考虑结合面影响的组合梁非线性预应力模态分析

为了研究结合面非线性特性对机械结构动态性能的影响，利用有限元分析软件，以组合梁结合面为研究对象，首先进行了考虑结合面非线性特性的非线性预应力模态分析，证明了结合面非线性特性对组合梁各阶弯曲振动固有频率有重要影响；然后采用单变量法研究了结合面法向载荷和摩擦系数对组合梁振动特性的影响。研究表明：结合面的法向载荷和摩擦系数都会使组合梁的固有频率降低，其中摩擦系数占主导地位。摩擦系数对组合梁低阶固有频率影响较小，高阶时影响较大。最后进行了模态试验验证，实验表明：模态试验所得组合梁弯曲振型与非线性预应力模态分析法所得振型相吻合，且二者所得固有频率之间的误差在接受范围之内，从而证明了非线性预应力模态分析的可行性。

Nonlinear Pre-stressed Modal Analysis of Composite Beam Considering the Influence of Joint Surface

In order to consider the influence of nonlinear characteristics of the joint surface on the dynamic characteristics of whole machine, the composite beam is taken as a research object, and the nonlinear pre-stressed modal analysis method is provided based on ANSYS. The nonlinear characteristics of the joint surface are proved to have an important influence on the natural frequency of the composite beam. Moreover, the influence of normal load and friction coefficient on the natural frequency is revealed with single variable method. The results show that the natural frequency is decreased by normal load and friction coefficient, and friction coefficient is the dominant. Finally, the modal test is conducted and the mode shape of composite beam got by the modal test and pre-stressed modal analysis is coincided. The natural frequency error between them is in an acceptable range which demonstrates pre-stressed modal analysis is correct.