结构动力学分析中阻尼模型的建立及实验研究

发布时间：2018-02-26 19:46

本文关键词： 动力学分析结构阻尼广义距离模态惯量振型　出处：《哈尔滨工业大学》2012年硕士论文　论文类型：学位论文

【摘要】：在航空航天、能源及土木等领域中，工程结构的动力学特性已经成为衡量其性能及质量的关键指标。在动力学分析中，结构阻尼一直是研究中的一个难点。其既不是结构的固有特性，又没有现成的结构阻尼数据库，，亟需对结构阻尼进行深入研究。本课题首次通过结构的模态质量和广义距离来定义结构的模态惯量，并基于模态应变能法，推导出了结构阻尼的数学模型，得到模态惯量与结构阻尼比间的线性关系。通过建立四种梁结构模型，进行仿真分析和实验研究建立了其线性关系，验证了阻尼模型的有效性和合理性。本文分析了结构阻尼产生的机理，基于模态应变能法，推导了结构阻尼计算的基本公式。把结构每阶模态的振型简化为结构主振动方向的振型，考虑了固有频率、结构形式和结构主振型等因素，建立了结构阻尼模型，得到其结构阻尼比和模态惯量之间的数学线性关系。基于结构阻尼模型，将阻尼等效为Rayleigh阻尼和克拉夫阻尼，为结构阻尼模型应用于动力学分析中提供理论支撑。通过建立四种梁结构模型，进行预应力模态分析和冲击实验计算出结构的阻尼比，并基于模态分析计算出各梁结构的模态惯量，通过拟合结构阻尼比和结构的模态惯量，得到了两者间的近似线性关系，并且通过拟合得到的阻尼比与原阻尼比之间的偏差较小，验证了结构的模态惯量和结构阻尼比基本满足线性关系，同时说明结构阻尼数学模型建立是有效和合理的。将建立的结构阻尼模型等效为Rayleigh阻尼和克拉夫阻尼，分别对四种梁结构进行谐响应分析，通过对比谐响应仿真分析结果与实验结果，得到两种等效模型计算结果与实验结果基本吻合，并且基于克拉夫阻尼模型的仿真结果与实验结果的偏差小于基于Rayleigh阻尼模型仿真结果与实验结果的偏差，等效的克拉夫阻尼模型可以提高动力学分析的精度。并进一步验证了利用结构阻尼模型来计算阻尼在实践中是可行和有效的。该结构阻尼模型计算的方法简单、对应的物理量意义明确，通过计算结构模态惯量，从拟合曲线中便可以得到结构阻尼比，从而定量的计算结构阻尼的大小，为结构阻尼的计算奠定了理论基础，在机械结构的动力学分析中具有广泛的应用前景。
[Abstract]:In the field of aerospace , energy and civil engineering , the dynamic characteristic of engineering structure has become a key indicator of its performance and quality . In dynamic analysis , structural damping has been a difficult problem in the study . In this paper , the mechanism of structural damping is analyzed . Based on the modal strain energy method , the basic formula of structural damping calculation is deduced . Based on the modal analysis , the modal inertia of each beam structure is calculated by establishing four beam structure models , and the modal inertia of each beam structure is calculated based on the modal analysis , and the relationship between the damping ratio and the original damping ratio of the fitting structure is small , and the linear relationship between the modal inertia and the structural damping ratio of the structure is verified , and the establishment of the structural damping mathematical model is effective and reasonable . The structure damping model is equivalent to Rayleigh damping and Kraff damping . The four beam structures are subjected to harmonic response analysis , and the results of the simulation are compared with the experimental results by comparing the simulation results with the experimental results . The deviation between the simulation results and the experimental results is less than that of the experimental results based on the results of the simulation results and the experimental results . The equivalent KCS damping model can improve the accuracy of the dynamic analysis . The damping model is further verified to be feasible and effective in practice . The method of the structure damping model calculation is simple , the corresponding physical quantity significance is clear , the structural damping ratio can be obtained from the fitting curve by calculating the modal inertia of the structure , so that the magnitude of the structural damping is quantitatively calculated , the theoretical foundation is laid for the calculation of the structural damping , and the structure damping model has wide application prospect in the dynamic analysis of the mechanical structure .

【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH113

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