A magnetic control method for large-deformation vibration of cantilevered pipe conveying fluid

Soft active materials have the ability to undergo large deformation in response to stimuli such as light, heat, magnetic, and electric fields. Due to their promising applications in the fields of soft robots, flexible electronics, and biomedicine engineering, they have attracted tremendous attention from different disciplines and developed rapidly in the past decades basing on mutual efforts. Recently, a new class of soft active materials, known as hard-magnetic soft (HMS) materials is successfully developed. By applying magnetic fields, unprecedented mechanical behaviors of HMS structures have been observed. To further explore the potential applications of HMS materials, this work will investigate the dynamical behaviors of fluid-conveying pipes made of HMS materials for the first time. By considering the exactly geometric nonlinearities due to the bending deformation of the pipe, the governing equation of a cantilevered HMS pipe conveying fluid is derived based on Hamilton's principle. The analyses of the stability, static deformation, and nonlinear vibration of the HMS pipe are conducted by solving the obtained governing equation. It is found that there is a critical flow velocity for the dynamic instability of the pipe. When the flow velocity is below this value, the HMS pipe may undergo a large static deformation in a stable state. However, the pipe would periodically oscillate with a large amplitude when the flow velocity is beyond the critical flow velocity. Results also indicate the mechanical responses including static deformation, loss of stability, and vibration of the HMS pipe conveying fluid can be effectively controlled by applying an external magnetic field.