基于非均匀分布复弹簧单元的螺栓连接薄板结构动力学有限元建模

Finite element dynamic modeling for bolted thin plate structure based on complex spring element with non-uniform distribution LIU Xiaofeng1,2,SUN Wei1,2,FANG Ziwen1,2

在创建螺栓连接结构动力学模型时,如何有效地模拟螺栓影响区对结构动力学特性的贡献至关重要。提出用非均匀分布复弹簧单元来模拟螺栓影响区力学特性,在此基础上针对一种螺栓连接薄板结构建立有限元模型并对其进行线性动力学分析。在确定螺栓影响区面积的基础上,分别假定了三种刚度非均匀分布的复弹簧单元来模拟螺栓结合部的力学特性,并提出用反推辨识技术确定复弹簧单元刚度及阻尼参数的方法。通过自编有限元程序创建了螺栓连接薄板结构线性动力学分析模型,重点描述了将非均匀分布复弹簧单元引入连接薄板动力学方程的方法。最后,以一个具体的螺栓连接薄板结构为对象进行了实例研究,结果表明:用所创建的有限元模型计算获得的固有频率、模态振型以及频响函数值与实测值均较为接近,从而证明了用非均匀分布复弹簧单元模拟螺栓影响区进而实施有限元建模可实现较高的仿真计算精度。

How to effectively simulate contribution of bolt influence zone to structural dynamic characteristics is very important when establishing dynamic model of bolted structures. Here, a complex spring element with non-uniform distribution was proposed to simulate mechanical characteristics of bolt influence zone. Then, a finite element model for a bolted thin plate structure was established and its linear dynamic analysis was performed. On the basis of determining the area of bolt influence zone, 3 kinds of complex spring elements with non-uniform stiffness distribution were assumed to simulate mechanical characteristics of a bolt joint, and the method of using the backstepping identification technique to determine stiffness and damping parameters of a complex spring element was proposed. The linear dynamic analysis model of bolted thin plate structure was established with a self-developed finite element program to mainly describe the method of introducing the complex spring element with non-uniform distribution into the dynamic equation of bolted thin plate structure. Finally, an example of a bolted thin plate structure was studied. The results showed that natural frequencies, modal shapes and frequency response functions computed with the established finite element model are closer to the actually measured values;using complex spring element with non-uniform distribution to simulate bolt influence zone and then perform finite element modeling can achieve higher simulation accuracy.