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Materials Assignement 5 Attempt 3

# Materials Assignement 5 Attempt 3 - WebCT Quiz Homepage...

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WebCT Quiz Homepage http://webct.mcmaster.ca/SCRIPT/MATLS_1M03_T2_06_newRestore/s... 1 of 4 25/03/2006 4:16 AM View Results Assignment 5 (Ch 8 & 9) Name: BRYCE JONES Attempt: 3 / 3 Out of: 9 Started: March 24, 2006 1:05pm Finished: March 24, 2006 1:33pm Time spent: 28 min. 51 sec. Question 1 (1 point) Which kind of fracture is associated with the intergranular crack propagation mechanism? Student response: Correct Response Student Response Answer Choices a. Ductile b. Brittle c. Either ductile or brittle General feedback: Intergranular fractures are brittle in nature, and crack propagation is along grain boundaries . For more information, see the section on Brittle Fracture in the text. Score: 1 / 1 Question 2 (1 point) A structural component in the shape of a flat plate 25.7 mm thick is to be fabricated from a metal alloy for which the yield strength and plane strain fracture toughness values are 507 MPa and 38.0 MPa-m 1/2 , respectively. For this particular geometry, the value of Y is 1.76. Assuming a design stress of 0.384 times the yield strength, calculate the critical length of a surface flaw (in mm). The critical length of a surface flaw is given by Here σ d is the design stress. Use decimal notation, digits after decimal: 2 Student response: 3.91 mm Correct answer: 3.91 mm General feedback: Use the equation given to solve for a c . Remember that σ d = 0.384 * σ y . Score: 1 / 1 Question 3 (1 point) A large plate is fabricated from an alloy that has a plane strain fracture toughness of 57.9 MPa-m 1/2 . While it is in service the plate is exposed to a tensile stress of 216 MPa. The value of Y for the plate is 1.3. Determine the minimum length of a surface crack (in mm) that will cause the plate to fracture. Use decimal notation, digits after decimal: 1 Student response: 13.5 mm Correct answer: 13.5 mm General feedback: The minimum surface crack length that will cause the plate to fail is given by: For more information, see the section on Fracture Toughness in the text. Score: 1 / 1 Question 4 (1 point) A fatigue test was conducted in which the mean stress was 32 MPa and the stress amplitude was 176 MPa. Calculate the maximum stress level (in MPa). Use decimal notation, digits after decimal: 0 Student response: 208 MPa Correct answer: 208 MPa General feedback: See section 8.7 Cyclic Stresses in the text for more information. Score: 1 / 1 Question 5 (1 point)

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WebCT Quiz Homepage http://webct.mcmaster.ca/SCRIPT/MATLS_1M03_T2_06_newRestore/s... 2 of 4 25/03/2006 4:16 AM Which phase fields does the liquidus line separate? Student response: Correct Response Student Response Answer Choices
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Materials Assignement 5 Attempt 3 - WebCT Quiz Homepage...

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