Modeling and analysis of workpiece static and dynamic structural characteristics for machining operations

In machining operations both static and dynamic responses of the workpiece are important. The applied forces are crated by interaction between the cutting tool and workpiece. The static forces induce deflections which need to be considered in order to maintain acceptable part tolerances. The dynamic loads are important since they can potentially excite resonances in the workpiece creating damaging chatter situations. Because of the multitude of possibilities available for many machining operations, careful consideration is required to select an appropriate setup which avoids any adverse situation. An accurate FEM is required to perform the analysis. However, most Finite Element updating methods concentrate solely on dynamics while ignoring the static behavior. The work presented in this paper evaluates an approach which will allow both the static and dynamic structural characteristics of the workpiece and fixturing system in relation to the manufacturing process to be evaluated. The method uses an effective Finite Element Model (FEM) developed in conjunction with an experimental static compliance matrix and an experimental modal data base. The background of FEM updating with both static and dynamic data is first developed. Next, it is applied in a controlled laboratory test to evaluate the capabilities and limitations of the method to accurately predict both the static and dynamic structural characteristics.