A computational study of drop-on-demand liquid metal 3D printing using magnetohydrodynamic actuation

• Published in: Additive manufacturing 2023-03, Vol.66, p.103462, Article 103462
• Main Authors: Shokraneh, Saman, Mojtahedzadeh-Faghihi, Omid, Amani, Ehsan
• Format: Article
• Language: English
• Subjects: Additive manufacturing; Computational Fluid Dynamics (CFD); Drop-On-Demand (DOD); Liquid metal 3D printing; MagnetoHydroDynamic (MHD)
• ISSN: 2214-8604; 2214-7810
• DOI: 10.1016/j.addma.2023.103462

In the present research, the liquid metal 3D printing of the 7075-aluminum alloy using contactless MagnetoHydroDynamic (MHD) Drop-On-Demand (DOD) actuation is studied numerically. After carefully validating the governing sub-models by experimental and theoretical benchmarks, the effects of amplitude, frequency, width ratio, and waveshape of the actuation pulse on the DOD performance parameters, including droplet size, uniformity, velocity, and generation frequency, are investigated, and the printability diagrams in terms of different non-dimensional parameters are presented. Then, the seven distinct droplet generation regimes identified on the printability diagrams are analyzed. In addition, a modified pulse waveform is proposed which extends the printable regime over a wider range of Strouhal (St), or non-dimensional actuation frequency, as well as Hartmann (Ha), or non-dimensional amplitude, numbers. This improved performance is revealed to be connected to the change of actuation mode from the “push-only” to “push-pause” mode. For the modified square pulse, the printable condition is confined to Ha>40 to provide sufficient Lorentz force for an effective actuation, Ha