title: Multiphysics-Multiscale Simulation of Additively Manufactured Functional Materials
Creators: name: Yang, Yangyiwei
Publisher: name: UNSPECIFIED
Year: 2024

description: Powder Bed Fusion (PBF), a popular additive manufacturing technique for metallic materials, has demonstrated both in industry and academia its flexibility and rapidness in creating novel and complex geometries, forming a critical component in the anticipated breakthrough of advanced material manufacturing. In this regard, establishing a transferable process-microstructure-property relationship for PBF-processed functional materials is crucial for achieving sustainable and reproducible manufacturing, yet previous studies have not fully covered this topic. Modeling and simulation of PBF processes aim to complement the current costly and time-consuming trial-and-error approach with an efficient computational design tool. Yet, this remains a significant challenge due to the sophisticated and interactive nature of the underlying physics, encompassing a wide range of time and length scales and heavily reliant on processing parameters like beam size, power, and scan speed. A comprehensive framework that accounts for scale effects and multiphysics interactions is therefore vital for reliable modeling and simulation of process-microstructure-property relationships.

This work is dedicated to developing a multiphysics-multiscale simulation framework, aiming to thoroughly investigate the process-property relationships in functional materials and further facilitate the simulation-guided property tailoring. It starts by modeling the PBF process with various complex and interactive physical processes using the based on the principles of non-equilibrium thermodynamics and fluid dynamics, including but not limited to coupled mass and heat transfer, melting and (re)solidification, grain growth, and cross-coupling effects. The developed PBF models are then integrated into a larger framework together with simulations of mesoscopic residual stress generation, nanoscopic solid-state phase transitions, and nanostructure-based magneto-elastic coupled micromagnetics. Meanwhile, a multilayer scheme is also proposed and integrated to bring the process simulations close to the practical PBF manufacturing. The framework is methodically structured to ensure clarity and depth, with emphasis on key concepts with corresponding physical backgrounds. Models employed in this framework are numerically implemented by finite element and finite difference methods, incorperated with other approaches, including discrete element and CALPHAD methods.

By employing the established framework, this work conducts batched high-performance computations, followed by regression analyses, to derive phenomenological relations between PBF-processing parameters and the resultant material properties. These properties include porosity, fusion zone geometry, residual stress, plastic deformation, effective elasticity, and magnetic hysteresis. Beyond delivering process-property relationships, the work proposes a novel powder-resolved mechanism to elucidate mesoscale residual stress formation, and uncovers the sensitivity of local magnetic coercivity to residual stress states in PBF-processed Fe-Ni permalloy. PBF-associated melt pool control and nanoparticle tracing are also sufficiently investigated and validated with experimental observations, delivering a dimensionless allometric scaling law for predicting and controlling melt pool width and statistic insights of nanoparticle dispersion and agglomeration in PBF processes, respectively.

The proposed multiphysics-multiscale simulation framework is anticipated to enrich the computational toolkits, thereby supporting sustainable manufacturing and the development of digital twins for functional materials.