Comparative study of the fracture toughness determination of a polymer-bonded explosive simulant

In this paper, a comparative study was carried out by using three-point bending, semi-circular bending, and flattened Brazilian disc tests to measure the plane-strain fracture toughness of a polymer-bonded explosive simulant. The K_IC magnitudes are 0.53±0.03MPam^1/2, 0.50±0.02MPam^1/2, and 0.53±0.01MPam^1/2 respectively, showing good consistency in the results measured by different methods. Considering the difficulties in the machining and pre-crack fabrication of brittle explosives, the flattened Brazilian disc test is recommended as an alternative method for measuring the K_IC of PBX and other explosives. In addition, real-time microscopic observation of test samples was conducted by using a scanning electron microscope (SEM) equipped with a loading stage, and the fracture surfaces of samples were examined. The damage modes and the corresponding failure mechanisms were analyzed.