Reduced Residual Stresses through Support Structure Optimization in Laser Powder Bed Fusion
At a glance
Metal additive manufacturing (AM) has proven to be an attractive and viable technology for industry to produce complex components and/or small lot sizes. The reliability and thus acceptance of metal laser powder bed fusion (LPBF) remains a challenge though. Severe thermal gradients can occur causing excessive residual stresses, distortion or cracking in AM components and thus result in costly iterations, material waste, and post-processing. Despite their major influence on thermal gradients, support structures are often defined heuristically with varying effectiveness. Investigations of the effect of support structures on residual stresses have been repeatedly identified as a research need by the scientific community. Recently developed Finite Element (FE) based thermo-mechanical process simulation (TMPS) approaches are able to predict residual stresses and distortions. Appropriate calibration and validation procedures as well as in-situ temperature and comprehensive residual stress related data for mechanical validation with focus on support structures are still missing.
The objective of this proposed project is to develop a TMPS-based optimization tool for material-efficient support structures that minimize critical residual stresses in components printed by LPBF. Within this scope, the following intermediate goals are pursued:
- to investigate the effect of support structures on the residual stress state in LPBF components to provide a validation database for TMPS models,
- to develop a high-fidelity and a simplified TMPS model together with a dedicated calibration and validation scheme including support structure homogenization based on in-situ experiments and simulated data
- to model the effect of the support structure on their homogenized thermo-mechanical properties using a response surface approach, and
- to develop and validate a parametric optimization tool for support structures based on TMPS and response surface models.
This research project addresses a prominent industrial problem that currently inhibits the adoption of LPBF. The in-depth investigation of support structure effects on residual stresses advances the state of science, while the TMPS models and the optimization tool developed in this project provide important guidance not only for an effective support structure design but to analyze residual stresses and distortions in detail. Reliability and cost-effectiveness of the LPBF process are improved supporting a more wide-spread adoption of the technology.