Iterative and transient numerical models for flow simulation of injection pultrusion

During injection pultrusion, the flow front is initially transient and approaches a quasi-steady-state in a short time. It is the steady-state flow front that determines the filling quality of the pultruded composite part. Both transient and iterative finite element/nodal volume models have been developed to predict the steady-state flow fronts during injection pultrusion processes. In the present paper, the numerical performance of the transient and iterative models is systematically investigated for various pultrusion process and material parameters, such as pull speed, injection pressure and the ratio of permeabilities in the pulling and the transverse directions. It is shown that the iterative model is numerically stable and robust. It predicts steady-state flow fronts which are in excellent agreement with those predicted by the transient model in all the cases investigated. More importantly, the iterative model is much more efficient than the transient model and the high efficiency is not affected by the modelling parameters used. It generally uses less than one tenth of the computer time required by the transient model to reach the converged solutions. Therefore, the iterative model should always be used to predict the steady-state resin flow fronts.