【摘要】 针对叶片裂纹诊断问题,基于裂纹引起的叶片任意两阶固有频率变化之比只与损伤位置有关的性质,提出了基于任意两阶固有频率变化比的裂纹位置参数、裂纹定位参数及裂纹定位准则;将叶片表面划分多个区域,每次在区域边界植入单个裂纹,计算裂纹定位参数,实现叶片裂纹所属区间定位;同时,研究叶片裂纹定位参数在裂纹区间内的变化规律,建立了裂纹定位参数与区间相对位置间的映射关系,实现了叶片裂纹区间内的精确定位。基于完好叶片与裂纹叶片一阶固有频率变化量的平方与一阶固有频率之比只与损伤程度相关的性质,建立了叶片不同裂纹位置下裂纹损伤程度函数模型,实现叶片裂纹损伤程度的识别。通过数值仿真分析及试验验证了该方法的有效性,且识别精度较高,为实际的应用提供有力的依据。更多还原

【Abstract】 The structure health condition of a wind turbine blade is closely related to public safety. Cracks in wind turbine blades affect safe operation of wind turbines. The diagnosis of blade cracks is of paramount importance. The cracks influence the natural frequency of the blades. In wind turbine blades, the natural frequency variation of the structure caused by the crack is related to its position. In terms of the ratio of the adjacent two-order natural frequency variation, it was found that the ratio is related to the crack position alone. Based on the ratio parameters, the blade can be fictitiously divided into multiple connected regions. The crack is implanted at each joint point of regions to establish the database of the ratio parameters for crack locating. The region where the crack exists can be ascertained. Then, a new position parameter in the region was proposed, and the mapping between this parameter and the detail position within the region was established. The crack can be located more accurate in the regions. In order to identify the degree of the crack, a parameter of crack degree, which is defined as the ratio of the variation of the natural frequency to the natural frequency itself, was proposed. Based on simulation and data analysis, the correlation between the parameter and the degree of crack was established. Based on the correlation, the degree of crack can be ascertained by the correlation after crack locating. Numerical simulation analysis and tests for blade with different cross-sectional shapes were performed, and the results all show that the method is effective and accurate.更多还原