@article{tu_paleocrassas_reeves_rajule_2014, title={Experimental characterization of a micro-hole drilling process with short micro-second pulses by a CW single-mode fiber laser}, volume={55}, journal={Optics and Lasers in Engineering}, author={Tu, J. and Paleocrassas, A. G. and Reeves, N. and Rajule, N.}, year={2014}, pages={275–283} }
 @article{tu_paleocrassas_2011, title={Fatigue crack fusion in thin-sheet aluminum alloys AA7075-T6 using low-speed fiber laser welding}, volume={211}, DOI={10.1016/j.jmatprotec.2010.09.001}, abstractNote={Reinforcing cracked aluminum structures with composite patches have been recognized as an efficient and economical method to extend the service life of cracked aluminum components. To further enhance the effectiveness of composite patches, it is envisioned that the crack can be first fused by laser welding to remove the high stress concentration at the crack front before applying the composite patch. In this paper, the feasibility of the envisioned fusion repair is investigated. A systematic approach for the fusion process design is proposed to overcome challenges related to alloy strength recovery, crack tracing, focusing position, welding speed, plate flatness, shielding gas pressure, thin-sheet factors, and skewed cracks. A thick-sheet, partial penetration model is first used to determine the starting point of laser welding conditions. A systematic approach to transfer the thick-sheet condition to successful thin-sheet welding is then presented. Based on successfully fused crack samples of AA 7075-T6, the ultimate tensile strength tests show that in average 74% of the alloy's original strength was recovered for a single-pass repair and 68% for a double-pass repair and the results are highly repeatable. It should be clear to see the benefit of the crack fusion because without crack fusion, the composite patch is bonded to a part with zero UTS at the crack region and with a high stress intensity factor at the crack front.}, number={1}, journal={Journal of Materials Processing Technology}, author={Tu, J. F. and Paleocrassas, A. G.}, year={2011}, pages={95–102} }
 @article{paleocrassas_tu_2010, title={Inherent instability investigation for low speed laser welding of aluminum using a single-mode fiber laser}, volume={210}, ISSN={["0924-0136"]}, DOI={10.1016/j.jmatprotec.2010.04.002}, abstractNote={The causes of instability are investigated for low speed welding of aluminum from 10 mm/s down to 1 mm/s using a 300 W single-mode fiber laser. Results show that the welding is stable until the speed drops below a certain threshold (∼1 mm/s) at which there was a significant change in the process mechanism, causing shallow, inefficient welds with many defects. A power distribution model and several tests are used to examine different types of power losses at low speeds. It is then hypothesized that, at low speeds, the CW laser beam mainly irradiates at the molten pool, which absorbs a large portion of the beam energy near the surface. The majority of this absorbed energy subsequently is either lost via evaporation or transferred into the bulk material via convection and conduction without being used for melting the solid at the welding front. A laser pulsing scheme was used to test the above hypothesis. It was found that, through proper control of the duty cycle and frequency to prevent overheating of the molten pool, a high aspect ratio weld shape can be restored at low speeds, thus, confirming the hypothesis. In addition, the 1 mm/s low speed threshold is found to be related to the initial molten pool propagation speed, which is found to be approximately 1.4 mm/s. Although this paper does not propose a solution to restore process stability, the understanding of the instability origin will be helpful in the search of such a solution to overcome the process instability for slow speed welding of aluminum.}, number={10}, journal={JOURNAL OF MATERIALS PROCESSING TECHNOLOGY}, author={Paleocrassas, A. G. and Tu, J. F.}, year={2010}, month={Jul}, pages={1411–1418} }
 @article{harp_paleocrassas_tu_2008, title={A Practical method for determining the beam profile near the focal spot}, volume={37}, ISSN={["1433-3015"]}, DOI={10.1007/s00170-007-1067-z}, number={11-12}, journal={INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY}, author={Harp, W. R. and Paleocrassas, A. G. and Tu, J. F.}, year={2008}, month={Jul}, pages={1113–1119} }
 @article{paleocrassas_tu_2007, title={Low-speed laser welding of aluminum alloy 7075-T6 using a 300-W,single-mode, ytterbium fiber laser}, volume={86}, number={6}, journal={Welding Journal}, author={Paleocrassas, A. G. and Tu, J. F.}, year={2007}, pages={179S–186} }