Plastic behaviour of an epoxy polymer under cyclic tension

The present paper is concerned with the experimental investigation of the progressive accumulation of deformation observed in cyclic tension tests performed on an epoxy polymer. The strain rate dependency is almost negligible and the material behaviour is elastic-plastic rather than elastic-viscoplastic or viscoelastic. Under cyclic loading and unloading, this polymer exhibits hysteresis (a phase lag), which leads to dissipation of mechanical energy and to the accumulation of cyclic plastic deformation. It is verified experimentally that this phenomenon is essentially due to kinematic hardening. Preliminary ideas for an elastic-plastic phenomenological model able to describe the plastic cyclic behaviour of this epoxy polymer are also presented.