基于非线性瞬时模态与模态局部化的近海风机叶片损伤机理、识别与监测研究

Offshore wind energy techniques are developing rapidly. The damage identification and monitoring of offshore wind turbine blades which are essential energy capturing parts are becoming of significant importance in their service life. In this proposal, mode localization model is to be established based on theoretical analysis, shaking table tests and wind tunnel tests, which are beneficial for recognition of environmental hazards and special aerodynamical properties of offshore wind turbine blades. Shaking table tests are employed for investigating local mode characteristics and their initialization mechanism. Wind tunnel tests are planned for studying the transferring mechanism from local modes to nonlinear instantaneous modes. Energy transferring and damage model is to be established by analyzing bifurcation and transition of nonlinear instantaneous modes. Simulation will be conducted for the verification of theory predication and comparison with experiment results. Damage identification and monitoring methods will be developed based on proposed mode localization and damage model considering local and global modes. The purpose of the project is to gain further insights of the damage mechanism and failure process of offshore wind turbine blades from the perspective of nonlinear mechanics. The proposed research has not only its scientific merits and theoretical significance, but is closely related to national strategic energy demands and promising in practical applications of offshore wind engineering projects.

近年来海上风力发电在全球蓬勃发展，捕获风能的关键部件-风机叶片在服役期内的损伤和监测变得尤为重要。本项目针对近海风机独有的空气动力学特点，通过振动台试验、风洞试验和实测分析等手段，进一步认识环境灾害荷载的作用机理，建立风机叶片模态局部化现象的力学模型；通过振动台试验研究局部模态的特点及其产生机理；通过风洞试验，掌握局部模态随激励变化向非线性瞬时模态转化的规律；研究非线性瞬时模态跃迁和模态分叉的机制，建立非线性瞬时模态能量交换与叶片破坏的模型；编制模拟计算软件，进行理论分析与试验分析的对比研究，验证理论研究的重要性；在认识近海风机叶片模态局部化规律的基础上，有针对性地考虑局部模态影响，开发局部与整体相结合的风机叶片损伤识别与监测方法。实现在非线性的层次上深入理解近风机叶片的损伤机理和破坏过程。该项研究不仅具有重要的理论意义和科学价值，而且切实结合国家新能源需求，具有显著的工程应用前景。

风机叶片的损伤识别是风机健康监测的重要环节。.本项目主要研究风机叶片模态局部化的产生机理以及基于模态局部化现象的叶片损伤识别方法：研究了风轮模态局部化的动力学机理与影响因素；基于矩阵摄动理论对模态局部化的定量描述；利用视频运动放大技术的风机叶片运行模态识别；利用模态局部化的叶片损伤进行识别；风机轮毂和塔筒的载荷识别。在研究中取得两项原创性成果：1）利用矩阵摄动原理揭示了风机模态局部化产生的机理；2）基于动态压缩感知和联合状态估计算法的风机气动载荷识别.该项研究不仅具有重要的理论意义和科学价值，而且对于将模态局部化思想应用于重大工程项目具有重要的实践意义。