A model to predict the dynamics of a workpiece-fixture system has been developed based on the equivalency of the dynamic frictional contact problem with a nonlinear friction law to that of a variation inequality problem. Nonlinear finite element method has been employed to solve the problem. A series of experiments under various fixture configurations were conducted on a modular fixture test-bed to determine the dynamic characteristics of the workpiece-fixture system. Model predictions of the dynamic characteristics have been compared to those obtained from the experiments and are found to be in good agreement. It was found that frictional sliding contact at the workpiece-fixture interfaces provides damping to the system and that the nature of this contact and level of damping are highly dependent on contact forces developed through clamping. Clamping sequence was also found to be important in determining dynamic characteristics.

Issue Section:
Technical Papers
Keywords:
machining, mechanical contact, friction, finite element analysis, damping, impact testing, machine control
Topics:
Clamps (Tools), Damping, Dynamics (Mechanics), Finite element methods, Friction, Stiffness, Transfer functions, Machining
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 by ASME
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