Fibre waviness defects in composite structures

复合材料现在被广泛应用于各种各样的应用领域。在风力涡轮机和航空航天领域，最近的创新，包括更大更复杂的结构，推动了对复合材料结构失效的更好理解的需求。使用低成本的工艺路线需要更好地了解这种复合结构中不可避免的缺陷。控制良好的平面复合板的失效现在普遍得到了很好的理解。然而，实际制造的部件包含一系列应力集中点，其中一些与相对可控的特征有关，如接头、厚度下降、夹芯板闭合和孔，而另一些则与纤维波纹、富含树脂的区域和夹芯断裂处的间隙等缺陷有关。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)描述工业部件和受控实验室样品中的实际缺陷；（ii）确定疲劳载荷下压缩失效的机制，并开发波浪状缺陷失效的预测模型，并通过实验验证；（iii）在加工过程中对缺陷形成进行建模。将使用工业合作伙伴Dowty和Vestas提出的螺旋桨和风力涡轮机叶片的案例研究。这些模型将被整合到软件工具中，与Simulayt有限公司合作，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.