I-Corps: Development of Self-healing, Fiber-reinforced Composites

这个i-Corps项目的更广泛的影响/商业潜力是自我修复纤维增强复合材料(FRC)的开发。该技术可用于自动修复服役过程中的分层损伤，从而提高现代结构的耐久性和寿命。在全球范围内，FRC代表着先进材料技术领域最大和增长最快的行业之一。这一增长源于FRC在包括航空航天、国防、绿色能源、汽车、海洋、基础设施和电子等广泛行业中的大量高性能应用。在最有价值的应用中使用的许多复合材料结构都是多层叠层板，在多年(高达30年)的使用中暴露在反复的应力下。提出的自修复复合材料是专门针对防止这些层合复合材料结构的过早破坏和延长使用寿命的。此外，自修复FRC还提供了一种更可持续的途径，可延长使用寿命并增强弹性和耐用性，使此类材料在维护和更换以及相关停机时间成本高昂的复合材料行业中尤其具有吸引力。航空航天等行业也可能从增强的安全性中受益，在这些行业，最终用户报告了分层敏感部件的问题，包括旋翼叶片和其他具有铺层脱落和紧固孔的部件，这些部件存在应力集中的地方。i-Corps项目基于开发一种自愈纤维增强复合材料(FRC)平台，通过热修复实现就地自愈。所提出的方法依赖于可修补的热塑性塑料(TP)，这种热塑性塑料直接打印到机织纤维增强件上，并与碳基电阻加热器共层压。在低于复合热固性树脂玻璃化转变的温度下，图案化的TP具有较高的熔体流动和自增压能力，可提供受限微裂纹传输。通过电阻加热实现快速(几分钟级)就地热修复。直接在增强体上打印TP会增加界面粘结，导致通过热塑性界面的粘结破坏。测试结果表明，与普通复合材料相比，I型断裂韧性提高了四倍，并且通过动态重新粘合实现了持续循环次数(100+)的一致自我修复性能(高达100%)。通过这种拟议的原位热修复策略实现的长时间恢复与现有技术相比，在自我修复重复性方面实现了数量级的飞跃。此外，用于自我修复的复合增强保留了机械性能，并与现有的制造工艺兼容，这两者对最终的商业化都至关重要。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The broader impact/commercial potential of this I-Corps project is the development of self-healing fiber-reinforced composites (FRC). The proposed technology may be used to autonomously repair delamination damage during service, thereby enhancing the durability and longevity of modern structures. Globally, FRC represent one of the largest and fastest growing sectors of advanced materials technology. This growth stems from the numerous high-performance applications for FRC in a broad range of industries that include aerospace, defense, green energy, automotive, marine, infrastructure and electronics. Many of the composite structures used in the highest value applications are multi-layer laminates that are exposed to repeated stresses over multiple years (up to 30) of service. The proposed self-healing composite is specifically aimed at preventing premature failure in these laminated composite structures and extending service life. In addition, self-healing FRC also provide a more sustainable pathway that prolongs service life and enhances resilience and durability, making such materials particularly attractive in composite industries where maintenance and replacement and associated downtime are costly. Industries such as Aerospace also may benefit from enhanced safety, where end-users have reported issues with delamination-susceptible parts including rotorcraft blades and other components featuring ply-drops and fastener holes where stress concentrations arise.This I-Corps project is based on the development of a self-healing fiber-reinforced composites (FRC) platform that achieves in situ self-healing via thermal re-mending. The proposed approach relies on mendable thermoplastic (TP) that is 3D-printed directly onto woven fiber reinforcement and co-laminated with carbon-based resistive heaters. The patterned TP exhibits high melt-flow and self-pressurization for confined micro-crack delivery at temperatures below the glass-transition of the composite thermoset matrix. Rapid (minutes-scale) in situ thermal re-mending is accomplished via resistive heating. Printing TP directly on the reinforcement increases interfacial bonding, resulting in a cohesive failure through the thermoplastic interphase. Test results show a four-fold increase in mode-I fracture toughness over a plain composite, and a consistent self-healing performance (up to 100%) via dynamic re-bonding for sustained cycle counts (100+). The prolonged recovery made possible via this proposed in situ thermal re-mending strategy represents an order of magnitude leap in self-healing repeatability compared to prior technologies. In addition, the composite augmentations for self-healing preserve mechanical properties and are compatible with existing manufacturing processes, both of which are critical for eventual commercialization.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.