Dynamic characterization and vibration transmissibility study of pneumatic handheld tools

摘要

The procedure followed and the initial results obtained in our efforts to mathematically characterize and analyze pneumatic hand tools are presented in this paper. The principal objective of the study is to provide a methodology as well as an evaluation tool that will aid in the prediction of transmissibility parameters. The general procedure is as follows: a set of mathematical models of the vibration source-hand system are established; tool characterization is performed in order to exercise the established models, and experimental data is collected to represent the system's response. The experimental responses are compared to the ones predicted by the established models. These models are based on previous work undertaken to study transfer function of human hands (i.e., fingers to wrist) subjected to controlled uniaxial excitations in all three orthogonal directions. The tool characterization is based on spectral analysis techniques used to dissect and collapse frequency domain data. The experimental data is collected by measuring vibration in the standard orthogonal directions by the use of tri-axial accelerometers rigidly attached to the tool being freely operated. The characterization is needed in order to be used as an input for the mathematical models. Results are presented for different subjects using an inline handheld pneumatic drill, which closely relates to uniaxial loading. The experimental data is collected while Subjects are performing drilling operation on sheet metal under standard position and conditions. Data is collected at two different locations, the fingers (tool) and the wrist. After comparison of the experimental results with the predicted results it is concluded that valid predictions are obtained, but there is a need for flexibility in tuning the developed models.