An Elastic Contact Model for the Prediction of Workpiece-Fixture Contact Forces in Clamping

The design and evaluation of machining fixture performance requires accurate knowledge of workpiece-fixture contact forces since they strongly impact workpiece accuracy during clamping and machining. This paper presents an elastic contact model for the prediction of workpiece-fixture contact forces due to clamping. The fixture and workpiece are considered to be elastic bodies in the vicinity of the contact region. The model is formulated as a constrained quadratic program by applying the principle of minimum total complementary energy. The model predicts the normal force, and the magnitude and direction of the tangential (friction) force at each workpiece-fixture contact due to clamping forces. Experimental verification of the model under different clamping loads shows good agreement between predicted and measured normal and tangential contact forces. The model can be used to analyze fixture performance in terms of the contact forces and contact region deformation.