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MATLS 1M03 - WebCT - Assignment 5 - Try 3

# MATLS 1M03 - WebCT - Assignment 5 - Try 3 - WebCT Quiz...

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WebCT Quiz Homepage http://webct.mcmaster.ca/SCRIPT/MATLS_1M03_T2_07/scripts/student... 1 of 6 3/24/2007 12:28 AM View Results Assignment 5 (Ch 8 & 9) Name: AARON MURENBEELD Attempt: 3 / 3 Out of: 11 Started: March 24, 2007 12:06am Finished: March 24, 2007 12:27am Time spent: 20 min. 44 sec. Question 1 (1 point) Which kind of fracture is associated with the transgranular crack propagation mechanism? Student response: Correct Response Student Response Answer Choices a. Ductile b. Brittle c. Either ductile or brittle General feedback: Transgranular fractures are brittle in nature, and crack propagation is through the grains. For more information, see the section on Brittle Fracture in the text. Score: 1 / 1 Question 2 (1 point) Suppose that a mechanical component on an aircraft is fabricated from an alloy that has a plane-strain fracture toughness of 42.0 MPa-m 1/2 . It has been determined that fracture results at a stress of 106 MPa when the maximum (or critical) internal crack length is 8.10 mm. For this same component and alloy, what is the maximum allowable stress level (in MPa) when the critical internal crack length is 5.93 mm? Use decimal notation, digits after decimal: 0 Student response: 124 MPa Correct answer: 124 MPa General feedback: Use equation 8.5 in the text to solve for the parameter Y. Then use the same equation to solve for σ with a new crack length. Assume Y and K Ic remain constant. Score: 1 / 1 Question 3 (1 point) Suppose that a wing component on an aircraft is fabricated from an aluminum alloy that has a plane-strain fracture toughness of 26 MPa-m 1/2 . It has been determined that the wing component will fracture when a stress of 112 MPa is applied and the maximum (or critical) internal crack length is 8.6 mm. Will the wing component fracture when 125 MPa is applied to it and the critical internal crack length is 6.0 mm?

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MATLS 1M03 - WebCT - Assignment 5 - Try 3 - WebCT Quiz...

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