ABSTRACT

As a weak link in large wind turbine blades, adhesively bonded joints have recently received unprecedented attention in the field of wind energy because they are easily damaged and have short lifetimes. This paper deals with the effects of geometrical dimensions and laminate layups on failure load and the associated failure mode of composite bonded joints for wind turbine blades. Single-lap composite-to-composite bonded joints were fabricated and tested to complete failure under tensile load, and the features of a thick adhesive layer, a large overlap length and width, and actual laminate layups were considered. The failure load and mode of bonded joints along with the geometrical dimensions and composite layups were analyzed and compared with previous studies. The results show that failure load decreases overall with adhesive thickness, while it increases rapidly with overlap length and increases slightly faster than is proportional with overlap width. A combination of both adhesive failure and thin-layer cohesive failure is prone to initiate in thick and short bonded joints, while fiber-tear failure is initiated in thin and long bonded joints. Thick adherends can enhance the bonded joint to some extent. Therefore, it is recommended that at least one unidirectional lamina is laid in the middle of the composite layups to avoid the premature failure of adherends for bonded joints in wind turbine blades.

摘要

作为大型风电叶片中的薄弱环节，粘接接头由于易损坏且使用寿命短，近来在风能领域受到了前所未有的关注。本文讨论了几何尺寸和叠层对失效载荷的影响以及风力涡轮机叶片复合材料结合接头的相关失效模式。制造并测试了单搭接复合材料与复合材料的粘合接头在拉伸载荷下完全失效，并考虑了厚粘合剂层、大重叠长度和宽度以及实际层压板铺设的特点。对粘合接头的失效载荷和模式以及几何尺寸和复合材料铺层进行了分析，并与之前的研究进行了比较。结果表明，破坏载荷随着粘合剂厚度的增加而整体降低，而它随着重叠长度的增加而迅速增加，并且比与重叠宽度成正比的增加略快。粘合破坏和薄层内聚破坏的结合容易在厚和短的粘合接头中开始，而纤维撕裂破坏则在薄和长的粘合接头中开始。较厚的被粘物可以在一定程度上增强粘合接头。因此，建议在复合材料叠层中间至少铺设一层单向薄板，以避免风力涡轮机叶片中粘合接头的被粘物过早失效。而纤维撕裂破坏则是在细长的粘合接头中开始的。较厚的被粘物可以在一定程度上增强粘合接头。因此，建议在复合材料叠层中间至少铺设一层单向薄板，以避免风力涡轮机叶片中粘合接头的被粘物过早失效。而纤维撕裂破坏则是在细长的粘合接头中开始的。较厚的被粘物可以在一定程度上增强粘合接头。因此，建议在复合材料叠层中间至少铺设一层单向薄板，以避免风力涡轮机叶片中粘合接头的被粘物过早失效。