梁结构中裂纹参数识别方法研究

以等效弹簧模型来模拟裂纹引起的局部软化效应,将该模型同Bernoulli-Euler梁理论、模态分析方法以及断裂力学原理等结合起来,利用传递矩阵法导出含裂纹梁振动的各种边界条件下的特征方程通解。借助于特征方程,提出两种识别裂纹深度和位置参数的数值方法,最后,通过对含裂纹悬臂梁的分析说明文中方法的有效性。

Investigation on crack identification in the beam-type structures

In this paper,the local effect of "softening" at the crack location can be simulated by an equivalent spring connecting the two segments of the beam. This model using the transfer matrix method in conjunction with the BernoulliEuler theories of beam vibration,modal analysis and fracture mechanics principle are applied to derive characteristic equation,which relates the natural frequencies,the boundary conditions including the more realistic(elastic) end supports to crack parameters.The procedure proposed is advanced by elimination of numerical computation of the high order determinant so that the computer time for calculating natural frequencies in consequence is significantly reduced.Furthermore,from this expression,two accurate crack identification methods are developed,which only require the variation of the first several natural frequencies due to the crack,with no other information needed concerning the beam geometry or material and the crack depth or shape.The proposed approaches are verified by simulated damage in the form of one-side cracks in a cantilever beam.