To obtain the dynamic fracture initiation toughness of composite modified double-base (CMDB) propellant

impact experiments of notched semi-circular bend (NSCB) specimens were performed by Hopkinson experimental technology. Pulse shaping technology was applied to obtain the load-displacement curve of CMDB propellant. The modified compliance changing rate method was used to determine the crack initiation point of the NSCB specimen. Finite element software ABAQUS was adopted to calculate the dimensionless structure factor of the NSCB specimen

and the dynamic fracture initiation toughness of the CMDB propellant was determined. The scanning electron microscope imaging technique was used to investigate the fracture micro-mechanisms of the NSCB specimen. Research results show that the dynamic fracture initiation toughness is dependent on the loading rate sensitivity significantly within the range of 5.41×105~8.94×105MPa·m1/2·s-1. With the increase of the loading rate sensitivity

the failure morphology of the particles in the cross section is gradually deteriorated

and the energy consumption is increased through the analysis of the scanning electron microscope.