Creep Properties of Hard Polyurethane Foam at Room Temperature

Compression creep test of hard polyurethane foam were carried out at room temperature and different stresses.According to the experimental creep curves,the classic Burgers model was used to describe the creep behavior of the material,and the creep constitutive model was obtained after the creep parameters were got,moreover,the creep rates during steady stage derived from Burgers model and the experiment measurement were compared.The results show that the compressive creep behavior of hard polyurethane foam at room temperature had obvious correlation with stress.With the increase of load stress,the creep strain and the steady creep rate were both increased.The compression creep process was divided into two distinct stages,in the first stage,creep rate decreased gradually with the increase of time,but during the second stage,the creep rate was maintained substantially constant.The steady state creep rate equation of the hard polyurethane foam derived from Burgers model can well predict the creep rate in compression creep steady stage.