A Simultaneous evaluation of for Young's modulus and friction coefficient by three-point bending test in large deflection mode

This paper describes a method for evaluating Young's modulus and the coefficient of friction between a beam and supporting member by three-point bending test in large deflection mode. The result of measurement, i.e., deflection-load curves, are employed for identifying both the elastic modulus of beam and the coefficient of friction. The large deflection three-point bending test with frictional force being considered is first analyzed on the basis of the large deflection theory of beam. Then, analytical results which consist of elliptical integrals, are represented by approximated polynomials in order to reduce the calculation cost in the identifying process. Next, an inverse procedure for determining the Young's modulus and the coefficient of friction is described by minimizing the evaluating function which includes unknown parameters. The approach is validated with experimental data using a piece of piano wire and an acrylic square bar. It is found that the present results showed good agreement with the values which are already known from the other experimental studies.