航空电连接器热疲劳失效机理研究

Research on Thermal Fatigue Failure Mechanism of Aviation Electrical Connectors

电连接器插孔是弹性元件,在交变热应力的作用下易产生热疲劳,出现应力松弛现象,从而影响电连接器的接触可靠性。结合加速寿命试验理论,提出了一种电连接器热疲劳试验方案,设计了试验电路并进行了试验,分析了电连接器的热疲劳失效机理。试验结果表明:试品的接触电阻值随温度循环次数的增加而缓慢增长,其宏观原因是插孔收口处孔径增加,接触件间接触力减小;循环应力中温差或温度变化率的增加,会加速连接器接触电阻的增长。试验后试品插孔的金相分析发现:温度循环条件下,连接器插孔中微观组织结构的变化,即插孔中的α相晶粒尺寸和滑移线密度均有所增加,滑移方向差异化程度增强,是导致其接触可靠性和性能逐步蜕化的根本原因;温差范围与温度变化率对电连接器性能蜕化的综合作用取决于滑移线密度与滑移方向差异化程度的"对抗"结果。

Jack of electrical connectors is an elastic element. It is easy to show thermal fatigue and stress relaxation phenomenon under the effect of alternating thermal stress, which affects the contact reliability of electrical connectors. A thermal fatigue test scheme is proposed, and a test circuit is designed for experiment. The thermal fatigue failure mechanism of electrical connectors is analyzed. The test result shows that the value of contact resistance increases slowly with the increase in the number of thermal cycles. The macroscopic reason is that the aperture of jack increases and the contact pressure between contacts decreases. During test, the temperature difference or temperature change rate will accelerate the growth of contact resistance. Based on the metallographic analysis of jack after experiment, it is found that the change of microstructure （the crystal size and slip line density increase, the difference of slip di- rection is enhanced） is the fundamental reason to lead to the stress relaxation phenomenon of jacks and the contact reliability degradation of electrical connectors. The comprehensive effect of the temperature difference and temperature change rate on the performance degradation of electrical connectors depends on the ＂confrontation＂ between slip line density and slip direction number.