A NOVEL METHOD FOR MEASURING PLANE-STRESS DYNAMIC FRACTURE-TOUGHNESS

By using the self-designed Rotating Circular Disk direct tensile impac t apparatus, a novel test method has been developed for studying the f racture properties of materials under impact loading. A double edge no tch specimen under a plane stress state is used in fracture test condi tions; the material exhibits elastic-plastic behavior at the crack tip . The SHPB technique is used to measure the dynamic loads and the disp lacements of the specimen; crack opening displacement is measured by a pplying the self-designed photoelectric transformation setup. For the evaluation of dynamic fracture toughness, the extended J-integral with the inertial effect is calculated by Rice's formula using the average load-displacement curve. The time to crack initiation is determined b y the compliance changing rate method. The fracture toughness of LY12c z aluminum alloy at a loading rate K(ID) greater than 10(6) MPa square -root m/sec is obtained.