Vibration Suppression Theory And Design Of Damping In Complex Structure

To improve the dynamic performance of structures, the viscoelastic damping material and the damper can enhance structures'damping and reduce the scope of the vibration of structures as far as possible, and the vibration intensity of structures can withstand the scope. In the space of the aerospace especially, the weight is limited strictly, so the condition of the complex environment should be used to optimize the location of the damping material and the damper. Both the viscoelastic damping material and the damper can absorb the energy of structures to enhance the dynamic performance of complex structures, which has the important value in practical engineering applications.This paper focuses on a damping system studied in structural dynamic analysis to improve the dynamic performance of structures, including:1) The viscoelastic material dynamics in frequency domain was analyzed, and the damping models were summarized. Based on the energy method and the principle of virtual work, the vibration equation modeling of constrained damping plate was analyzed. The method of the finite element analysis and the three parameters modeling of the viscoelastic were utilized; the dynamic model of the constrained damping structure was constricted; the solution of the model and the sensitivity of the modal coefficient were studied, providing the theory basis of the research on structural topology optimization. Based on the above work, the Krylov theory was introduced. Results indicate that the dynamic performance of the constrained damping structure topology optimization is feasibility.2) Based on the question of layout optimization of constrained damping structure, the independent sensitivity of the modal coefficient constrained damping layer was studied, and the relocation of sensitivity was filtered in view of the volume as the constraint function and the modal damping coefficient as the target function by the method of variable density topology. The MAC matrix was introduced, the optimization of the modal shape was tracked to optimize the fixed–order modal. The design method of the variable density topology was presented for constraint damping layer and the optimized shape of the constraint damping layer was proposed. In order to suppress the numerical instabilities such as checkerboards, the perimeter constraint of the nodal independent variable method with a variational upper bound was utilized. The most optimization topology configuration of constrained damping layer was obtained.3) Based on Love's assumption and the theory of thin shell, the equation of constrained cylindrical shell is derived. Topology optimization of the constrained damping cylindrical shell for the maximized modal damping coefficient was studied. According to the first 3-order modes, a novel topological optimization model on the basis of the volume as the constraint function, and the function of the modal damping coefficient as the target function was analyzed. The reasonable topology configuration was obtained for the damping structure. Results show that this method can be applied to solve the problem of optimization of the constrained damping cylindrical shell is verified by numerical simulations carried to the effectiveness of the presented method.4) Based on the damping placement and parameter optimization design for vibrating systems, the step by step optimization method was used. To begin with, the placement sensitivity of the modal damping coefficient in the common damping structure was investigated. The mathematical model of optimal damper placement was established, and the optimal placement of damper was searched, based on the placement sensitivity of the modal damping coefficient. In addition, the weight of the damper and the damping coefficient as the main objects were considered, and the objective function were founded by using the law of the minimum energy structure and the Lyapunov equation. Results indicate that the numerical method was utilized to complete the parameter optimization of the damper in the known best positions.5) In real engineering environment, some structures are often subjected to serious vibration and shock, high-decibel noise or poor weather conditions, which lead to the structural life reduced and instruments in structure failed. Therefore, a lot of problems and a series of serious accidents might be produced by the above reasons. Laying damping materials and playing dampers were employed to optimize the structural dynamic performance. An overall-local-global idea and different methods of vibration suppression were proposed for the complex structure. The result of each component was connected to the whole structure in the end. Results indicate that the vibration control will be realized more effectively in this way.