Evaluation of stiffness of string bed in tennis racket and numerical simulation using by FEM

Abstract

In this study, FEM numerical simulation was made to estimate surface pressure of string beds. This model is able to calculate all axis direction displacement of all nodes by setting an arbitrary load. Two tests were conducted to measure the relationship between a load and a displacement of nodes. One was compressing test of square string beds in static. The other test was tennis balls was collided against string beds. Square string beds of three string pattern was produced in FEM. The reasonableness of this FEM numerical simulation was verified by comparing the result of simulation and the result of the experiment. As a result, this FEM model is able to evaluate stiffness of string bed properly in static behavior. On the other hand, in collision test, velocity of ball and displacement of string bed were measured. Kinetic energy loss of before and after the collision was calculated. Stiffness of string bed calculated in FEM and displacement of string bed measured in collision test were used to get the potential energy of string bed. The relationship between kinetic energy loss of tennis ball and the potential energy of string bed was considered.