The tensile test, as known as the”tension test”,is one of a most fundamental type of mechanical test that used on a material.Tensile test is really inexpensive which makes this test more preferable. From tensile test, how thematerial will react to forces being applied in tension can be determined. Asthe material is pulled by machine, material’s strength can be found along itselongation.From the stress-strain curveof the tensile test, the values which can be found are Modulus of Elasticity,Yield Strength, the Tensile Strength, Percentage of Elongation and theReduction in Area. Also the Toughness, Resilience, Poisson’s ratio can be foundby using the tensile test. In the report, these valueswill be found by doing the calculations and in the Results and Discussion partof the report, these calculations will be explained and discussed. Thisexperiment is made with two different specimens.
(one is made from aluminum andthe other is made from steel) Specimen’sraw material = Aluminum Specimen’s raw material = SteelDiameter ofspecimen = 12 mm Diameter of specimen = 15 mmGage length= 59 mm Gage length = 84 mmFinal Gagelength = 69 mm Final Gage length= 95 mm After fracture : Max.load =39.56276(kN) Max.
load = 86.94378 (kN)Max.stress = 349.8033 (MPa) Max stress = 492(MPa) ?Theory of Experiment Formulas That Will Be Used in Lab Report Engineering Stress ?= P/A0 Engineering stress can be found by dividing the AppliedForce to Cross Sectional area of the specimen before the deformation has takenplace. True Stress?T =P/A True stress can be found by dividing the AppliedForce to Cross Sectional area of the specimen at the point which the load is applied. Engineering Strain ? = ? / L0 Engineering strain can be found by dividing theTotal Elongation to Original value of the gage length. TrueStrain L ?T = ?(1/L)dL = ln(L/L0) L0 True strain can be found by taking the integral of(1/(Changed value of gage length)) which is equal to ln((Changed value of gagelength)/(Original value of the gage length)).
Hooke’s Law? = Normal Stress? = ? * E ? = NormalStrain E = Modulus of Elasticity(Young’sModulus) Yield Point In order to find the yield point, take the load at the point wherestrain is (0.2%) divided by the cross-sectional area. Ductility Ductility is ability ofmaterial that undergoes permanent deformation (through the reduction in crosssection area) by flexing or twisting at room temperature without fracturing. Gage LengthDistance along the specimenthat the calculations of extension are made is called ”gage length”. Sometimes,distance between the grips are taken as gage length.Difference Between Engineeringand True Stress/Strain True stress and strain are often not required. When the yieldstrength is surpassed, the material deforms. The component hasfailed because it doesn’t have the original intended shape anymore.
Furthermore, a significant difference develops between the two curves only when necking begins.But when the necking begins, the component is extremely deformed and no longersupplies its expected use. In the graph, true stress continues increasing after necking,although the load requireddecreases, the area decreases even and even more. ToolsUsed in Experiment Aluminum SteelSpecimen Specimen Caliper Instron Load?Procedure of Experiment To determine the gage lengthand the diameter of the cross section of aluminum specimen, the aluminumspecimen was measured with the caliper. The diameter of the aluminum specimenwas determined (12.00 mm), the gage length of it was determined (59.00 mm) andscribed into the specimen in order to measure the distance between the two marksafter the tensile test was completed. After that, same measurements are madefor the steel specimen and the gage length was determined (84.
00 mm), thediameter was determined (15.00 mm). To space the specimen equally between the twoclamps, the specimen got loaded to Instron load frame’s jaws. The extensometerswere fitted to the reduced gage section of the specimen, providing that theaxial extensometer was set correctly when attaching it to the gage and that thetransverse extensometer was attached to complete the diameter of specimen.
The Instron load frame was loadedby using the scroll wheel to provide that the specimen was accurately loaded intothe frame and ensured that it wasn’t slipping in the jaws. After that, by usingthe software, load was released so that the extensometers were zeroed. The testgot started and the specimen was loaded, resulting in a mensureable strain.
This increase in the rate of strain may caused some error but this increasesped up the test.