Theoretical considerations of biaxial stretching of viscoelastic fluid sheets with application to plastic sheet forming

Abstract

A theoretical analysis of biaxial stretching of viscoelastic fluid sheets has been carried out. In the first part of the paper emphasis is placed on the transient buildup of stress in an initially virgin material when it is subjected to constant deformation rate stretching. At low deformation rates the stress builds up slowly to a steady state value. At higher deformation rates, the stress rises to infinity. The influence of the detailed form of the constitutive equation of the stress buildup is described. Stress buildup under other deformation conditions and stress relaxation following deformation are also considered. In the second part of the paper, the possibility of growth of defects originating as either geometric or material property nonhomogeneities is investigated.