Vibration Reduction Characteristics And Dynamic Topological Optimization Of Damping Structures

Vibration damping structure is a practical and effective passive control technology for vibration reduction, which viscoelastic damping material adhesion is a kind of common way. In some higher requirements on the product performance or nearly harsh demanding industry field, higher requirements for viscoelastic damping materials suppression vibration was made such as aeronautics and astronautics, weapons equipment and so on. The damping structure of the vibration characteristics and vibration reduction optimization, inevitably becomes very important. The vibration damping structure in terms of dynamics characteristic and the topology optimization of damping materials was studied mainly in this paper.Damping structure dynamics finite element model(FEM) is on the basis of the research work. Considering the damping material paste thickness and width are more orders of magnitude, generally plate shell structure was present. And the damping structure displacement continuity between layer and layer, displacement field equations were derived. Then a dynamic FEM for damping structure was established, the model solution based on ANSYS secondary development programming language and results from this model were compared with experimental data and analytical solutions to validate the mode well. For subsequent research topological dynamics calculation basis was provided for iterative optimization.From differential Angle, pros and cons study of different size, different location of the damping materials, and the idea of the application of damping material topology optimization was formed. The statics application research in the mature variable density method was expanded to the field of dynamics. Aimed to maximize plate’s multi-modal loss factor, while taking the amount of damping material, frequency equation and frequency region and MAC as constraint, a topology optimization model was developed. After penalty factor for mass matrix were introduced, multi-modal loss factor sensitivity formula was deducted. In the simulation, found that the positive and negative impact is not uniform sensitivity numerical optimization iteration can’t update every design variable, and analyzed the root cause discrete optimization. On account that the optimal objective function was non-convex, if a general optimal criterion was employed to solve this function, some of the computed topological variants would be negative, and if the negative variants were overlooked, it would consequently be a local optimization, so a moving asymptotes method of mathematical programming were adapted to improve the optimal criterion(OC). In the improved criterion, whole topological variants were taken into optimization process so as to avoid the occurrence of local optimization. In the proceed, it was proposed the creative conception of the sensitivity of ∞-norm. Applied the theory of vibration FEM and the improved algorithm in this paper simulate the common structural damping, and from the single mode and modal and harmonic response analysis the optimization results of data analysis and display was given.Results demonstrated that introduction of layer upon layer displacement continuous FEM model has higher precision, damping effect of damping material paste volume in 50%-80% is better and the position of best vibration reduction is maximum strain, freedom damping structure in optimization of the structure of the modal loss factors was decreased and the constraint damping structure has certain increase. In the contrast analysis of the OC optimization, the improved method owns a better iterative stability and a faster speed of optimization, and is able to provide a more global solution. Harmonic response analysis to explain the multimodal optimization of the improved algorithm can well restrain the peak amplitude.