3D‐DIC for mechanical characterization of composite solid propellant under uniaxial compression

A novel experimental setup, utilizing 3D Digital Image Correlation (3D‐DIC), is employed to characterize the mechanical behaviour of composite solid propellant (CSP) under uniaxial compression at three displacement rates (1, 7, and 50 mm/min). At larger deformation, 3D‐DIC consistently shows smaller strains than nominal strain values, and this difference increases with deformation across all the displacement rates. Displacement rates significantly affect the non‐linear stress‐strain response of the CSPs. After the completion of the compression test, the specimen is unloaded, and the lengths of the unloaded specimens measured after 24 hour indicate a recovery of 90–94 % of the original length of the specimens. The recovered length increases with an increase in the displacement rate. Initially, Poisson's ratio is close to 0.5, and dilatation is zero, indicating an incompressible behaviour. However, both Poisson's ratio and dilatation increase with an increase in longitudinal strain, indicating a transition to compressible behaviour. Comparing the scanning electron microscope (SEM) micrographs of the virgin and compressive‐loaded samples, noticeable debonding is observed at the matrix‐particle interfaces.