MENG_3331_Lab_2_individual_report

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Executive Summary Department of Mechanical Engineering Aug.24, 2021, Statesboro, Georgia, USA 1 Copyright © 2023 by ASME TENSILE TESTING ON BRASS Lawrence Almeter Group 5 Objective The objective of this experiment is to find the stress-strain curve, ultimate tensile strength, Young’s Modulus, yield strength, and percent elongation of a brass tensile testing coupon. These values can be solved using the load and displacement over time data given by the tensile testing machine as well as the dimensions of our sample. Brief Introduction/Theory The modern UTM or universal testing machine was not formally developed until the 19 th century. However, Robert Hooke, who discovered Hooke’s law or the law of Elasticity, put forth many efforts during the 17 th century for testing the properties of materials. [1] Stress is equal to force over the cross-sectional area. Strain is equal to the length of deformation over the original length of the deformed material. The stress-strain curve is used to graphically represent the overall performance that the material exhibits while under load, and it allows many different mechanical properties of materials to be found easily. [2] Method/Procedure Start by turning on the material testing machine and starting the data collection software. Select the Gauge + ESM 303 with Travel configuration and open the setup file MENG 3331 Tensile. After setting up the machine and software, prepare the sample. Draw two lines centered on the sample 2” apart along the width of the sample. Measure the distance again three times and record the average and standard deviation for better data. Measure the width and thickness three times and record the average and standard deviation. With the sample prepared, it can be put in the testing machine. Place the sample in the lower grip and then adjust the upper grip till it is at the height of the two lines drawn previously. Adjust the upper grip as close to zero travel as possible. Click start on the software and wait till the sample fails. Data& Results The sample dimensions were 0.160in or 4.056mm in width, 0.003in or 0.076mm in thickness, 2.567in or 65.21mm in gauge length, and the cross-sectional area was 0.12in 2 or 0.309mm 2 . These values are found in Table 1. The data given by the machine over 108.4 seconds showed the max load applied to the sample was 31.7lbf, and the max displacement in the brass was 0.901in or 22.8854mm. The max force calculated was 141.00N. The max stress was 456.269MPa, and the max strain was 0.3509mm/mm. These values are found in Table 2. Discussion Most of our results compared neatly to the known values. Our calculated cross-sectional area of 0.309mm 2 was close to the known 0.303mm 2 . The known tensile max tensile strength of brass is 430 MPa and our value is close at 458 MPa. Our estimation of elongation percent was 35% which is off from the known value of 25%. This is partially due to calculating it by converting the max strain into a percent which is not highly accurate, but it is a rough estimation. Our calculated Modulus of Elasticity was 41.18 GPa which was far off from the known 117 GPa. This could be due to defects in the material, improper placement in the testing machine, or even a bad estimation of the slope [Figure 2]. Performing more tests could give more consistent data and remove many outliers. Conclusion These are the calculated values for the brass testing material. The Young’s Modulus is 41.14 GPa. The Yield Strength is 300 MPa. The Ultimate Tensile Strength is 458 MPa. The percent elongation is 35%. These values are found in Table 4. Lab Questions 1. The upper yield strength of the 1004 steel is approximately 380 MPa and the lower yield strength is approximately 360 MPa. 2. Copper has a higher ductility since it has a larger strain value. 3. The 1020 steel has a higher toughness since the area under its curve is larger than the area under the 1004 steel curve.

