Jaroniek, Mieczysław2017-09-062017-09-062016Mechanics and Mechanical Engineering Vol. 20, No. 4, 2016, str. 467–4881428-1511http://hdl.handle.net/11652/1665A series of experiments was carried out to examine the effects of elastic–plastic deformation on the state of stress and the flow stress mechanism under static tension. The strain distribution determined from the fringe pattern using the Moire method allows one to determine the strain and the crack propagation of not–notched specimens an isotropic and elastic–plastic materials. In the analysis of stress the method of calculating using the bipolar coordinate is proposed. The theoretical model is divided into two elements and the condition of incompressibility is satisfied in each element. The proposed method is compared with the elastic-plastic FEM (ANSYS 12, 14) and it is satisfied approximately. The tensile test is aimed to verify the mathematical model that can be applied in the logarithmic stain in further computations.enstress–strain relationshipbi–polar coordinatesmoir´e methodfinite element methodwspółrzędne biegunowemetoda moir'emetoda elementów skończonychArtykuł