Computational Analysis of Power Attenuation During Directed Energy Deposition

Open Access
Author:
Kozuch, Christopher David
Area of Honors:
Mechanical Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Timothy William Simpson, Thesis Supervisor
  • Zoubeida Ounaies, Honors Advisor
Keywords:
  • metal
  • additive
  • manufacturing
  • directed
  • energy
  • deposition
  • ray
  • tracing
  • simulation
Abstract:
Directed energy deposition (DED) is a type of metal additive manufacturing that uses a laser to continuously fuse a stream of metal powder to a workpiece, thereby building a component layer by layer. The attenuation coefficient is a process parameter that describes the reduction of the laser power as it passes through the powder. This work presents a method for calculating the attenuation coefficient by discretizing the laser into numerous rays and tracing the rays through the powder. The method was applied to iron and copper powders with normally distributed sizes that were irradiated by CO2 and Nd:YAG lasers. The results were compared against experimental values, and the average absolute error was found to be 24.2%. Although this error is higher than optimal, it is low enough to develop trends. One such trend was developed for the dependence of the attenuation coefficient on the refractive index of the metal powder. The development of a trend such as this demonstrates that computational ray tracing can be used to assist in the analysis of the DED process.