Process simulation of LFT-D compression molding with flow-orientation coupling and process-induced initial conditions

Long fiber reinforced thermoplastics compression molding with direct in-line compounding (LFT-D) has gained increased popularity for semi-structural components. Yet process simulation that accounts for the material’s irregular initial conditions at the onset of molding remains largely unexplored. In particular, experimental work in the literature has shown that the flow front during compression molding of plates exhibits a pronounced skewness, which is attributed to the plastificate’s spatially varying void-content distribution along the extrusion direction. In addition, the initial fiber orientation field is highly anisotropic and spatially varying, resulting in anisotropic macroscopic flow behavior. In this work, we present a methodology to incorporate this initial condition into a two-way flow–orientation coupled simulation framework for LFT-D compression molding considering a no-slip boundary condition. The experimentally determined void-content distribution is modeled through a geometric approach that scales the plastificate height, and the three-dimensional initial fiber orientation field is prescribed using a geometric generation methodology. ... mehrThe framework is applied to parallel plate compression molding with lateral plastificate positioning of a CF-PA6 LFT-D, and the predicted fiber orientations are compared with experimental observations. The simulations confirm that the inhomogeneous void content is a major contributing factor to the skewed flow front.