CAREER: Microscale Deformations Underlying Multiscale Mechanics of Fiber Networks

该学院早期职业发展计划（CAREER）奖支持基础研究，以研究由微观纤维随机网络制成的材料的特性。在人体健康方面的应用最为直接，因为纤维材料形成了人体许多组织的结构。这些组织的机械性质与损伤（例如韧带撕裂）和疾病（例如癌症进展）有关。纤维材料也具有潜在的工程应用，因为它们重量轻，但对损伤具有高耐受性。在人类健康和工程这两个应用中，了解结构特性（如纤维尺寸和数量）与机械特性（如刚度和强度）之间的关系至关重要。这项研究将建立这些关键关系，这将促进疾病的治疗，并使纤维材料的工程应用成为可能。由于这项研究的许多未来应用是在人类健康，未来的工程师将需要在工程和生物学方面进行培训。因此，该项目的另一个目标是使学生能够应用多个不同科学领域的原理来解决工程问题。为此，工程专业的本科生将练习将工程概念应用于生物学和人类健康问题。此外，生物学的高中生将学习如何使用物理学原理来理解生物学。预计这种跨学科的培训将加强工程和科学劳动力。本研究的具体目标是确定网络中单个纤维的性质如何影响不同负载条件下的力学。为了实现这一点，实验将使纤维网络受到全局和局部载荷，并测量纤维尺度下的位移。将比较具有不同纤维浓度、长度和交联的网络的结果。与此同时，一个模拟每根纤维弯曲和拉伸力学的理论模型将用于测试最先进的理论与实验数据。结果将建立纤维的性质，应变大小，和长度尺度的非线性，异质性，非亲和性，和可塑性，每一个影响的力学。这些发现将共同确定在预测纤维材料对一般载荷条件的响应的模型中必须考虑哪些变形机制。该奖项反映了NSF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 Faculty Early Career Development Program (CAREER) award supports fundamental research to study properties of materials made of random networks of microscopic fibers. Applications are most direct in human health, as fibrous materials form the structure for numerous tissues in the human body. Mechanical properties of those tissues relate to injury, for example in tearing of ligaments, and to disease, for example in progression of cancer. Fibrous materials also have potential engineering applications, as they are light in weight yet have high tolerance for damage. In both applications--human health and engineering--it is crucial to understand the relationship between structural properties, like fiber size and number, and mechanical properties, like stiffness and strength. This research will establish these crucial relationships, which will advance treatments to disease and enable engineering applications for fibrous materials. As many future applications of this research are in human health, there will be a need for future engineers to be trained in both engineering and biology. Therefore, an additional objective of this project is to enable students to apply principles from multiple different scientific fields to solve engineering problems. For this, undergraduate students in engineering will practice applying concepts of engineering to problems in biology and human health. Additionally, high school students in biology will learn how principles of physics can be used to understand biology. It is expected that this interdisciplinary training will strengthen the engineering and scientific workforce.The specific objective of this research is to determine how properties of the individual fibers within a network affect the mechanics under different loading conditions. To accomplish this, experiments will subject fibrous networks to both global and local loads and measure the displacements at the scale of the fibers. Results will be compared for networks having different fiber concentration, length, and crosslinking. In parallel, a theoretical model simulating the mechanics of how each fiber bends and stretches will be used to test the state-of-the-art theory against experimental data. The results will establish the fiber properties, strain magnitudes, and length scales for which nonlinearity, heterogeneity, nonaffinity, and plasticity each affect the mechanics. Together, these findings will establish which deformation mechanisms must be accounted for in a model that predicts the response of fibrous materials to general loading conditions.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.