The high surface accuracy design of a cable-net antenna structure under the disturbance of the extremely harsh space environment requires the antenna to have good in-orbit adjustment ability for surface accuracy. A shape memory cable-net (SMC) structure is proposed in this paper and believed to be able to improve the in-orbit surface accuracy of the cable-net antenna. Firstly, the incremental stiffness equation of a one-dimensional bar element of the shape memory alloy (SMA) to express the relationship between the force, temperature and deformation was effectively constructed. Secondly, the finite element model of the SMC antenna structure incorporated the incremental stiffness equation of a SMA was established. Thirdly, a shape active adjustment procedure of surface accuracy based on the optimization method was presented. Finally, a numerical example of the shape memory cable net structure applied to the parabolic reflectors of space antennas was analyzed.

This article presents the bolt self-loosening mechanism in curvic coupling due to the structural ratcheting under cyclic loading. Finite element simulations are carried out under several loading conditions with different preloads and cyclic torque loadings on curvic coupling. To avoid relative rotation between bolt and nut in simulation, the surface between the threads of bolt and nut are connected together. The finite element analysis results reveal that the local cyclic plasticity occurring near the roots of the engaged threads resulted in cyclic strain ratcheting. The structural ratcheting causes the gradual loss of clamping force with loading cycles in bolts and the stresses to redistribute in the curvic coupling. Either the structural ratcheting behavior or the fatigue strength of the curvic coupling is more sensitive to the magnitude of the torque load in contrast to the magnitude of the preload of the bolt. Comparatively, the large preload of the bolt or the low magnitude of the torque load is benefit for improving the structural integrity in curvic coupling under the bolt selfloosening.

Fretting wear is a common cause of failure of an electrical contact (EC). In this study, we analyzed in detail the failure of EC induced especially by sliding using the representative electrical terminals. Furthermore, combining the friction energy dissipation theory, we proposed a prediction model to evaluate the electrical connector endurance (ECE) based on the contact stress and geometrical changes during the wear process obtained from a numerical model. The study helps establish that the friction energy dissipation theory is a powerful tool to analyze a contact failure due to wear. The proposed model proves to be effective in predicting the ECE for all considered cases such as micro-slip amplitude, contact force, overturning angle, superficial layer thickness, and friction/wear coefficients.

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