HYPERELASTIC INDENTATION MODELS AND THE DUAL-INDENTATION METHOD BASED ON ENERGY DENSITY EQUIVALENCE

For the hyperelastic problems of materials under indentation conditions, based on the mean-value energy density equivalence principle, semi-theoretical hyperelastic-material indentation models(SHIM) are proposed to describe the relationship among load, depth, indenter dimension and Mooney-Rivlin constitutive parameters under independent indentation with spherical indenter, flat indenter and conical indenter, respectively, and then the indentation method due to dual indenters(IMDI) is presented. The forward verification shows that, based on a series constitutive relation parameters of hyperelastic materials, the force-depth curves of spherical, conical and flat indentation respectively predicted by SHIM are closely consistent with the FEA results; and the reverse verification shows that, based on the force-depth curves under FEA conditional constitutive relation of a series of hyperelastic materials, the Mooney-Rivlin constitutive relations predicted by the dual indentation experimental method are closely consistent with the FEA conditional constitutive relations. For three hyperelastic rubbers, the spherical, flat and conical indentation tests were carried out, three constitutive relationships of the hyperelastic rubbers obtained by IMDI are all in good agreement with the uniaxial tensile results.