基于模态柔度与有限元模型修正的海洋平台结构损伤识别研究

Research on structural damage identification of the offshore platform based on modal flexibility and FEM updating

结构模态特征的改变直接揭示了结构的损伤,基于模态柔度较频率、振型对结构损伤的识别更为敏感的特点,文中提出了一种基于模态柔度和有限元模型修正相结合的结构损伤识别方法。文中以某海上导管架平台为例,在设定的3个损伤样本下建立了导管架21-DOF测试模型,获得该模型低阶结构模态参数,通过模态柔度差的方法进行结构损伤层定位;然后通过21-DOF测试模型与2454-DOF导管架有限元模型的自由度匹配,采用贝叶斯的有限元模型修正方法,对某导管架结构损伤层中具体损伤杆件的损伤程度、损伤位置进行识别。其识别结果与原设定的3个损伤样本基本一致,表明了该方法的正确性和有效性,可应用于海上导管架结构损伤检测与评价。

The change of structural modal characteristics directly reveals the structural damage. In this article,based on the fact that modal flexibility is more sensitive to structural damage identification,compared with frequency and mode of vibration,the method of structural damage identification based on the combination of modal flexibility and finite-element model updating is proposed. With the offshore jacket platform as an example,the 21-DOF test model of the jacket is set up with three damage samples,and the modal parameters of the model’s low-order structure are identified. Then,the structural damage layer is positioned by means of flexibility difference. In addition,by matching the freedom degree of the 21-DOF test model and the 2454-DOF finite-element model,and with the help of the Bayesian finite-element model updating method,the damage degree and location of the damaged rod in the jacket structure’s damaged layer are identified. These results are basically consistent with the results obtained from the original damage samples,which indicates that this method which is correct and effective and can be applied in terms of detection and evaluation of structural damage for offshore jacket structures.