Research On Mechanics Modelingand Experiment Of Hyperelastic Hinges

Deployable truss mechanisms have been widely applied in aerospace missions.Aerospace missions are more complicated and larger in recent years which leads to the deployable truss mechanisms more lightweight, lower energy, no fricition and with no need for dirve mechanism. Hyperelastic hinges can be rotated, driven, and self-locked which could be applied in the deployable truss mechanisms to reduce weight and energy by replacing classic mechanical hinges.Hyperelastic hinge is a space curved thin-walled cylindrical shell. Folding and deployment moments of hyperelastic hinge are high nonlinear property. There are some unsolved common problems, such as how to describe nonlinear mechanical models of the folding and deployment, multiobjective optimization which involves large deformation, nonlinear snapthrough buckling, and large angle shock etc. All the unsolved commom problems restrict the aerospace application of the hyperelastic hinge.Fristly, considering the effects of both the transverse and longitudinal curvatures, the elastic strain energy theory models of the single hyperelastic hinge under pure bending are built based on Calladine shell t heory and von Karman thin plate large deflection theory. The Nonlinear bending moment response models of the single hyperelastic hinge for equal and opposite bend are established based on the minimum potential energy principle s. The quasi-static test apparatus is designed and conducted.The quasi-static folding experiments of12 different single hyperelastic hinges for equal and opposite bend verif y the precision of nonlinear bending moment theoretical models,thereby providing a good foundation for thestudy of the characteristics of the hyperelastic hinge large deflection and deployable stability properties ofcompositional hyperelastic hinges used in triangular prism mast.For the deployable stability of different compositional hyperelastic hinges, folded moment theoretical models for multi-layer equal and opposite hyperelastic hingesunder pure bending are derived based on Eular beam buckling theory and Timpshenko theory, respectively. The quasi-static deploying experiment is performed for the multi-layer equal and opposite hyperelastic hingesto modify the relative finite element models. The quasi-static folding of 12 different multi-layer equal and opposite hyperelastic hinges are simulated by the modified finite element models to verify the correctness of the established theoretical models.For stress concentration affecting instances of the use of the hyperelastic hinges and drive moments meet requirements, surrogate models for quasi-static folding maximum stress, deploying peak moment, and steady moment of different compositional hyperelastic hinge are built based on response surface method. Slot parameter influences on the surrogate models are studied. The optimal design of integral tube hinge with double-layer are obtained based on modified non-dominated sorting genetic algorithm.Equal double-layer tape springs hinge are performed multi-objective optimizations for both quasi-static mechanical properties and dynamical characteristics. Shock angle and compete locking time are set as objectives for deploying shock phenomenon.The maximum stress is set as constraint.The thicknesses of the double-layer tape springs locatedoutside the bend are set as variables. The dynamical properties of the double-layer hyperelastic hinge are optimized based onprevious quasi-static deploying optimization. Thus, solving the low shock and fast lock of the triangular prism mast is important.A ten-modulus triangular prism mast with equal double-layer hyperelastic hinge is proposed, and two-modulustriangular prism mast is conducted.The fundamental frequency and modal are analyzed by finite element method. The bending and axial stiffness for the two-modulus triangular prism are obtained by static analysis and testing. In repeated deployment experiments, the hub of thetwo-modulus triangular prism mast was attached to the frictionless rotational bearing.The two-modulus triangular prism mast was hungusing bungee cables. The hammering method is employed to test the fundamental frequencies and modal shapes of the two-modulus triangular prism mast in hanging position and cantilever position.The finite element modeling method of the ten-modulus triangular prism mast are applied to establish the finite element model of the two-modulus triangular prism mast. The fundamental frequency relative errors of the finite element model and test for the two-modulus triangular prism mast are no more than 5.501%. And the front five vibration modes between test and simulation of the two-modulus triangular prism mast are agreed.These studies provide a theoretical foundation and technical guidance for the ten-modulus triangular prism mast design.