Also, tension test is considered as an acceptance test for the specification of materials. Provision of basic design information on materials strength is the purpose of conduction of tension test. The tension test would be the most common type of test incorporated in measurement of the mechanical properties of materials. Consequently, a number of experimental techniques have been developed by engineers for the purpose of mechanical testing of engineering materials subjected to tension, compression, bending or torsion loading. Once a material is meant to be applied within an engineering structure that will be subject to loading, it must be guaranteed that the material possesses enough strength and rigidity to withstand the loads it will experience in its service life. The significant role of the mechanical properties in evaluation of the fundamental properties of engineering materials along with development of new materials and also quality control of materials for application in design and construction cannot be neglected. Also, it is concluded that the maximum true stress values are almost 15% higher than that of the maximum engineering stress values while the maximum true strain failure values are 1.5% smaller than the maximum engineering strain failure values. The results indicate that the properties of steel materials are independent from their thickness and they generally yield and fail at the same stress and strain values.

For the purpose of achieving this aim, evaluation of values such as ultimate tensile strength, yield strength, percentage of elongation and area reduction, fracture strain and Young's Modulus was done once the specimens were subjected to uniaxial tensile loading. Investigation of the engineering and true Stress-strain relationships of three specimens in conformance with ASTM E 8 – 04 is the aim of this paper. Its main objective would be to determine the properties relevant to the elastic design of machines and structures. The most commonly accepted method in evaluation of the mechanical properties of metals would be the tension test.

Engineering stress vs true stress pdf