Abstract: The inelastic behavior of T300/5222 composite laminates is dealt with by experimental and theoretical researches.Experimental results of creep,stress relaxation and history-dependent stress-strain curves at different temperature levels are reported.Both loading and unloading pro-cesses are included.In the theoretical consideration,the locally averaged constitutive functionals are established on the basis of rational thermomechanics.Applying thecoleman-Noll method to the thermodynan1ic constraints on the constructed locally averaged functionals obtained from theo-retical discussions with the experimental data,it leads to the determination of the non-linear creep constitutive equations.Comparisions of the theoretical prediction and the experimental results show that the predictions are satisfactory.A detailed examination of the results reveals that most of the material coefficients are:trongly temperature-dependent,but the relatipnship between the characteristic retardent time and temperature can not be described by the WLF equation。

Key words: composite materials-laminates, constitutive equatjons, creep strength