Strength criterion of composite solid propellants under dynamic loading

Abstract

Based on the dynamic loading (1-100 s−1) experiments under different temperatures (223–298 K) and stress states, uniaxial and biaxial strength criterion of a Hydroxyl-terminated polybutadiene (HTPB) based composite solid propellant were further investigated. These experiments were conducted through the use of a new uniaxial INSTRON testing machine, different new designed gripping apparatus and samples with different configurations. According to the test results, dynamic uniaxial tensile strength criterion of the propellant was directly constructed with the master curve of the uniaxial maximum tensile stress. Whereas, a new method was proposed to determine the dynamic uniaxial compressive strength of the propellant in this study. Then uniaxial compressive strength criterion of the propellant was constructed based on the related master curve. Moreover, it found that the uniaxial tensile-compressive strength ratio of the propellant is more sensitive to loading temperature under the test conditions. The value of this parameter is about 0.4 at room temperature, and it reduces to 0.2–0.3 at low temperatures. Finally, the theoretical biaxial strength criterion of HTPB propellant under dynamic loading was constructed with the unified strength theory, the uniaxial strength and the typical biaxial tensile strength. In addition, the theoretical limit lines of the principal stress plane for the propellant under dynamic loading at different temperatures were further plotted, and the scope of the limit line increases with decreasing temperature. Keywords: Strength criterion, Unified strength theory, Composite solid propellant, Dynamic loading, Biaxial tension