To Determine Yield Strength & Tensile Strength of a Steel Bar
UTM, Test Specimen, Vernier Calipers, Ruler etc.
A machine designed to perform tensile, compression, bend and shear tests, is called UTM,. It mainly consists of two parts.
Gauge length = 8 inch
Determine the yield strength by the following methods.
To determine the yield strength by the this method, it is necessary to secure data (autographic or numerical) from which a stress-strain diagram with a distinct modulus characteristic of the material being tested may be drawn. Then on the stress-strain diagram, lay off om equal to the specified value of the offset (i.e. yield strength ~0.2%), draw mn parallel to OA, and thus locate r, the intersection of mn with the stress-strain curve corresponding to load R, which is the yield strength load. In recording values of yield strength obtained by this method, the value of offset specified or used, or both, shall be stated in parentheses after the term yield strength.
Figure - Stress-strain diagram for the determination of yield strength by the offset method.
This method is also referred as the tangent, secant or chord modulus for the line drawn from the shear stress-shear strain curve at 5% (1/20) and 33% (1/3) of the maximum compressive shear stress. This region usually lies well within reasonably linear part of the curve. Lower part of the curve, representing a straight region being associated with closing up the interfaces between mortar and units is ignored, as they normally close up due to self weight in real structures. Calculations for Ec are as follows.
Ec = ∆ Shear Stress / ∆Shear Strain
∆ Shear Stress = (Shear stress corresponding to 1/3 of the compressive strength) - (Shear stress corresponding to 1/20 of the compressive strength)
∆ Shear Strain = Difference of the Shear strain at corresponding values of Shear stress.
Elongation = 9.8 – 8 = 1.9
Bend Test on Steel Bar
Reaction in Simply Supported Beam
Deflection in Overhanging Beam