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