Numerical simulation of CFRP transverse failure considering non-linear viscoelastic/plastic constitutive equation with entropy damage

A viscoelastic/plastic model of resin based on irreversible thermodynamics and viscoelastic theory is suggested in order to predict the failure of CFRP matrix resin. Single axis tensile tests and creep-recovery tests are performed under various temperature and strain rates to identify the material properties. The change of viscoelastic properties with temperature and strain rate are converted using the time-temperature superposition principle. The proposed model can express the strain behavior of creep and recovery process. In numerical analysis, A FORTRAN program is created to introduce a proposed nonlinear viscoelastic model into matrix resin. Failure analysis of unidirectional CFRP is performed under various temperatures and strain rates. The analysis model can express the progress damage of CFRP.