| Productivity when milling thin, monolithic components is often limited by regenerative chatter. The vibrations are partially controlled by the use of stability lobe diagrams, which enable the selection of spindle speed/axial depth combinations to avoid chatter. However, this requires knowledge of both the tool and structure dynamics.;The objective of this numerical study is to model the dynamics of thin-walled structures. A complete finite element analysis is carried out using ABAQUS/Standard. An analytical model is developed for the natural frequency and minimum lateral stiffness of thin plates with clamped-clamped-clamped-free boundary conditions. The stiffness is determined using the first (most flexible) transverse bending mode. The dynamic characteristics of the plate were predicted using finite element analysis and the accuracy was experimentally validated. Based on these studies, the predicted and measured natural frequency, stiffness values, and mode shapes showed good agreement. Using the numerical finite element modeling capability, the natural frequency and minimum stiffness for the first (most flexible) mode was evaluated over a range of lengths, thickness, and heights. The trends were combined into a look up table that can be used to identify the natural frequency and minimum rib stiffness for any selected geometry. Using the interpolated natural frequency and stiffness values, the workpiece dynamics can be defined and, using milling stability methods, stable machining parameters may be identified. |
