Optimal Melting Interface Tracking in Laser-Aided Powder Deposition Processes

This paper presents a systematic control inputs optimization method for melting interface tracking in laser-aided powder deposition (LAPD) processes. Using a proposed interface approximation and a coordinate system moving with the laser source, and adopting the enhanced thermal conductivity method, the process model is first reduced to a set of coupled partial differential equations (PDEs) in fixed spatial domains. Then, the control problem of achieving process target properties is formulated as one of optimizing the control inputs to track a prescribed melting interface which is approximated from required process target parameters. This proposed optimization scheme is solved by the adjoint-based gradient method for which an algorithm is provided. A weighting scheme is also proposed to overcome feasibility issues with poor interface specifications and still achieve improved tracking of target parameters. The proposed scheme is illustrated through a simulation-based case study on a laser cladding process.