A Study on Wrinkling Characteristics of NBR Material

Abstract

This work details wrinkling for hyperelastic materials with the Ogden material model. First, generalized expressions are derived for stresses and tangent stiffness terms. Material constants obtained through testing work have been used to determine stiffness terms as well as second Piola–Kirchhoff’s stress for a range of stretch ratios. This is then followed with a new model based upon modified deformation gradient tensor and hence Green tensor. Wrinkling parameter is monitored with material constants and stretch ratios. Analytically performance of material has been accessed for different conditions of uniaxial tension, equi-biaxial loading and plane strain condition. It has been observed that over a range of stretches; uniaxial condition and plane strain condition results in a situation which is consistent in the context of wrinkling, i.e. possibility of wrinkling gets boosted. On the other hand, when equi-biaxial loading or stretch ratio approaches unity for a region, chances of wrinkling being triggered reduce substantially. Developed numerical models are validated against tested work on planar hyperelastic structures for the cases of uniaxial, biaxial as well as shear loading. It has been observed that numerical results obtained hint possible scenarios of wrinkling.