Model-based feedforward control of part height in directed energy deposition

Qian Wang, Jianyi Li, Abdalla R. Nassar, Edward W. Reutzel, Wesley F. Mitchell

Research output: Contribution to journalArticlepeer-review

Abstract

Control of the geometric accuracy of a metal deposit is critical in the repair and fabrication of complex components through Directed Energy Deposition (DED). This paper developed and experimentally evaluated a model-based feedforward control of laser power with the objective of achieving the targeted part height in DED. Specifically, based on the dynamic model of melt-pool geometry derived from our prior work, a nonlinear inverse-dynamics controller was derived in a hatch-by-hatch, layer-by-layer manner to modulate the laser power such that the melt-pool height was regulated during the simulated build process. Then, the laser power trajectory from the simulated closed-loop control under the nonlinear inverse-dynamics controller was implemented as a feedforward control in an Optomec Laser-Engineered Net Shape (LENS) MR-7 system. This paper considered the deposition of L-shaped structures of Ti-6AL-4V as a case study to illustrate the proposed model-based controller. Experimental validation showed that by applying the proposed model-based feed-forward control for laser power, the resulting build had 24–42% reduction in the average build height error with respect to the target build height compared to applying a constant laser power through the entire build or applying a hatch-dependent laser power strategy, for which the laser power values were obtained from experimental trial and error.

Original languageEnglish (US)
Article number337
Pages (from-to)1-20
Number of pages20
JournalMaterials
Volume14
Issue number2
DOIs
StatePublished - Jan 2 2021

All Science Journal Classification (ASJC) codes

  • Materials Science(all)

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