School of Marine Sciences and Engineering - Design Stage 2 - BEng: DSGN 215

2010/2011 Assignments, Guidance for Reports, Lecture / Self Study Programme and References.

Lecture / Self Study Program - with Links to Notes
Suggested Books

0 Context
Design is a key subject for many engineers and aspects of design are included in all years of the Engineering courses at Plymouth University. In the first year communication and representation of a design (sketching, and solid modeling) are covered together with lectures on the generic nature of design and an introduction to working in teams, design specification and management of design.
In the second year students undertake a reverse engineering task and have to develop an 'improved' design. This work is supported by a course of lectures on machine elements and topics including environmental considerations and ethics. Students are also introduced to CAE simulation tools: finite element analysis, motion analysis and systems simulation. Details of the second year course are given below.
In the final year students develop group working skills by working in teams normally of 5 to 9 on significant projects.
This integrated approach has been developed to ensure students have a good grounding which will provide them with an excellent start in many engineering careers.

Students should note that unlike most other engineering subject that you have been studying, including physics, for design problems there is not normally a 'right' or 'obvious best' solution. The design you produce will have to be a compromise between a great many conflicting requirements. A very important part of being a designer and engineer is to develop how to judge and balance the contradictory requirements that you will be faced with. The conflicting requirements will not just involve the traditional engineering aspects but also ethical, sustainability and environmental aspects.

1 Introduction.
These notes are intended primarily for BEng students and distance learning BSc students. Plymouth based BSc students have a slightly different course with a separate home page and assignments however quite a few of their links are to the pages below and these pages are a good place to start to look for information etc.

Design, which is used to integrate other subject areas is having a distinctive 'marine flavour' added to it, which will be further developed in other subjects and in other stages of the course. SoE for a few years will be concentrating on under water vehicles as a theme.

There are three types of assignment this year:
A remotely operated under water cutter, (targeted at Marine Technology students and any other groups who are interested).
A 'fish'.
Work relating to a petrol engine to be undertaken by all other students.

In this module many of you are required to carry out some 'reverse engineering' on the parts of the system that you are assigned or some experimental work to facilitate design. You will need to examine the system, see 'how it works' and critically appraise the design. You will be given a target for the system to be uprated and you will have to produce detailed designs for the parts of the system that you have been allocated. You should note that in this context 'detailed design' does NOT mean detailed formal drawings, but design calculations, details of materials and manufacturing methods to be used and hand drawn sketches.

Although this module is titled 'design', you will be expected to include appropriate work in assignments on materials and manufacture. The marking scheme includes allowances for these topics.

You should work in groups of 3 in all these assignments, each group will submit 1 report for each assignment and normally all members will receive the same mark. BUT YOU MUST put a persons name on the bottom of every page, to indicate who was primarily responsible for its contents and writing.
NB: If difficulties do arise with group members not contributing, then the module leader reserves the right to remove a group member(s) or require them to write and submit an individual report or to give a lower mark (or zero) to the person(s) concerned.

2 Support for Assignments
A programme of lectures (normally about 1.5 hours per week) will be run during the year, covering topics that are appropriate (see schedule). Students on the distance learning 'top up' BSc should normally follow this scheme for their self study. There is no specific time tabled tutorial slot provided, students with queries should raise these at the end of the class sessions when there will be an opportunity to discuss your ideas with the lecturer and to seek advice. Distance learning students can use e mail and / or telephone to raise queries with the module leader.
A number of slots are time tabled in the CAE suite to provide you with an introduction to the CAE packages, Solid Works Cosmos FEA. It is important that you attend the specified sessions.

The study programme, below, has links to notes, some of which contain interactive Java applets, and web sites that provide information appropriate to the assignments. These are designed to assist you - you will probably save a lot of time if you make full use of this support material.

3 Tasks / Assignments:

Students may opt to be part of a group (normally of 3 people) working on the assignment relating to (a) the engine, or (b) relating to the remote operated underwater vehicle (RoV) or (c) relating to the 'Fish', see below. Groups working on (a) and (b) will be assigned one of the specifications (A, B, C, D, E, F, listed below) around the middle of October.

Report number: Remote operated underwater vehicle (RoV) Engine
Tasks for report 1 Carry out some appropriate experimental work / research to determine cutting forces needed for the cutter.
NB. Access to the lab for this work is only available at limited times.

