基于应变模态差的海洋平台构件的损伤识别研究
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摘要
对于具有一定损伤的导管式海洋平台钢管梁来说,实验模态分析得到的位移模态和固有频率难以有效的反应结构损伤的实际状况,特别是对早期的轻微损伤。为了提高损伤识别的效率和效果,根据海洋平台钢管梁架的受力特点,由节点位移模态推到出节点应变模态。然后利用损伤前后的应变模态差作为损伤识别的指标。将这个指标用在海洋平台钢梁构件焊缝和跨中单元的损伤识别上。通过建立钢管梁焊缝损伤的ANSYS模型,进行数据模拟分析,该方法能够在低阶模态条件下,有效的识别早期的轻微损伤。
For steel-tube beam of jacket platform with certain degree of damage,it is difficult for the displacement modal and natural frequency,obtained by experimental modal analysis,to adequately capture the real structural damage conditions,especially for the minor damage encountered by beam early in its service life.To improve the precision and efficiency of damage identification,the present paper first derives nodal strain modal through its corresponding displacement modal,and then evaluates the strain modal,both prior and post damage.The difference between these two values is used as a criterion to assess the damage experienced by platform beam welds and mid-span elements.The formulated method has been demonstrated through ANSYS numerical modeling to be capable of effectively identifying the early low mode minor damage.
For steel-tube beam of jacket platform with certain degree of damage,it is difficult for the displacement modal and natural frequency,obtained by experimental modal analysis,to adequately capture the real structural damage conditions,especially for the minor damage encountered by beam early in its service life.To improve the precision and efficiency of damage identification,the present paper first derives nodal strain modal through its corresponding displacement modal,and then evaluates the strain modal,both prior and post damage.The difference between these two values is used as a criterion to assess the damage experienced by platform beam welds and mid-span elements.The formulated method has been demonstrated through ANSYS numerical modeling to be capable of effectively identifying the early low mode minor damage.
引文
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[2]李永梅,高向宇,史炎升,等.基于单元应变模态差的网架结构损伤诊断研究[J].建筑结构学报,2009(3):152-159.
[3]Guyanj.Reduction of stiffness and mass matrices[J].AIAAJoum-al,1965,3(2):380.
[4]王熙堃,蒋济同.基于遗传算法的海洋平台水下构件的损伤识别[D].青岛:中国海洋大学,2008.
[5]顾培英,陈厚群,李同春,等.用应变模态技术诊断梁结构的损伤[J].地震工程与工程振动,2004(4):50-53.
[6]马宏伟,杨桂通.结构损伤探测的基本方法和研究进展[J].力学进展,1999,29(4):513-527.
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