Lab1 - Introduction Tensile specimens of Cast Iron Steel 1045 Aluminum 6061 Stainless Steel 304 and PMMA will be tested by putting them under a

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Introduction Tensile specimens of Cast Iron, Steel 1045, Aluminum 6061, Stainless Steel 304 and PMMA will be tested by putting them under a uniaxial tensile loading. By testing the afore mentioned specimens in tension, useful mechanical as well as deformation and failure properties may be obtained. The tension tests will be able to determine the modulus of elasticity (E), yield strength ( y σ ), ultimate strength ( u ), and fracture strength ( f ). These material properties occur in materials used every day by the general public and therefore come into play quite often in many engineering problems. Other properties that will be looked at and compared between materials are percent elongation, percent of reduction in area, as well as the different types of fractures in both ductile and brittle materials. Procedure Tensile specimens of Cast Iron, Steel 1045, Aluminum 6061, and Stainless Steel 304 are tested using a Rockwell Hardness tester (the PMMA sample is not tested due to the fact that it is so soft the specimen will become damaged). Three hardness measurements are made and the average is taken. Round tensile specimens are used that taper in the center portion known as the gauge. The thicker ends are called the grips. The grip diameter is measured once and the gauge diameter is measured three times and averaged. After the hardness test each specimen is loaded into the bottom grip of the Instron model 4400 load frame, the top grip is then lowered down until the specimen is centered in the machine. Next, the extensometer is then put onto the middle of the gauge of the specimen. After the strain indicator is set to zero and the initial cross-head position is recorded by the machine, control is handed over to a computer which will take and record, load, time, position and strain data. The test commences and the specimen is put under a tensile load until failure. After the specimen fails the final diameter at the rupture point is measured and the rupture surface is recorded. Results After all of the data is collected from the tensile testing it can be analyzed from the website. The data must be put into an excel spreadsheet in order to make the engineering stress vs. strain graph. The engineering stress is calculated by dividing the load data recorded by the computer by the initial area obtained from the initial diameter. Once the stress versus strain graph is obtained the modulus of elasticity, the yield strength, and the ultimate strength can be calculated from the graphs. While the percent elongation is the final non- erroneous strain data point read by the computer, the percent reduction of area can be calculated by the following formula: % 100 % 0 0 × - = A A A RA f (1) The modulus of elasticity can be calculated by measuring the slope of the linear region of the stress vs. strain curve. However due to the fact that cast iron acts in a non-linear fashion, the secant modulus had to be taken in order to estimate the modulus of elasticity. The secant modulus is the slope of the
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This note was uploaded on 04/20/2008 for the course GE 312 taught by Professor Reis during the Spring '06 term at University of Illinois at Urbana–Champaign.

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Lab1 - Introduction Tensile specimens of Cast Iron Steel 1045 Aluminum 6061 Stainless Steel 304 and PMMA will be tested by putting them under a

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