半潜式海洋平台肘板中超声导波传播规律研究

Study on the propagation of ultrasonic guided waves in the bracket of a semi-submersible offshore platform

半潜式海洋平台肘板连接处裂纹属于典型的变厚度板裂纹,导波在变厚度板中的传播规律非常复杂,为解决肘板连接处裂纹检测的问题,本文拟通过数值计算和仿真的方式探索超声导波的传播规律。在仿真软件中建立肘板节点模型,在肘板上以及X轴方向布置传感器,进行单点激励多点接收信号,通过监测不同距离处的波动情况、导波模态转化和幅值变化等,总结变厚度肘板在有无裂纹情况下导波的传播规律,得出导波在包含裂纹的肘板中幅值和波达时刻发生改变,但传播规律不变的结论。

The crack at the joint of the bracket plate of a semi-submersible offshore platform belongs to the typical variable-thickness plate crack,and the propagation of guided waves in the variable-thickness plate is very complicated.In order to examine the crack at the joint of the brackets,the propagation law of ultrasonic guided wave is explored by numerical calculation and simulation.By the simulation software,the bracket node model is established,sensors are arranged on the bracket in the x-axis direction,the single point excitation and multi-point reception of signals are carried out,and the propagation rule of guided wave with or without crack is summarized by monitoring the fluctuation at different distances,the guided wave mode transformation and the amplitude change.Finally,it can be concluded that the guided wave mode transformation will not change when the amplitude and moment change in the crack of the brackets.