The heat build-up of a polymer matrix composite under cyclic loading: Experimental assessment and numerical simulation

In order to experimentally measure the heat build-up within a polymer matrix composite under cyclic loading, the real-time temperature monitoring of a solid composite propellant (HTPB propellant) subjected to cyclic uniaxial, strain-controlled fatigue tests at various loading conditions was carried out. The results obtained show that surface temperature of HTPB propellant during the fatigue test increased by up to dozens of degrees, which due to its viscoelastic nature. The effect of applied strain levels and frequencies of tested material on the deterioration of HTPB propellants during fatigue process were quantitatively assessed by the variation of dynamic moduli. It has confirmed that the influences of self-heating on tested materials mainly lies in softening polymeric matrix and extended debonding along particle/matrix interface. Additionally, the pattern of increased fatigue lifetime with a reduction in loading frequency and strain level under was also observed. Moreover, based on an uncoupled thermomechanical coupling algorithm, the finite element analysis incorporating a hyper-viscoelastic constitutive model of tested material was proposed to simulate the mechanical and thermal responses of tested material. The results of simulation agree well with experimental ones, which helps to validate the accuracy of proposed model.