Magnetic actuation of switchable bistable structures: A numerical study

Bistable laminates have posed a significant research interest in the recent past owing to their potential applications in morphing and energy harvesting. An important aspect of research has been their snapthrough analysis, wherein the use of solid state actuators like shape memory alloys (SMAs) and macro-fiber composites (MFCs) has been prevalent. These actuators however, interfere with the structural response of the laminate altering its bistability and snapthrough characteristics. Recently, reversible snapthrough was demonstrated in 3D printed thermoplastic filaments composed of PLA with finely ground iron particles embedded. Remote actuation was achieved by means of permanent magnets providing the necessary snapthrough loads. In this manuscript, a numerical model has been developed based on a Rayleigh-Ritz minimization scheme, to predict the equilibrium states and the snapthrough loads. The means of snapthrough is the interaction between the ferromagnetic layers and the nonlinear magnetic field generated by a solenoid, which has been modeled using Biot-Savart's law. The developed numerical model has been validated against finite element simulations in ABAQUS®, wherein the magnetoelastic interactions have been modeled as body forces using the DLOAD subroutine. This manuscript details one of the preliminary efforts in modeling of the remote snapthrough of switchable multistable structures and can provide valuable insights into the design of such non-contact actuation systems.