Executive Summary Department of Mechanical Engineering Aug.24, 2021, Statesboro, Georgia, USA 2 Copyright © 2023 by ASME Support Materials Data Table 1 summarizes the measurements taken on the brass testing material. Table 2 shows the data given by the testing machine as well as converted and calculated values used to find our resulting values. Due to the vast number of data points, only the first and last ten data points are shown in Table 2. Table 3 contains two data points that are used to solve the slope which is the Young’s Modulus. Table 4 contains the results and values of the experiment. Table 1. Measurements T [in] T [mm] W [in] W [mm] A [in 2 ] A [mm 2 ] GL [in] GL [mm] 0.003 0.0762 0.161 4.0894 0.0123 0.3116 2.5 63.5 0.003 0.0762 0.16 4.064 0.0122 0.3097 2.622 66.5988 0.003 0.0762 0.158 4.0132 0.0120 0.3058 2.58 65.532 Avg 0.003 0.076 0.160 4.056 0.012 0.309 2.567 65.210 StdD 0 0 0.0015 0.0388 0.0001 0.0030 0.0620 1.5743 Table 2. Testing Data and Calculations Load [lbF] Disp [in] Disp [mm] t [s] F [N] σ [MPa] ε [mm/mm] 0.6000 0.0010 0.0254 0.4000 2.6688 8.6360 0.0004 3.0000 0.0030 0.0762 0.6000 13.3440 43.1800 0.0012 4.9000 0.0040 0.1016 0.8000 21.7952 70.5274 0.0016 6.9000 0.0060 0.1524 1.0000 30.6912 99.3141 0.0023 8.9000 0.0070 0.1778 1.2000 39.5872 128.1008 0.0027 10.5000 0.0090 0.2286 1.4000 46.7040 151.1302 0.0035 12.3000 0.0110 0.2794 1.6000 54.7104 177.0382 0.0043 14.2000 0.0120 0.3048 1.8000 63.1616 204.3855 0.0047 15.8000 0.0140 0.3556 2.0000 70.2784 227.4149 0.0055 17.3000 0.0160 0.4064 2.2000 76.9504 249.0049 0.0062 31.7000 0.8860 22.5044 106.6000 141.0016 456.2691 0.3451 31.7000 0.8870 22.5298 106.8000 141.0016 456.2691 0.3455 31.7000 0.8890 22.5806 107.0000 141.0016 456.2691 0.3463 31.8000 0.8900 22.6060 107.2000 141.4464 457.7085 0.3467 31.8000 0.8920 22.6568 107.4000 141.4464 457.7085 0.3474 31.8000 0.8940 22.7076 107.6000 141.4464 457.7085 0.3482 31.8000 0.8960 22.7584 107.8000 141.4464 457.7085 0.3490 31.8000 0.8970 22.7838 108.0000 141.4464 457.7085 0.3494 31.7000 0.8990 22.8346 108.2000 141.0016 456.2691 0.3502 0.0000 0.9010 22.8854 108.4000 0.0000 0.0000 0.3509 Detail Results Table 3. Calculation of Slope (Young’s Modulus) x y Point 1 0.0012 43.1800 Point 2 0.0066 267.7163 Slope 41175.668 Table 4. Calculations UTS [MPa] 458 %EL 35 Young's Modulus [MPa] 41176 Young's Modulus [GPa] 41.18 Yield Strength [MPa] 300 Stress is defined as force applied over a cross-sectional area (see equation 1). Strain is defined as the ratio of the length of deformation and original length (see equation 2). Stress and strain are both calculated in Table 2. Figure 1 describes the relationship between the calculated stress and strain. Figure 2 shows a closer view of the elastic region and the linear approximation of the slop (modulus of elasticity) as well as the yield strength. Figure 1. Stress over Strain for Brass Figure 2. Yield Strength and Young’s Modulus 𝜎 = ி௢௥௖௘ ஺௥௘௔ = ி[ே] ஺[௠௠ మ ] = 𝑆𝑡𝑟𝑒𝑠𝑠 [𝑀𝑃𝑎] - Equation 1 𝜀 = ஽௘௙௢௥௠௔௧௜௢௡ ை௥௜௚௜௡௔௟ ௟௘௡௚௧௛ = ௱௅ ௅ బ = 𝑆𝑡𝑟𝑎𝑖𝑛 - Equation 2 0 100 200 300 400 500 0.00 0.10 0.20 0.30 0.40 Stress [MPa] Strain [mm/mm] Brass… 0 100 200 300 400 500 0.000 0.005 0.010 0.015 0.020 Stress [MPa] Strain [mm/mm] Brass… Yield Strength Slope (Young’s Modulus) 0.2% off set

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