Phenomenological-Based Constitutive Model and Simulation of Fiber Interaction for Short Fiber Composite Processing

短纤维聚合物复合材料在工业上得到了广泛的应用，这在很大程度上是由于其高的强度与重量比和多样化的制造工艺。然而，目前常用的预测纤维微观结构和热机械性能的S熔体流动模拟工具采用了简化的经验推导的纤维碰撞模型，这些模型最近被证明高估了加工过程中纤维的排列速度。本研究的主要目的是建立一种基于唯象的纤维在一般流体中碰撞的本构模型，并使用这种新的建模方法来预测工业级产品的纤维取向状态。这项工作包括从纤维-纤维和纤维-流体相互作用运动学出发的新的单纤维碰撞模型、相关的多尺度连续介质表示、适用于工业应用的简化计算过程、对其在纳米管加工中的适用性的研究以及模型的验证和验证。预计这种新的纤维相互作用模型的基础性发展将为更广泛的应用提供独特的见解，从而产生更准确和更高效的复合材料工艺设计程序。这项研究的广泛影响来自于旨在提高当地青年、高中生和工科本科生对在工程中使用计算的认识的新的和独特的教育活动。具体任务包括为地区青年组织和准备上大学的高中生开发新的工程培训材料，以及为本科工程师开发新的计算项目。拟议的活动将利用现有努力吸引任职人数不足的群体的学生，同时通过合作活动加强研究基础设施。

Short-fiber polymer composites enjoy widespread industrial application due in large part to their high strength-to-weight ratios and versatile manufacturing processes. However, today?s melt flow simulation tools, which are commonly used to predict fiber microstructure and thermo-mechanical properties, employ simplified empirically-derived fiber collision models that have recently been shown to over-predict the rate of fiber alignment during processing. The main objectives of this research are to develop a phenomenological-based constitutive model for fiber collisions in a general fluid and to use this new modeling approach to predict fiber orientation states for industrial-level products. This work includes a new single fiber collision model derived from fiber-fiber and fiber-fluid interaction kinematics, a related multi-scale continuum representation, a simplified calculation procedure suitable for use with industrial applications, an investigation into its applicability to nano-tube processing, and model validation and verification. It is expected that the foundational development of this new fiber interaction model will provide unique insight into a wide range of applications resulting in more accurate and efficient composite processing design procedures.Broader impacts of this research stem from new and unique educational activities aimed at increasing the awareness of local youth, high school students, and undergraduate engineering students to the use of computation in engineering. Specific tasks include the development of new engineering training materials for regional youth organizations and college-bound high school students, and new computational projects for undergraduate engineers. The proposed activities will leverage existing efforts for attracting students from under-represented groups while enhancing the research infrastructure through collaborative activities.