基于固有频率的悬臂梁裂缝识别

Identification the crack of a cantilever beams by natural frequencies

结构中裂缝的存在使其模态参数发生改变 ,如局部刚度减小、阻尼增大、固有频率降低。把裂缝梁模拟成由扭曲弹簧连接 ,并对其前三阶固有频率的变化与裂缝位置和深度之间的关系进行计算和分析 ;利用特征方程以及前三阶固有频率 ,通过作图法对裂缝参数进行识别。识别结果证明 ,这种方法精度较高、简单可行 ,可用于机械工程实时监测。

The presence of crack in structure usually caused the change of mode parameters,such as local reduction in stiffness,increasing in damping and reduction in natural frequencies of structure The crack beam simulated by connected with a rotational spring,and the article calculated and discussed the effect of crack upon the natural frequencies change of a cantilever beam A method based on measurement of natural frequencies is presented for identification of the location and depth of a crack in a cantilever beam by obtaining plots of its stiffness with crack location for the first three natural modal through the characteristic equation The results of identification demonstrated the simpleness and accuracy of the method,and the method outlined in the paper can be used to inspecting the mechanical engineering on line