https://popups.uliege.be/esaform21/index.php?id=377 Index terms fr 0 https://popups.uliege.be/esaform21/index.php?id=1938 Wet compression molding (WCM) provides large-scale production potential for continuous fiber-reinforced structural components due to simultaneous infiltration and draping during molding. Due to thickness-dominated infiltration of the laminate, comparatively low cavity pressures are sufficient – a considerable economic advantage. Experimental and numerical investigations prove strong mutual dependencies between the physical mechanisms, especially between resin flow (mold filling) and textile forming (draping), similar to other liquid molding techniques (LCM). Although these dependencies provide significant benefits such as improved contact, draping and infiltration capabilities, they may also lead to adverse effects such as flow-induced fiber displacement. To support WCM process and part development, process simulation requires a fully coupled approach including the capability to predict critical process effects. This work aims to demonstrate the suitability of a macroscopic, fully coupled, three-dimensional process simulation approach, to predict the process behavior during WCM, including flow-induced fiber displacements. The developed fluid model is superimposed to a suitable 3D forming model, which accounts for the deformation mechanisms including non-linear transverse compaction behavior. A strong Fluid-Structure-Interaction (FSI) enforced by Terzaghi’s law is applied to assess flow-induced fiber displacements during WCM within a porous UD-NCF stack in a homogenized manner. Accordingly, resulting local deformations are considered within the pressure field. All constitutive equations are formulated with respect to fiber deformation under finite strains. Results of a parametric study underline the relevance of contact conditions within the dry and infiltrated stack. The numerically predicted results are benchmarked and verified using both own and available experimental results from literature. Tue, 23 Mar 2021 10:43:52 +0100 Mon, 12 Apr 2021 10:09:34 +0200 https://popups.uliege.be/esaform21/index.php?id=1938 https://popups.uliege.be/esaform21/index.php?id=2771 With a growing interest in the application of carbon fibre Sheet Moulding Compound (SMC), a number of commercial software packages have been developed for the simulation of compression moulding of SMC. While these packages adopt different algorithms and meshing strategies, the constitutive material model and processing control are usually adapted from injection moulding process simulation. Little has been done in the literature for assessing the capabilities of these software as design tools, and more importantly, validating the process simulation results using experimental data. This paper aims to provide an independent and comprehensive assessment of existing well-known process simulation software for SMC compression moulding. The selected software will be compared in terms of material models, and available processing settings in order to determine their robustness as a compression moulding design tool. The predictive accuracy of the software will also be assessed by comparing the compression force and filling patterns against the experimental data. Wed, 24 Mar 2021 18:58:02 +0100 Fri, 09 Apr 2021 10:43:25 +0200 https://popups.uliege.be/esaform21/index.php?id=2771 https://popups.uliege.be/esaform21/index.php?id=506 In composite sheet preforming, the combination of binder-ring force and friction induce in-plane tension that mitigates the onset of wrinkling, but too much force can induce tearing. Thus, the processing conditions must be designed to strike a balance between these competing manufacturing-induced defects. Compounding the challenge to prescribe the appropriate processing conditions is the potential change in thickness of the sheets as a function of in-plane shear. The variation in the thickness from point to point in the ply stack will result in a nonuniform pressure under the binder ring. In the current research, the preforming step is simulated using a discrete mesoscopic modeling approach in LS-DYNA. Thickness-stretch shell elements are used to capture the evolution in the sheet thickness and the in-plane shear stiffness of the deformed sheet. Finite element simulations and preforming experiments are completed for the same processing conditions. The preliminary results for the punch force as a function of displacement, the state of shear over the part surface, and the distribution and magnitude of the wrinkles showed excellent correlation between the model and the experiment. The simulation results show that the shape of the punch force vs. tool depth curve gives insight into the onset of wrinkles. The simulation is then used to predict a binder-ring force that would mitigate wrinkle formation in a four-layer preform. Sat, 20 Mar 2021 00:19:42 +0100 Fri, 02 Apr 2021 17:09:08 +0200 https://popups.uliege.be/esaform21/index.php?id=506 https://popups.uliege.be/esaform21/index.php?id=883 Finite element (FE) forming simulation offers the possibility of a detailed analysis of the deformation behaviour of engineering textiles during forming processes, to predict possible manufacturing effects such as wrinkling or local changes in fibre volume content. The majority of macroscopic simulations are based on conventional two-dimensional shell elements with large aspect ratios to model the membrane and bending behaviour of thin fabrics efficiently. However, a three-dimensional element approach is necessary to account for stresses and strains in thickness direction accurately, which is required for processes with a significant influence of the fabric’s compaction behaviour, e.g. wet compression moulding. Conventional linear 3D-solid elements that would be commercially available for this purpose are rarely suitable for high aspect ratio forming simulations. They are often subjected to several locking phenomena under bending deformation, which leads to a strong dependence of the element formulation on the forming behaviour [1]. Therefore, in the present work a 3D hexahedral solid-shell element, based on the initial work of Schwarze and Reese [2,3], which has shown promising results for the forming of thin isotropic materials [1], is extended for highly anisotropic materials. The advantages of a locking-free element formulation are shown through a comparison to commercially available solid and shell elements in forming simulations of a generic geometry. Additionally, first ideas for an approach of a membrane-bending-decoupling based on a Taylor approximation of the strain are discussed, which is necessary for an accurate description of the deformation behaviour of thin fabrics. Mon, 22 Mar 2021 09:49:49 +0100 Tue, 30 Mar 2021 09:49:12 +0200 https://popups.uliege.be/esaform21/index.php?id=883 https://popups.uliege.be/esaform21/index.php?id=376 In this study, a sequential thermoforming and squeeze flow simulation approach for Glass Mat Thermoplastic (GMT) material is proposed and applied to a hat section geometry using input properties based upon Tepex flowcore, a long glass fiber reinforced polyamide (PA/GF) mat manufactured by Lanxess. First, a fully-coupled thermomechanical simulation is conducted based on a purely Lagrangian description, to efficiently capture thermoforming. Subsequently, relevant state variables are mapped and initialized for a Coupled-Eulerian-Lagrangian (CEL) approach. The CEL approach is adopted to accurately capture squeeze flow, which is not possible by a purely Lagrangian description. While numerical techniques differ, both approaches use the same three-dimensional and thermomechanical constitutive equations including an equation of state, a nonlinear viscosity model, and crystallization kinetics, implemented through a material user-subroutine (VUMAT) for the commercially available simulation software package ABAQUS/Explicit. Fri, 19 Mar 2021 17:35:11 +0100 Tue, 30 Mar 2021 09:42:01 +0200 https://popups.uliege.be/esaform21/index.php?id=376