基于试验和薄层单元仿真的接触阻尼识别方法

Contact Damping Identification Method Based on Experiment and Thin Layer Element Simulation

接触刚度和阻尼是影响螺栓连接的装配结构动力学特性的关键参数,为了实现接触刚度和阻尼的同时识别,在前期开展的螺栓连接结构接触刚度识别的基础上,提出一种基于试验和薄层单元仿真的接触阻尼识别方法。通过在单螺栓连接结构中巧妙引入试验垫片,试验获得有界、对称且均匀接触状态下结构的固有特性与动态响应;进而建立模拟接触面刚度与阻尼的薄层单元,并仿真获得结构的动态响应特性;通过结构固有频率测试与仿真结果构建误差函数实现接触刚度识别,通过动态响应测试与仿真结果构建误差函数实现接触阻尼的识别,进而获得接触刚度与阻尼随接触法向力变化的模型。结果表明,接触刚度随法向力非线性增大而接触阻尼则非线性减小,当法向力较大时,接触刚度和阻尼趋于稳定。研究结果为接触刚度和阻尼的同时识别提供了一种行之有效的方法,识别平均误差分别为4.5%,14.8%,所识别的刚度和阻尼以合适的薄层单元形式,可直接应用到包含多接触面的装配系统动力学分析中。

Contact stiffness and damping are the key parameters that affect the dynamic characteristics of the assembly structure with bolt joint.In order to realize the simultaneous identification of contact stiffness and damping,on the basis of the identification of the contact stiffness of the bolted structure,a contact damping identification method based on experiment and thin-layer element method was proposed.Through the introduction of experimental gasket into the single bolt connection structure,the inherent characteristics and dynamic response of the structure under the condition of bounded,symmetrical and uniform contact were obtained through the experiment;then the thin-layer element simulating the stiffness and damping characteristics of the contact surface was established to realize the finite element simulation of the structure dynamics,the error function of the natural frequency test and the simulation results was constructed to realize the identification of the contact stiffness.At the same time,an error function of dynamic response testing and simulation results was constructed to identify contact damping,and then the model of contact stiffness and damping changing with contact normal force was obtained.The results show that the contact stiffness increases nonlinearly with normal force and the contact damping decreases nonlinearly.When the normal force is large,the contact stiffness and damping tend to stabilize.The research results provide an effective method for the simultaneous identification of contact stiffness and damping with average identification errors of 4.5%and 14.8%,respectively.The identified stiffness and damping can be directly applied to the dynamic analysis of engineering structures with multiple contact surfaces in the form of appropriate thin-layer elements.