As manufactured material behaviour in injection moulded parts

The nearly unlimited design freedom, cost efficient production and increased structural performance have made injection moulding of short fibre filled polymers (SFRP’s) a valid alternative to replace metals and ceramics in many fields, such as medical, automotive and aerospace industries. In the case of SFRP injection moulded products, there is a clear need to couple the injection moulding processing of the material to the structural analysis of the product. One of the most important factors which has been under less attention in the literature is the effect of local thermal conductivity of SFRP’s on the parts’ mechanical performance. Thermal conductivity has been considered as a scalar constant value in the majority of existing models, while it has been shown that not only it may vary at different locations within the injection moulded part but also it is a direction-dependent variable. Since this can affect local cooling rates, part’s shrinkage and warpage, and hence the mechanical performance, one of the aims of this research is to predict the thermal conductivity over the part by considering the local fibre orientation and fractions. Another objective of this project is to link the processing parameters to the weld-line strength. In case of weld line formation within injection moulding, none of the currently existing numerical simulation tools is considering the local fibre orientation and hence local cooling rate influencing the local mechanical performance. Typically, the weld line location is one of the weakest parts within the injection moulded parts; therefore, it should be taken into account in developing models for predicting the overall mechanical behaviour of these parts.