This article presents the method that will determine the crack propagation angle of fracturing occurring in a plain plate. Theoretically speaking, the method we are proposing establishes a functional dependence between the value of the J integral and the virtual crack propagation angle. The crack propagation angle is calculated from maximum of the J integral. It means that in order for the crack to be propagated along a certain direction, the J integralâs value has to be greatest. The condition is similar with the principle of the minimum of the strain energy condition in the system equilibrium state.
