The Experimental And Numerical Investigation On Ductile Fracture Of A Pure Copper Under Tension-Shear

Failure criterion of material is the theoretical basis of strength analysis and design of engineering materials and components. The author here through the finite element method analyses experiments by using different plate notched specimens of T2 copper, focusing on the influence of stress triaxiality, Lode parameter, equivalent fracture strain and other stress state parameters, performed the investigation of failure and destruction under tensile load. And corresponding fracture criterion was further discussed in the mixed tension-shear failure mode. The main contents are:(1) Calibrate the elastic-plastic parameters of the pure copper through the uniaxial tensile test associated with FEM similation of cylinder-shaped solid bars.(2) A series shear destruction tests under tensile load were carried out by plate notched specimens, in which the notches were designed in different relative angles with relative angles. The crack initiation and propagation and further the fracture morphology of sample were observed and analyzed.(3) Combined experiment results and with numerical simulation analysis, the corresponding initial cracking point and crack growing path of specimen in test were determined by microscopic observation associated with the FEM calculationusing ABAQUS. Further discussion was further done to explore the relationship between stress state and damage.(4) Two failure criteria were established for T2 pure copper materials based on stress triaxiality of the crack initiation starting point (in the range 0.33-0.67) and stress triaxiality average stress state of whole process (in the range 0.00～0.57).The main conclusions are following:(1) The main research of this paper is to study the failures of notched plate specimen under tensile stress,shear stress and mixed stress loads:the crack initiation point of specimen under the tensile stress begins at the center of the notched ligament; the crack initiation point of specimen under the shear stress begins at the edge of the notched ligament, while also at the edge of the notched ligament under the mixed stress loads.(2) Under the experimental conditions of this research, the influence of stress-strain historical accumulation can take consideration on the fracture criterion of using average stress state of whole process stress as parameter. Whereas the crack initiation starting point as parameter is more convenient in practical applications.