Long‐Term and Short‐Term Creep Characteristic Analysis for HTPB Propellant

Abstract

AbstractA solid rocket motor is in storage for most of its life cycle, and propellant creep occurs subjected to gravity load. To analyse the creep characteristics of HTPB propellant during long‐term storage, MSC Marc is used to calculate the maximum von Mises stress of the motor under horizontal and vertical storage conditions. Based on the numerical results, the short‐term reciprocating creep test and long‐term creep test are designed and carried out. The results illustrate that the process of propellant creep from deformation to final failure can be divided into four stages: instantaneous deformation stage, attenuation creep stage, steady‐state creep stage and accelerated creep failure stage. When the creep stress level is less than 0.1 MPa, the creep characteristics tend to be stable. When the creep strain exceeds a certain critical value, the propellant will enter the steady‐state creep stage. The damage caused by creep rises with the increase of creep time and stress. When the maximum creep strain is less than 10 %, the creep damage can be fully recovered. The splicing curve of short‐term creep test data is in good agreement with that of long‐term creep test data. A mechanical long‐term creep test method is provided, and the parameters of the modified Burgers model are fitted. The text methods and conclusions can provide a reference for the evaluation of structural integrity and storage life of solid motor.