A small scale RoV is to be designed to operate at a radius of up to 1000m from the 'base', capable of operation at a depth as shown in the table below and able to cut wire and bar as specified in the table below.
Summarise the changes or key features needed in the designs, outlining your reasoning and evidence.
'Reverse engineer' the system (a single cylinder Honda engine - GX 160, 163 cc capacity - is available in Brunel W6) determining key dimensions, clearances, masses, inertias, spring forces, coefficients of friction, materials used in construction and deduce manufacturing processes where possible. You will not be able to measure the bearing dimensions accurately enough to carry out hydrodynamic lubrication calculations, use data given in the workshop manual for these calculations.

NB. Access to the lab for this work is only available at limited times.

A new system is to be designed - the engine is required to develop greater power / torque. Summarise the changes needed in the designs outlining your reasoning. It may be that the current design is over engineered, in which case you should be aiming to make it more efficient - probably with less weight

Tasks for reports 2 and 3 - general Each group must produce a detail design of a suitable system to meet the specification they have been allocated (see below). Normally a group will contain 3 students and a complete design will be expected. Not all aspects will require the same amount of detail - see notes below. Where groups contain fewer students, less detail work will be required, groups with more than 3 members will be expected to produce better, more detailed designs. Explain why you have chosen the changes you are going to make.
Report 2 - detail Detail design of cutter mechanism / system. NB: It is not permissible just to say you are purchasing an off the shelf cutter model 'XYZ', you are required to produce a fairly detailed design of a suitable unit. Valves, cam shaft, piston, rings, cylinder head
Report 3 - detail Hull design and propulsion. Connecting rod, crankshaft, bearings, cylinder block, cooling

Every group will be allocated one of the specifications below:
RoV Specification A: Cut 10mm diameter solid steel bar (UTS 400 MPa), 22 mm diameter stainless steel wire rope800 m maximum working depth
RoV Spec. B:Cut 15mm diameter solid steel bar (UTS 400 MPa), 25 mm diameter stainless steel wire rope2000 m maximum working depth
Engine Spec. D:20% power output increaseat 15% higher rpm
Engine Spec. E:35% power increase at 25% higher rpm
Engine Spec. F:50% power increaseat 35% higher rpm

The Fish
Researchers have successfully made prototype 'fish' that mimic the swimming motion (to some extent!) of real fish. During 2009/2010 session a group of students designed and built a simple but reasonably effective 'fish'. This assignment - rather different to those above - is for a group of students to assess the current design and improve upon it and build a 'better fish'. and test the new prototype.
Ideally the fish should be able to swim some distance while independent from the surface but it will be acceptable to feed power from the surface through (thin) wires. Sophisticated control is not expected, but the fish should surface (be recoverable!) when required (or the internal power exhausted). Money is available (against receipts) for expenditure which has prior approval - up to 800. The three reports should contain the following, but need not be divided as exactly as suggested below:
Report 1 Discussion of possible approaches, with critical appraisal of the current design.
Report 2 Detailed design of the 'new fish' and manufacture.
Report 3 Testing and development.

Underwater Glider
This assignment involves designing an underwater glider. Details will be provided in the next few days.

Dates Reports Are Due In:
Report 1Report 2Report 3
Dates reports due in, ..:11.00 am on Monday 15th November 2010 11.00 am on Monday 31st Jan. 2011
11.00 am Tuesday 29th March 2011
Dates for feedback/collectionBy Monday 6th December 2010By Monday 21st February 2011By Monday 9th May 2011

All DSGN 215 reports carry equal marks (worth a total of 20 credits).

4 Reports

The report for assignment 1 should concentrate on the existing system and in general terms describe the changes that will be needed to meet the new requirements. The reports for assignments 2 and 3 should concentrate on the new designs.

For assignments 2 and 3 student reports must include samples of appropriate design calculations, including the assumptions these were based on, references to British Standards and other sources of information and data that have been used. You should note that some of the design work involves repetitive work / complex analysis and extra marks will be gained for appropriate use of spreadsheets, finite element analysis and other modeling software, eg. Matlab Simulink.

Any drawings you submit to describe parts should be good quality, i.e. carefully labeled (isometric) sketches (or CAD drawings if you prefer - BUT they must be fully labeled). Do NOT use valuable time doing formal drawings where they are not called for. There will be no formal teaching of how to use the CAD system.

