利用试验模态分析进行残余应力评估的研究

STUDIES ON ESTIMATION OF RESIDUAL STRESS USING MODAL ANALYSIS

通过试验模态分析实验,对有残余应力的构件和无残余应力的构件进行了对比实验,得出了关于构件固有频率和阻尼变化规律的4点结论,即:(1)有残余应力存在时,构件固有频率发生变化;(2)高阶频率受残余应力影响比低阶频率的大;(3)在其他因数不变时,大尺寸构件的固有频率受残余应力的影响比小尺寸构件的小;(4)构件的阻尼发生变化,高阶阻尼变化量的绝对值一般比低阶阻尼的大。探讨了利用构件固有频率或阻尼的变化量来判断构件残余应力的方法。改进了振动时效的幅频特性监测法。

Through the experimental modal analysis on a lots of components with welding residual stress, some conclusions have been obtained. (1) Due to residual stress in components, all natural frequencies and damping ratios are changed. (2) The changes of higher order natural frequencies and damping ratios under the influence of residual stress are larger than those of lower order natural frequencies and the higher the order number is, the larger the absolute changes of natural frequence and damping ratio are, etc. A method to estimate residual stress is provided on the base of the changes of natural frequencies and damping ratios. The traditional amplitude-frequency characteristic curve monitoring method only taking note to the first order natural frequency is modified into a new one taking note to the multi order frequencies. The monitoring result of vibrational ageing effort by the new method is better than that by the traditional method.