Nonlinear thermoviscoelastic analysis of solid propellant grains subjected to temperature loading

Abstract

Traditionally, the nonlinear thermoviscoelastic analysis of solid propellant grains subjected temperature loading was not considered, and quasi-elastic analysis was widely adopted for structural integrity because of simplifying the analytical task. But it does not mean that the nonlinear 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 material and geometrical nonlinearities, a step-by-step finite element model accompanied by concepts of time–temperature shift principle, reduced integration and thermorheologically simple material assumption was used. Results show that the material nonlinear effect is important for structural integrity of solid propellant grains under higher temperature surrounding, the effect of nonlinearity is not obvious under lower temperature surrounding, and the differences between linear and nonlinear analysis results become more and more predominant as temperature increases. In addition, the maximum shear stress obtained from the nonlinear simulation considering bulk modulus variation with compressive stresses are higher than those from linear simulation, and the effect of material nonlinearity is more predominant as compared to the effect of geometrical nonlinearity. From the work of linear and nonlinear analyses, the nonlinear thermoviscoelastic analysis highlighted several areas of interest and a more accurate and reasonable result could be obtained for engineer.