GOALI: Inter-Laminar Toughening of Composite Structures: Bonding Mechanisms and Delamination Resistance

GOALI研究项目是一项研究聚合物基复合材料层间增韧的新工艺。增韧复合材料结构的需要源于优先选择平面纤维/基材的脆性脱粘(分层)。该方法的目的是通过将纤维布层和热固性环氧基紧密结合，在每个现有应力集中部位附近的纤维布层之间局部集成坚韧的热塑性聚合物夹层。这种紧密的粘合是通过(1)将热塑性塑料夹层与纤维热熔合以深度包裹纤维，以及(2)在随后的真空辅助树脂传递模塑固化中将其与热固性基质扩散粘合来实现的。分析将对纤维-夹层和夹层-基质粘结对预制件复合材料的断裂韧性和抗分层性能的耦合效应产生重要的影响。对界面分辨的润湿和粘性流动行为以及热固性-热塑性互扩散动力学的研究将阐明这些粘结机制背后的相互作用。该项目的预期结果将为设计和制造更高效、更耐分层的复合材料部件开辟新的方向。PI与一个主要工业合作伙伴的密切互动将通过特定用途的层压板制造和测试导致热塑性交错方法的快速发展，从而使这一重要的可再生能源具有更大的竞争力，从而产生更广泛的社会影响。如果风力涡轮机叶片等大型锥形叠层复合材料的韧性得到提高，更长的叶片和更高的风力涡轮机将有助于降低成本，推广风能使用，并减少对环境的影响。从这项工作中获得的工艺知识和建模开发可以扩展到广泛的材料制造技术，如不同材料的连接和密封：热固性-热塑性复合材料粘接，以及热固性复合材料与金属的粘接。

This Grant Opportunity for Academic Liaison with Industry (GOALI) research project investigates a novel process for the inter-laminar toughening of polymer matrix composites. The need to toughen composite structures arises from the preferential planar fiber/matrix brittle de-bonding (delamination). The method aims to locally integrate a tough thermoplastic polymer interleaf between fiber fabric plies near each existing stress concentration site by intimately bonding it to the plies and the thermoset epoxy matrix. The intimate bonding is achieved through (1) hot melt bonding the thermoplastic interleaf with fibers to deeply encapsulate the fibers, and (2) diffusively bonding it with the thermoset matrix in the subsequent vacuum assisted resin transfer molding curing. Analysis will yield significant insights into the coupled effects of fiber-interleaf and interleaf-matrix bonding on the fracture toughness and delamination resistance of preform composites. Investigation into the interface resolved wetting and viscous flow behaviors as well as thermoset-thermoplastic inter-diffusion kinetics will elucidate interactions underlying these bonding mechanisms. The expected results from this project will develop new directions for the design and fabrication of more efficient composite components with greater delamination resistance. The PI's close interaction with a key industrial partner will lead to the rapid development of the thermoplastic interleaving method through application-specific laminate fabrication and testing, leading to greater competitiveness of an important renewable energy source and thus broader societal impact. If the toughness of large, tapered laminate composites such as wind turbine blades is enhanced, longer blades and taller wind turbines will help reduce cost, spread wind energy usage, and reduce environmental impact. Process knowledge and modeling developments gained from this work may be extended to a wide range of material fabrication techniques such as dissimilar materials joining and sealing: thermoset-thermoplastic matrix composite bonding, and thermoset matrix composite to metals bonding.