**6. Conclusions**

This paper presents a fracture-based model for brittle material cutting using cohesive zone concept, namely ECZ–FEM. In this model, cohesive zone elements are embedded in the material body to allow free development of cracks to emulate the undetermined fracture during a cutting process. The research results have shown a certain degree of agreement with the experiment in terms of chip formation and cutting forces while also revealed some limitations. First, controlling the maximum deflection

of the cohesive zone element through a scaling factor is a critical step in this method, and for that, an experimental calibration is necessary. This factor is currently determined on a qualitative basis in terms of chip size and crack propagation, because it is a behavior indicator instead of a property. Also, the current model is limited to brittle materials in order to scale the force linearly with the fracture energy. The model should also not be used for flexible material because the CZ mesh does not have enough degrees of freedom to handle deformation. For future work, modifications in CZ element or a new type of CZ element that can address these issues can further improve the model.

**Author Contributions:** B.T. developed the proposed model, conducted and analyzed the experiment, and wrote the manuscript. B.L.T. conceived the model concept, provided general guidance to this research, wrote and edited the final manuscript.

**Funding:** This research was partially funded by the Office of Energy Efficiency and Renewable Energy, U.S. Department of Energy, grant number DE-EE0008605.

**Acknowledgments:** The authors acknowledge the support from Texas A&M University and Texas A&M Engineering Experiment Station (TEES).

**Conflicts of Interest:** The authors declare no conflict of interest.
