An identification of mechanical properties of soft materials by using indentation test of thin circular plate

抄録

To fabricate soft actuators, it is necessary to know the material constants of soft materials. To determine the material constants of soft materials such as rubber, not only uniaxial tensile tests but also multiaxial tensile tests are required. However, multiaxial testing requires special equipment and is not easy to perform. In this study, we focus on the fact that a biaxial condition can be created by indentation test of a thin soft disk with fixed circumference. An apparatus for indentation of thin disks is constructed using a conventional universal testing machine. Using this apparatus, the indentation shape and indentation load of the disk are measured. Since, the linear theory is not agreement with the measured data, FEM simulation is proceeded. The parameter of energy functions of rubber are identified in order to minimize the square error between the simulated data and the measured data through 138 fitting points by the four kinds of hyperelastic energy functions which are Neo- Hookean, Mooney-Rivlin, Yeoh and Ogden model. The number of the mechanical properties are 1, 2, 4 and 6 respectively. The squarer error is decreasing with the increasing the parameter number. It is confirmed that the parameter of the hyperelastic energy function can be determined by the present method.