Elongation aging model of HTPB propellant under constant strain

Accelerated aging tests at the conditions of 3%, 6% and 9% strain levels were conducted on HTPB propellant with the goal of studying effects of constant strain on its maximum elongation. An elongation aging model was developed to analyze the effects of constant strains and temperature on model parameters by fitting the experimental data. Results show that physical tension effect caused by constant strains can increase elongation significantly, and the increasing amplitude exhibits a linear relationship with aging temperature and pre-strains. Physical tension effect shows obvious characteristics of stress relaxation with aging times at various constant strains, increasing elongation exponentially. There is a critical temperature between 65℃ and 70℃ in the aging process of propellant. Constant strains have almost no effect on elongation aging rate below critical temperature, but they decrease elongation aging rate above critical temperature.