Non-Destructive Blade Sharpness Characterization Using a High-Shear Responsive Fluid and Analytical Drag Modeling

For various thin-edged blades and tools, the traditional sharpness measurement techniques (e.g., optical measurements and solid material cutting tests) suffer from drawbacks such as lengthy testing time, high cost, and material waste. To fill this gap, a sharpness evaluation method based on a high-shear-responsive fluid was proposed in this study for such scenarios. A tailored fluid formulation was developed to detect edge variation with micron-scale sensitivity. The drag-decomposition framework, by utilizing cross-model rheology with Hiemenz and Falkner-Skan solutions, was established, and the real-fluid behaviors for sharpness evaluation were predicted by simulation. Experiments were carried out using a specifically developed platform to model the relationship between edge radius, cutting speed, penetration depth and force responses. Furthermore, an analytical sharpness index by integrating wedge-flow theory with shear-rate-dependent viscosity was proposed, proving the positive contribution to sensitivity. These results highlight the need for nonlinear modeling and precise fluid selection in blade-sharpness measurement, and provide a basis for further investigation of fluid-mediated sharpness evaluation.