1M03 2009 ASSIGNMENT 5-3 ¿¯

1M03 2009 ASSIGNMENT 5-3 ¿¯ - View

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View Results Name: SOO NAM Attempt: 3 / 3 Out of: 15 Started: March 24, 2009 2:02pm Finished: March 24, 2009 2:53pm Time spent: 50 min. 50 sec. Question 1 (1 point) How is the plane strain fracture toughness of a metal expected to change with rising temperature? Student response: Correct Response Student Response Answer Choices a. Increase b. Decrease c. Remain constant General feedback: The magnitude of the plane strain fracture toughness, K I c , increases with rising temperature. For more information, see the section on Fracture Toughness in the text. Score: 1 / 1 Question 2 (1 point) A structural component is fabricated from an alloy that has a plane strain fracture toughness of 31.6 MPa-m 1/2 . It has been determined that this component fails at a stress of 186 MPa when the maximum length of a surface crack is 1.11 mm. What is the maximum allowable surface crack length without fracture for this same component that is made from another alloy that has a plane strain fracture toughness of 58.1 MPa-m 1/2 ? The components will all be subject to the same amount of stress while in use. Use decimal notation, digits after decimal: 2 Student response: 3.75 mm Correct answer: 3.75 mm General feedback: Recall that Y is dependent on specimen sizes and geometries, so for a structural component this would be constant, even if it was made out of a different material. The components will all experience the same amount of stress while in use, so the applied stress will not exceed 186 MPa in the second alloy. Use equation 8.5 to solve for Y, and then equation 8.7 to find the maximum allowable crack length in the second component. Score:
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This note was uploaded on 04/04/2011 for the course MATLS 1M03 taught by Professor Okon during the Spring '09 term at McMaster University.

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1M03 2009 ASSIGNMENT 5-3 ¿¯ - View

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