1. A method for measuring and calculating elongation to failure on a tensile specimen, the method comprising: providing a tensile specimen having gage markings at predetermined intervals; tensile testing the specimen to failure, the specimen after failure having a fracture; measuring locations of the gage markings and fracture relative to a minimum diameter, the minimum diameter comprising a location on the specimen having the smallest diameter; measuring diameters of the specimen at the gage markings, the fracture and the minimum diameter; determining local elongation as a function of location on the specimen; determining end point elongation values at zero and at infinite locations; and determining from the elongation and end point elongation values a value of elongation for modeling plastic deformation of a device made of the same material as the specimen.