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22-Mec-B8 Engineering Materials: December 2017

Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)

  1. Question 1 Magnesium sacrificial anode in a hot water heater
  2. Question 2 Why carbon embrittles high-tensile steel, and how maraging steels avoid it
  3. Question 3 Poisson's ratio for perfectly plastic, constant-volume deformation
  4. Question 4 Replacing 2024-T4 with 7075-T6 on a stretched commercial jet
  5. Question 5 Processing routes for aerospace FRP laminated components
  6. Question 6 Composition of a barium-borate glass-ceramic in weight percent
  7. Question 7 Necking of a ductile wire — Considère's criterion
  8. Question 8 Three aluminium alloys for transport-aircraft floor beams

Start with Question 1 →

Paper format. National Exams, December 2017 — 16-Mec-B8 Engineering Materials. Three hours, open book; any non-communicating calculator permitted. Eight problems, all of equal value; any FIVE constitute a complete paper, so each problem is worth 20 marks. Candidates are urged to submit a clear statement of any assumptions made. All eight problems are solved below, because the set as a whole is the study resource.

Reference texts (22-Mec-B8 Engineering Materials).

  • Askeland & Wright, The Science and Engineering of Materials, 7th ed. — the primary syllabus text.
  • Callister & Rethwisch, Materials Science and Engineering: An Introduction, 10th ed.
  • Dieter, Mechanical Metallurgy, 3rd ed. — Considère's construction, plastic instability and volume constancy.
  • Shackelford, Introduction to Materials Science for Engineers, 8th ed. — ceramics, glasses and glass-ceramics.
  • Fontana, Corrosion Engineering, 3rd ed. — galvanic series, sacrificial protection and Faraday's law.
  • Ashby, Materials Selection in Mechanical Design, 5th ed. — selection criteria and material indices.
  • Polmear, Light Alloys, 5th ed. — aluminium tempers, Al–Li alloys and maraging steels.
  • Groover, Fundamentals of Modern Manufacturing, 7th ed. — shaping and consolidation of polymer-matrix composites.

Note on this sitting. Two of them are worth flagging because the fresh data changes the answer, not merely the arithmetic. Question 8 raises the copper content of the incumbent alloy, which makes it denser, and as a result both candidate alloys now meet the customer’s weight request so the selection turns on strength parity rather than on who clears the bar. Question 4 changes the aeroplane from a twelve-seat business jet to a hundred-seat commercial transport and the stretch from 25 to 30 per cent, which sharpens rather than softens the damage-tolerance objection. Every number below has been re-worked from this paper's own data.