裂纹梁的动力特性与裂纹位置识别

Dynamic Characteristics of a Cracked Beam and Identification of Crack Positions

根据能量原理和断裂力学理论导出了模拟未开裂部分韧带效果的线弹簧模型的刚度矩阵，从而建立了一种裂纹梁分析的有限元模型．运用该模型，研究了不同裂纹长度和位置对悬臂梁动力特性的影响．算例结果与现有实验数据的比较表明，当无量纲裂纹长度小于０．６时，两者吻合得非常好；反之，两者之间存在较大的误差．

In this paper a stiffness matrix of the line spring model to simulate the effect of net ligament for the uncracked part is first derived on the basis of the energy principle in conjunction with the fracture mechanics method. A finite element model of cracked beam is then established. The effects of different crack lengths and different crack positions on the dynamic characteristics of cracked cantilever beam are investigated using the model. A comparison between the numerical results and the available experimental data is made. It is shown that both are very agreeable when the non dimensional crack lengths are less than 0.6; on otherwise, there are considerable discrepancies between them.