Dynamic Modeling And Topology Optimization Of Constrained Damping Structure Flat Spring

The UAV is playing an increasingly important role in the modern life. The aircraft has a high demand for undercarriage while in the process of landing, and the undercarriage with good damping performance can improve the stability of aircraft landing process. Flat spring landing gear is one of the many layout forms which has many advantages, such as high reliability, simple structure, low cost and easy maintenance and mainly used in small and medium speed UAV. Because of the important influence on the stability of the aircraft by improving the damping performance of the flat spring, the paper studies the method of establishing the damping model and the topology optimization method of constrained damping layer. The main research contents include:According to the experimental data of the single freedom vibration of the flat spring, the changing trend of frequency and viscous damping factor under different amplitude is analyzed, and the dynamic model of the flat spring is established according to the energy method. Finally, calculate the test data into the model, which proves the correctness of structural damping model.From the energy point of view, the dynamic equations of constrained damping layer are established and the relationship between the modal loss factor and the strain energy is obtained according to the modal strain energy method. The modal loss factor is used to characterize the damping performance of the flat spring structure, which provides the target parameters for the topology optimization. The finite element dynamic analysis model of constrained damping structure is derived by finite element method. The dynamic analysis model of constrained damping structure is derived by finite element method.A differential equation of constrained damping plate vibration is established by horizontal displacement ‘w’, and an analytical expression of the natural frequency of the cantilever structure is derived from the theory in the condition of one end being fixed and another being freed. The sensitivity expression of the objective function of the constrained damping structure is derived by using the first three order modal loss factor, which is obtained by the modal strain energy method. The topology optimization of constrained damping structure is carried out by the optimization criterion method based on SIMP interpolation. The retained material has a greater contribution to the structural damping performance, by removing 50% of the viscoelastic and corresponding constrained layer material. In order to reduce the overall weight of the composite structure, the topology optimization of damping material layer is realized.The result of topology optimization is verified by experiments. The result shows that the change of viscous damping factor of constrained damping structure is less than 5% when the viscoelastic and corresponding constrained layer material is removed.