Engineering Materials – Tutorial Assignment 1, SAIBT 2014 semester 1
This assignment is based on tutorials and answers should be supported by illustrations (sketches and graphs) wherever relevant. Any references used should be specified after each question. Whilst discussions between students are encouraged the assignment itself must be individual work.
The assignment is in 2 parts, with answers to questions 1 to 6 due at end of class in week 6. The second half will be distributed later in the semester. It is strongly suggested that the assignment be progressively attempted throughout the first half of the study period.
1. Explain how an understanding of the 4 classes of materials and their generalised properties aid in the initial selection or elimination of materials suitable for a specific application.
I.E. First outline some of the main general properties of each class and then describe how you would apply that knowledge to choose a suitable material for a specific component.
ONLY ONE COMPONENT SHOULD BE PRESENTED (24%)
2. Explain why yield strength is more useful in design than tensile strength. Illustrate your answer with suitable stress strain curves. (10%)
3. Explain how the chemical composition of carbon and low alloy steel (less than 5% alloy material composition) may affect the steels’ elastic modulus, (i.e Young’s Modulus E).
Support your answer with tabulated material property data from literature. (16%)
4. Why is hardness testing often performed in preference to tensile testing? (10%)
5. Explain the advantages of fracture toughness (Kc) in engineering design, manufacture and service compared to Charpy impact test results. (16%)
6. From the force – extension curve below determine:
1) yield strength, 2) tensile strength, 3) elastic modulus, and 4) % elongation,
if the test piece was of circular cross section with a diameter of 14mm and an original gauge length of 50mm. (24%)