Numerical Simulation of Resin-Fiber Interactions for Advanced Composites Manufacturing

Abstract

Advanced composites are key enablers to initiatives such as aircraft/automobile light-weighting and construction of Out of Autoclave (OOA) and reused/recycled composite sports equipment [1-13]. The integrity of composite materials is only as good as the manufacturing process used to create it, thus a detailed understanding of that process and the imperfections it entails is paramount [14-15]. Manufacturing of many ubiquitous composites involves the wetting of fibers (such as glass fiber, or carbon fiber) with liquid resin. The wetting efficiency of the resin prior to hardening/curing directly affects the resulting material’s strength and integrity. In this study, we consider a canonical setup in which an isolated resin droplet interacts with a bed of fibers below. We use computational fluid dynamics (CFD) to gain detailed insight into the wetting process itself, making use of ANSYS CFD tools. Within the framework of ANSYS Fluent, we use the volume-of-fluid (VOF) method to capture the dynamic interface between the resin, air, and fibers. Fiber wetting processes involve drop-to-fiber diameter ratios in the hundreds to thousands, which can make the simulation approach computationally expensive. In this work, we use two-dimensional simulations (e.g., see Figure 1) to characterize the drop-fiber interaction and qualitatively verify the governing nondimensional parameters revealed through dimensional analysis. Three-dimensional simulations are then used to assess resin spreading and penetration as a function of fiber orientation, comparing results to experimental data obtained at the University of Southern California.