Vertically Aligned Ferromagnetic-fibre Reinforced (VAFeR) Films for Enhanced Damage Tolerant Composites

众所周知，分层损伤是层压复合材料的主要失效机制。已经提出了许多技术来解决这种失效机制，其中许多最先进的方法，如Z钉扎、簇绒、纳米纤维增强材料，都存在制造挑战、不一致的增韧性能以及昂贵的材料和基础设施成本等问题。因此，这些技术在工业上的商业用途很少。显然，需要一种低成本、一致性和广泛适用的复合材料结构全厚度增强技术，在该提案中，引入了一种新的概念，该概念可以在复合材料内的关键界面处提供全厚度对齐的微纤维增强。使用电磁场对准，铁磁微纤维将在聚合物树脂膜内垂直取向，然后可以在标准铺层过程中插入复合材料中。在固化过程中，树脂的软化和施加的压力将使各层固结，迫使对齐的增强物穿透相邻的层压板，提供了一种将显著增加复合材料的断裂韧性的机制。通过这种方法，可以以相对于当前技术的一小部分成本生产高度损伤容限的复合材料结构。将在三个关键目标中研究几个实际和科学挑战：（1）识别具有高磁场敏感性的铁磁微纤维材料，（2）生产具有控制各种操作条件的能力的VAFeR膜，用于在部分固化的热固性树脂膜内排列和整合微纤维（3），研究微纤维长度和体积含量对复合材料层合板机械性能的影响，并应用VAFeR薄膜。这是一个令人兴奋的机会，可以开发一种新的具有成本效益的工艺，能够显着提高复合材料结构的损伤容限能力，这对英国复合材料研究和工业来说是一个潜在的变革性前景。

It is well established that delamination damage is the dominant failure mechanism in laminated composites. There have been numerous technologies proposed to address this failure mechanism, with many state-of-the art methods such as Z-pinning, tufting, nano fibre reinforcements all suffering from problems such as manufacturing challenges, inconsistent toughening performance and expensive materials and infrastructure costs. For this reason there has been very little commercial use of these technologies in industry. There is clearly a need for a low cost, consistent and widely applicable through thickness reinforcement technology for composite structures.In this proposal a new concept is introduced which can deliver through thickness aligned micro-fibre reinforcements at the critical interfaces within a composite material. Using electromagnetic field alignment, ferromagnetic micro-fibres will be vertically orientated within a polymer resin film which can then be interleaved in a composite material during the standard layup process. During the cure process, the softening of the resin and the applied pressure will consolidate the layers, forcing the aligned reinforcements to penetrate the adjoining laminates, providing a mechanism which will significantly increase the fracture toughness of composite materials. With this approach, highly damage tolerant composite structures can be produced at a fraction of the costs relative to current technologies. Several practical and scientific challenges will be investigated in three key objectives: (1) Identify ferromagnetic micro fibre materials with high magnetic field susceptibility, high stiffness and strength and compatible with a suitable thermosetting resin system(2) Produce VAFeR films with capability to control various operating conditions for alignment and integration of the micro-fibres within a partially cured thermosetting resin film(3) Investigate effect of micro-fibre length and volume content on the mechanical performance of composite laminates with the application of the VAFeR filmsThis is an exciting opportunity to develop a new cost effective procedure with capability to significantly increase the damage tolerance capability of composite structures, a potentially transformative prospect for the UK composites research and industry.