Coursework on Structures and Mechanical Properties of Engineering Materials

·The course work aims to address all the module learning outcomes by focussing on the quantitative descriptions on Structures and Mechanical Properties of Engineering Materials and by incorporating a comprehensive understanding of the various failure modes and design criteria for materials selection.

·The module learning outcomes are provided in the resit coursework brief (Page Number - 5).

·Please look into the resit coursework brief for the questions (Page Number – 7 to 12).

Question with Answers to the Course Work will be uploaded in the Blackboard after the submission deadline. Detailed discussion of the solutions to the Course Work will be discussed in the class during the revision lecture session for the module.

1.The coursework should be your own work and should be properly type-written in your own words. Your assignment must be submitted electronically via blackboard by the submission time or before.

2.Drawings can be done by hand or electronically but at the same time students are not allowed to copy paste the images from different e-resources directly. They can either be scanned / copied into your Word or pdf document

3.Please see the instructions to candidates for more information (Page Number - 4).

1.The coursework should be your own work and should be properly type-written in your own words. Marks will be reduced for the typo-errors and missing units. The assignment will be checked for plagiarism using TURN-IT-IN software. Any plagiarism or copying from others will be dealt through the university’s plagiarism procedures.

Similarity (plagiarism) level higher than 10% is highly suspicious.

2.The assignment is divided into two sections, Section A and Section B. Section A and Section B constitutes equal weightage (50%) of the total marks with no choices. Answer all parts of the questions from each section. The whole report should be 1500 words plus any relevant material (figures, calculations, tables, etc.,). Any references to materials should be given in standard Harvard or Vancouver form.

3.Your assignment must be submitted electronically via blackboard by the submission time or before. The report should be contained in a Word document or pdf document. No other means of submission will be accepted.

4.Drawings can be done by hand or electronically but at the same time students are not allowed to copy paste the images from different e-resources directly. They can either be scanned / copied into your Word or pdf document.

5.Any assignment submitted late, but within 5 working days of the deadline, will be given a maximum mark of 50%. Assignments submitted more than 5 working days after the deadline will not be marked, and a mark of 0% will be recorded.

Coursework Questions

6.Students with special needs will be addressed on individual basis.

(Candidates that may require any special requirement will be dealt with on a one-on-one basis which must be discussed with the module tutor/lead before the due date).

Learning Outcome to be assessed:

1. Able to communicate effectively on material selection with material scientists

2. Able to understand the implications of different modes of material failure

3. To understand the effects of composition and heat treatment on the properties of different types of material

4. To select materials to minimise the likelihood of component failure

QUESTION B1

(a)Draw the Time Temperature Transformation T-T-T diagram for nickel-based superalloy (Inconel 718) used in jet engines and show on the diagram the critical cooling curve, the transformation lines, the phases, the axis.

(b)Explain the change of structure with martensitic transformation in steels used in jet engines.

(c)With help of a phase diagram illustrate the various phase transformation occurring in the commercial titanium alloys (Ti - 6Al - 4V) used in the jet engines.

(d)With help of a phase diagram discuss the following phase transformation reaction occurring in the commercial Titanium alloys (Ti - 6Al - 4V) used in the jet engines

(i)Peritectic reaction and Peritectic point

(ii)Peritectoid reaction and Peritectoid point

QUESTION B2

Using suitable industrial examples, explain creep and oxidation of nickel based super alloys used in jet engines at high temperatures. Discuss three strategies to reduce creep and three strategies to reduce oxidation in jet engines at high temperatures.

QUESTION B3

An aluminium alloy for an airframe component used in jet planes were tested in the laboratory under an applied stress which varied sinusoidally with time about a mean stress of zero. The alloy failed under a stress range Δσ of 300  MPa after 105  cycles.  Under a stress  range of  220 MPa, the alloy failed after 108 cycles. Assume that the fatigue behaviour of the alloy can be represented b

(a)Find the number of cycles to failure for a  component subject to  a  stress range  of  200 MPa.

(b)A jet plane using the airframe components has encountered an estimated 3.2 ×108 cycles at a stress range of 200 MPa. It is desired to extend the life of the airframe by another 4.5 ×108 cycles by reducing the performance of the aircraft. Use Miner’s rule to find the decrease/increase in the stress range needed to achieve this additional life.

A jet engine spline coupling made up of high strength steel, is subjected to axial load, bending moment and torque during the flight take-off and landing. The spline coupling is tested under the laboratory using the scaled spline testing simulating the real operating conditions. The initial axial load applied was 55 kN, alternating bending moment was ± 650 Nm and a torque of 15 kNm. The specimen is subjected to fatigue loading until failure. The test is performed under a tension - tension cycle with a stress ratio of 0.1. The yield strength of the material is 1350 MPa.

(a)Calculate the initial stresses applied on the sample.

(Hint: Use the equation of the maximum principal stresses and shear stresses for a bi-axial loading condition).

(b)After 90,000 cycles the crack propagation is faster and leads to final fracture. Explain with help of a simple sketch, the various regions of fatigue crack growth and microstructural variation seen in the jet engine spline coupling during the fatigue crack growth testing.