Coursework Assessment Brief Coversheet
|
Module code
|
MECH0053
|
|
Module name
|
Power Transmission and Auxiliary Machinery systems
|
|
Academic year
|
2024/25
|
|
Term
|
Term 1
|
|
Assessment title
|
Coursework Shafts, Couplings and Clutches
|
|
Individual/group assessment
|
Individual
|
|
Word count or page count limit (if applicable)
|
6 pages, the font should be no smaller than 11 pt.
|
|
% contribution to module
|
25%
|
|
Submission Date
Please see the submission portal on Moodle for the due date for this assessment.
|
|
Word count or page count penalty
Work that exceeds the word/page count by up to 10% will be reduced by 10 percentage points. This must not take the mark below the Pass Mark. Any material in addition to the 10% excess may not be taken into account in grading.
|
|
Eligibility for Delayed Assessment Permit (DAP)
This assessment is eligible for Delayed Assessment Permit. Mitigation available: 5 working days.
|
Use of Generative AI
This assignment is classified as Category 2: AI tools can be used in an assistive role. More implications of this can be found in the assessment brief.
Assessment Criteria
|
Mark range
|
Expected standard
|
|
20-25
(80-100%)
|
Outstanding submission demonstrating a deep understanding of a wider range of topics. All calculations are accurate and values are provided to an appropriate level of precision. Parameters and examples are chosen
with great insight and fully justified. Presentation is impeccable, of the
publishable standard: phrasing is concise and precise and figures are
perfectly formatted and labelled, providing information efficiently and in
full detail with descriptive informative legends and cross-references to the text.
|
|
17.5-19.5
(70-79%)
|
Excellent work, subjected to a rigorous quality assessment that
addresses main concepts and theories. All calculations are accurate and justification is given for choices of parameters and/or assumptions made.
Wider knowledge and understanding of the meaning of the work is
demonstrated; discussions are thoughtful and conclusions are
appropriate and fully justified. Text is concise and precise and figures are clear, fully and accurately labelled and described in the text and legends.
|
|
15-17
(60-69%)
|
Good quality work with some exceptions for example a few minor
mistakes in calculations or weak justification for some of the chosen
parameters or examples. Values are provided to an appropriate level of precision, final answers are clearly distinguishable and working is shown, with some attempt at reasoning or justification included. Figures are
useful and correct though may benefit from some additional labelling, formatting and/or more specific description.
|
|
12.5-14.5
(50-59%)
|
Acceptable submission where the majority of the goals of the assignment have been understood and tackled, demonstrating that some key
engineering principles have been applied correctly. Some calculations
show minor mistakes, lack of explanation, or are attempted using incorrect methods. Justifications may be weak or missing in the descriptions of engineering decisions, methods, and conclusions.
|
|
7.5-12
(30-49%)
|
Submission shows attempts at answering the assignment but with many gaps in knowledge and only limited understanding being demonstrated
through text, figures and calculations. Sections of the assignment may be
left unanswered. Many calculations exhibit major mistakes, many methods are incorrect or missing.
|
|
0-7
(0-29%)
|
A submission demonstrating major gaps in understanding the
assignment, failing to meet the majority of the assignment’s goals.
Solutions are largely incomplete and show major mistakes and/or lack of the required knowledge.
|
Learning outcomes assessed:
L1 design and select components in a power train.
L2 design shafts for static and fatigue loading and select an appropriate type of coupling. L3 design friction clutches and distinguish friction materials and mating surfaces.
Please turn over for specific guidance:
Specific guidance:
There is an upper limit of 6 pages (excluding a title page) and a maximum 5000-word limit for this report, which must be typed. Pages should be numbered, and the font should be no smaller than 11 pts to make the document easier to read and mark. If you do use external material, then this should be referenced in accordance with UCL procedures. If you are using any table or graphs that are provided in the lectures or are from the reference list of the lectures, you just need to cite the table number and identify the reference that you are using, e.g. Table 5.4 of Childs. Do not use the space to replicate those tables or graphs.
It is essential to read and answer the questions and to ensure that all aspects are addressed. Working methods need to be clearly presented so that markers can credit your work even if the answers are not fully correct. Ensure that your work is presented in a professional way and that any figures used are labelled correctly. Use a maximum of 6 pages in the most efficient way to ensure that you present all the information that you need to answer the questions. This will give you the greatest opportunity to gain higher marks.
Tips for success:
Q1:
a) Provide a clear schematic of your design. You may scan a schematic drawn by hand but it should be of a professional standard (e.g. use a ruler). You may use CAD software for the drawing but it is not a requirement. You should show clearly the dimensions and any provision you use to locate the components, reduce stress concentration, etc.
b) Demonstrate your calculation clearly. If you are choosing any parameter you need to justify it but be concise and clear.
Q2:
a) You need to clearly state your reason for choosing a specific type of coupling based on the problem and the information provided. State any assumptions that you make.
b) Similar to Q1 (a) demonstrate your calculations clearly and justify any parameter that you need to choose.
Use of AI:
Category 2:”AI tools can be used in an assistive role” . Students are permitted to use AI tools to assist with giving feedback on content, or proofreading content and the creation and formatting of figures, but the design and technical content is the student’s responsibility and must be their individual contribution.
If you have used AI in anyway, you need to declare it in the report or presentation in the following way:
• Name and version of the generative AI system used, e.g. ChatGPT-3.5
• Publisher (company that made the AI system); e.g. OpenAI
• Brief description (single sentence) of context in which the tool was used.
More details are given here:
https://library-guides.ucl.ac.uk/referencing-plagiarism/acknowledging-genAI
Assessment Brief
1. You are tasked with the design of a high-speed driveshaft which is used to transfer power in a pharmaceutical application. The machine works at varying temperatures but it would not exceed 100 °C. The schematic of the locations of the components is shown in Figure 1. The power to be transmitted is 19 kW at 11000 rpm. The shaft is driven by spur gearA and the power is transferred through coupling B to a separate shaft (not shown in Figure 1). Assume no bending moment or shear force is transferred via the coupling and its mass can be ignored.
The shaft is supported with two ball bearings. Assume the gear hub has a width of 30 mm with a fillet radius of 1.5 mm. The gear is 20° pressure angle spur type with a pitch circle diameter of 90 mm and a mass of 3 kg. The shaft is to be manufactured using alloy steel with σut = 1200 MPa, σy = 900 MPa, E = 205 GPa, G = 80 GPa and Brinell hardness approximately 300 BHN.
a) Provide a schematic drawing for your designed shaft. You need to justify your choices for your design, for example how you would locate components, etc. [5 marks]
b) Obtain the size of your shaft for unlimited life and faultless operation. Your shaft should be sized for a reliability of 99.9%. Consider an appropriate factor of safety and any other parameter that you need to define. You must justify your choice of parameters. [10 marks]
Figure 1. The schematic view of the assembly of question 1.
2.
a) Select an appropriate coupling to connect the two shafts of question 1. State your assumptions and justify your choice of the coupling. [4 marks]
b) The coupling of the shaft in question 1 is connected to a clutch that would operate frequently and would partially cool down between applications. It accelerates a mass of 12 kg with a radius of gyration of 0.2 m from rest. The system is driven by an electric motor. The friction surfaces would be made of woven materials. Design a disk clutch and obtain its parameters. Show clearly how you obtained the parameters, justifying your choices, where appropriate. What would be the slip time of your clutch? [6 marks]