Size-dependent energy release rate formulation of notched beams based on a modified couple stress theory

The modified couple stress theory is employed in this paper in order to formulate the size-dependent strain energy release rate of Euler–Bernoulli and Timoshenko notched beams. As a case study, the normalized energy release rate of the aforementioned beams has been developed for three-point bending as a function of the ratio of material length scale parameter to the beam depth. The results of the current model are compared to the experimental data. The good agreement between the present results and the experimental values indicates that the current model can be successfully applied to evaluate size dependent energy release rate of structures.