Good written submissions will be a key to achieving high marks, but this does not mean long reports. I would expect a good report to contain perhaps 3000 to 6000 words plus extensive well labeled diagrams and calculations with careful explanations and appendices. Report text must be word processed, a basic word processor (where equations and diagrams are added by hand) will be quite satisfactory. Report pages must be numbered, but this can be done by hand. Carefully labeled sketches must be used to assist in the explanation of calculations. We are looking for evidence that you have a good understanding of the work that you have carried out. For this reason, if you are designing a sub-assembly containing several components, rather than do superficial analysis of all the components, you will get better marks by providing a detailed analysis of perhaps only one or two components together with full information about the materials selection, processing and cost estimates. An example of good and bad descriptions of materials processing is given below:

If local loading could cause indentation, you might previously have said the component was to be made from 'case hardened steel'. This design / manufacturing / materials specification is worth about 5 % !

To gain a full mark you need to specify the steel, BS or ASM etc. number, the depth of case (total and possibly the fully hard depth) and core hardness / tensile strength, how the part is to be carburised and how it is to be hardened, eg austenitising times and temperatures, method of quenching (oil, polymer solution or water) temper time and temperature. This degree of detail is NOT required for every component, but is essential for safety critical parts and for parts that are critical to the performance of the product.

Do NOT make the mistake of writing a miniature text book on materials or manufacturing. You must explain why you have selected the materials and manufacturing processes that you have chosen for YOUR proposed design.

Normally all design calculations should be carried out in SI units and have:

  • an introduction, including the assumptions and simplifications you have made, design factor(s) chosen
  • labeled sketches to clarify the context, layout diagram(s) which include X, Y, Z axis directions.
  • labeled free body diagrams of every component including X, Y, Z axes to correspond to those above.
  • equations describing the equilibrium or the motion of each component
  • the calculations, with units and explanations
  • conclusions, eg what is the 'next' preferred size, might a further iteration be sensible

You should keep in mind that some of the components may be:

Operating in corrosive environments - material choice will be restricted and protection may be needed.
Operating at high temperatures as additional heating will occur due to higher output and losses - systems and components will need to be designed so that adequate cooling occurs.
Subjected to cyclic loading - the fatigue strength of critical components will need to be considered.

Additional Information About Assignments / Reports.
In the second and subsequent reports that you hand in, you do not need to repeat work included in the first / previous report(s). You should hand back the appropriate report and reference the page(s) where the discussion / calculation(s) appears. You must join the reports together.

NB It is acceptable for you to include copied diagrams and tables in your reports, but you MUST include full reference to the original. In the case of a web address include the date and time it was accessed. Failure to do this may well be considered to be plagiarism, which attracts heavy penalties, see the University Regulations.

5 Notes on Assessment
Marking scheme will be: 10% presentation, 30% analytical, 20 % for materials / manufacture, 40% quality of design(s), conclusions / discussion. However you should note that if the presentation is so poor that I am not able to understand some of your design or calculations, then more than 10% of marks may be lost. You should note that 1 mistake does NOT equate to 1 mark lost. A minor mistake may well not result in any marks lost, however 1 major mistake which shows serious lack of understanding, gross carelessness, eg absurd values being proposed, may result in the loss of several marks.

One of the aims of this module is to provide you with an introduction to design as an open ended subject. There is almost never single 'correct' solution - two very different designs might be equally good. Consequently it is not possible at the outset to give a simple marking scheme, the assessor must use his / her professional judgement when assessing your work.

In many cases you will have to make assumptions, using your judgement, because other aspects of the design have not yet been completed. Provided you give some good reasons why you made such assumptions, you will be given credit if you later in the year report that on the basis of more recent work, an earlier assumption was not correct.

As there is group work in this module, inevitably not all tasks are equally difficult. Students who have a simple piece of work will have to complete it rigorously and with few mistakes to get as good a mark as a student who makes a reasonable job of a much more complicated part of an assignment.

General information about the type of work expected for various grades of mark can be found in section 4 of the 'Handbook for students studying Mechanical, Marine and Composites Modules', if you are not familiar with this, you should look at it in the near future.

6 Lecture / Self Study Program

Most of the links below take you to introductory notes on the topics and indicate a reference for further details. Some of the links, both below and in the notes, are to external sites. A list of useful reference is situated at the bottom of this page.

This is a 'Design' module and does not include 'Stress Analysis' which is covered in our 'Mechanics' and 'Engineering Structures' modules. Theory and examples on stress analysis can be found on the Mississippi State University pages. Click on 'Classes' then on the 'Tutorial Page of Aerospace Structures'. Some further information about the design of machine elements can be found on the Mechanical Engineering Department pages at the University of Western Australia.

