基于遗传算法的海洋平台损伤诊断

Damage Diagnosis for Offshore Platform Based on Genetic Algorithm

海洋平台结构在环境因素下可能出现局部破损,提出一种快速诊断结构损伤的损伤探测方法,而遗传算法因其方法简单及较强的鲁棒性成为近年来发展较快的一种全局优化方法。以海洋平台实测的固有频率和振型为诊断依据,将海洋结构的损伤诊断归结为优化问题,采用遗传算法进行优化搜索。考虑到平台结构刚度的方向性,针对测量噪声和海洋平台模态的特点,提出了一种修正的目标函数作为遗传算法进行损伤诊断的适应度函数。数值模拟和物理模型试验结果表明,该方法能够准确地诊断出导管架海洋平台结构的损伤,改进了进化搜索的鲁棒性,提高了海洋平台结构损伤诊断的可靠性。

In the exploitation of ocean oil and gas,many offshore structures maybe damaged due to severe environment,an effective method for diagnosing structural damage is needed to locate the damage and evaluate its severity.And genetic algorithm has become one of the most important global optimization tools and is widely used in many fields in resent years because of its simple operation and strong robustness.Based on the natural frequencies and mode shapes of the structure,the damage diagnosis of jacket offshore platform is attributed to an optimization problem and studied using genetic algorithm.According to the principle that the structure stiffness of a certain direction can be affected only when the brace bar of corresponding direction is damaged,an improved objective function is proposed based on noise measurement and the characteristics of modal identification for offshore platform,it is used as fitness function of genetic algorithm.Both numerical simulation and physical model test results show that the improved method can locate the structural damage and evaluate its severity of jacket offshore platform,thus it can improve the robustness of evolutionary searching and the reliability of damage diagnosis.