计入关节摩擦的空间桁架结构动力学建模及共振分析

Dynamic modeling and resonance analysis of space truss structures with frictional joints

  • 摘要: 关节非线性对大型可展开空间桁架结构整体动力学特性有着重要影响。将关节模拟为具有六个方向刚度且其中任意方向可含有非线性特性的弹簧系统,研究了空间桁架结构非线性动力学建模与共振分析方法。采用双线性滞回模型模拟关节的摩擦特性,基于描述函数法得到了关节等效刚度和等效阻尼的解析表达式。在对两端含非线性关节的桁架构件进行动力学缩聚的基础上,建立了桁架结构在频域下的整体缩聚动力学模型,并采用 Newton?Raphson 迭代方法进行频域响应求解。通过数值算例将本文方法的计算结果与有限元分析结果进行比较,验证了本文方法的准确性和高效性。

     

    Abstract: The joint nonlinearity has an important influence on the overall dynamic characteristics of large deployable space truss structures. By modeling the joint as a combination of six spring elements which can have nonlinearity in any direction,the nonlinear dynamic modeling and resonance analysis of truss structures are studied. The bilinear hysteresis model is used to simulate the friction in the joint,and the analytical expressions of its equivalent stiffness and equivalent damping coefficients are derived based on the describing function method. The dynamic condensation of the truss member with nonlinear joints at both ends is carried out to establish the overall condensed dynamic model of the truss structure in the frequency domain,and the dynamic response is solved by the Newton-Raphson iteration method. A numerical example is given to compare the results of the presented method and the finite element method,which verifies the accuracy and efficiency of the presented method.

     

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