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BSc (Hons) Mechanical Engineering (MC)
Level 6 - Spring 2016-2017
Submission instructions
• Cover sheet to be attached to the front of the assignment
• Question paper to be attached to assignment
• All pages to be numbered sequentially
Module code
Module title
BSc (Hons) Mechanical Engineering (MC)
Module leader/ Assignment tutor Eirini Varouti/ Eirini Varouti
Assignment number
Assignment title
CW1 –Materials selection case study
Handout date

Submission date

Learning outcomes assessed by this assignment
(see module guide)
Learning outcomes: 1&2
Materials dominate in human’s everyday life, as their presence is obvious in every single activity. Advanced technological progress, that beyond any argument, has a positive impact on our lives, is intimately associated with the accessibility in suitable materials.
As a consequence, the choice of the most suitable material for utilization in a specific engineering application is a constant challenge for engineers, as their choice will influence the overall performance and the eventual technical success of the product. Satisfaction of complex design problems, by ensuring strength and endurance, by meeting a set of engineering design requirements and by avoiding undesirable cost implications and early failure should be among the elements to be taken into consideration during the process of materials selection.
Learning Outcomes
The present assessement sheet covers the following learning outcomes:
On successful completion of the module, students will be able to:
1. Apply advanced materials concepts to the analysis of specific high technology components in case studies to enhance performance.
2. Critically evaluate advanced engineering materials concepts and use appropriate analytical methods in materials selection.
The students are required to use reason, analysis and critical thought, along with the corresponding knowledge base, gained during the lectures, in approaching a materials selection and a materials substitution engineering issue.
In the framework of the current assignment the students will describe and analyze a materials selection process related to the shaft of a centrifugal pump.
Centrifugal pumps constitute some of the hardest working and most critical plant components within industry. Although relatively elementary in principle of operation, the humble centrifugal pump produces an inherently challenging environment to the materials used to construct it. During operation, pump shafts usually suffer from degradation as a result of corrosion and/or mechanical degradation, usually in the form of fatigue failures. In many cases corrosion precedes fatigue failure and can actually accelerate the rate of failure.
Pump shafts are generally exposed to the liquid being pumped either on a continual basis or at certain locations along the length of the shaft. Specialized sealing arrangements comprising sleeves and O-rings can be used to reduce the amount of liquid ingress, however, where these sealing systems are not implemented or where the integrity of these seals is compromised, damage to the shaft in the form of corrosion may occur.
Thus, it is obvious that knowledgeable design/materials selection can reward the engineer with both reliability and durability against unexpected pump failures that can occur.
The current assignment consists of the following parts:
PART A (50%)
During their service life, components may be subjected to corrosion in addition to the normal stresses they are designed to bear. Experience has shown that the corrosion rate of some materials is accelerated as a result of stress. In some cases, chemical attack does not take place in the absence of stresses.
Describe to the main types of combined action of stress and corrosion (1 paragragh each approximately)
1. Stress corrosion cracking (10%)
2. Corrosion Fatigue (10%)
3. Erosion Corrosion (10%)
4. Cavitation Damage (10%)
5. Fretting fatigue (10%)
PART B (45%)
Case Study:
Selecting the Optimum Material for a shaft of a centrifugal pump.
The Problem
It is required to select the optimum material for a shaft of a centrifugal pump. Assume that the pump is used for lifting slurry (assume 25oC for fluid temperature).
A systematic design-oriented approach to a material selection methodology should contain the following stages:
1 Translation
2 Initial screening -Rejection
3 Comparing/Ranking alternative solutions (Use Performance Indices method)
4 Selecting the optimum solution
Assessment Declarations
The assignment should be accomplished individually. It is acceptable and advisable to discuss the given tasks with other students but do not copy their files or ideas as that could be considered as plagiarism.
The length of the assignment should be approximately 3000 words. The assignment should be in technical report format. The number of the question should be mentioned before answering each question. The answers should be robust, accurate and clearly justified.
Reference sources can be freely drawn on, but remember to cite the source(s) used, and identify them properly in the References section. Additional supporting data (e.g. regulatory codes, sketches, etc) should be included within your Appendices, but must be suitably explained and referenced from the main text.
Topics to be covered
Advanced material properties, factors (in order of importance) affecting performance in service, classification of candidate materials, materials selection procedure.
Marking Criteria
The marking of this assessment will be based on the following requirements:
Presentation (10%) Part A Part B
Appropriate Structure, Format, Cover and Index pages, References and citations. 2.5%
Readability and clarity of the assignment, use of technical language 2.5%
A1 10%
A2 20%
A3 10%
A4 10%
A5 10%
B 45%
Total (100%) 5% 50% 45%
Reading Materials
• Module lecture and support notes
• Internet sources
Proposed English Bibliography
1 Ashby, M.F., (2010) Materials Selection in Mechanical Design, 4th edition, A Butterworth-Heinemann Title
