School of Engineering
UCLan Coursework Assessment Brief
|Academic Year 2022-2023|
|Module Title: Materials, Tribotechnology and Surface Engineering Module Code: MP3702||Level 7|
MP3702 – COURSEWORK BRIEF
|This assessment is worth 40% of the overall module mark|
· 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% in the answers are highly suspicious. Cover sheet and assessment questions would have great similarity as expected.
· The whole report should be 1500 words plus any relevant material. Any references to materials should be given in standard Harvard or Vancouver form.
· Answer all the questions.
· Each question has the marks indicated. Total marks are 100.
· 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).
· This assessment is testing all the learning outcomes listed in the module descriptor. Learning outcome (LO) 1. Accurately explain the ways in which structure and composition of materials influence their mechanical properties; LO2. Assess the differences in the loading conditions and materials properties that lead to failure by fast fracture and fatigue in ductile and brittle materials; LO3. Evaluate ways in which the mechanical properties of materials and components can be controlled by appropriate choice of composition and heat treatment; LO4. Analyse the causes of friction and wear in engineering systems and the importance of appropriate choices of materials and surface topography in influencing the stresses at sliding contacts and in controlling friction and reducing wear; LO5. Distinguish between the various methods by which the surface structure and properties of materials and components can be modified by surface engineering.
|PREPARATION FOR THE ASSESSMENT
· In order to prepare for this assessment you need to make the tutorial questions and follow the lectures within the module.
· Take advantage of the tutorial sessions to ask question you may have in relation to this assessment or request support.
· Reading list available at the library for MP3702
|RELEASE DATE AND HAND IN DEADLINE
Assessment Release date: 19th Oct 2022 Assessment Deadline Date and time: 18th Dec 2022 at 18:00
Please note that this is the final time you can submit – not the time to submit!
Your feedback/feed forward and mark for this assessment will be provided on 20/01/2023
· 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.
· Drawings can be done by hand or electronically. They can either be scanned / copied into your Word or pdf document.
· 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.
|HELP AND SUPPORT
· You will find information links to all our Library resources in the Library area of the Student Hub. For support with using these resources, please contact your subject librarian at [email protected].
· You can get support with your academic skills (academic writing, critical thinking and referencing) through WISER. For details of the WISER support services go to the Study Skills section of the Student Hub.
|Disclaimer: The information provided in this assessment brief is correct at time of publication. In the unlikely event that any changes are deemed necessary, they will be communicated clearly via e-mail and a new version of this assessment brief will be circulated.||Version: 1|
A composite material consists of 40% parallel carbon fibres with a Young’s modulus of 405 GPa in a matrix of epoxy resin with a Young’s modulus of 2.5 GPa.
Calculate the Young’s modulus of the composite in the parallel and in the perpendicular directions of the fibres.
Use the graphical method seen in class to show the possible value of the overall young modulus of your composite material.
Aluminium 6061 is widely used in the aircraft and high-tech industries. With the suitable heat treatment, aluminium 6061is also used in welded structures such as bicycle frames. In the laboratory, some probes of Aluminium 6061-T6 are tested against fatigue failure. The probe shown in Figure 1 has failed after 107 cycles and 105 cycles at respectively 95 MPa and 115 MPa stress range respectively.
- Applying Basquin’s law, estimate the stress range for the probe to fail at 104
- Applying Goodman’s rule, estimate the stress range for the probe to fail at 107 cycles, when the probe is subjected to a mean continuous tensile stress of 72 MPa. (σTS=0.26 GPa)
Figure 1: Sample probe
Using the information provided, calculate the safe stress ranges for the above application.
A tie is subjected to a maximum tension force of 15 kN. The tie might have a 0.5 mm depth crack on its surface as bigger cracks than this can be detected in the quality control. The material for the tie is structural steel EN 10025-1 with a fracture toughness of 30 MPa m0.5. The provider of the raw tie material can supply these sizes:
|Size||Height (mm)||Width (mm)|
Select the smallest safe size.
A bearing pad, shown in Figure 2 and consisting of two steel plates bonded to an artificial rubber, is subjected to a shear force F = 8 kN during a static test. The pad has dimensions of a = 150 mm and b = 220 mm and the artificial rubber has a thickness t = 50.8 mm. When the force F equals 8 kN, the top plate is found to have moved laterally by 5 mm with respect to the bottom plate.
