Young’s Modulus Testing or modulus of elasticity testing is a measurement of the rate of change of strain as a function of stress. It represents the slope of the straight-line portion of a stress-strain curve. With respect to tensile testing, it may be referred to as Tensile Modulus. This method of testing is used to determine a sample’s behavior under an axial stretching load. Young’s Modulus is reported commonly as N/mm2 (lbs/in2), MPA (psi).