Buckling phenomena in AM lattice strut elements: A design tool applied to Ti-6Al-4V LB-PBF

Abstract

Additive Manufacturing (AM) technologies such as Laser-Based Powder Bed Fusion (LB-PBF) enables the manufacturing of high efficiency lattice structures. However, the LB-PBF processes inherently generate local geometric effects. The practical implications of these geometric effects on structural performance is of critical importance to effective AM design; however, these effects are poorly understood. In response to this uncertainty, this research compares predictive and experimental data for the structural response of LB-PBF lattice strut elements subject to compressive loading; this comparison is made for LB-PBF manufactured Ti-6Al-4V LB-PBF but is generally applicable to all AM systems and materials. This data provides insight into the influence of geometric design parameters, including: node and strut diameter, strut length, and manufacturing inclination angle. The effect of these geometric parameters on the associated critical buckling load, and the accuracy of predictive failure models is quantified. Furthermore, the eccentricity ratio, a classical measure of column efficiency widely used in civil engineering design, is applied for the first-time as a systematic metric to characterise the structural efficiency of as-manufactured AM strut element.

Keywords

• Design For Additive Manufacturing (DFAM)
• Effective eccentricity
• Ti-6Al-4V
• Cellular structures
• Process optimisation
• Certification