An effective vibration isolator (VI) strategy isolates payloads from vibration sources by introducing compliance. Passive isolators are low cost and easy to install but are tuned to a specific vibration spectrum, and rapidly lose effectiveness if the design point shifts. In contrast, adaptive vibration isolators using magnetorheological fluids (MRFs) continuously adapt to changing vibration spectra by adjusting a magnetic field using an appropriate control algorithm. Traditional fabrication methods using injection molding are economical only when large numbers are produced, which precludes customizing VIs for a specific available jitter space, natural frequency, or static displacement. 3D printing is advantageous for a magnetorheological vibration isolator (MRVI) because designs can be customized: the shape of the hydraulic rubber reservoir can be economically customized to meet the requirements of a specific application by tuning such properties as axial stiffness, bulge stiffness, diameter, height, and Shore hardness of the membrane wall. The MRVI, which is a squeeze-mode device, consists of a reservoir or rubber bellow with customizable stiffnesses, a plastic lid which houses an electromagnetic coil, and an MRF (Figure 1). The rubber bellow and plastic lid were fabricated using a Masked Stereolithography (MSLA) 3D printer. The electromagnet was mounted onto the lid, the reservoir was filled with an MRF, and the lid was twisted onto the reservoir using a large thread. Using a testing machine, the damper forces of the 3D-printed MRVI were measured under constant velocity conditions for different magnetic fields. From these tests, the magnetic field-controllable performances such as the dissipated energy and the dynamic force range of the MRVI were obtained (Figure 2). The feasibility of the 3D-printed MRVI was experimentally confirmed. In addition, using 3D printing, and by selecting Shore hardness of the material, wall thickness, bellow shape, and MRF Fe particle volume fraction, a broad range of VI applications can be addressed with this design methodology.

References:

1. S. Kaul, “Modeling and Analysis of Passive Vibration Isolation Systems,” Elsevier, 1st Ed., 2021, DOI: 10.1016/C2019-0-00013-1.
   
2. M. Brigley, Y. T. Choi and N. M. Wereley, “Experimental and Theoretical Development of Multiple Fluid Mode Magnetorheological Isolators,” Journal of Guidance, Control, and Dynamics, Vol. 31, No. 3, pp. 449-459, 2008, DOI: 10.2514/1.32969.