Toolpath-based geometry modeling and thermal simulation of a multi-axis directed energy deposition process

Abstract

Directed Energy Deposition (DED) as an additive manufacturing (AM) method offers great potential across various applications. However, chal- lenges persist in controlling thermal history, grain structure, distortion, and residual stresses when manufacturing. Numerical simulation of the DED process enables prediction of these characteristics and supports first-time-right manufacturing. In most cases, computer-aided design (CAD) models of the post-machined component are used for toolpath planning and simulation. Since AM parts are produced layer by layer, their as-built geometry deviates from the idealized CAD model due to process-specific effects. This mismatch introduces errors in process simulations. To ad- dress this problem, a path-based geometry modeling tool is introduced that reconstructs a geometry closely approximating the as-built part, based on the actual toolpath and deposition bead dimensions. This model more accurately represents the final part’s volume and geometry. For thermal process simulation, material deposition is also modeled based on the same toolpath, establishing a unified workflow that uses standardized toolpath data for both geometry creation and thermal analysis. This ensures independence from specific machine types and enables early-stage simulation. The approach is validated through thermal simulations and experimental measurements, demonstrating high agreement and confirming that the proposed geometry modeling method improves the prediction of process parameters such as correct dwell times or interlayer temperatures.