梁结构裂纹参数的识别方法

以Bernoulli-Euler梁振动理论为基础，引入断裂力学中能量释放率的概念，得到承弯梁出现横向裂纹时其固有频率的变化与裂纹参数的简化表达式，讨论梁裂纹参数、几何参数对固有频率的影响。利用这一表达式，提出一种识别裂纹位置和深度的数值方法，最后，用含裂纹等截面悬臂梁的实验验证所提方法。结果表明，在固有频率误差较小的情况下，文中方法可给出梁结构中裂纹位置和深度，可为更精确的局部探伤指出探测范围。

CRACK IDENTIFICATION IN THE BEAM-TYPE STRUCTURES

Based on the theory of Bernoulli-Euler beam vibration, a simple function between parameters of crack and fractional change of the natural frequency was obtained for beam-type structures. Effect of the geometry and crack parameters on the natural frequency was discussed. Due to the fact that the relations between the natural frequencies and the parameters of the crack, namely, the location and the depth of the crack are very complex, a feasible crack identification method was proposed. It is tested that the location and the depth of the crack can be worked out when at least three orders of the fractional changes of the natural frequency are known. The experimental results showed that in the case of the lesser frequency error, the approach presented here is suitable for damage detection on practical engineering.