2007 Midterm w sol - Applied Science 278 Midterm...

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Unformatted text preview: Applied Science 278 Midterm Examination - October 17, 2007 1 THE UNIVERSITY OF BRITISH COLUMBIA Department of Materials Engineering APSC 278 Engineering Materials MID-TERM EXAMINATION, October 17, 2007 Name: Student #: This is a closed book examination. Use of relevant material stored in programmable calculators prohibited. Answer all questions. Show all work and units. The complete exam is 7 pages in length Applied Science 278 Midterm Examination - October 17, 2007 2 (4) A standard tensile sample (meeting ASTM standards) with a gauge length of 50 mm was originally used as a demonstration for APSC 279 laboratory. For this sample, the change in length for at the necking point was measured to be 20 mm and the change in length between the necking point and failure was found to be 10 mm. i. calculate a. the percent uniform elongation b. percent total elongation Solution: a) Uniform Elongation (%) = % 40 100 50 20 100 = × = × − l l l neck b) Total Elongation (%) = % 60 100 50 30 100 = × = × − l l l f ii. later in the term, a lack of material led to redesign of the sample such that the gauge length was reduced to 25 mm. Assuming the material was exactly the same, predict the percent total elongation for this test. Solution: To do this problem one needs to appreciate that the change in length up to necking is proportional to the gauge length and the post-necking change in length is independent of l . Thus: Uniform Elongation (%) = % 80 100 25 ) ( 10 10 100 = × + = × Δ + Δ mm mm l l l neck uniform (4) For a load of 250 kN, a cylindrical tensile sample with initial diameter of 20 mm was observed to have a diameter under load of 19.94 mm. have a diameter under load of 19....
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This note was uploaded on 03/28/2012 for the course APSC 278 taught by Professor Poole during the Spring '08 term at The University of British Columbia.

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2007 Midterm w sol - Applied Science 278 Midterm...

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