Modal experiment for a spherical hinged space truss structure
WANG Guilun1,2, JIANG Dong1,3, ZHOU Lizhenhui1,2, FEI Qingguo1,2
1.Institute of Aerospace Machinery and Dynamics, Southeast University, Nanjing211189, China;
2.Department of Engineering Mechanics, Southeast University, Nanjing210096, China;
3 College of Mechanical and Electronic Engineering, Nanjing Forestry University, Nanjing210037, China
Abstract：The accurate dynamics characteristics of a flexible and joint-dominated space truss structure is difficult to obtain in the ground test.The ground modal test of truss structure is susceptible to test conditions.The experimental modal analysis of a spherical hinged space truss was conducted using the hammer method.The modal parameters were obtained based on the experiment results.The MAC (Modal Assurance Criterion) was utilized to verify the reliability of the results.Combined with different cases in the test, the influence of suspension condition and response point position on the modal experimental results of the truss structure was analyzed.The modal analysis of the truss structure under free boundary condition was carried out using FEM.The results obtained through the experiment method and FEM were compared.The results show that lower added stiffness of suspension can avoid modal coupling.distributing suspension points uniformly and symmetrically improves the repeatability of the modal experiment.placing accelerometer near the center of the structure reduces the energy loss of the excitation, which can ensure the completeness of the modal results.increasing length of suspension can reduce the influence of suspension effect on low order modes.
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