Probabilistic Process-Structure-Property Modelling for Hardness and Porosity Estimation in High-Speed DED-Reprocessed Components in the context of the Circular Factory

In Circular Factory (CF) environments, used components are disassembled, characterized, and reprocessed, based on a reliable estimation of the resulting material properties and taking measurement and remanufacturing uncertainties into consideration. For reprocessing steps such as High-Speed Laser Directed Energy Deposition (HS DED-LB), uncertainties and process variability critically affect the robustness and stability of process-structure-property predictions. Additionally, measurements introduce uncertainties that propagate into the estimation of the post-process material state. For remanufactured structural components, hardness and porosity serve as key quality indicators describing the material state. Both are investigated as key determinants of fatigue performance, since hardness governs local fatigue strength, while porosity acts as a stress concentrator that promotes early fatigue crack initiation and reduces fatigue strength and component lifetime. In HS DED-LB, laser power and scan speed govern the thermal input and thereby influence microstructure development and resulting material properties. The process parameters can act as physically based features representing the thermal history and its fluctuations to correlate the process to the material state. ... mehrTo address this issue, Gaussian Mixture Models (GMMs) are adopted as a unified probabilistic framework to represent multimodal uncertainty and enable consistent inference under process variability and measurement noise. This paper presents a probabilistic approach for modelling and fusing measurement and process uncertainties using GMMs, resulting in probability density functions of hardness and porosity after HS-DED-LB reprocessing. The approach enables uncertainty-aware estimation of the material state and supports adaptive tuning of reprocessing parameters to achieve the desired target quality characteristics in circular factories.