# t2f06 - MSE 200 Test #2 Circle the instructor's name ID...

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MSE 200 Test #2 ID Number: Circle the instructor’s name Jag Kasichainula Alexei Gruverman This is a closed book test. No notes, books, or information stored in calculator memories may be used. Cheating will be punished severely. All of your work must be written on these pages and turned in. To receive full or partial credit on problems, you must show your step-by-step calculations starting with the relevant equations. Units must be shown and all plots must have labeled axes. Sketches must be clear and well labeled, and your writing must be legible. Be sure that you read and answer all parts of each question. Equations given in the last page may be used. Show your detailed calculations below each question to get partial credit. Q1. A test bar of aluminum has a diameter of 0.505 inches. Upon applying a tensile load, the sample exhibited 0.002 plastic strain at 1700 lb and the maximum load during testing was 3100 lb; and breaking occurred at 2200 lb. The sample diameter at fracture was measured to be 0.169 inches. (points:10) 1. The yield strength at a strain offset of 0.002 of the material is a. 9493 psi b. 8487 psi c. 16975 psi ( b ) 2. The ultimate tensile strength of the material is a. 16975 psi b. 15477 psi c. 30954 ( b ) 3. The fracture strength of the sample is a. 11000 psi b. 98075 psi c. 138197 psi ( b ) 4. Percent reduction in area at fracture is a. 50% b. 45% c. 89% ( c ) 5. True strain at fracture is a. 0.57 b. 0.64 c. 0.11 ( b ) 6. Draw the stress-strain curve for the aluminum sample described above and, using given parameters and parameters that were calculated above in tasks 1-5, show the following points and segments: elastic and plastic deformation segments of the stress- strain curve, engineering stress-strain curve, true stress-strain curve, yield strength at a strain offset, ultimate tensile strength, engineering stress and true stress at fracture (points:10)

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1/2 has a yield strength of 1200 Mpa. If fracture were to take place at the yield stress, answer the following questions. (points:8) 1. Surface crack size at yielding leading to failure is (Y=1.1) a. 0.411 cm b. 0.994 cm c. 0.249 cm ( a ) 2. If the fracture toughness is increased to 300 Mpa*m 1/2 , what is the stress value in MPa at which failure takes place for the same crack size.
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## This note was uploaded on 03/20/2008 for the course MSE 200 taught by Professor Wholedepartment during the Spring '08 term at N.C. State.

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t2f06 - MSE 200 Test #2 Circle the instructor's name ID...

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