Snap-through buckling in heavy hard magnetic elastica

Snap-through buckling is widely used in bistable structures for rapid actuation and energy-efficient designs. While gravity is often neglected in traditional slender structures, its impact on heavy hard magnetic elastica (h-HMEs) is significant due to their high-density and ultra-soft matrix, resulting in a large gravity-elastic constant. This study investigates the snapping behaviour of h-HMEs under combined magnetic–gravitational fields. A theoretical framework is developed to describe the stability, critical magnetic fields and the influence of gravity on the optimal position of single magnetization interface (M-interface). Results reveal that gravity introduces a directional dependence in the snapping transitions, facilitating the process in the direction of gravity while hindering it against gravity. These effects become more pronounced with increasing gravity-elastic constant. Although the optimal M-interface position remains nearly unaffected, gravity significantly alters the magnitude of critical fields. Scaling laws and design guidelines are proposed, providing valuable insights for applications in snapping-based metamaterials where gravity's effect cannot be ignored.