A mixed mode partition method for delaminated beam structure

•A simple mode partition method is developed for delaminated beam structure.•Distribution factors were proposed to physically correlate the loads and the SIFs.•The general load configuration is reduced to a simplified one.•Highest accuracy was achieved compared with other methods in literature.

A delaminated beam structure of elastic material under axial forces and bending moments is analyzed. A new mode partition method is proposed to calculate the mode I and mode II stress intensity factors. Simple analytical expressions of the stress intensity factors are derived based on classical beam theories and the local continuum analysis. The physical meaning of the unknown non-dimensional parameters in the expressions, named the distribution factors, is demonstrated, which helps to better understand the relationships between the loads and the crack tip stress states. Furthermore, comparison with different mode partition methods under different conditions shows that the current method possesses the highest accuracy while retaining the advantage of simplicity.