ENGR 244 Lab 2.docx

Lab Report 2 Tension Test On Metals ENGR 244 Lab Section CI - X Winter 2022 Professor Ahmed Soliman Concordia University Montreal, QC, Canada Tuesday, January 18 th , 2022

Objective: The purpose of this experiment is to gather more information about the strength and ductility of steel and aluminum. Introduction: The strength of a metal can be seen in many ways. Last lab, we tested the Brinell hardness of aluminum and steel which shows the metals resistance to permanent indentation. Following up the tests on aluminum and steel we have the tension test to measure the tensile strength, the metals’ ability to stretch. Much like the Brinell Hardness test, this test allows us to see which metal will better suit anything that we are designing based off the tensile loading. It will allow us to know if there would be permanent elongation, the thickness of the metal required for the load desired, the elasticity of the metal (how much stretching motion you have without permanent elongation), and the load the metal can take before failing. The only assumption made this lab was that both metals would reach their yield strengths at approximately 5000N which is why the scaling (see below in procedure) will change at that time to get more detailed results. Procedure: Measure the diameters of both your 100mm aluminum and 100mm steel rods using the vernier provided and record them. Place one of the rods into the deformation measuring device and make sure it is placed tightly so it cannot move. Reset the digital load reader and begin applying the load. Add 500N and record the corresponding length of deformation. Continue this step until you reach 5000N. Once you reach 5000N continue by adding only 200N of pressure until you reach a point where the deformation is much higher than before for a smaller load. After this point, take measurements based on the length of deformation (0.5mm and 0.25mm for aluminum and steel respectively). Continue this until the metal rod reaches failure and then record the maximum load recorded by the digital scale. Remove the two pieces of the fractured metal rod and record the final deformation by placing the two pieces together on the V groove device provided. Also record the diameter of the fracture section using the caliper provided.

Results: These are the numbers recorded while performing the experiment.

Figure 1: Steel test results Figure 2: Aluminum test results

Sample Calculations Formulas used: σ = P(N)/A(mm 2 ) where σ is stress and A = (π/4)(d 2 ), ε = δ/L where ε is strain, δ is the change in length and L is the original length, %A reduc = (A final -A initial )/A initial , %Elongation = (L final -L initial )/L initial , E = σ/ε where E is the modulus of elasticity, ultimate strength = σ max /A initial , true fracture stress = FractureForce(N)/A final Legend: P(N) is the load in newtons D is the initial diameter of the gauge Fracture Force is the load, in newtons, when the gauge breaks ε(mm/mm) 0.0031 0.0035 0.00 39 0.00 43 0.0047 0.0049 0.0053 0.0056 0.00 6 0.00 68 0.00 74 0.00 99 0.019 0.02 52 0.0305 0.0337 0 100 200 300 400 500 600 Stress vs Strain of Steel σ(Mpa) Strain ε Stress σ Figure 3: Stress vs strain graph of steel Yield strength ~ 400MPa Proportional limit ~ 550MPa

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