Explain stress-strain relationship graphically (Behavior ofmetallic wire)?

The relationship between the stress and strain that a particular material displays is known as that particular material`s Stress-Strain curve. It is unique for each material and is found by recording the amount of deformation (strain) at distinct intervals of tensile or compressive loading (stress). These curves reveal many of the properties of a material (including data to establish the Modulus of Elasticity, E).[1] Stress–strain curves of various materials vary widely, and different tensile tests conducted on the same material yield different results, depending upon the temperature of the specimen and the speed of the loading. It is possible, however, to distinguish some common characteristics among the stress-strain curves of various groups of materials and, on this basis, to divide materials into two broad categories; namely, the ductile materials and the brittle materials.[2] Consider a bar of cross sectional area A being subjected to equal and opposite forces F pulling at the ends. If this were a rope, we would say that it is experiencing a tension force. Taking this concept over, we say that the bar is under tension, and is experiencing a stress that we define to be the ratio of the force to the cross sectional area: Stress = F/A This stress is called the tensile stress because every part of the object is subjected to a tension. The SI unit of stress is the Newton per square meter, which is called the Pascal. 1 Pascal = 1 Pa = 1 N/m2 Shear Stress and Strain Now consider a force that is applied tangentially to an object The ratio of the shearing force to the area A is called the shear stress If the object is twisted through an angle q, then the strain is Shear Strain = tan q Finally, we can define the shear modulus, MS, as The shear modulus is also known as the torsion modulus