含裂纹梁的动力响应

The Dynamic Response of Beam with Crack

本文提出了一种计算含裂纹梁动力响应的有限元方法.采用时域方法辨识出模态参数,所得固有频率随裂纹长度和位置的变化值与实验结果吻合较好.计算了裂纹闭合而引起的结构响应变化,指出:外激励均值对固有频率影响较显著.最后,给出了判断裂纹位置的方法:用一阶振型和固有频率的差异确定;由不同测点频响函数变化来估计.

In this paper, a finite element method to compute dynamic response of beam with crack is proposed. The eigenfrequecies are determined for different crack lengths and locations by means of the identification technique in time domain. Computation results show a good agreement with the experimental data. Results also show: difference of displacement response between the beam and the cracked beam, due to the effect of crack closing, is reduced; the eigen frequency is affected by the mean value of exciting force notably. Two methods to determine the crack position are presented by investigating the changes in the eigencouple and transfer function of cracked beam. In principle, the suggested method may be extended to complex structure with various cracks, if the stress intensity factors of cracks are known.