Model to predict shrinkage and ejection forces of injection moulded tubular parts of short glass fiber reinforced thermoplastics

摘要

This work presents a model to predict shrinkage and ejection forces for glass fiberreinforced thermoplastics of tubular geometry. This mathematical model was based inJansen’s Model to predict shrinkage and residual stresses in fiber reinforced injection moldedproducts and Pontes’s Model to predict ejection forces for tubular parts of pure PP. Themodel used the modified classical laminate theory applied to injection moulding and it usesthe fiber orientation state, temperature and pressure field as input and which predicts theshrinkage and ejection forces. The fiber orientation state was determined experimentally andthe temperature and pressure fields were obtained by MOLDFLOW simulations. The model topredict ejection forces considers also the fiber orientation state, friction coefficient betweensteel and polymer, elastic modulus of polymer, both in the ejection temperature anddiametrical shrinkage. The model is validated by experimental results.