**Acoustic emission measurements**

The only signal detected was the ultrasonic vibration assistance, which permits the frequency characterization of the assisting ultrasonic vibration.

Any signal due to possible damage in the material of the specimens was detected.

**Author Contributions:** Conceptualization, I.F.-O., A.E.-U., J.L., R.J.-M. and J.A.T.-R.; methodology, I.F.-O., E.V.-C., A.E.-U., J.L., R.J.-M. and J.A.T.-R.; software, A.E.-U., E.V.-C. and D.V.; validation, A.E.-U., D.V. and J.L.; formal analysis, I.F.-O., A.E.-U. and J.L.; investigation, R.J.-M.; resources, A.E.-U., J.L., R.J.-M. and J.A.T.-R.; data curation, A.E.-U.; writing—original draft preparation, I.F.-O., A.E.-U. and R.J.-M.; writing—review and editing, J.A.T.-R.; visualization, R.J.-M.; supervision, A.E.- U.; project administration, J.A.T.-R.; funding acquisition, J.A.T.-R. and R.J.-M. All authors have read and agreed to the published version of the manuscript.

**Funding:** Financial support for this study was provided by the Ministry of Science, Innovation and Universities of Spain, through grant RTI2018-101653-B-I00, which is greatly appreciated. Additional support was provided by the regional government of Catalonia and FEDER funds for regional development through grant 001-P-001822.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Acknowledgments:** We want to thank the CDIF research group for their support.

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