Fibre waviness defects in composite structures

复合材料现已广泛应用于各种领域。在风力涡轮机和航空航天领域，最近的创新，包括更大和更复杂的结构，促使人们需要更好地了解复合材料结构的失效。使用低成本工艺路线需要更好地了解此类复合材料结构中不可避免的缺陷。控制良好的平板复合板的失效现在通常是很好的理解。然而，实际制造的部件包含一系列应力集中器，其中一些与相对可控的特征相关，如接缝、铺层脱落、夹层板闭合和孔洞，另一些更不确定的与缺陷有关，包括纤维波纹度、富含树脂区域和夹层芯层断裂处的间隙。该项目的目的是了解和模拟这些缺陷如何影响结构的强度。该项目有三个主要方面：(I)表征工业部件和受控实验室样本中的实际缺陷，(Ii)识别疲劳载荷下压缩破坏的机理，并开发波浪形缺陷失效的预测模型，并通过实验进行验证，(Iii)加工过程中缺陷形成的模型。工业合作伙伴Dowty和Vestas建议的案例研究将使用螺旋桨和风力涡轮机叶片。这些模型将与Simulayt有限公司合作，纳入软件工具，用于设计。

Composites are now widely used in a wide range of applications. In the wind turbine and aerospace sectors recent innovations, including larger and more sophisticated structures, have driven the need for better understanding of failure of composite structures. Use of lower-cost process routes requires a need for better understanding of the inevitable defects in such composite structures. Failure of well-controlled flat composite panels is now generally well understood. However real manufactured components contain a range of stress concentrators, some associated with relatively controlled features such as joints, ply drops, sandwich panel closures and holes, some more uncertain associated with defects including fibre waviness, resin-rich areas and gaps at sandwich core breaks. The aim of the project is to understand and model how such defects affect the strength of the structure.The project has three main strands: (i) characterising realistic defects in industrial components and in controlled laboratory specimens, (ii) identifying mechanisms of compressive failure under fatigue loading and developing predictive models for failure at waviness defects, validated with experiments, (iii) modelling of defect formation during processing. Case studies suggested by industrial partners Dowty and Vestas of a propeller and a wind turbine blade will be used. The models will be incorporated into software tools, in collaboration with Simulayt Ltd, for use in design.