Research On Dynamic Fracture Behavior Of CT Specimen Based On The Digital Speckle Correlation Method

Metal material is widely used in the practical engineering application,so it is pretty necessary to study the fracture mechanics behavior of metal material.In this paper,the quasi-static and dynamic fracture toughness of 2A12-T4 aluminum alloy CT specimen were studied based on the digital speckle correlation method.Numerical simulation method was also used to study the problems.In the fracture experiment,the traditional method and digital speckle method were used to calculate the fracture toughness of CT specimen and verify the reliability of digital speckle method.In addition,this paper studied the influence of crack processing type,specimen size and the location of loading holes on the fracture toughness of CT specimen.The main points of this paper are as follows:The basic material parameters were tested in the quasi-static experiment,which will provide basis for the parameter setting of numerical simulation.Through the quasi-static test,the reliability of digital speckle method was verified by comparing with the calculation results of the method given by national standard.After that,the influence of crack processing type was also studied based on the digital speckle method.Based on the Hopkinson tension bar,the dynamic fracture experiment on the CT specimen was carried on.the digital speckle method and traditional strain gauge method were used to calculate the dynamic fracture toughness of 2A12T4 aluminum alloy CT specimen.The reliability of digital speckle correlation method on the dynamic fracture problems was verified by comparing with the results of traditional strain gauge method.After that,the influence of specimen size and the loading holes location on the dynamic toughness were also studied based on the digital speckle method.After the test,the finite element method was used to analyze the process of dynamic fracture of CT specimen.In this paper,the contour integral method and the extended finite element method were used.At first the one dimension stress wave theory premise,dynamic stress equilibrium and J integral path independent were verified.Then the extended finite element method was used to calculate the dynamic fracture toughness and compared with the results of test and the contour integral method to show the reliability of extended finite element method.After that the influence of loading stress on the dynamic fracture behavior was studied based on the extended finite element method,the dynamic fracture toughness and crack extension conditions under different loading stress were analyzed.