基于一阶振型的海洋平台二阶段损伤定位方法

A Two-stage Damage Localization Method Based on the First Mode Shape of Offshore Platform Structure

海洋平台等大型复杂结构其高阶模态难以激起和测试,甚至只能识别出一阶模态振型和前几个低阶模态频率,因此,利用少量低价模态进行损伤诊断显得尤为重要。本文提出了仅利用一阶模态振型对海洋平台进行损伤位置诊断的二阶段法:先利用模态曲率变化率确定损伤的大体位置,再利用一阶模态应变能分别确定主导管和撑杆是否损伤及其位置。最后通过一个三腿导管架海洋平台有限元数值模型验证了该方法的可行性和有效性。研究发现,本文提出的方法具有较好的识别精度,具有一定的适用性。

Offshore platforms are so large and complex that it is difficult to activate and measure the higher order modes, even only modal parameters of lower modes can be identified accurately. Thus it is particularly important to diagnose structural damage using a few lower modes. In this paper, a two-stage damage localization method based on the first mode shape of offshore platform structure is presented. In the first stage, the primary damage location is determined by using mode curvature change ratio. In the second stage, dominant pipe legs and braces are judged and damage localized by using the mode strain energy respectively. Finally, a numerical model of damage locations detected three-leg jacket offshore platform is used to validate the proposed method. The results indicate that the proposed method has good identification accuracy and is efficient for large and complex structural damage detection.