Various wind turbine blade components, such as shear webs and skins, commonly use fiber-reinforced composite sandwich structures with a core material like balsa or foam. During manufacturing, core gap defects may result from the misalignment of adjacent foam or balsa core sheets in the blade mold. It is important to understand the influence that core gaps have on the structural integrity of wind turbine blades and how to mitigate their influence. This research characterized the effects of core gap defects at the manufacturing and mechanical levels for both epoxy and next-generation thermoplastic composites. Common repair methods were assessed and compared. Multiple defect sizes were compared using temperature data gathered with thermocouples embedded during manufacturing to core gap defect characteristics obtained using image-mapping techniques, optical microscopy, and mechanical characterization by long beam flexure. Results showed that peak exothermic temperatures during curing were closely related to core gap size. The long beam flexure tests determined that transverse core gaps under pure bending loads can have a substantial effect on the ultimate facesheet strength of both epoxy and thermoplastic composite sandwich structures (up to 25% strength reduction), although the size of the defect itself had less of an influence on the magnitude of the strength reduction. The supporting image-mapping techniques indicated that the distortion of the composite facesheets by the core gaps contributed to the premature failures. The repair methods used in this study did very little to improve the ultimate strength of the sandwich panels that previously had core gap defects. The repair of the thermoplastic panel resulted in a further loss in ultimate facesheet strength. This research demonstrated that there is a vital need for the development of a compatible thermoplastic polymer repair resin system and appropriate resin specific repair procedures for the next generation of recyclable thermoplastic wind blades.

各种风力涡轮机叶片部件，如抗剪腹板和蒙皮，通常使用纤维增强复合夹层结构，其芯材如轻木或泡沫。在制造过程中，芯间隙缺陷可能是由于叶片模具中相邻泡沫或轻木芯板的未对准造成的。了解核心间隙对风力涡轮机叶片结构完整性的影响以及如何减轻其影响非常重要。这项研究描述了环氧树脂和下一代热塑性复合材料在制造和机械水平上的核心间隙缺陷的影响。对常见的修复方法进行了评估和比较。使用在制造过程中嵌入热电偶收集的温度数据与使用图像映射技术获得的核心间隙缺陷特征进行比较多种缺陷尺寸，光学显微镜和长光束弯曲的机械表征。结果表明，固化过程中的峰值放热温度与芯间隙尺寸密切相关。长梁弯曲测试确定，纯弯曲载荷下的横向芯线间隙会对环氧树脂和热塑性复合夹层结构的最终面板强度产生重大影响（强度降低高达 25%），尽管缺陷本身的尺寸较小强度降低幅度的影响。支持的图像映射技术表明，复合面板的核心间隙变形导致过早失效。本研究中使用的修复方法对提高以前存在核心间隙缺陷的夹芯板的极限强度几乎没有作用。热塑性面板的修复导致最终面板强度的进一步损失。这项研究表明，迫切需要为下一代可回收热塑性风力叶片开发兼容的热塑性聚合物修复树脂系统和适当的树脂特定修复程序。