Experimental and XFEM Simulation Research on HTPB Propellant Precracks Based on Microscopic Observation and DIC

In this research, penetrating cracks with different angles were prefabricated on viscoelastic propellant material specimens. Tensile tests were carried out on a universal testing machine, microscopic observations were performed, and strain fields on specimen surface and around the crack were obtained based on digital image correlation (DIC) method. The crack propagation law of pre-cracked specimens within 30 % strain has been studied. Microscopic images (50x magnification) of stretching process were recorded. Stress-strain curves and tensile microscopic images of different prefabricated crack angles were obtained, finite element simulations of tensile tests were carried out by finite element method, and experimental and simulation results were compared. It was concluded that the crack propagation process of hydroxy-terminated polybutadiene (HTPB) propellant could be mainly divided into three stages, namely linear, nonlinear and failure stages. DIC analysis method quantitatively determined strain field on specimen surface and intuitively showed the variation law of strain field. The feasibility of XFEM method for crack propagation in propellant materials was verified.