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Magnetic brush: a soft structure with highly tunable stiffness

Wei Hong (Iowa State University)

Instability in Solids and Structures

Tue 2:40 - 4:00

Barus-Holley 190

Subject to a magnetic field, a magnetorheological fluid (MRF) increases its apparent viscosity to the point of becoming a solid. From a solid point of view, the effective stiffness of the material changes from 0 to finite under a magnetic field. The MRF is useful in many applications but because of its fluidic nature it has the drawback of sedimentation and always needs a container. As a particle-filled composite, the magnetorheological elastomer (MRE) overcomes the issue of handling and storage, but can only change its stiffness by ~50%. The new structure presented utilizes the tunable stiffness of an MRE and the mechanical instability to enhance the range of stiffness change. It is found that the application of a magnetic field significantly increases the buckling stress of the structure. By applying a load below the critical value under a magnetic field but beyond the value without field, the response of structure exhibits a tunable stiffness by an order of magnitude. The performance of the magnetic brush resembles that of an MRF, but it is also as stable as a solid MRE.