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  1. 1. Title: The Tensile test Objective: • To become familiar with tensile testing system • To learn how to develop stress-strain curve from load-displacement curvefor materials • To learn how to extract important material properties from these curvesuch as engineering stress, strain, yield stress, percentage of elongation…etc Introduction: In order to compare and select materials for various applications, one musthave access to the important properties of that material i.e. material constant.On e o f t h e mo s t o f t e n u s e d t e s t s p e r f o rme d t o d e t e rmi n e a n umb e r o f imp o r t a n t me c h a n i c a l p r o p e r t i e s o f ma t e r i a l i s t e n s i l e t e s t . Th i s t e s t i s conducted to specimens that have uniform horizontal cross section in theUniversal Testing Machine that can show the load applied for any elongationthat is obtained from the gauge lengthBased on the load and displacement obtained from the experiment, we canget:(a)Engineering tensile stress,ε = F/A o (N/mm²)(b) Strain,ε = L 1 – L o / L o (c) Yield stress,σ y = Yield load / initial cross-sectional area (N / mm²)(d) Ultimate tensile stress,σ m = Maximum load / initial cross-sectional area (N / mm²)(e) Elongation percentage,%EL = (L 1 – L o / L o ) × 100 (%) (f)Reduction percentage in area(%) = (A o – A 1 / A o ) × 100Where:F = Load (N)A
  2. 2. o = Initial horizontal cross- sectional area, (mm²)A 1 = Final horizontal cross- sectional area, (mm²)L o = Initial gauge length, (mm)L 1 = Final gauge length, (mm)Yield load and maximum load can be obtained from the load-displacementcurve produced from each experiment is( 1 ) M i l d S t e e l F y = Yield load, (N)F m = Maximum load, (N)F p = Load at break, (N) Displacement (mm)FyFpFmLoad (N)
  3. 3. (2) For aluminium alloys or specimen that does not have certain yield load, itcan be obtained with “offset strain 0.2 % method” and known as ‘pruf stress’.F m = Maximum load (N)F p = Load at break (N)F 0.2% = pruf stress Specimen: • Mild Steel • Aluminiun Alloy Apparatus:
  4. 4. Universal testing Machine Procedure: (a)The diameter and gauge length for all the specimen provided is taken (b) The specimen is installed inside the testing machine and load is addedlittle by little until the specimen break, Value of the load applied andelongation is recorded F 0.2% F p F m Displacement (mm)Load (N)