Dynamic analysis and optimization for double-layer tape-spring hinges unfolding

Flexible tape-spring hinges can be folded elastically and can self-unfold by releasing stored strain energy with fewer component parts and slight weights. The unfolding dynamic behaviors of double-layer tape-spring (DLTS) hinges were studied and optimized to reduce unfolding shock. A platform for unfolding test of DLTS hinges was built and tests were performed to verify the correctness of the FE numerical model for double-layer tape-spring hinges. The unfolding shock angle and the locked time were taken as objectives, the thicknesses of outer layer tape-spring and inner layer one in outer bending direction of a DLTS hinge were taken as design variables. The modified non-dominated sorting genetic algorithm was employed to conduct the optimal design of DLTS hinges. The finite element models for the non-equal thickness optimal design based on numerical methods were established and validated. The optimization results had relative errors no more than 5.008%. Comparing unfolding behaviors of the non-equal thickness optimal design and those of the equal thickness one for DLTS hinges, it was shown that the unfolding shock angle and locked time for the former reduce 52.154% and 29.104%, respectively; after optimization, the shock of the structure is reduced obviously. The parameter study showed that the unfolding shock angle is more sensitive to the outer layer thickness of tape-spring, and the locked time decreases firstly and then increases with increase in the thickness of tape-spring.