基于应变模态的风机叶片损伤诊断研究

针对多种受损工况下的风机叶片损伤诊断问题,文章基于模态理论对受损前和受损后的风机叶片进行位移和应变模态分析。首先建立风机叶片的三维模型并对其进行有限元分析;然后模拟叶片两位置不同的损伤状况,比较各工况下位移模态曲线、应变模态曲线和应变模态差分曲线在受损前后的变化规律,进而对叶片进行损伤辨识;最后选取应变模态变化率和由差分曲线建立的直接定位损伤指标I_SMSD作为风机叶片损伤诊断指标,进一步辨别叶片的损伤程度。通过结构损伤前后模态频率、位移模态及应变模态参数的对比可以发现:在受损量不同的情况下,叶片模态频率损伤前、后变化较小,位移模态几乎没有产生变化;在受损区域应变模态及其差分曲线均有突变产生,裂纹的长度越大突变越明显。可将应变模态变化率和I_SMSD作为损伤诊断的特征参数,为风机叶片的预报维修提供参考。

Damage identification of wind turbine blade based on strain mode analysis

In order to identify the damage degree of wind turbine blade,the displacement and strain modal analysis of intact and damaged blades are studied.Firstly,the three-dimensional model of wind turbine blade is established for finite element analysis.Secondly,different damaged location and degree of wind turbine blade are simulated,the change rules of the displacement modal shapes,the strain modal shapes and the strain modal difference curves are compared.Finally,the strain modal variable ratio and the Strain Modal Shape Difference(ISMSD)are selected as the damage indicator,in order to identify the damage degree of wind turbine blade.The results show that the variation of modal frequency between intact and damaged blade is minor,the displacement modal shapes have almost no change,but the strain modal shapes and the strain modal difference curves have obvious change in the damaged area,the mutation increased with the expanded crack size.The strain modal variable ratio and ISMSD can be selected as the damage indicator,which can provide reference for the prediction and maintenance of wind turbine blade.