Analysis And Experiment Of Pure Bending Mechanical Properties Of Triangular Rollable And Collapsible Boom

The deployment mechanism is folded and fixed in the launch vehicle in the process of launching,with the smallest volume.After being launched into orbit,it gradually expands into a large and complex aerospace structure,which is locked and kept in working state.It is mainly used in the support back frame and detection arm of large space deployable antenna and solar sail.The TRAC boom is one of the main supporting parts of the large spacecraft structure,and it is also a driving deployment mechanism which is worthy of further study after the bistable circular section hyperelastic boom and the CFRP boom.Based on the large deflection bending theory of von Karman thin plate,this thesis establishes the constitutive equation between the internal force and strain,moment and curvature of the middle surface of the isotropic material single band reed,deduces the total strain energy of the TRAC boom,obtains the bending moment of both ends of the TRAC boom by the numerical method according to the principle of the minimum potential energy,builds the pure bending experimental platform of the TRAC boom,conducts multiple bending experiments on the TRAC boom and extracts Peak moment: analyze and compare the relative error between the theoretical value of peak moment and the experimental value,verify the accuracy of the established strain energy mathematical model;analyze the parameter influence of peak moment when the TRAC boom is bent purely,and study the influence of material thickness,center angle,width of straight-line bonding section and cross-section radius on the peak moment,so as to provide a theoretical basis for the application of TRAC boom in folding and unfolding mechanism.The finite element model of flattening of TRAC boom was established,the relationship of pressure changing with time was analyzed,and the experimental platform of flattening of humanoid bar was built.The pressure was measured for many times,and the law of pressure changing between theory and experiment was analyzed and compared to verify the accuracy of the finite element model of flattening of TRAC boom.In view of the problem of stress concentration in the process of flattening the TRAC boom,the display dynamics method is used to carry out the non-linear numerical simulation analysis for the flattening process of TRAC boom,with single material,layering manners of two materials and TRAC boom stress characteristics for different layering angles compared,the layering method with the least stress is selected.This study is of great significance for the reasonable selection of the optimal lamination method for TRAC boom in the deployable mechanism.The finite element model of TRAC boom wrapping was established,and the experimental platform was built to test the torque in the wrapping process,so as to verify the accuracy of TRAC boom wrapping model.The finite element model of wrapping of TRAC boom consists of three steps: flattening,end compaction and wrapping.The stress change characteristics are analyzed,the minimum stress distribution area is defined,and the stress is used as the constraint condition to provide a path for the optimization of various parameters of TRAC boom,so as to improve the service time of the mechanism.