Controlling mixed-mode electromagnetic fracture to create patterned cuts into metallic foils: Fundamentals and...

This study presents a novel method for creating patterned cuts into metallic foils by harnessing mixed-mode fracture, induced by the simultaneous application of electric current pulses and mechanical loading. Building on the principles of fracture under electromagnetic forces, i.e., passage of electric current pulses of moderately high densities through a pre-cracked metallic foil, with or without a mechanical stress, can lead to propagation of sharp crack in mode I, and crack deflection under mixed-mode loading, i.e., propagation of the crack along an angle relative to original configuration when a mechanical load is applied under mixed-mode during the application of electric current pulse through the foil, a specialized setup was developed to induce and control mixed-mode crack propagation through the coordinated application of mechanical loads at an angle and a series of electric current pulses. Conjugate finite element analysis provided the selection of optimal electric current pulsing and mechanical loading parameters to propagate the crack at the precise deflection angle under mixed-mode fracture by a predetermined incremental length. The working of the system was demonstrated by creating a predefined sinusoidal cut in a 25 μm-thick Al foil, confirming directional control over crack propagation. The combined experimental and computational approach offers distinct advantages, including high-resolution, tool-free patterned cutting of thin metallic sheets with sub-3 μm precision, representing a significant advancement in microfabrication technologies.