Formation of divergent testing efforts and experimental evaluation of material strength under biaxial stretching

A method for forming multidirectional testing efforts during the mechanical testing of laboratory samples using the typical one-driving testing machine is suggested here. In the proposed method, this system of forces acting on the sample is created by the inclined faces of the sample and the resulting contact reactions on them when it interacts with parallel support having appropriate ramps. The authors consider the scheme of supporting and the loading of the prismatic sample which implements the considered formation of the test efforts. The justification of choice of angles of the sample inclined faces based on the numerical simulation of model deformation using the numerical finite element method apparatus and solving the contact problem of deformable solids is provided here. Recommendations for using optimum angles of inclination of the supporting surface for creating circuitry biaxial stretching have been given. The results of computational analysis of VAT prismatic samples depending on its basic geometric parameters are described here. The testing of the proposed models is described in determining the strength parameters of spring-tempered spring steel 50HFA located in a biaxial stretching. The analysis of the results obtained by the destruction of the samples is based on the limit state equation of Pisarenko-Lebedev. The determination of these parameters is based on the numerical analysis of VAT tested series of samples at the time of their destruction. The analysis includes consideration of the nature of the contact interaction of the sample with the support elements and the possible occurrence of plastic deformation in the sample. It became possible to present the experimental evaluation of reducing the limit value of the first principal stress in the hearth of destruction of samples of steel 50HFA under biaxial stretching compared to uniaxial tension.