Flow front advancement during composite processing: predictions from numerical filling simulation tools in comparison with real-world experiments

Abstract

Liquid composite molding (LCM) techniques are innovative manufacturing processes for processing fiber reinforced polymer parts used e.g. for aerospace structures. Thereby the reinforcing material is placed in a mold and infiltrated with a low viscosity polymer matrix. Increasing production rates as well as part complexity lead to high production risks such as air inclusions or incomplete mold filling. Numerical mold filling simulations are promising tools enabling the composite manufacturing engineer to detect dry spots in the mold and find the optimal positions of the resin entry and ventilation system at an early process development stage. Today, different numerical models and software packages are available for modeling the flow through the reinforcing structure for visualization of the flow behavior. The goal of this study is the systematic comparison of two different software packages, namely PAM‐RTM® and OpenFOAM. Both software tools are operated as they are commonly foreseen. Real world experiments under real process conditions are the basis for the assessment of the numerical predictions. The resin transfer molding (RTM) experiments are executed in a tool with a transparent upper mold half in order to see the flow front advancement. POLYM. COMPOS., 37:2782–2793, 2016. © 2015 Society of Plastics Engineers

Identification of the effect of typical curvatures encountered in RTM parts on localized permeability of fibrous preforms

“…13 This hypothesis was verified in experiments where disagreement between filling simulations and actual flow in terms of time of flow advancement was only found close to the inlet. 15 (3) Structural deformation of the preform (i.e. tow shifting) may take place if injection pressure is higher than the compaction pressure.…”

“…For the identification of the in-plane permeability, an optical permeameter was used; a mold with a transparent top tool that allows visual observation of the flow front by camera. The principle of operation as well as the measurement procedure for the specific instrument was described in detail in the past 15 in a study that exploited the optical permeameter to compare real world experiments with simulation results produced by different software packages. For the required measurements of flow time within a draped zone, an RTM tool with an prevent contact with carbon (conductive) fibers, the tip can be electrically isolated with a thin glass wrap.…”

Simulating Mold Filling in Compression Resin Transfer Molding (CRTM) Using a Three-Dimensional Finite-Volume Formulation

“…Solving all governing equations for both fluids enables to better predict the formulation, movement, compression and dispersion of entrapped air in the cavity as also stated in the introduction chapter. Furthermore, because of its CFD based approach, it is possible to combine porous regions with non-porous regions and therefore using OpenFOAM can have advantages, for example when modeling race-tracking [9].…”

“…To minimize the cycle-time and ensure a complete filling, the injection strategy and process parameters like resin mass flow or temperature have to be optimized. To avoid time-consuming and expensive experimental studies, numerical simulations of the mold filling are increasingly used [4][5][6][7][8][9].…”

Material Characterization for Reliable Resin Transfer Molding Process Simulation

“…In this direction, Finite Element Method (FEM) software has been developed in the last few years to assist in component design and processing, predicting issues such as resin-rich areas, air bubbles, dry spots, zones of high porosity, etc., and for optimization of mold geometry and process parameters, such as port and vent locations [4][5][6][7]. In the case of critical molds, therefore, it is advantageous to perform a preliminary study by means of numerical simulation in order to avoid expensive experimental setups and prototypes.…”