(Dr. Shreyes N. Melkote, advisor)

"Finite Element Approach to Modeling Deformation in a Fixture-Workpiece System "

Abstract

The machining of parts for industrial and commercial use requires a mechanism to restrain the workpiece during machining. Various types of machining fixtures are used to accurately, repeatedly, and firmly restrain a workpiece. A key point of investigation is the deformation produced by clamping forces as such compliances can cause inaccuracies in final part quality. Traditionally, empirical investigations have been used to determine the deformations produced in a fixture-workpiece system. More recently, numerical methods have been used to predict fixture system parameters.

The work in this study was aimed at utilizing finite element analysis (FEA) as a tool to predict deformation in a workpiece. A modeling strategy was developed to study the effects of friction and FEA mesh density. Additionally, the selected modeling approach was used to predict reaction forces present in the fixture-workpiece system. Experimental results were used as the benchmark for assessing the accuracy of the models.

FEA was also used to study compliance in the fixture itself. A set of FEA models and laboratory experiments were used to characterize modeling error introduced by the omission of various fixture components from the FEA model. An application of the fixture modeling guidelines derived from FEA studies was the analysis of deformations in a hone pot assembly. Such an analysis required the modeling of a non-linear material as well as axisymmetric loading conditions.