Various defects produced during the manufacture of a wind turbine blade can affect the damage evolution under fatigue loads. In this paper, a calculation model based on energy dissipation was used to predict damage evolution. Based on the structure of the unidirectional laminates in the main spar of a 1.5-MW blade, specimens with voids or delamination defects of different dimensions were fabricated. Fatigue tests of the specimens were monitored with an infrared thermography system. The energy dissipation density was calculated from the surface temperature. A damage parameter D is proposed to represent the degree of damage evolution. By analyzing the energy dissipated during cyclic loading, it is possible to evaluate the critical moment when a defect evolves into initial critical damage. The calculation model agrees well with the observed damage evolution. This innovative method could be used to detect the initial damage in a main spar with defects during a fatigue test.

中文翻译：

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检测风力涡轮机叶片主翼梁的缺陷

风力涡轮机叶片制造过程中产生的各种缺陷会影响疲劳载荷下的损伤演变。在本文中，基于能量耗散的计算模型被用于预测损伤演化。基于 1.5 MW 叶片主梁中单向层压板的结构，制备了具有不同尺寸空隙或分层缺陷的试件。用红外热成像系统监测试样的疲劳试验。从表面温度计算能量耗散密度。提出了损伤参数 D 来表示损伤演化程度。通过分析循环加载过程中耗散的能量，可以评估缺陷演变为初始临界损坏的临界时刻。计算模型与观察到的损伤演化非常吻合。这种创新方法可用于在疲劳试验期间检测有缺陷的主梁中的初始损伤。