During this project, the evolution of plasma produced by intense nanosecond laser ablation of metal in vacuum under an external magnetic field has been studied using a two-stage model.  It has been found that under the investigated conditions, due to the presence of the magnetic field, the plasma velocity is reduced, while the plasma overall temperature is increased, and its parameter spatial distributions (e.g., temperature and density) become relatively more uniform. Using a three-dimensional electromagnetic (EM) and mechanical model, theoretical calculations under the simulated conditions have shown that passing a “coil” with an electric current pulse can induce EM forces in an aluminum alloy workpiece placed nearby, and can generate surface compressive residual stress at the bottom of a pre-existing hole in the workpiece, which, however, requires a very high coil current. An EM shot peening process that requires a lower coil current has been experimentally studied. It has been found that under the studied conditions, the EM shot peening process has enhanced the surface morphology quality around the boundary of a laser-machined microhole, and the surface morphology change also suggests that compressive surface plastic deformation has probably occurred around the hole boundary, which may be potentially beneficial to the material mechanical properties.         

Intelectural metrit: This project 1) leads to fundamental technology advances by bringinghybrid  manufacturing  into  laser  materials  processing;  2)  provide  a  quantitative  understanding  of hybrid physical processes through experimental study and multiphysics simulation, and set up a solid science base for EPALM applications; 3)  open new ways to obtain enhanced mechanical properties by studying the hybrid nanostructures formed in EPALM.     

Broader impact: 1)  EPALM will increase the manufacturing efficiency and  product qualityof  industries related to micromachining, such as electronics, automotive, aerospace, medical device, and optics industries.  2)  EPALM will benefit  sustainability,  environmental protection,  and energy and material saving.  EPALM is environmentally friendly without involving any harmful chemicals. Better product quality and longer lifetime decrease the need of re-manufacturing and hence imply less energy and material consumption and waste generation.    3) This project will meet the challenges of  education  in  manufacturing  through  (a)  integrating  interdisciplinary  science  and  advancedmanufacturing  programs  in  research  and  education;  (b)  providing  multidisciplinary  research opportunities  for  graduate  and  undergraduate  students  to  promote  discovery  and  understanding  of advanced  manufacturing  process;  (c)  outreaching  for  good  undergraduate/graduate  students  and retaining  them in science and engineering, especially underrepresented and minority students.

Last Modified: 01/11/2015
Modified by: Gary J Cheng