Formation mechanism and evolution of interfacial residual stress between composite propellant and rubber liner during curing process

This study focuses on the solid rocket engines, which are commonly used in satellite launches and space exploration. The residual stress at the interface between the composite propellant and rubber liner generated during the curing process can lead to several issues, such as debonding, shrinkage, and deformation. This study aims to examine the mechanism and evolution law of the residual stress development. A finite element model is established to examine the residual stress during the full curing process. The composite propellant undergoes intricate temperature and curing gradients. The stress in various parts of the propellant and liner is monitored throughout the entire curing cycle. The propellant's temperature exhibits a delayed response during the heating and cooling phases of the curing process. The interface undergoes curing throughout the stage of constant temperature, with its chemical shrinkage primarily taking place prior to the cooling step. Considerable stress exists at the contact before cooling. The stress caused by thermal influences becomes more noticeable during the cooling phase. The influence of propellant composition and curing process parameters on interface stress is investigated. In addition, a specific vision-based device is innovatively designed to monitor deformation changes during the curing process. The key parameters of the simulation are optimized by combining the detected deformation, aiming to minimize the deformation difference between the experiment and the simulation, so as to realize the corresponding stress evaluation. The measurement results show an average deformation error of 10.71% and an average stress error of 10.58%.