Demonstrator 4: Magnetorheological Damper Integrated with a Swivel Type Fixturing System for Automotive Applications

Tunable dampers based on MR elastomers have been developed during the project. As final demonstration, MATZAT provided a fixture which suffered from chatter problems in certain demanding conditions. The DVA is efficient only when its natural frequency is close to the natural frequency of the original system. When the natural frequency changes, it is important to be able to change the DVA stiffness and damping factor. This is the reason why we used smart concepts in our prototypes. We conceived a damper for a fixture’s plate modal mass. On this drawing, the outer part is attached to the fixture’s plate. The internal part, the electromagnet, is the moving mass of the DVA which is attached to a disk of steel which plays the role of a spring and will provides the required stiffness. With this modification, it was possible to tune the damper to the resonance frequency of the fixture and effectively damp it. With an appropriate tuning, the resonance peak of bending of fixture will be split in two peaks with lower amplitude and thus higher damping. Some cutting tests were performed comparing the result with and without the DVA. The damper managed to eliminate chatter and obtain nice surface quality in a wide range of cutting conditions.