ИСТИНА

Standing shear waves in a resonator in the form of layer of gel-like medium placed between two rigid plates are studied. The bottom plate is fixed to the vibrator and oscillates in the horizontal direction with a preset amplitude. Two rubber threads attached to the upper plate can displace the plate by a specified value in the horizontal direction. The change in the tension of the threads creates an additional static deformation of the elastic layer resulting in the effective shear elasticity increase. The measured static stress-strain dependence of the elastic layer can be described by the cubic parabola. We measured the dependences of the resonance frequency on the static deformation of the layer. For static deformations of the layer less than 0.3 h (h—is the layer thickness) the resonance frequency increases linearly that can be explained by a linear growth of the elastic force of rubber threads. In the deformation range of 0.3-1 h an additional shift of the resonance frequency caused by the nonlinearity of a gel-like medium appears. The method allows the dynamic nonlinear parameter measurement in gel-like media at the low frequency range.