基于工作应变模态的管道损伤识别试验研究

Experimental Study on Damage Identification of Pipeline Based on Operational Strain Modal Shape

为了检测管道损伤、进行实时安全评估和长期寿命预测,防止管道事故发生,利用振动损伤检测方法,针对管道的一维性质,推导了求解管道损伤应变模态差分公式,建立定位损伤、确定损伤程度的直接指标数学模型.对3根管道进行不同损伤工况下的物理模型试验和损伤识别分析,结果表明:管道固有频率最大变化率仅为6.71%,固有频率作为全局性参数用于结构损伤诊断存在模态频率识别效果不明显且信息量较少的局限性;应变模态敏度比差值在损伤区域出现明显的突变,能直观准确地识别管道损伤.

In order to make damage detection,real-time safety evaluation and life prediction of pipelines,and hence prevent pipeline accidents,difference formulas of strain mode for damaged pipelines are derived based on vibration tests and the character of one-dimensional continuum of pipelines,and a mathematical model of direct indexes for damage location and degree identification was built. Then,physical model tests for three pipelines in different damage status are carried out to identify their damage. The results show that when using the natural frequency as an identifying global indicator for damage identification,the maximal change rate of pipeline natural frequency is only 6. 71% and the damage cannot be identified effectively due to the limitation of less information; the difference value of strain sensitivity,however,has more obvious mutations in damage area and can identify the pipeline damage correctly.