On the mathematical description of the tensile stress-strain curves of polycrystalline face centered cubic metals

The stress-strain curves of polycrystalline face centered cubic metals (aluminium, copper, gold, silver and nickel) were measured by an Instron tensile test machine controlled by a computer registering 20 points per second along the load-elongation curve. The large number of measured points makes it possible to perform a detailed analysis of the mathematical structure of the stress-strain curves. General conditions are introduced which must be fulfilled by the functions which approximately describe the whole stress-strain curves. It is shown that the limiting value of a special set of suitable functions in practice describes the stress-strain curves exactly.