84 A. Allen et al. One drawback of using the BB-gun is the force at which it hits the parts. The BB’s dented the surface of the brackets. Currently, there is not a way to measure the speed of the BB either. Future work will be aimed at addressing these drawbacks. As an excitation technique the BB-gun extended the dynamic range by at about 5000 Hz over the small modal hammer. Since the parts tested in this study did not have modes of interest above 8500 Hz, the data acquisition system was set to record data up to 11 kHz. The dynamic range the BB-gun can provide could be higher than 11 kHz. 9.5 Conclusion As an alternative to traditional dynamic testing, acoustic and BB-gun testing is a viable option for higher frequency excitation. The acoustic and BB-gun testing extended the frequency range by approximately 8000 Hz and 5000 Hz, respectively. Although viable options, more testing is needed using these methods. Future testing for the speakers will investigate the signals coming from each speaker and the speaker configuration. Optimizing these parameters will aid in providing a more uniform signal to the base of the plate. For the BB-gun, future testing will be aimed at measuring and controlling the speed at which the BB’s exit the gun to avoid damaging the surface of the parts. Acknowledgements This work was funded by the Department of Energy’s Kansas City National Security Campus which is operated and managed by Honeywell Federal Manufacturing Technologies, LLC under contract number DE-NA0002839. References 1. Karme, A., Kallonen, A., Matilainen, V.-P., Piili, H., Salminen, A.: Possibilities of CT scanning as analysis method in laser additive manufacturing. Phys. Procedia. 78, 347–356 (2015) 2. NIST: Measurement science roadmap for metal-based additive manufacturing. Energetics. https://www.nist.gov/sites/default/files/documents/ el/isd/NISTAdd_Mf g_Report_FINAL-2.pdf (2013) 3. Johnson, K., Blough, J., Barnard, A.: Frequency response identification of additively manufactured parts for defect identification. In: Annual International Solid Freeform Fabrication Symposium, Austin, TX [Online]. Available: http://sffsymposium.engr.utexas.edu/archive (2018). Accessed 7 Mar 2019 4. Allen, A., Blough, J., Barnard, A.: Frequency inspection of additively manufactured parts for layer defect identification. In Annual International Solid Freeform Fabrication Symposium, Austin, TX (2019)
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