Collaborative Research: Mechanics of Structural Toughening in Sutured Composites

该基金将研究缝线几何形状如何影响复合材料性能的机制。生物盔甲和甲壳采用缝合关节，这是一种波浪状、柔顺的夹层，连接刚性材料域，这些缝合线的长度范围从几纳米到毫米不等。一般认为，在复杂的载荷条件下，缝合接头可以增强生物复合材料的强度和韧性，但其潜在的机制尚不清楚。材料结构在必要长度尺度上的加工和表征的最新进展将使该项目能够提供第一个系统的实验研究和缝合力学的理论建模。这一新知识可以为打印性能更高的聚合物复合材料的新增材制造范式提供基础。教育和推广计划将开发参与幼儿园到研究生，暴露他们在力学和材料科学的引人入胜的概念。活动包括课程开发、本科生研究、拓展课程和落基山力学研讨会。该项目的具体目标是建立缝线几何形状与复合材料破坏的三个关键阶段（裂纹成核、裂纹捕获和机械联锁）之间的结构-性能关系。该项目将寻求以下问题的答案：哪些结构缝合参数促进或抑制了三个阶段中的每一个阶段，以及如何平衡参数以提高复合材料的强度和韧性，并延长使用寿命？更具体地说，本项目的研究目标包括：(i)了解薄膜中的单缝线力学；（ii）了解薄膜中缝合线的相互作用，（iii）建立一个双波长增材制造平台，将薄膜的知识推断到3D结构中，可以研究弯曲、扭转和压缩载荷下的性能。为了实现这些目标，两阶段反应性聚合物将被用于制造由不同波长、振幅、线宽和联锁角度的缝合线组成的复合材料；原子力显微镜将用于快速力映射模式，以纳米分辨率表征缝线性能的变化；将利用有限元建模将缝合几何形状与整体复合材料性能联系起来。研究结果将为分层复合材料的结构增韧机制和断裂行为提供新的见解，并将带来单树脂、双波长3D复合材料打印方法。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This grant will investigate the mechanics of how suture geometry influences composite performance. Biological armors and carapaces employ suture joints, which are wavy, compliant interlayers that connect rigid material domains, and these sutures can manifest at length scales ranging from a few nanometers to millimeters in size. It is generally assumed that suture joints amplify the strength and toughness of biological composites in the presence of complex loading conditions, but the underlying mechanisms are not understood. Recent advancements in processing and characterization of material structure at requisite length scales will enable this project to provide the first systematic experimental investigation and theoretical modeling of suture mechanics. This new knowledge could provide the basis for a new additive manufacturing paradigm for printing polymer composites with improved performance. Education and outreach programs will be developed to engage kindergarten to graduate students, exposing them to engaging concepts in mechanics and materials science. Activities include course development, undergraduate student research, outreach lessons, and a Rocky Mountain Mechanics Symposium.The specific goal of the project is to establish structure-property relationships between suture geometry and three key stages of composite failure: crack nucleation, crack trapping, and mechanical interlocking. This project will seek answers to the questions such as: which structural suture parameters promote or inhibit each of the three stages, and how can parameters be balanced to amplify composite strength and toughness, and increase service life? More specifically, the research objectives of this project include: (i) understanding single-suture mechanics in thin films; (ii) understanding suture-suture interactions in thin films, (iii) establishing a two-wavelength additive manufacturing platform to extrapolate knowledge from thin films to 3D architectures where performance in the presence of bending, torsion, and compressive loadings can be studied. In pursuit of these objectives, two-stage reactive polymers will be employed to fabricate composites comprised of sutures with varying wavelength, amplitude, line width, and interlocking angles; atomic force microscopy will be used in fast force mapping mode to characterize variations in suture properties with nanometer resolution; finite element modeling will be leveraged to relate suture geometry to bulk composite performance. Results will offer new insights on structural toughening mechanisms and fracture behavior in hierarchical composites, and will lead to a single-resin, two-wavelength 3D composite printing methodology.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.