Research On The Influence Of The Precrack Offset Angle On Dynamic Fracture Toughness Of Material

As a new subject, fracture mechanics gets outstanding development in the study of defect material and structure damage,which has positive significance. The study of material fracture in qua-static problems is mature but has some issues in fracture dynamics due to the complexity of experiment condition. So the study method of fracture toughness under dynamic loading is the hotspot.Due to the errors in fixture machining and fatigue testing machine,crack angle has offset phenomenon during precrack. In this paper, the dynamic fracture toughness of 2A12-T4 aluminum alloy CT specimens with different offset angles based on Hopkinson pressure bar.The fracture initiation time, dynamic fracture toughness and crack extension condition of CT specimens were studied by ABAQUS software with the conventional finite element method and extended finite element method.The main contents of this paper are as follows:Select rate-independent 2A12-T4 aluminum alloy as experiment object and use fracture machine to prefabricating straight cracks. The qua-static tensile test on CT specimens was carried out with universal testing machine, obtaining the J integral value. Then the dynamic tensile test was carried out with Hopkinson Pressure bar, obtaining the dynamic J integral value. And compare the two groups of results.Take the Hopkinson bar method as sampler, the straight crack specimens were simulated by ABAQUS conventional software with conventional and extended finite element method.Compare the simulated results and test results to verify the correctness of simulation,then observe and analyze crack extension condition.Use conventional and extended finite element method to simulate CT specimens with different offset angles and different directions of the crack, calculating the fracture initiation time, dynamic fracture toughness and crack extension condition of cracks with different angles to compare and analyze the influence of offset angles on dynamic testing results and crack extension conditions.Then,get the extend rate of CT specimens with different offset angles of the crack.At last, analysis the influence of the crack growth rate on the crack propagation velocity and the dynamic fracture toughness along the thickness direction of the CT specimen in different crack angles.