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The stiffness and damping of a flexible smart cantilever structure controlled by a magnetic field is investigated in this research. The cantilever structure is fabricated by using flexible polyvinyl chloride as a host structure of rectangular cross-section embedded with magnetorheological (MR) fluid. The deflection of the cantilever structure at the free end is used to analyze the stiffness change of the cantilever structure. The stiffness of the specimen with MR fluid at magnetic flux density of 0.171T is greater than that of the specimen without subjected to magnetic field. The strength of the applied magnetic field is directly related to the structure’s stiffness. Under the influence of a magnetic field, the MR fluid embedded inside the flexible PVC cantilever structure significantly dampens the vibrations of the structure.

Polylactic acid (PLA) is an environmentally friendly, biodegradable, and lowcost thermoplastic material suitable for 3D printing. Complex shapes can be easily produced and hence PLA has been used for many applications. This study presents the damping characteristics of two robotic gripper fingers. The first gripper is composed of a PLA surface layer and a magnetorheological (MR) fluid core and the second gripper is composed of a PLA surface layer bonded to a surface of unimorph piezoelectric Macro Fiber Composite (MFC).The magnetic field is applied by using permanent magnets while the magnetic field strength is varied by changing the distance between the permanent magnets. The electric field is applied by using a micro-amplifier and regulated using data acquisition systems. The natural frequency and damping ratio of the PLA gripper finger are determined by free vibration analysis using LabVIEW software. The damping ratio and vibration amplitude suppression for the PLA grippers was increased as the magnetic field strength changed from 0G to 600G (MR) and as the electric field changed from 0V to 360V (MFC).

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