A Novel Digital Design Approach for Metal Additive Manufacturing to Address Local Thermal Effects

Abstract

The reliability and performance qualification of additively manufactured metal parts is critical for their successful and safe use in engineering applications. In current powder-bed fusion type metal additive manufacturing processes, local thermal accumulations affect material microstructure features, overall part quality and integrity, as well as bulk mechanical behavior. To address such challenges, the investigation presented in this manuscript describes a novel digital design approach combining topology optimization, process simulations, and lattice size optimization to address local thermal effects caused during manufacturing. Specifically, lattices are introduced in regions of topology optimized geometries where local thermal accumulations are predicted using the process simulations with the overall goal to mitigate high thermal gradients. The results presented demonstrate that the proposed digital design approach reduces local thermal accumulations while achieving target mechanical performance metrics. A discussion on how post-manufacturing heat treatment effects could be also considered, as well as comments on the computational implementation of the proposed approach are provided.

Additively manufactured metallic biomaterials

“…The regions with such local heat accumulations experience grain nucleation and growth for more extended periods, leading to different crystalline properties than the surrounding areas. This also leads to residual stresses that cause part distortions and failure sites at the structural scale [ 251 ].…”

Topology Optimisation in Structural Steel Design for Additive Manufacturing

“…Multiphysics problems in optimisation are usually deemed to address thermal and mechanics conditions [521]. Recently, Cheng et al employed the Lattice Structure Topology Optimisation (LSTO) to design a cooling channel system [522] and Perumal et al found a technique to mitigate thermal accumulations by optimising lattice structures locally where such concentrations are more prone due to the metal AM process with a powder-bed fusion [523].…”

Manufacturing Constraints in Topology Optimization for the Direct Manufacturing of Extrusion-Based Additively Manufactured Parts

“…The integration of manufacturing constraints into TO is, therefore, crucial to turn the design proposal into a manufacturable geometry [5][6][7]. While in the early 2000s, casting processes were the focus of research [8][9][10][11][12], additive manufacturing (AM) is currently of most interest [13][14][15][16][17][18][19], as it allows the fabrication of bio-inspired [20] and numerical optimized structures [21][22][23][24] with ease. Nevertheless, even AM processes have restrictions, most prominently, the overhang-angle needed to provide temporary supports to prevent collapsing or warping, which have to be considered during TO [25,26].…”