Using the above information, calculate the shear modulus of elasticity, G, of the artificial rubber.
Figure 3 shows the Copper-Antimony (Cu-Sb) phase diagram.
Figure 3: Copper-Antimony (Cu-Sb) phase diagram
- a) Calculate the chemical formula for the compound marked X (atomic weights of Cu and Sb are 63.54 and 121.75 respectively).
- b) The Cu-Sb system contains five particular points: 2 eutectics, 1 eutectoid, 1 peritectic and 1 peritectoid.
- i) Mark them on the Figure 3;
- ii) Write down the temperature and composition of each point, and identify the phases involved in each reaction taking place at each point.
[Hint] You need to understand these characteristics points reactions. An example of eutectic reaction is
- c) An alloy containing 90 wt% Sb is cooled slowly to room temperature from the melt. Explain the phase changes that occur during cooling, using schematic sketches of the microstructure at key temperatures to illustrate your answer.
- d) Sketch a temperature-time curve for the 55 wt% Sb alloy over the range 700 to 500 and account for the shape of the curve. Explain every sharp change in slope of the curve.
Total Marks 20
- Brass (Naval brass, CuZn38Sn1, C46400) has a Young’s modulus of 102 GPa and a Poisson’s ratio of 0.34. Calculate the effective modulus at the interface when two brass plates are loaded together.
- Copper (C10500) is subjected to a rolling process to work harden . After that, it has a hardness of 930 MPa. The Young’s modulus is 130 GPa. Estimate the elastic strain in rolled copper at the yield stress.
Total Marks 6
A steel shaft with a Ra value of 0.6 μm is rotating in a brass bush with a Ra value in its inner diameter of 0.9 μm. The shaft and bush are immersed in oil and, during operation, an oil film thickness of 1.3 μm is developed. In which lubrication regime is the sliding interface operating? Your answer should be supported by a suitable example of a situation where this regime is often found.
[Hint] You may need to make an estimation in order to be able to calculate lambda.
It is found that a polymer-based bearing supporting a rotating steel shaft has a depth wear rate of 0.2 mm in 800 hours both at a bearing pressure of 5 MPa and speed of 0.2 ms-1, and at a pressure of 1 MPa and a speed of 1 ms-1.
(a) Show that the bearing is operating in the range where the specific wear rate is constant.
(b) Calculate the time taken to reach a wear depth of 0.2 mm if the pressure and speed are 2 MPa and 0.2 ms-1.
(c) Given the above information, decide if you could safely calculate the wear rate at a pressure of 5 MPa and a speed of 1 ms-1, and give reasons for your decision.
(d) The test results are obtained using a polished steel shaft in a laboratory environment and at room temperature. Suggest changes in these conditions that could cause the specific wear rate to be different.
Total 12 marks
“To reduce wear on an aluminium component, a hard wear resistant ceramic coating is applied”.
(a) With the aid of diagrams, illustrate two different techniques by which this could be done. Give details showing how these techniques can be applied on an aluminium substrate and discuss the advantages or disadvantages of the two techniques. You may use appropriate examples and references.
“A metallic coating is applied to a ceramic substrate to increase the reflectiveness of light in its surface”.
(b) With the aid of diagrams, illustrate one technique by which this could be done. Give details showing how this technique can be applied on a ceramic substrate. You may use appropriate examples and references.
Total Marks 25
A Tungsten carbide ball 10 mm in diameter is loaded under an increasing normal force against a stainless steel plate with a hardness of 1800 MPa, as shown below.
- Calculate the force where plate first yield?;
[Hint] Due to the stresses in the contact region, the plate first yield in the subsurface.
- Calculate the corresponding contact width?
- Calculate the mean and maximum pressures in the contact zone?
- What are the magnitude and the location of the maximum shear stress?
The relevant Hertz equations for this contact are:
Radius of the circle of contact, a = (3PR/4E*)1/3 (equation 1)
Maximum pressure, p0 = 3P/2πa2 = (6PE*2/π3R2)1/3 (equation 2)
Where P is the normal load, R is the radius of the ball and E* is the composite modulus at the contact.
Start writing down the unique data for the diameter.
Total Marks 10
END OF ASSESSMENT