Deformation, fracture and mechanical properties of PBX under dynamic loading by using digital speckle correlation method

Brazilian test, semi-circular bend (SCB) test and compression experiments under dynamic loading were performed on a polymer bonded explosive (PBX) stimulant by using a split Hopkinson pressure bar (SHPB). A high-speed photography was used to record the dynamic deformation and fracture process of the samples during impact. Based on the digital speckle correlation method (DSCM), the displacement and strain fields on the sample surface were obtained at macro-scale, revealing the deformation and fracture mechanisms of the specimen under dynamic loading. In addition, an optical microscope combined with a high-speed camera was used to record the dynamic deformation process of a local region near the preset crack in a SCB simulation sample. The strain field was computed by the DSCM technique at micro-scale, demonstrating the microscopic damage evolution and predicting possible failure growth of microcracks in the SCB specimen. Moreover, based on Mohr-Coulomb criterion, the ultimate failure parameters under dynamic uniaxial loading can be obtained. The experimental results are in agreement with theoretical analysis, demonstrating that the DSCM technique is effective to study the dynamic behavior of PBX materials.