**5. Conclusions**

In this study, an FEA simulation was conducted for sheet metal simultaneously subjected to a tensile test and superimposed hydrostatic pressure. The modified GTN model is used when the shear damage mechanism is considered. It is determined that the superimposed hydrostatic pressure increases the ductility significantly as hydrostatic pressure delays or eliminates growth of microvoids or microcracks as well as damage by the shear mechanism. However, it is clearly observed that the shear damage mechanism is dominant over the void growth under high pressure. The numerical results clearly show that the type of fracture changes from microvoids mechanism to shear failure under superimposed hydrostatic pressure. Finally, to sum up the conclusion remarks, the salient points are listed as follows:


**Author Contributions:** Conceptualization, M.S. and P.W.; methodology, M.S. and P.W.; software, P.W., Z.X.; validation, M.S. and P.W.; formal analysis, M.S., C.T. and P.W.; investigation, M.S., C.T. and P.W.; writing—original draft preparation, M.S., C.T., A.P., Z.X. and P.W.; writing—review and editing, M.S., C.T., A.P., Z.X. and P.W.; visualization, M.S., C.T., A.P., Z.X. and P.W.; supervision, P.W.; project administration, M.S.; funding acquisition, P.W. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC, project No: RGPIN-2016-06464).

**Data Availability Statement:** Not applicable.

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