Dynamic Fracture Study Of Three-Point Bending And Compact Tensile Specimen

Metals have always been a concern in engineering.The conventional strength calculation method often can not achieve the design strength.Because there are always flaws in the structure.Based on the Hopkinson loading system,this paper makes a comparative analysis of the three-point bending specimen(dynamic compression)and the CT specimen(dynamic stretch).Materials select 2a12-t4 aluminum alloy.The specific research contents are as follows:(1)In the quasi-static condition,the sample selection of three-point bending specimen and the CT specimen are selected.The simulation data is processed by quasi-static state standard,and the fracture toughness of two specimens is obtained,which lays the foundation for dynamic loading simulation.(2)Based on the specimen size of the quasi-static GB,the dynamic load simulation of the three-point bending specimen and the CT specimen was carried out,and the dynamic fracture toughness of the two specimens was obtained.Compared with other papers,the test piece of 16 mm thickness meets the plane strain condition.(3)The dynamic fracture simulation is carried out on the three-point bending samples of aspect ratio,and the influence rule of the long width ratio on the detachment is found out.And the relationship between L/W and S/ L is determined by fitting data.It is found that the polynomial fitting effect is better.The relationship between the contact state,the deformation velocity and the integral value is found.It was found that the loading rate of the specimen was affected by the contact state of the support,and the load rate affected the fracture toughness value.(4)In this paper,the dynamic fracture simulation of the CT sample is carried out,and the influence of the loading hole diameter and the loading hole position on the stress balance of the specimen is studied.And the J integral value in different cases is given.By comparing the crack propagation path of the compact tensile specimen and the three-point bending specimen,the key points of the difference between the two sample J integral values are found.And give reasonable suggestion to the above problem.