A study of loading history effect for thermoviscoelastic solid propellant grains

The results of an investigation on solid propellant grains considering loading history effect are presented. Traditionally, the thermal loading history effect of solid propellant grains was not considered for simplifying the analytical task, and a higher safety factor was inevitable for structural integrity. But this does not mean that the thermal loading history effect is not useful and could be neglected arbitrarily, and this effect usually plays a very important role for some critical design. In order to simulate the time–temperature-dependent behavior of thermoviscoelastic and incompressible polymer materials, concepts of time–temperature shift principle, cumulative damage theory and reduced integration were used. In addition, five different types of thermal loading history assumption were performed using the finite element method for discussing the thermal loading history effect. Results show that the thermal loading history effect is important for structural integrity of solid propellant grains, and improper negligence may cause structural failure of missile systems.