Matsci Lab2 - Title: Determination of the Tensile...

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Title: Determination of the Tensile Properties. Purpose : Test and compare metal, polymer, and polymer composite materials for tensile strength. Procedure: For each sample, make 2 marks at opposing ends of the gauge section and measure the distance between the two marks (using metric measurements). Measure the gauge width and thickness for each sample. Use this to determine the best area calculation. Insert each tension sample into the Instron test machine and commence the test. Save the stress-strain curves for plotting at the end of all tests. Measure the final dimensions at the failure Measurements: Pure LDPE LDPE w/ Glass Fiber LDPE w/ Glass Bubble L 0 / L 1 (mm) 43.38 51.16 44.35 45.53 43.79 44.13 Thickness (before and after in mm) 4.69 3.20 4.22 2.89 4.30 3.89 Width (before and after in mm) 6.52 6.22 7.36 7.10 7.25 6.99
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Discussion: Of the materials we tested, the best material for building or other heavy duty use would be the brass. This is because it can withstand the most stress before fracturing. Due to brass’s metallic bonding, brass has a very strong structure and some elastic properties. The
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atomic structure can be seen as a sea of electrons in which positively charged cores are moved around during stress. Because of this, the positively charged cores can move around freely to a degree without fracture and still maintain a strong overall structure. The best material for something that needs to be flexible and strong while being light is the LDPE. LDPE is made up of many polymer strands that interact with each other, which gives LDPE a flexible property. Under stress, the polymer strands are straightened and the resistance to stress increases since now the force has to break the bonds within each polymer. 1. Calculate a) Calculate the total % elongation: %elongation =100 x (Lf-Lo)/Lo LDPE: 100 * (51.16-43.48)/43.48 = 17.66% LDPE glass fiber: 100 * (45.52-44.35)/44.35 = 2.64% LDPE glass bubble: 100 * (44.13-43.79)/43.79 = .78% b) Estimate the final cross sectional area at failure. Calculate the % Reduction in Area:
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This note was uploaded on 06/02/2008 for the course MSE 27100 taught by Professor Bockstaller during the Spring '07 term at Carnegie Mellon.

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Matsci Lab2 - Title: Determination of the Tensile...

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