Experimental Investigation on High Strain Rate Tensile Behaviors of HTPB Propellant at Low Temperatures

Abstract

AbstractTo study the high strain rate tensile behaviors of hydroxyl‐terminated polybutadiene (HTPB) propellant at low temperatures, uniaxial tensile tests were conducted at different strain rates (0.4–42.86 s−1) and temperatures (233–298 K) using an INSTRON testing machine. Scanning electron microscopy (SEM) was employed to observe the tensile fracture surfaces. Experimental results indicate that strain rate, temperature and test environment remarkably influence the tensile behaviors of HTPB propellant. The stress‐strain curves exhibit three different shapes. The elastic modulus and maximum tensile stress increase with decreasing temperature and increasing strain rate. However, the strain at maximum tensile stress decreases with increasing strain rate at low temperatures and there is a maximal value at 298 K and 14.29 s−1. The effects of strain rate, temperature and test environment on the tensile behaviors are closely related to the changes of properties and fracture mechanisms of HTPB propellant. The dominating fracture mechanism depends on not only temperature but also strain rate, and it changes from the dewetting and matrix tearing at room temperature and lower strain rate to the particle brittle fracture at low temperatures. Based on the time‐temperature superposition principle (TTSP), the master curves of mechanical parameters for HTPB propellant were obtained.