Review of the Numerical Modeling of Compression Molding of Sheet Molding Compound

Abstract

A review of the numerical modeling of the compression molding of the sheet molding compound (SMC) is presented. The focus of this review is the practical difficulties of modeling cases with high fiber content, an area in which there is relatively little documented work. In these cases, the prediction of the flows become intricate due to several reasons, mainly the complex rheology of the compound and large temperature gradients, but also the orientation of fibers and the micromechanics of the interactions between the fluid and the fibers play major roles. The details of this during moldings are discussed. Special attention is given to the impact on viscosity from the high fiber volume fraction, and the various models for this. One additional area of interest is the modeling of the fiber orientation.

A 3D finite element stochastic framework for the failure of tow-based discontinuous composites

“…Finally, note that the adopted approach is based on the compression moulding simulation of an homogenised materials. Other approaches proposed in the literature simulate explicitly the tows and the matrix [19,46,47]. While these may achieve a better accuracy, for the purpose of the present work, a commercially available tool was necessary.…”

Advancing on viscosity characterization and modeling of SMC for compression molding simulation

“…Moreover, after a high-quality material-specific viscosity data generation, a viscosity model fitting must be carried out as this is a basic input for any process simulation. 25 At this point, it is important to be aware that, even if SMC materials are concentrated fiber suspensions composed by high volume fractions of long fibers, and their viscosity is driven by this fact, most commercially available simulation tools define the composite's flow behavior applying macroscopic models; based on standard flow-governing equations of fluid dynamics, which neglect micro-or meso-scale effects of the material [26][27][28][29][30] Although this simplification is assumed, the conversion of the experimental data to accurate viscosity model parameters turns out to be vital. At this extend, it must be assured that the industrial partners are not facing any extra difficulties during the already complex material modeling stage.…”

3D flow and fibre orientation modelling of compression moulding of A-SMC: simulations and experimental validation in squeeze flow

“…When the mould closes the SMC stack melts, flows out and fills the mould after which the resin cures and the solidified composite can be removed from the mould. Process modelling of SMC is rather complicated for a number of reasons [1]. Chief among these are the complex material properties of SMCs, the presence of high-volume fractions of fibres and the steep temperature gradients.…”

“…Two different approaches are discussed here. The first approach uses Ansys CFX, a commercial general fluid mechanics modelling software for the displacement of the charge (previously discussed in [14]) where the reorientation of the fibres is modelled using self-implemented functions. The second approach uses 3DTimon, a more specialized composite modelling code where Direct Fiber Simulation (DFS) is used for the fibre orientation modelling [15].…”