DESIGN OF METHOD FOR NONLINEAR SHEAR MODULUS MEASURING IN GEL-LIKE MEDIUM BY APPLYING AN ADDITIONAL STATIC STRESS TO AN ACOUSTIC RESONATOR

Measurements of the nonlinear parameter of a gel-like medium were carried out in an acoustical resonator fixed without slipping between two solid-state boundaries. A sample of thickness L is fixed on an oscillating plate (x = 0). The other plate of finite mass on the free surface of the sample (x = L) moves together with this surface. By changing the mass of the plate (x = L), it is possible to achieve additional static deformation of the resonator up to 65%. The dynamic method assumes measuring resonance curves at various static deformations. Nonlinear properties appear at deformations of more than 20%. The nonlinear parameter and shear modulus measured dynamically were compared to static measurements where the dependence becomes nonlinear at strains greater than 30%. The static values of the shear modulus and the nonlinear parameter correspond to the values obtained in the dynamic method within an error.