The fracture process in elastic-plastic materials under biaxial cyclic loading

Abstract

The fracture process in elastic–plastic materials under biaxial loading was investigated. Energy conversion behaviours taking place ahead of crack tip were assumed to be very important. Therefore an analysis of the deformed zone at the front of the crack was performed. It was shown, and underlined, that plastic zone size and also plastic zone shape affect crack growth behaviour. A new model for the description of the fracture process was proposed and analysed. The model took into account loading parameters and material properties as well as microstructure properties. The W-criterion was discussed, and crack growth angles were calculated for different biaxial stress ratios. A new parameter of the plastic zone shape was introduced and analysed. A method for determining the crack growth trajectory was suggested. In this method, a crack growth increment was variable and was correlated with minimum value of the plastic zone radius. A constant crack growth direction in the plastic zone was supposed. Then, a formula to compute crack growth rate was proposed and verified. The simulations of fracture processes in austenitic stainless steel under biaxial cyclic loading were conducted. An agreement between calculated data and experimental results was promising.