Fingertips deformation under static forces: analysis and experiments

Abstract

Introduction: When designers, physicians, and engineers are working in a new design or calculation forces exerted by fingertips they need to consider that each person's fingertip is different. Taking into account the material properties for each person the Poisson's ratio, Young,s modulus, and density are different. These properties will be influential in the fingertip force. Objectives: Development of a three-dimensional human fingertip model to simulate with finite element methods a behavior of soft finger when it is under a force. In a soft finger, Poisson´s coefficient can be different according to person and age. Other factors like temperature have influence on this coefficient. Young,s modulus can be used for the dermis, epidermis, soft tissue, grease, and tendons. Once we have collected all of these dates we create a three-dimensional model. Methods: With a caliper and a precision balance Tefal-EASY we measure three times the force and deformation of fingertips, with O N no deformation to 7 N maximum deformation in z-axis (axis normal to balance and fingertip) using the same conditions for each experiment. Once we have done experiments with a person we introduce constrains in a finite element program to campare deformation in z-axis and force with the results and experiments.