Effect Of Notch Type On Dynamic Fracture Toughness Of Three-Point Bending Specimens

The defects contained in the metal materials can be mainly classified into cracks and notches,and V-notches and U-notches are the two main types of notches.Based on the split Hopkinson pressure bar,the dynamic fracture toughness of the 2A12-T4 aluminum alloy pre-cracked three-point bending specimen was simulated.The influence of different notch types on the dynamic fracture toughness of the three-point bending specimen was studied.The fracture process of Q345 steel three-point bending specimens subjected to dynamic loading at different loading rates was carried out.The cracking time and J-integration of cracks and notches at different loading rates were analyzed.The main contents of this paper include:(1)Dynamic fracture simulation of 2A12-T4 aluminum alloy pre-cracked three-point bending specimen based on split Hopkinson pressure bar.The sample size is designed according to GB/T21143-2007 national standard,and the dynamic fracture toughness of the sample is obtained.Compared with the experiments in other papers,the reliability of the simulation is verified.(2)The dynamic J-integration of the notch tip of the V-notch and U-notch three-point bending specimens of 2A12-T4 aluminum alloy was simulated,and the variation of J-integration when the gap opening angle and radius of curvature were changed were studied.And compared with the dynamic fracture toughness value of the pre-cracked three-point bending specimen,the influence law on the dynamic fracture toughness of the material when the gap type is different is analyzed.(3)Dynamic fracture simulation of Q345 steel pre-cracked three-point bending specimen,V-notch three-point bending specimen and U-notch three-point bending specimen at a loading rate of 2.5?12.5m/s.The sample size is designed according to the national standard GB/T21143-2007.The variation of the crack initiation time and dynamic J integral with the loading rate of the three samples is obtained and compared.It is found that the sensitivity of the loading rate is from U to notch.V-notch specimen,pre-cracked specimen.