An Experimental Investigation into the Deflection of a Fixture-...

The role of fixturing forces in the distortion of machined components is investigated in this paper. A scaled engine block was mounted in a compression test machine using a modular fixture. The workpiece displacement was measured for a range of clamping and support conditions. The effect of boundary conditions for the part subjected to loads representative of the fixturing was captured and compared to the FEA (Finite Element Analysis) prediction. The measured displacements were found to strongly depend on the boundary conditions at the clamping and support locations. This study indicates that discrepancies between measured and FEA distortions may be attributed to rigid body motion not comprehended by the FEA and uncertainty in accurately describing the boundary conditions in FEA. Authors: Y. Gene Liao (General Motors Corporation, Warren, MI), Robin Stevenson (General Motors Corporation, Warren, MI), Raghunath Khetan (Delphi Automotive Systems, Warren, MI).