Thermal Stress Analysis Of Electrical Connector Operating At Cryogenic Temperatures

An electrical connector is an electro-mechanical device that connect components modules and units in various kinds of electronic systems, playing an important role in energy transfer and electrical signal transmission. Unlike the connectors for the common applications, the connecters used in space missions must adapt to the harsh working conditions, one of which is cryogenic temperature (for instance,90K and20K)The base of connector is matching sealed between the glass and metal materialto realize the signal transmissions and seals. In general, electric vacuum glass DM-305and DM-308, and7070glass are used as sealing materials to match the expansion alloys in China. The coefficients of thermal expansion of glass and expansion alloy are required to be close in the operating temperature region, so that the residual stress at the sealing part can be reduced to enhance the sealing performance and life span of connectors. Currently, connectors for the room-temperature applictions are well developed, while the sealing performance of cryogenic connectors used in the space applications is untable and desired to be improved. The reason lies in the fact that the materials and the corresponding physical property data used for the room-temperature connectors are still adopted in cryogenic connectors’design and manufacture processes, and the effects of cryogenic conditions are not taken into account.To improve the sealing performance of cryogenic connectors, this thesis focuses on the following two problems:1) the lack of linear expansion coefficient data of expansion alloy and sealing glass at cryogenic temperatures are in shortage; and2) the little consideration of the thermal stress caused by cryogenic temperatures. The research work was conducted on the following three aspects.After the declaration of the basic principal and method of measuring coefficient of linear expansion, the relationship between linear expansion and strain gages are given based on measurement technology.The linear expansion at cryogenic temperature measurement system is designed and built up to measure the coefficient of linear expansion at different temperatures for several kinds of materials.1) Electrometric method was used to measure linear expansion coefficients of expansion alloys and sealing glasses from room temperature to liquid nitrogen temperature, based on the comparison of present measure methods. The principal of electrometric method was presented to derive the formula for the dependence of the linear expansion coefficient on the strain gauge resistance. And then, an experimental apparatus was designed and built up to conduct the measurement.2) The linear expansion coefficients of commonly used expansion alloys (4J29,4J33,4J34,4J36) and sealing glasses (DM-305, DM-308, DW-211) were measured in the range from room temperature to liquid nitrogen temperature.3) Based on the measured linear expansion coefficients, the stress caused by thermal distortion due to the cooling process from room temperature to liquid nitrogen temperature was stimulated with the software ANSYS. The effects of the linear expansion coefficients, the operating temperature, and the distance between pins on the thermal stress of connectors were analyzed.