Study of Compression‐Induced Damage in HTPB‐Based Composite Propellants Using 3D DIC Technique: Effect of Displacement Rate and Temperature

ABSTRACT This study investigates the compression‐induced damage in HTPB‐based composite solid propellant (CSP) over a wide range of temperatures (55, 25, −10, and ) and displacement rates (1, 50, and 1000 mm/min). The 3D digital image correlation (3D‐DIC) technique is employed to quantitatively determine the full‐field 3D surface deformation and its evolution during compression, revealing considerable differences between nominal strain and DIC‐based true strain, particularly at large deformation. The results show that the stress–strain response of the material is nonlinear and depends on both the displacement rate and temperature owing to the viscoelastic nature of the binder and damage evolution associated with particle–binder interfacial debonding. The material exhibited pronounced barreling at , , and , while an hourglass‐shaped deformation was observed at . 3D‐DIC also facilitated the determination of damage‐related parameters, that is, Poisson's ratio and dilatation, which exhibit nonlinear damage evolution with increasing strain, indicating progressive particle–binder debonding and void formation. Onset of dewetting is observed to be delayed with decreasing temperature, appearing at the strain of 7% –8% for and 10% for in comparison to 5% for and . Fractography analysis confirmed the presence of voids and debonded solid particles, indicating the predominance of interfacial failure mechanisms.