Typical Mechanical Connection Structure Finite Element Modeling And Experimental Validation Studies

Under the background of a National Defense Project, this paper is concerned with modeling theory and method of typical mechanical joint structures by combination of theoretical analysis, numeric calculation and experiment. The main contents of this paper are as follow:Firstly, classical modal analysis theory was investigated, including theory about viscous damping system and the structural damping system, and then mechanical properties of typical joints such as welding, bolting and riveting were examined. Based on design and analysis experience, finite element models of these joints were built up by means of ANSYS software. The models of the welding board were constructed by three means, including model ignoring the weld joints, method using the MPC constraint, and approach using the solid elements. The bolting board was simulated by the beam elements, solid elements and coupling elements, respectively. The riveting board was simulated by the beam elements, spring elements and rigid elements, respectively. The nature frequency and mode of vibration were calculated by different methods for I-type, T-type and X-type aluminum alloy structures, and the comparison results show that the modeling method had no obvious effect on the welding and bolting structures, but the influence becomes obvious for the riveting structure. At the same time the models of steel clamped beam and simple beam were built, the influence of modeling methods of the bolt on the clamped beam and the pin on the simple beam was studied.The hammering modal test system was built according to the modal analysis and experimental testing technology and the available conditions of the laboratory. The modal properties of the aluminum alloy structures and steel beams were tested three times by this experiment system, and then the vibration frequencies and modes along Z direction were retrieved. The mean tested data was compared with the simulated result, which can validate each modeling method.According to the error between the FEA results and the test data, the updated finite element models were built by choosing the corrected parameter, the state variables and the constraint conditions for welding, bolting and riveting. The updated computational results show that the accuracy of the modified FEA models was improved obviously.The research result of this paper will provide reference for model refining of such mechanical joints.