Design Criteria Based on Modal Analysis for Vibration Sensing of Thin-Wall Plate Machining

Machining complex thin-wall components, such as casings and compressor disks in aircraft engines, is a challenging task because continuous deformation and vibration renders poor precision and quality in final products. However, monitoring workpiece vibration is hindered by harsh working conditions like cutting fluids, not to mention investigation into the vibration principle during cutting. In order to establish criteria for designing noncontact sensors to monitor workpiece vibration, this study presents a plate dynamic model along with experimentally identified damping ratios for an annular workpiece under constraints emulating those of a duplex turning machine. Formulated as a dimensionless boundary value problem, the solutions that have been numerically verified with finite element analysis provide a rational basis for identifying key cutting process parameters and quantifying their effects on thin-wall component vibration sensing. With a detailed modal analysis, the dynamic model provides a simple yet practical method for vibration measurements using an eddy-current sensing approach. Experiments were carried out to justify the proposed method, validate the stability of eddy-current sensing under the harsh cutting condition, and investigate the effect of sensor placement on sensing configuration design.