Reduced Residual Stresses through Support Structure Optimization in Laser Powder Bed Fusion

Description

Metal additive manufacturing (AM) has proven to be an attractive and viabletechnology for industry to produce complex components and/or small lot sizes. Thereliability and thus acceptance of metal laser powder bed fusion (LPBF) remains achallenge though. Severe thermal gradients can occur causing excessive residualstresses, distortion or cracking in AM components and thus result in costly iterations,material waste, and post-processing. Despite their major influence on thermalgradients, support structures are often defined heuristically with varying effectiveness.Investigations of the effect of support structures on residual stresses have beenrepeatedly identified as a research need by the scientific community. Recentlydeveloped Finite Element (FE) based thermo-mechanical process simulation (TMPS)approaches are able to predict residual stresses and distortions. Appropriatecalibration and validation procedures as well as in-situ temperature andcomprehensive residual stress related data for mechanical validation with focus onsupport structures are still missing.

The objective of this proposed project is to develop a TMPS-based optimization tool formaterial-efficient support structures that minimize critical residual stresses incomponents printed by LPBF. Within this scope, the following intermediate goals arepursued:

to investigate the effect of support structures on the residual stress statein LPBF components to provide a validation database for TMPS models,
to develop ahigh-fidelity and a simplified TMPS model together with a dedicated calibration andvalidation scheme including support structure homogenization based on in-situexperiments and simulated data
to model the effect of the support structure ontheir homogenized thermo-mechanical properties using a response surface approach,and
to develop and validate a parametric optimization tool for support structuresbased on TMPS and response surface models.

This research project addresses a prominent industrial problem that currently inhibitsthe adoption of LPBF. The in-depth investigation of support structure effects onresidual stresses advances the state of science, while the TMPS models and theoptimization tool developed in this project provide important guidance not only for aneffective support structure design but to analyze residual stresses and distortions indetail. Reliability and cost-effectiveness of the LPBF process are improved supporting amore wide-spread adoption of the technology.