Investigations on Transport Phenomena Governing Interfacial Bonding Evolution in Thermoplastic Composites

热塑性树脂基复合材料是通过将纤维增强热塑性树脂预浸带逐层堆叠和熔融粘接成所需的形状和厚度而制成的。层间粘结强度的演变-预浸料产品质量的衡量标准-受界面接触面积的发展所控制，界面接触面积的发展是通过预浸料表面的平整（称为“紧密接触”过程）和聚合物分子在接触区域的相互扩散（称为“愈合”）来实现的。表面粗糙结构的几何复杂性，以及“紧密接触”和“愈合”的强耦合微观过程的机械复杂性，对加工过程中界面结合演变的可靠描述提出了根本性的挑战。该项目的总体目标是克服这些障碍。微尺度固有的几何复杂性将通过一种新颖的表面粗糙度分布的分形表示而变得易于处理。这将形成微尺度的transportphenomenon模型的基础上开发描述的凹凸扩展和聚合物的相互扩散过程。耦合的微观工艺描述与宏观尺度的热量和动量传输现象modelswill被用来引出一个全面的理解界面bondingdevelopment作为工艺参数的函数。将进行补充实验研究，旨在验证理论发展。

Thermoplastic-matrix composites are fabricated by incrementally stacking andfusion-bonding layers of fiber-reinforced thermoplastic prepreg tapes to adesired shape and thickness. The evolution of interlaminar bond strength---aprincipal product quality measure---is governed by the development ofinterfacial contact area through flattening of the prepreg surfaceasperities (referred to as the "intimate contact" process), and theinterdiffusion of polymer molecules across the contacted areas (termed"healing"). The geometric complexities of the surface asperity structures,and the mechanistic complexities of the strongly coupled microscaleprocesses of "intimate contact" and "healing" pose a fundamental challengeto a reliable description of interfacial bonding evolution duringprocessing. The overall goal of the project is to overcome theseimpediments. The inherent geometric complexities of the microscale will berendered tractable using an innovative fractal representation of surfaceasperity profiles. This will form the basis of microscale transportphenomena models to be developed for describing the asperity spreading andpolymer interdiffusion processes. A coupling of the microscale processdescription with the macroscale heat and momentum transport phenomena modelswill be used to elicit a comprehensive understanding of interfacial bondingdevelopment as function of the process parameters. Complementaryexperimental studies will be conducted aimed at validating the theoreticaldevelopments.