Mechanical Strain Tailoring via Magnetic Field Assisted 3D Printing of Iron Particles Embedded Polymer Nanocomposites

The development of efficient, energy-saving, and automated manufacturing of free-form variable-thickness polymer composite components has created a step-change and enabled technology for the composites industry seeking geometry tailoring during a mould-less and/or additive manufacturing such as that in 3D printing. The current article presents research on magnetic field assisted 3D printing of iron particles-embedded thermoplastic polylactic acid, during a fused deposition method based 3D printing. The magnets are symmetrically fixed on both sides of the printed nanocomposite. The setup utilised Neodymium magnets with a constant strength below one Tesla. Observations have shown that the nanocomposites being printed undergo permanent macro-scale deformations due to the extrinsic strains induced by the iron particles' magnetisation. To provide a theoretical understanding of the induced strains, a Multiphysics constitutive equation has been developed. The evolution of magnetisation within a relatively thick nanocomposite (5 mm thickness) has been studied. A correlation has been established between the extrinsic strains from the experimental data and the theoretical solution. The theory exhibits an accurate description of the field-induced strains provided that real-time temperatures for the printed layers are accounted for. The results demonstrate a viable and disruptive magnetic field-equipped fabrication with ability for permanent geometry control during a process.