Mechanics of Multi-functional Biocomposites

该奖项的目的是制造高度耐用和多功能的天然纤维复合材料。纤维增强聚合物复合材料是通过将聚合物与强增强纤维结合在一起制成的。玻璃纤维和碳纤维都是相对昂贵的人造纤维。然而，天然纤维是丰富的，可回收的和便宜的。天然纤维增强复合材料在汽车、建筑、体育用品和电子产品等多种商业应用中的使用趋势日益增长。尽管天然纤维复合材料已经用于几种工业应用中，但由于它们的耐久性和机械性能（例如刚度、强度、裂纹萌生和抗扩展性）差，它们在承载应用中的使用非常有限。多功能特性，如刚度，强度和抗裂性，以及损伤传感将通过用石墨烯涂覆天然纤维并在层压板之间嵌入短碳纤维来实现。此外，将进行研究，以了解在各种机械载荷下的天然复合材料的损伤演化使用嵌入式石墨烯和短碳纤维元件产生的三维导电网络。该项目将为研究生和本科生提供将石墨烯嵌入天然纤维，复合材料制造和多尺度机电表征的培训机会。研究活动还将通过在当地公立高中的推广活动，促进招募和指导代表性不足的学生掌握尖端科学技术。将进行一项全面的实验研究，研究多功能天然纤维增强复合材料在不同长度尺度下的损伤演化。为了实现这一目标，新的和具有挑战性的实验纳入三维导电网络的机电响应将在准静态机械载荷条件下进行。通过将石墨烯沿着面内方向嵌入天然纤维层压板中，并在层压板之间沿着厚度方向植绒短碳纤维，将产生高灵敏度的导电网络。据推测，所产生的导电网络将在机械负载过程中发生变化，以反映损伤机制，如纤维从层压板中拉出，基体开裂，层压板之间的分层，和裂纹桥接。除了宏观尺度的实验，纳米尺度的实验也将使用嵌入式微拉伸测试仪，导电模式原子力显微镜捕捉在拉伸和剪切载荷条件下的电流分布的变化。

The objective of this award is to fabricate natural fiber composites that are highly durable and multi-functional. Fiber-reinforced polymer composites are made by combining a polymer together with strong reinforcing fibers. Both glass and carbon fibers are relatively expensive, man-made fibers. However natural fibers are abundant, recyclable and cheap. There is a growing trend to use natural fiber reinforced composites in several commercial applications such as automobiles, building construction, sporting goods, and electronic goods. Although natural fiber composites are already used in several industrial applications, their use in load bearing applications is very limited due to their poor durability and mechanical properties such as stiffness, strength, crack initiation and propagation resistance. Multi-functional properties such as stiffness, strength and crack resistance, and damage sensing will be achieved by coating natural fibers with graphene and embedding short carbon fibers between the laminates. In addition, research will be performed to understand the damage evolution of the natural composites under various mechanical loads using the three-dimensional electrical conductive network generated by the embedded graphene and short carbon fiber elements. This project will provide training opportunities to graduate and undergraduate students on embedding graphene into natural fibers, fabrication of composites, and multi-scale electro-mechanical characterization. The research activities will also promote the recruitment and mentoring of underrepresented students in cutting-edge scientific techniques through outreach in local public high schools.A comprehensive experimental study will be conducted to investigate damage evolution at different length scales in multi-functional natural fiber reinforced composites. To accomplish this objective, novel and challenging experiments incorporating the electro-mechanical response of three dimensional electrical conductive networks will be performed under quasi-static mechanical loading conditions. Highly sensitive conductive networks will be generated by embedding graphene in natural fibers laminates along in-plane directions, and by flocking short carbon fibers along the thickness direction between the laminates. It is hypothesized that the generated conductive network will undergo changes during mechanical loads to reflect damage mechanisms such as fiber pulling from the laminates, matrix cracking, delamination between laminates, and crack bridging. In addition to macro-scale experiments, nano-scale experiments will also be performed using a micro-tensile tester embedded, conductive mode atomic force microscope to capture change in current profile under tensile and shearing loading conditions.