Estimation of nonlinear parameters applying uniaxial and shear stress to inhomogeneous viscoelastic media

Abstract

Static shear deformations of a plane-parallel layers of several viscoelastic media created simultaneously with the uniaxial compression are considered. Each layer is fixed between two rigid plates. Displacement of one plate relative to the other resulted in shear strain of the layer. This strain could reach 0.6 of the layer thickness. At such strain, effects due to the cubic nonlinearity arise. It is shown that measuring the dependence of the shear stress on the shear strain along one axis at different compression along the perpendicular axis one could determine nonlinear Landau parameters. The measurements were performed in layers of plastisol, gelatin, and farina-gelatin of 7 mm thickness with a rectangular base 8.9 × 8.9 cm, mounted between three aluminum plates. The upper plate was loaded with masses ranging from 0 to 25 kg and was fixed in each series of the stress-strain measurements. The values of the Landau coefficient A were measured in layers with different value of linear shear modulus. The different behavior of stress-strain curves was observed for media with different composition. [Work supported by the Russian Foundation for Basic Research (Grant Nos. 12-02-00114 and 12-02-31418), and grant of the Government of the Russian Federation 11.G34.31.0066.]