2 Ashby, M.F., Shercliff, H., and Cebon, D., (2009) Materials: Engineering, Science, Processing and Design, 2nd edition, A Butterworth-Heinemann Title
3 Benham, P.P., Crawford., R.J and Armstrong, C.G., (1996) Mechanics of Engineering Materials, 2nd edition, Prentice Hall
4 Gere. J., (2008) Mechanics of Materials, SI Edition, 7th Edition, Nelson Engineering
5 Hibbeler, R.C., (2010) Mechanics of Materials, 8th Edition, Pearson Ed Asia
6 Farag, M., (2014), Materials and Process Selection for Engineering Design, 3rd Edition, CRC Press
7 Callister, W.D, Rethwisch, D.G., (2007) Materials Science and Engineering: An introduction, 7th Edition, Wiley
8 Askeland, D.R, Fulay P.P., (2010) The Science and Engineering of Materials, 6th Edition, Cengage Learning
9 Dieter, G.E., (1988) Mechanical Metallurgy, SI Metric Edition, McGraw Hill
Proposed Greek Bibliography
1 Tsamasfyros, G. I., Theotokoglou, E. E., The Finite Element Method I & II, Athens: Symmetria,
2 Gkotsis, P, (2008) Finite elements, 2nd Edition, Ziti.
Note: These sources are guides only to commonly available material. Students will also be expected to consult other relevant source material according to the nature of their project.
Submission Dates
See front sheet.
The assignment must be handed in using the electronic submission system.
There is no automatic right to late submission, with a capped mark of 40%. However, the University acknowledges that there may be circumstances which prevent students from meeting deadlines and there are now three distinct processes in place to deal with differing student circumstances:
1) Assessed Extended Deadline (AED)
Students with disabilities or long term health issues are entitled to a Support Plan. The Support Plan will outline any adjustments to assessments which are required to accommodate an individual student’s needs. For further details refer to the link below:
2) Exceptional Extenuating Circumstances (EEC)
The EEC policy applies to situations where serious, unforeseen circumstances prevent the student from completing the assignment on time or to the normal standard. Students who submit a successful EEC claim will usually be required to complete a different assessment to that which was originally set. All EEC claims will be considered by Faculty/UDC panels, which will convene on a monthly basis.
For further details refer to the link below:
3) Late Submission up to One Week
Covering unexpected and severe disruption to study, where circumstances do not require the additional time allowed for by an EEC, the Late Submission process enables students to complete their existing assessment up to one week late, without a cap on the grade. Requests for late submission will be made to the relevant Subject Manager in the School who can authorise an extension of up to a maximum of one week. The Subject Manager will expect to see compelling evidence that such an extension is appropriate.
? Assessment Criteria
The grading scale applies to Levels 3, 4, 5 and 6 in the University Credit Framework. The descriptors are typical characteristics of the standard of work associated with each grade, and are given in details by level. Please refer to the 3Rs document for a comprehensive view of this scale.
? Academic offence
An “academic offence” is committed when a student tries to gain improper advantage for her/himself, or not following the Academic Regulations, concerning any part of the assessment process. Please refer to the 3Rs statement:
Performance Criteria
% mark Mark Descriptors Class
Outstanding; high to very high standard; a high level of critical analysis and evaluation, incisive original thinking; commendable originality; exceptionally well researched; high quality presentation; exceptional clarity of ideas; excellent coherence and logic. Trivial or very minor errors. For the highest marks (90 - 100%): an exceptional standard of work illustrating thorough and in-depth understanding, communicated with exceptional authority. First
60-69% Very good
A very good standard; a very good level of critical analysis and evaluation; significant originality; well researched; a very good standard of presentation; commendable clarity of ideas; thoughtful and effective presentation; very good sense of coherence and logic; Minor errors only. Second
Div 1
50-59% Good
A good standard; a fairly good level of critical analysis and evaluation; some evidence of original thinking or originality; quite well researched; a good standard of presentation; ideas generally clear and coherent, some evidence of misunderstandings; some deficiencies in presentation. Second
Div 2
40-49% Satisfactory
A sound standard of work; a fair level of critical analysis and evaluation; little evidence of original thinking or originality; adequately researched; a sound standard of presentation; ideas fairly clear and coherent, some significant misunderstandings and errors; some weakness in style or presentation but satisfactory overall. Third
35-39% Unsatisfactory
Overall marginally unsatisfactory; some sound aspects but some of the following weaknesses are evident; inadequate critical analysis and evaluation; little evidence of originality; not well researched; standard of presentation unacceptable; ideas unclear and incoherent; some significant errors and misunderstandings. Marginal fail. Marginal
21-34% Poor
Below the pass standard; a poor critical analysis and evaluation; virtually no evidence of originality; poorly researched; presentation unacceptable and not up to graduate standard; ideas confused and incoherent, some serious misunderstandings and errors. A clear fail, short of pass standard. Fail
1-20% Very poor
Well below the pass standard; a poor critical analysis and evaluation; no evidence of originality; poorly researched; standard of presentation totally unacceptable; ideas confused and incoherent, some serious misunderstandings and errors. A clear fail well short of the pass standard.

NS Non-submission
No work has been submitted.
Z Academic offence notation
Applies to proven instances of academic offence.