Application of finite strain viscoplasticity to polymeric fiber composites

The tensile behavior of polymer matrix fiber composites has been described in terms of an anisotropic model of finite viscoplasticity. Our constitutive approach is based on the kinematics of the additive form of the deformation rate tensor D generalized by Mandel [Mandel, J., 1971, Plasticité classique et viscoplasticité. Courses and Lectures, No. 97, International Center for Mechanical Sciences/Springer, Udine/Wien-New York] and Dafalias [Dafalias, Y.F., 1985. The plastic spin. ASME J. Appl. Mech. 52, 865–871]. The constitutive laws for Dp and Wp were written in accordance with the material anisotropy, whereas the constitutive law of hypoelasticity has been accordingly written in its objective form. Moreover, a viscoplastic model has been applied to represent the non-linear rate dependence. Experimental results performed in a wide strain rate region and in a wide strain range were simulated in a very accurate way. Additionally, the model was proved to predict creep behavior of the same material type as well.