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Improving the delamination bridging behaviour of z-pins through material solutions

通过材料解决方案改善 z 形销的分层桥接行为

基本信息

批准号：
2096017
负责人：
金额：
--
依托单位：
University of Bristol
依托单位国家：
英国
项目类别：
Studentship
财政年份：
2018
资助国家：
英国
起止时间：
2018 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=studentship-2096017
关键词：
Improving delamination bridging behaviour pins

项目摘要

Z-pinning is the most effective method for embedding through-thickness reinforcement in prepeg laminates. Composite Z-pins have been traditionally manufactured employing carbon fibres combined with a bismaleimide (BMI) resin. These materials allow achieving a substantial enhancement of the mode I interlaminar fracture toughness of Z-pinned laminates. Nonetheless, the toughness improvements in mode II are much more modest, due to the inherent brittleness of fibrous carbon/BMI when transversely loaded.Through-thickness reinforcement elements such as Z-pins act as micro-fasteners, restraining the opening and sliding displacements of delaminations and hence inhibiting interlaminar crack growth. As such, ensuring a balanced mode I and mode II performance will reduce the chance of catastrophic failure of damaged composite structures. Mode II delamination toughness is especially crucial in reducing the damage and crack propagation in impacted composite laminates. This includes applications such as gas turbine blades.The aim of this PhD project is to address the poor performance of composite Z-pins under mode II delamination conditions. This will be carried out by means of materials solutions, with the objective of understanding the inherent properties that affect the pin's performance. Ultimately, single-type Z-pins that provide a balanced mode I and mode II delamination toughness will be identified.The key objectives to be completed throughout the length of the project are:- Identify potential reinforcement/matrix materials to be used in Z-pins to achieve a balanced bridging performance in mode I and mode II regimes.- Develop, as necessary, resin blends and fibre architectures that increase the mechanical performance of the pins under mode II loading.- Successfully manufacture candidate Z-pins using the selected materials and architectures, optimising the process to obtain a high-quality output.- Experimentally characterise the meso-mechanics of the candidate Z-pins for the full range of mode mixity and compare with the performance of commercially available Z-pins.Most published work on Z-pinning has concentrated on understanding the performance of only the commercially available carbon/BMI Z-pins. These materials have remained almost unchanged for over a decade. Throughout the project, novel resin blends and fibre architectures will be developed to specifically satisfy the requirements of Z-pins and Z-pinned laminates. Additionally, the study will help to better understand the relationship between the mechanical properties of the pins and their ability to supress mode II delamination.

Z 形钉扎是在预浸层压板中嵌入全厚度增强材料的最有效方法。复合材料 Z 形销传统上采用碳纤维与双马来酰亚胺 (BMI) 树脂相结合来制造。这些材料可以显着提高 Z 形钉扎层压板的 I 型层间断裂韧性。尽管如此，由于纤维碳/BMI 在横向加载时固有的脆性，模式 II 的韧性改进要小得多。Z 销等全厚度加固元件充当微型紧固件，限制分层的张开和滑动位移，从而抑制层间裂纹扩展。因此，确保平衡的模式 I 和模式 II 性能将减少受损复合材料结构发生灾难性故障的机会。 II 型分层韧性对于减少冲击复合材料层压板的损坏和裂纹扩展尤其重要。这包括燃气轮机叶片等应用。该博士项目的目的是解决复合材料 Z 形销在 II 型分层条件下性能不佳的问题。这将通过材料解决方案来实现，目的是了解影响销钉性能的固有特性。最终，将确定提供平衡 I 型和 II 型分层韧性的单一类型 Z 型销钉。在整个项目期间要完成的关键目标是：- 确定 Z 型销钉中使用的潜在增强材料/基体材料，以在 I 型和 II 型体系中实现平衡的桥接性能。- 根据需要开发树脂混合物和纤维结构，以提高 II 型负载下销钉的机械性能。- 使用所选材料和架构成功制造候选 Z 销，优化工艺以获得高质量输出。- 通过实验表征候选 Z 销的细观力学特性，以实现全范围的模式混合，并与市售 Z 销的性能进行比较。大多数已发表的 Z 销研究都集中于了解市售碳/BMI Z 销的性能。这些材料十多年来几乎没有变化。在整个项目中，将开发新型树脂混合物和纤维结构，专门满足 Z 型销和 Z 型销层压板的要求。此外，该研究将有助于更好地理解销的机械性能与其抑制 II 型分层能力之间的关系。