Fracture in cutting of ductile as well as brittle materials can be characterized using parameters such as K, G, R, and J-integral; of these, R has been widely used. To accurately evaluate the contribution of fracture energy in total cutting energy, J-integral would provide a more comprehensive basis as it encompasses several fracture modes, material plasticity, and nonlinear behavior. Therefore, this work adopts J-integral to evaluate the contribution of fracture energy to the size effect during microcutting of AISI 1215 steel. The work uses explicit integration method within ansys/ls-dyna to simulate two-dimensional (2D) orthogonal microcutting. U- and V-shaped cutting edges were used to represent a sharp crack-tip and a blunt crack-tip, respectively. Considering several alternative contours around crack-tip, covering the plastic zone, J-integral was calculated. Upon benchmarking J-integral values with other simulations in the literature, the approach was adopted for microcutting simulations in this work. It is observed that J-integral increases with uncut chip thickness, whereas it decreases with cutting speed, rake angle, and tool edge radius. The term (J/t0) defines contribution of fracture to the size effect in terms of J-integral, which is in the range of 4–24% under various parametric conditions. The corresponding values of R were always found to lie above those of the J-integral indicating that J-integral is relatively more appropriate parameter to quantify the fracture energy during microcutting.

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