螺栓联接梁结构非线性动力学建模及特性参数辨识

发布时间：2018-05-11 21:23

本文选题：螺栓联接梁 + 结合部　；参考：《东北大学》2012年硕士论文

【摘要】：螺栓联接是机械结构系统中最常见的联接形式之一,通常情况下,螺栓联接结构的结合部会对系统的动力学特性产生很大的影响。与刚性联接对照,结合部的力学特性参数会使结构的固有频率、刚度和阻尼等发生改变,而表现出非线性动力学特性。因此,为了精确的分析螺栓联接结构的动力学特性,预测其振动响应,有必要创建螺栓联接结构系统的非线性动力学模型,并辨识结合部的动力学特性参数(主要是刚度和阻尼参数)。本文以螺栓联接梁为例,主要研究螺栓联接结构结合部对系统动力学特性的影响,以及辨识结合部的动力学特性参数的方法。首先,对非线性系统的辨识方法进行分类概述,介绍多种不同的非线性参数辨识方法,提出通用的辨识流程,为螺栓联接梁的非线性参数辨识提供技术参考。其次,对螺栓联接梁结构进行非线性表征测试,介绍检测原理以及相应的测试实施方法,搭建针对螺栓联接梁结构的振动测试系统,并分别采用谐波失真、相干函数和频响函数三种方法检测螺栓联接梁非线性的存在性及其特征。然后,在表征测试和机理分析的基础上,采用并联的Iwan模型模拟接触面之间的非线性动力学现象,对悬臂螺栓联接梁,提出用Duffing方程描述螺栓结合部的动力学特性,建立非线性解析模型。结合实验测试,用改进的力映射状态法(Force-state mapping method)识别出了螺栓联接梁结合部的刚度和阻尼参数。最后,研究了从频域辨识螺栓联接梁结合部参数的方法。基于振动梁理论,建立螺栓联接梁的两自由度非线性模型,定义结合部的连续性条件,采用经典的多尺度法对模型的四阶偏微分方程进行半解析求解,获得线性项的解析解和非线性项的频率响应函数。并在实验的基础上分别辨识出模型中的线性参数和非线性参数,获得完整的两自由解析模型,进而辨识出螺栓联接梁结合部的动力学特性。本文是从非线性振动学理论出发,在创建螺栓联接梁非线性动力学模型的基础上,分别研究从时域和频域辨识其结合部动力学特性参数的方法。所提出的技术思路和方法可以作为辨识其他组合结构非线性动力学特性的参考。
[Abstract]:Bolt connection is one of the most common connection forms in mechanical structure system. In general, the joint of bolt connection structure will have a great influence on the dynamic characteristics of the system. Compared with rigid joints, the mechanical properties of the joints change the natural frequency, stiffness and damping of the structure, and exhibit nonlinear dynamic characteristics. Therefore, in order to accurately analyze the dynamic characteristics of bolted connection structure and predict its vibration response, it is necessary to establish a nonlinear dynamic model of bolted connection structure system. The dynamic characteristic parameters (stiffness and damping parameters) of the joint are identified. In this paper, the effect of bolted connection structure on the dynamic characteristics of the system and the method of identifying the dynamic characteristic parameters of the joint are mainly studied in this paper, taking the bolted connection beam as an example. Firstly, the identification methods of nonlinear systems are classified and summarized, various nonlinear parameter identification methods are introduced, and a general identification process is proposed, which provides a technical reference for nonlinear parameter identification of bolted connection beams. Secondly, the nonlinear characterization test of bolted connection beam structure is carried out, the detection principle and corresponding test implementation method are introduced, and the vibration testing system for bolted connection beam structure is built, and harmonic distortion is adopted respectively. Coherence function and frequency response function are used to detect the nonlinearity of bolted connection beam. Then, on the basis of characterization, testing and mechanism analysis, a parallel Iwan model is used to simulate the nonlinear dynamic phenomena between contact surfaces. For the cantilever bolt connection beam, the Duffing equation is proposed to describe the dynamic characteristics of the bolt joint. A nonlinear analytical model is established. Combined with the experimental results, the stiffness and damping parameters of the bolted connection beam are identified by the improved force mapping state mapping method (Force-state mapping method). Finally, the method of identifying the joint parameters of bolted connection beam in frequency domain is studied. Based on the vibration beam theory, a nonlinear model of two degrees of freedom for bolted connection beam is established, and the continuity condition of the joint is defined. The fourth order partial differential equation of the model is solved semi-analytically by the classical multi-scale method. The analytical solution of the linear term and the frequency response function of the nonlinear term are obtained. On the basis of experiments, the linear and nonlinear parameters of the model are identified, and the complete two-free analytical model is obtained, and then the dynamic characteristics of the bolted joint are identified. Based on the theory of nonlinear vibration and the establishment of nonlinear dynamic model of bolted connection beam, this paper studies the method of identifying the dynamic characteristic parameters of the joint from the time domain and the frequency domain, respectively. The proposed technical ideas and methods can be used as a reference for identifying nonlinear dynamic characteristics of other composite structures.
【学位授予单位】：东北大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH131.3

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