粘弹性约束阻尼夹层结构振动分析及优化设计

发布时间：2018-07-07 13:15

本文选题：约束阻尼结构 + 模态损耗因子　；参考：《天津大学》2014年硕士论文

【摘要】：粘弹性阻尼材料以其良好的振动能量耗散能力在汽车阻尼减振技术中得到了广泛的应用。粘弹性约束阻尼复合结构与黏贴或涂敷阻尼材料相比具有良好的减振降噪效果，但其阻尼性能对温度、振动频率等工作环境的依赖度很大，如何准确地建立阻尼复合结构的模型一直是工程分析中的难点。本文依据模态应变能理论，建立约束阻尼结构计算模型，利用基因遗传优化算法和渐进优化算法进行相应的阻尼结构优化设计。本文主要工作内容如下首先，分析影响粘弹性阻尼材料性能的重要环境因素，通过数学模型近似描述粘弹性阻尼材料的力学性能，，依据模态应变能理论，将粘弹性阻尼材料引起的结构振动复特征值问题简化为实特征值问题，运用ANSYS/APDL建立约束阻尼(CLD)矩形板有限元模型进行求解，并与传统复特征值法进行对比，结果显示模态应变能法计算过程简便，且能够满足计算精度要求。其次，针对粘弹性阻尼材料的温变和频变特性，改进模态应变能法，通过ANSYS/APDL与MATLAB联合仿真，分析环境温度、结构参数以及结构形式对阻尼结构模态固有频率和损耗因子的影响。算例结果表明联合仿真方法能够灵活的对阻尼复合结构振动特性进行研究，在阻尼结构设计中具有一定的理论和实用意义。然后，引入基因遗传优化算法（GA），建立以阻尼处理起始位置、阻尼处理长度、阻尼层厚度和约束层厚度为优化变量，以结构模态损耗因子、结构模态频率改变量及阻尼处理附加质量为优化目标的约束阻尼梁多目标优化的数学模型，采用MATLAB遗传算法工具对不同优化方案进行优化。对比不同方案的优化结果表明遗传算法优化效果显著，能够灵活地对阻尼结构进行优化设计。最后，推导结构模态损耗因子相对于阻尼胞单元位置的灵敏度表达式，基于渐进优化算法的优化准则，设计渐进拓扑优化计算流程，通过ANSYS/APDL参数化的程序设计语言编写拓扑优化程序，对约束阻尼矩形薄板的阻尼处理位置进行拓扑优化，分析满足阻尼处理体积约束条件下，不同模态阻尼损耗因子最大化时的约束阻尼处理构型。结果表明，环境温度、各层厚度和结构形式是影响阻尼结构减振性能的重要参数，基于模态应变能法的阻尼结构振动分析和优化设计能够满足工程分析精度要求，具有一定工程应用价值。
[Abstract]:Viscoelastic damping materials have been widely used in automobile damping technology because of their good vibration energy dissipation ability. Viscoelastic constrained damping composite structure has better vibration and noise reduction effect than adhesive or coated damping material, but its damping performance is highly dependent on temperature, vibration frequency and other working environment. How to accurately establish the damping composite structure model has been a difficult point in engineering analysis. Based on the theory of modal strain energy, the computational model of constrained damping structure is established in this paper, and the genetic optimization algorithm and progressive optimization algorithm are used to carry out the corresponding optimization design of damping structure. The main work of this paper is as follows: firstly, the important environmental factors affecting the properties of viscoelastic damping materials are analyzed, and the mechanical properties of viscoelastic damping materials are approximately described by mathematical model, and the modal strain energy theory is used to describe the mechanical properties of viscoelastic damping materials. The complex eigenvalue problem of structural vibration caused by viscoelastic damping material is simplified to a real eigenvalue problem. The finite element model of constrained damping (CLD) rectangular plate is established by ANSYS / APDL, and compared with the traditional complex eigenvalue method. The results show that the modal strain energy method is simple and accurate. Secondly, according to the characteristics of temperature and frequency variation of viscoelastic damping materials, the modal strain energy method is improved, and the effects of ambient temperature, structural parameters and structure form on the natural frequency and loss factor of damping structure are analyzed through the joint simulation of ANSYS / APDL and MATLAB. The numerical results show that the joint simulation method can study the vibration characteristics of damped composite structures flexibly and has certain theoretical and practical significance in the design of damped structures. Then, genetic optimization algorithm (GA) is introduced to establish the structural modal loss factor based on the initial position of damping treatment, the length of damping treatment, the thickness of damping layer and the thickness of constraint layer. The mathematical model of multi-objective optimization of constrained damped beam with structural modal frequency change and additional mass of damping treatment is used to optimize different optimization schemes by using MATLAB genetic algorithm tool. Compared with the optimization results of different schemes, the genetic algorithm is effective and flexible in the design of damping structures. Finally, the sensitivity expression of the structural modal loss factor relative to the position of the damping cell unit is derived. Based on the optimization criteria of the progressive optimization algorithm, the computational flow of the progressive topology optimization is designed. The topological optimization program is compiled by ANSYS / APDL parameterized programming language to optimize the damping position of constrained damping rectangular thin plate. The constrained damping treatment configuration when the damping loss factor of different modes is maximized. The results show that the ambient temperature, the thickness of each layer and the structure form are the important parameters affecting the damping structure's vibration absorption performance. The vibration analysis and optimization design of the damping structure based on the modal strain energy method can meet the requirements of the engineering analysis precision. It has certain engineering application value.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB535.1

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