Periodic Rod Support Structure Continuum Equivalent Parametric Analysis

With the development of China’s large-scale equipment manufacturing and aerospace engineering,the role of the three-edge straight truss structures in large-scale and lightweight design is becoming more and more significant.The structure has the characteristics of periodicity and complex design.Because of its larger-length ratio,it has a certain degree of flexibility.To ensure the stability of its work,its dynamic modeling and analysis have certain practical significance and theoretical value.The main research content and results of the thesis are as follows:（1）Based on the theory of elasticity and the principle of energy equivalence,the three-edge straight truss model is dynamically constructed.Based on the principle of energy equivalence,the discrete truss is equivalent to a continuous beam,the equivalent matrixes of stiffness and matrix of the continuous beam are obtained,and the stiffness and natural frequency of the continuous beam are calculated.ANSYS is used to perform finite element analysis on the truss model to obtain the first several natural frequencies and mode shapes.The comparison of the numerical results of the truss structure with the theoretical results of the continuous beam verifies the equivalent calculation.By considering the mass of the joints,the equivalent model of the truss structure is revised.（2）Structural parametric characteristics of the three-edge straight truss are analyzed.The different load-bearing requirements and dynamic characteristics of the three-edge straight truss structure in all directions are taken into account.By changing the proportion of the side length of the cross-section,the transverse bending frequency and stiffness are studied.The relation of cross-sectional shape and the load-bearing performance of the truss structure are studied.Subsequently,the influence of cell-form on the transverse bending frequency and stiffness of the truss and the influence of the number of cells on the equivalent accuracy are analyzed.（3）Based on finite element software,active control of the three-edge straight truss is studied.The harmonic response of the three-edge straight truss is analyzed,and the amplitude-frequency characteristic curve of the truss structure under harmonic excitations is obtained.The active control of vibration of truss structure is studied by ANSYS.（4）Vibration experiments are carried out for the three-edge straight truss.CREO is used for three-dimensional modeling and overall assembly.Experimental prototypes are made.The suspension method is used to offset the influence of gravity,and modal tests are performed under special boundary conditions.The experiments are basically consistent with the analytical and numerical results,which verifies the dynamic analysis.