Fatigue failure of incorporated crack HTPB(Hydroxyl-terminated polybutadiene) propellant under strain control

Abstract

To study the fatigue properties of incorporated crack HTPB (hydroxyl terminated polybutadiene propellant) propellant under strain control, fatigue tests with different strain amplitudes were carried out on the MTS fatigue testing machine. Four groups of specimens were set up in this test, namely one group with specimens and three groups with incorporated crack specimens with different angles (0°/45°/75°/ to the horizontal) of cracks. During the fatigue test, an infrared camera was used to monitor the temperature of the whole test piece in the whole process. The results show that at the same frequency, the increase of the strain amplitude will shorten the fatigue life. The fatigue life of the three incorporated crack specimens is similar reaching at 20000times, all in the same order of magnitude, and the fatigue life of the un-cracked specimen is larger reaching at 100000times, showing a cross-order phenomenon. In the fatigue test, the samples exhibit obvious strain hysteresis phenomenon and has significant viscoelastic material properties, in terms of the surface temperature monitoring of the specimens, the four groups of specimens all show a trend of temperature increase, and the final surface temperature and fatigue life are positive related.