A shell model for resin flow and preform deformation in thin-walled composite manufacturing processes
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ORIGINAL RESEARCH
A shell model for resin flow and preform deformation in thin-walled composite manufacturing processes Da Wu1 · Ragnar Larsson1 Received: 11 June 2019 / Accepted: 10 October 2019 © The Author(s) 2019
Abstract The paper proposes a novel approach to model the in-plane resin flow in deformable thin-walled fiber preforms for liquid composite molding processes. By ignoring the through-thickness flow in large scale thin-walled components, the 3-D resin flow is simplified to an in-plane flow inside the preform by a specialized divergence theorem. Shell kinematics are used to describe the fiber preform deformation, and the compressible flow is modeled in the context of the free surface flow in porous media. For simplicity and efficiency, the normal stretch, which is driven by the internal fluid and applied external pressure, represents the fiber preform expansion and compression. As compared with full 3-D models, the proposed shell model significantly reduces the problem size, while it still represents the primary physical phenomena during the process. The effects of neglecting the through-thickness flow are illustrated in a numerical example that compares the flow for a set of preforms with different thickness. The model is demonstrated from the numerical example of the mold filling in a doubly curved thin-walled fiber preform. Due to the applied vacuum and the consequent resin flow motion, the relevant deformation of the preform is observed. Keywords Fiber preform deformation · Resin flow · Liquid composite molding · Process modeling · Porous media theory
Introduction The class of liquid composite molding (LCM) processes has been widely employed for manufacturing fiber reinforced polymer composite materials (FRPCMs) and helps manufacturers to carve out a niche amid the keen market competition. Since the mid-1980s, the automotive industries started to utilize the resin transfer molding (RTM) method to produce high volume production net shape structural components. Then the vacuum assisted resin transfer molding (VARTM) process sprung up in marine, energy and aerospace industries. The VARTM process can reduce the emission of volatile organic compounds, and produce high-quality FRPCM parts with flexible, handy and lowcost tooling. However, the challenges of defects also appear
Ragnar Larsson
[email protected] 1
Division of Material and Computational Mechanics, Department of Industrial and Materials Science, Chalmers University of Technology, SE-412 96, G¨oteborg, Sweden
during LCM processes, e.g., dry spots, spring-in, microvoids and thickness variations [1]. The resin flow distribution arrangement dramatically influences the whole filling process, so it is keen to model and simulate the process numerically instead of relying on trial and error physically. Between the late 80s and early 90s, Chan and Hwang [2] started to solve the pressure distribution in the RTM process based on the Darcy’s law, which describes the fluid transfer in porous media. Fracchia et al. [3] employed the control vo
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