Three-dimensional, finite deformation, viscoplastic constitutive models for polymeric materials

• Published in: Mechanics of materials 1997-05, Vol.25 (4), p.235-253
• Main Authors: Bardenhagen, S.G., Stout, M.G., Gray, G.T.
• Format: Article
• Language: English
• Subjects: Constitutive modeling; Polymers; Strain-rate sensitivity; Viscoelasticity; Viscoplasticity
• ISSN: 0167-6636; 1872-7743
• DOI: 10.1016/S0167-6636(97)00007-0

A general methodology for developing three-dimensional. finite deformation, viscoplastic constitutive models for polymeric materials is presented. The development begins with the presentation of a one-dimensional spring and dashpot construction which exhibits behavior typical of polymeric materials, namely strain-rate dependence, stress relaxation, and creep. The one-dimensional construction serves as a starting point for the development of a three-dimensional, finite deformation, viscoplastic constitutive model which also exhibits typical polymeric behavior. Furthermore, the three-dimensional constitutive model may be easily generalized to incorporate an arbitrary number of inelastic processes, representing (inelastic) microstructural deformation mechanisms operating on different time scales. Strain-rate dependence, stress relaxation, and creep phenomena are discussed in detail for a simple version of the constitutive model. Test data for a particular polymer is used to validate the simple model. It is concluded that the methodology provides a flexible approach to modeling polymeric materials over a wide range of loading conditions.