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

分层损伤是复合材料层合板的主要破坏机制。已经提出了许多技术来解决这种失效机制，许多最先进的方法，如Z-钉扎、簇绒、纳米纤维增强，都面临着制造挑战、增韧性能不一致以及昂贵的材料和基础设施成本等问题。出于这个原因，这些技术在工业上的商业应用一直很少。显然，需要一种低成本、一致性和广泛适用的复合材料结构厚度增强技术。在该方案中，引入了一种新的概念，可以在复合材料内的关键界面通过厚度定向的微纤维增强材料。利用电磁场对准，铁磁性微纤维将在聚合物树脂膜内垂直定向，然后在标准铺层工艺中交织在复合材料中。在固化过程中，树脂的软化和施加的压力将使各层固结，迫使定向增强材料穿透相邻的层合板，从而提供了一种显著提高复合材料断裂韧性的机制。采用这种方法，可以以当前技术的一小部分成本制造出高损伤容忍度的复合材料结构。(1)识别具有高磁场敏感性、高刚性和高强度并且与适当的热固性树脂系统兼容的铁磁性微纤维材料(2)生产能够控制各种操作条件以使微纤维在部分固化的热固性树脂膜中排列和整合的VAFeR薄膜(3)研究微纤维长度和体积含量对使用VAFeR薄膜的复合材料层压板机械性能的影响这是一个令人兴奋的机会，以开发一种新的成本效益的方法，能够显著提高复合材料结构的损伤容限能力，这对于英国的复合材料研究和行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.