Research On The Reliability Of Wire Spring Connector

A hyperbolic wire spring connector is a kind of jack component with high reliability.The elastic wires in the jack are arranged in straight generating of one sheet hyperboloid form and form a fixed angle of inclination with the straight generating of the inner sleeve.When the pin is inserted into the jack,the pin and wire springs in the jack are simultaneously in contact with each other to form independent current paths.Wire spring connectors are currently used in separating shedding equipment because of its low and stable contact resistance,soft withdrawn force,anti-vibration,impact resistance,long insertion life(more than 5000 insertion times).With the continuous improvement of reliability requirement of the system equipment,long-term storage at room temperature requirements are put forward,so that the connector components also need long-term storage life correspondingly.However,the failure mechanism and degree of degradation of the wire spring connector during the degradation of electrical contact performance under long-term storage conditions are not clear.Therefore,through theoretical analysis and experimental verification,the contact characteristics of wire spring contact pairs and the degradation characteristics of electrical contact properties under long-term storage conditions are discussed and analyzed in this paper.Based on the failure mechanism,a prediction method of storage degradation parameters is proposed,which lays a theoretical foundation for the design and storage reliability of wire spring connectors in the future.Aiming at the stress relaxation failure mechanism that may occur under long-term storage,the effect of structural dimension error on contact force is firstly analyzed by the size distribution characteristics of the wire spring contact.The wire spring contact pair is taken as the research object,the size error characteristics affecting the contact force of the wire spring contact pair are analyzed first.The probability distribution of the relevant structure size of the wire spring contact pair is obtained by actual testing,and then the probability distribution of the contact force is simulated by Monte Carlo and the distribution model is validated.The statistical model of contact force obtained in theory can be used to judge the qualifications of products and to anticipate possible problems.Finally,by comparing the theoretical value range of contact force with the design requirements of product contact force,it is found that the tolerance range is below the design requirements,which does not fully meet the design requirements of the spring connector product.In practical applications,electrical contact failures such as instantaneous turnoff and bad contact are more likely to occur.In order to explore the failure of the wire spring connector under long-term storage condition,on the one hand,on the basis of the existing research results of the stress relaxation of wire spring contacts in the mated state,the wire spring jack and the pin are separated and placed in a high-temperature box.Accelerated degradation experiments were carried out and the changes of separation force and contact resistance of wire spring contacts were monitored at regular intervals.The stress relaxation in the un-mated and mated state were compared and analyzed.Based on Larson-Miller formula and experimental data,the stress relaxation degradation model of wire spring connectors is established.It is predicted that about 4.57%stress relaxation will occur in un-mated state after 30 years storage at room temperature(25?),which is less than 10%.It is considered that the stress relaxation can be neglected.On the other hand,by detecting the copper concentration on the surface of the wire spring after high-temperature acceleration experiment and the contact resistance of the wire at the corresponding time,the speculation of the copper diffusion to the gold layer is verified.The relationship between contact resistance and copper concentration diffusion was established by diffusion formula and experimental data.Based on the diffusion failure mechanism,it is predicted that the mass fraction concentration of copper diffused into the surface of the gold plating layer after 30 years is 39.68%in the three components of copper,oxygen and gold,and the contact resistance of the wire spring contact is increased by about 1.19m?.According to relevant theory and experimental results of electrical contact,the mode and degree of influence of two failure mechanisms on electrical contact performance degradation of the wire spring connector under long-term storage are discussed.Finally,from the point of view of failure physics,the internal factors and external environment which cause the failure of the wire spring connector under long-term storage conditions are analyzed.The failure physical equation of the wire spring connector under temperature stress is established as Arrhenuis equation,and the reliability statistical model of the wire spring connector is finally determined as Arrhenuis-Weibull model by combining the probability and statistics theory of the failure life distribution of the electrical connector.It provides technical support for accelerated reliability life test and calculation of characteristic values of reliability life of electrical connectors in the future.