-speed image measurement technique,and then the theoretical model and the simulation model is verified further by comparing the simulation data and the theoretical data with the test data.Chapter 4 introduces the failure analysis of locking mechanism.The failure of the locking mechanism is defined,and the failure criterion is determined.With the aid of the simulation model,the effect rules of various factors to unlock and separation performance for locking separation mechanism are analyzed.The FMEA method is used to analyze the reliability of the locking mechanism and determine the main failure mode and the weak link of the mechanism.Combined with the dynamic model,the failure criterion of the locking mechanism is quantified,which provides the basis for reliability modeling,evaluation and reliability optimization design.Chapter 5 focuses on the reliability modeling of locking mechanism.The reliability characteristic parameter and reliability index of the locking mechanism are determined.Reliability structure level of the mechanism is established,and the security boundary equations of the first stage unlocking,the collision,the second stage unlocking and the connector separation are established.The distribution rules of the geometrical dimensions,material properties,load and electrical performance parameters are determined.A random Quasi-Monte Carlo reliability computing method is proposed,and the separation reliability of the locking separation mechanism is calculated out,but it is 99.83% which cannot reach reliability index 99.99%.So the mechanism needs following reliability designing.In Chapter 6 the reliability optimization design of locking and separating mechanism is introduced.Considering the given reliability index,the optimization design criteria based on the minimum basic size variety of the locking mechanism is proposed.The random Quasi-Monte Carlo method is used to further analyze the impact law of stochastic variables of mechanism on the reliability.The wire diameter,the mean coil diameter and the active coils number of the electrical unlocking spring,the rod spring and the separation spring are determined as design variables.The minimum absolute value of the change rate of each parameter is the objective function,the spring index,the strength,preventing solid condition and geometric relations are considered as the deterministic constraints.The probability constraint is that the mechanism separation reliability needs to be greater than 99.99%.The All-At-Once(AAO)reliability design model of locking separation mechanism is established.In view of the high dimension of the model,the analysis target cascading(ATC)and the random Quasi-Monte Carlo(RQMC)strategy for reliability optimization is proposed to optimize the reliability of the separation mechanism design.Finally,the whole research the paper is summarized and the future work is forecasted in Chapter 7.