Analysis of the contact interactions between fingertips and objects with different surface curvatures.

Previous experimental observations indicated that the contact interactions between finger and tool handle interfere with the grasp stability, affecting the comfort and manipulations of handheld tools. From a biomechanical point of view, the curvature of the contact surface should affect the contact pressure and contact area, and thereby the comfort and manipulations of hand tools. The current authors analysed, via a finite element model, the contact interactions between fingertips and objects with different curvatures. The effects of the curvature on the contact stiffness, fingertip deformations, contact pressure distributions, and stress/strain distributions within the soft tissues were analysed. The simulation results indicated that the curvature of the contact interface influences the contact characteristics significantly. For a given contact force, the contact area and the contact stiffness increase but the contact pressure and the fingertip deformation decrease with the decrease of the contact surface curvature. The present simulation results will be useful for ergonomic designers in their aim to improve the design of tool handles.