**4. Conclusions**

We have printed TC4 materials with different porosities by designing the printer parameters and experimentally investigated the effect of porosity on the dynamic response of SLM TC4 materials. Experimental results indicate that:


Therefore, materials with various dynamic properties can be produced by selecting certain printing parameters. This work may guide AM technology to design materials for certain applications under extreme conditions.

**Author Contributions:** Conceptualization, J.H.; methodology, Z.L.; validation, Y.C., Z.J. and J.C.; formal analysis, Z.L., L.H. and Y.C.; investigation, Y.C.; resources, J.H.; writing—original draft preparation, Y.C.; writing—review and editing, Z.L. and J.H.; project administration, J.H. and Z.L.; funding acquisition, J.H. and Z.L. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the National Natural Science Foundation of China grant number No. 12072331 And the Science Challenge Project grant number No. TZ2018001. Z.L. thanks the support of the project of Key Laboratory of Impact and Safety Engineering (Ningbo University), Ministry of Education (CJ202007).

**Acknowledgments:** We thank Yang Liu and Jinhui Meng of Ningbo University for their support in characterization analysis.

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

#### **References**

