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22-Mec-B8 Engineering Materials: December 2018

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

  1. Question 1 ABS versus phenolic for an engine-mounted box
  2. Question 2 Why carbon embrittles high-tensile steel, and how maraging steels avoid it
  3. Question 3 Processing routes for aerospace FRP laminated components
  4. Question 4 Necking of a ductile wire — Considère's criterion
  5. Question 5 Poisson's ratio for perfectly plastic, constant-volume deformation
  6. Question 6 Aluminium–lithium substitution for aircraft floor beams
  7. Question 7 Magnesium sacrificial anode in a hot water heater
  8. Question 8 Two applications where corrosion is an issue

Start with Question 1 →

Paper format. National Exams, December 2018 — 16-Mec-B8 Engineering Materials. Three hours, open book; any non-communicating calculator permitted. Eight problems, all of equal value; any five of the eight 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.
  • Shackelford, Introduction to Materials Science for Engineers, 8th ed.
  • 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.
  • Dieter, Mechanical Metallurgy, 3rd ed. — the tension test, true stress and necking.
  • Polmear, Light Alloys, 5th ed. — aluminium tempers, Al–Li alloys and maraging steels.
  • Strong, Fundamentals of Composites Manufacturing, 2nd ed. — FRP consolidation routes.

Note on this sitting. Two questions carry data specific to this paper and have been worked from this paper's own numbers: the necking wire (Q4, with σ = 218ε0.33 MPa for one cubic metre) and the aluminium–lithium floor beams (Q6, where the target is quoted as an absolute 10 000 N, and the ask is to test a specific “more than 90 %” claim — which turns out to be false).