基于振动特性的高温管线蠕变损伤的识别

Identification on Creep Damage of High-temperature Pipelines Based on Vibration Characteristics

以高温主蒸汽管线为例,应用有限元方法分析了大型高温管系在实际工况下的应力情况、蠕变损伤特点以及基于振动特性的损伤识别.以典型弯管为例,分析了在不同损伤情况下高温管道的振动模态变化特性.结果表明:在微小损伤的条件下,高温直管/弯管的频率变化较小,考虑到实际测量噪声的影响,单纯从结构的固有频率变化来识别微小的损伤是比较困难的;通过分析冲击响应的变化可以判断是否已经出现损伤,尤其是在损伤大于30%时,弯管对冲击响应的变化非常明显.

The stress distribution,creep damage characteristics and vibration-based damage identification of high-temperature main steam pipelines were analyzed using finite element method.Taking typical elbow pipes as an example,vibration modal properties of high-temperature pipes were studied under various damage conditions.Results show that it is different to identify tiny damages in high-temperature straight/elbow pipes purely based on the natural frequency variation,since under tiny damage conditions,the frequency varies little,and there also exists noise in actual measurement,which may interrupt the identification.However,the damage in elbow pipes can be identified by analyzing the variation of impulsive response,especially when the damage is more than 30% due to obvious variation of impusive resonse.