Download JNTUA M.Tech 1st Sem 2018 Aug-Sept 9D15104 Fracture Fatigue And Creep Deformation Question Paper

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Code: 9D15104

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M.Tech I Semester Supplementary Examinations August/September 2018

FRACTURE, FATIGUE & CREEP DEFORMATION

(Machine Design)

(For students admitted in 2013, 2014, 2015 & 2016 only)

Time: 3 hours

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Max. Marks: 60

Answer any FIVE questions

All questions carry equal marks

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1. (a) Define fracture. What are the different modes of fracture failure in materials?
   

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   (b) Explain different modes of crack opening.
2. Explain Griffith's theory and also compare this theory to Irwin-Orwin extension.
3. Explain briefly the ductile/brittle fracture transition temperature for notched and unnotched components.
4. With the help of a neat sketch, explain the process of crack initiation and explain the stages of crack initiation.
5. Determine the value of K1 for the following cases:
   1. Single edge cracked plate under uniform tension a = 15 mm, W = 120 mm subjected to 250 MPa.

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   2. Center-cracked plate under uniform tension; 2a = 30 mm, 2W = 150 mm, subjected to 250 MPa.
6. (a) Discuss in detail the significance and test methods for fracture toughness.
   (b) Explain the effect of metallurgical variables on fatigue properties.
7. Explain the term fatigue cycle. Explain the fatigue crack closure mechanism in metals with suitable sketch.

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8. (a) Explain the role of diffusion in creep deformation.
   (b) Discuss the effect of overload during fatigue crack propagation.

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