Remote magnetic-field-actuated helical spring magnets: Micromagnetic simulation and analytical modeling

We explored a new helical spring magnet (HSM) concept using micromagnetic simulation along with analytical modeling. The present HSMs can be made of a single magnetic material or micro/nano-scale magnetic particles in a polymer matrix, which provides for active control over the motion of the HSMs by additional forces generated by the magnetic interactions inside the HSMs. A finite-element micromagnetic simulation was performed to calculate the different magnetic forces employed in the HSMs under applied magnetic fields. The effects of the HSMs' geometrical parameters, such as pitch length, wire diameter, and coil (spring) diameter, on their magnetic and mechanical forces were examined. The numerical calculations of an analytical model of a simplified three-rod magnet were in good quantitative agreement with the micromagnetic simulation results for the whole HSM geometry. The magnetic forces acting on the HSMs vary remarkably with the dimensions of the spring-geometrical parameters as well as the constituent material parameters. Thus, if the dimensions of HSMs are appropriately tuned in consideration of both the mechanical and magnetic parameters of the constituent materials, the resultant geometrical and material optimization will allow for an exter nal field control over the HSMs’ motion and, consequently, performance improvement. This could make the proposed HSMs highly suitable for active-control vibration dampers in mechanical engineering applications as well as soft robots in biomedical applications.