Snap buckling of active bistable beams under magnetic actuation

Bistable structures featuring two distinct stable configurations are central in the design of many functional devices, both in nature and in technology. Here, we investigate the snap buckling of a bistable beam made of magnetorheological elastomer (MRE) prepared by incorporating micron-sized magnetic particles into a polymer matrix. We demonstrate that the snap buckling of our magnetic beams can be triggered in the presence of an external uniform magnetic field. We make use of precision experiments to quantify how the critical field strength required for buckling depends on both the imposed end-to-end shortening and the beam geometry. In parallel to the experiments, we perform finite element simulations. The experimental and numerical results are rationalized through a magneto-elastic beam model. Using magnetic fields to actuate the snap-through of bistable beams could enable a new class of devices with contactless actuation, across length scales; from MEMS to robotic applications.