基于振动传递率的钢质导管架海洋平台结构损伤识别方法研究

Study on the Damage Identification Method of Steel Jacket Offshore Platform Based on Vibration Transmissibility Function

基于振动的结构损伤识别方法在应用过程中会遇到激励信息难以获得、实测模态参数不完备以及对有限元模型的依赖等问题。为此,利用白噪声激励下的结构两点加速度响应构造振动传递率函数,通过主成份分析降低其维数,将结构损伤前、后振动传递率函数幅值的主成份变化量作为结构损伤特征向量,输入BP神经网络进行结构损伤识别,并考虑了不同程度噪声对损伤识别结果的影响。钢质海洋平台结构数值模拟和模型试验结果表明,该方法能识别出结构损伤位置并且具有一定的抗噪声能力。

During the application process of structural damage identification methods based on vibration,problems such as the excitation information is difficult to obtain,the measured modal parameters are incomplete,the method is dependent to FEM model will be encountered.So,in this paper,two node acceleration responses of the structure excited with the white noise are directly used to construct the vibration transmissibility function,and principal component analysis(PCA)is pursued to the amplitude of the vibration transmissibility for dimensionality reduction.The combinations of principal component variation before and after damage are used as the damage characteristic vectors,which are input into the BP neural network for damage identification,the influences of different degrees of noise during the damage identification are considered simultaneously.The results of numerical simulation and model experiment of offshore platform show that the method can identify the damage location and has reasonable noise resisting capability.