Characterisation of in-situ alloyed titanium-tantalum lattice structures by laser powder bed fusion using finite element analysis

Abstract

Lattice structures are widely used in the industry for aerospace, automotive and biomedical applications as they are strong yet lightweight. Due to the complex geometry, lattice structures are mostly fabricated with additive manufacturing (AM). Despite AM having many advantages compared to traditional manufacturing methods, defects such as cracks and pores are commonly found in AM-produced samples, which could affect their actual performance. Thus, in this work, finite element analysis (FEA) is used to study the mechanical performances of in-situ alloyed titanium-tantalum (TiTa) lattice structures fabricated using laser powder bed fusion (L-PBF). Based on the established experimental data, the CAD models of the as-fabricated samples are reproduced and analysed using two modelling approaches. It is found that the elastic modulus is well-predicted by both simulation methods with high accuracy, while the yield strength is highly underpredicted by the two models for around 50% and 65% respectively. The FEA model is then used to analyse the performances of uniform lattice structures with 50% to 90% porosity and the results are found in agreement with the Gibson-Ashby model. To further improve the prediction accuracy of the simulation, more information on the defect condition is needed.

Keywords

• additive manufacturing
• 3d printing
• powder bed fusion
• selective laser melting
• finite element analysis
• lattice structures