Materials Assignement 5 Attempt 1

# Materials Assignement 5 Attempt 1 - WebCT Quiz Homepage...

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WebCT Quiz Homepage http://webct.mcmaster.ca/SCRIPT/MATLS_1M03_T2_06_newRestore/s. .. 1 of 5 21/03/2006 11:24 PM View Results Name: BRYCE JONES Attempt: 1 / 3 Out of: 9 Started: March 21, 2006 3:44pm Finished: March 21, 2006 11:21pm Time spent: 7 hr, 36 min., 37 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) Estimate the maximum stress (in MPa) experienced in a brittle material if it is known that fracture occurs by the propagation of an elliptically shaped surface crack of length 0.179 mm and tip radius of curvature of 8.12 x10 -3 mm when a tensile stress of 87.1 MPa is applied. Use decimal notation, digits after decimal: 0 Student response: 818 MPa Correct answer: 818 MPa General feedback: See equation 8.1 in the text. Score: 1 / 1 Question 3 (1 point) Suppose that a mechanical component on an aircraft is fabricated from an alloy that has a plane-strain fracture toughness of 45.4 MPa-m 1/2 . It has been determined that fracture results at a stress of 104 MPa when the maximum (or critical) internal crack length is 7.53 mm. For this same component and alloy, what is the maximum allowable stress level (in MPa) when the critical internal crack length is 5.46 mm? Use decimal notation, digits after decimal: 0

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Materials Assignement 5 Attempt 1 - WebCT Quiz Homepage...

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