There are a number of 'Calculators' included in the notes which enable you to type in values (in the units stated) click on the 'Calculate' button and see the answer. Any value(s) can be changed and when the 'Calculate' button is clicked, the new result is displayed. There are some 'interactive plots' provided, again values in the appropriate units are typed in and when the 'calculate' button is clicked, a plot is drawn displaying relevant information. In some cases changing one or more values and clicking on 'Calculate' updates the plot. Please note these plots are done with Java Applets which require Netscape 4.5 or later or IE4 or later to run. These are designed to help you, it is foolish not to make full use of them.

Week Comm.Lecture / Self Study Topics
27-9-10 Introduction to module, Introduction to Design, design as an iterative process, group working, discussion of assignments, how to get good marks.
Sources of information, British Standards and CE Marking.
Types of design problems.
Some initial thoughts on engines and ROVs
4-10-10 Writing a Product Design Specification
Model Based Design
The importance of simplicity. Some basic design principles. Avoiding failure. Variability, factors of safety.
11-10-10Methods for solving design problems, brainstorming, evaluation matrix, quality function deployment.
TRIZ: Glenn Mazur: Theory of Inventive Problem Solving
Statistical considerations, and Tolerances and fits. Reliability.
HSE introduction to Risk Assessment
Consequences of an initial failure, FMEA.
18-10-10Failure: General Introduction
Failure modes and Failure theories and
Stress concentration.
25-10-10 Failure under combined loading. and Java Script for determining shaft diameter under combined bending and torque
2-D stress investigation - Mohr's circle and von Mises failure criterion - interactive plots.

* FEA applications to beams, bending and shear, 2 D stress.

1-11-10Transmission systems. and Belt Drives - simple theory.
Gear design home page (36kB file) and gear nomenclature, (57kB file).
Automotive gear box features
8-11-10Motors and Drives, hydraulic and pneumatic
Related products: Automotion Limited.
Clutches, with clutch torque "Calculator" and brakes.
15-11-10 Bolted and welded joints. Interactive "Plot and Calculator" for bolt proof loads and Bolt ultimate load "Calculator";
Stresses in an array of bolts subjected to an offset load and Interactive "Plot / Calculator" for stresses in an array of fasteners.
Self-Piercing Rivets - link to Henrob Limited site.
Structural Adhesives - Huntsman web site
22-11-10Selection of materials. also ferrous metals. and aluminium alloys also Superform Aluminium, also titanium and its alloys. also magnesium alloys. also brasses.
Copper - Nickel alloys, especially marine applications, click here
For information about plastics see SpecialChem Omnexus site.
There is a lot of useful information on the SKF site.
Link to INA Bearing Company Ltd.
6-12-10 Lubrication of plain bearings.
Link to Java Applet that computes the load capacity and pressure distribution for a tilted pad thrust bearing
A Java Applet to assist with journal bearing design is given here
Comparison of Raimondi and Boyd chart result with Java applet (above) click here
10-1-11Costs, Bill of Materials and Preferred sizes.
Design tool - simulation package: Matlab Simulink
17-1-11Gaskets and Seals, Flexitallic web site - look under 'Products',
Peak cylinder pressures in IC engines and
Stresses in engine gudgeon pin
Stresses in engine piston rings and friction losses
24-1-11 See: Ethics notes and
Engineering and the Environment.
Loughborough University site on 'Ecodesign'
31-1-11 Fatigue and fracture mechanics. and Goodman fatigue criterion and "Calculator". or Goodman fatigue criterion "Calculator with interactive plot".
7-2-11 Continue above.
14-2-11 Effect of pre-load in bolt Example calculation of bolt pre-load
21-2-11 Mechanisms, valve train accelerations and forces and
valve stresses. Also Valve stresses due to valve bounce
A lot of useful mechanism information and animations is on the Brock Institute for Advanced Studies site.
Link to web site: Exploring Machine Motion Design - Cornell University.
Velocities, accelerations, forces and moments in a slider crank mechanism.
Torque generated by piston force on crank
28-2-11 Buckling, and buckling "Calculator with interactive plot", or buckling "Calculator". Buckling of a cylindrical shell, using FEA.
Shock Loading
7-3-11 Springs. and Spring Design calculator with interactive plot
Sensors Engine management, Actuators
14-3-11 Intellectual Property Rights, Patents, Registered Designs.

* In parallel with the lecture program, during the autumn term, I plan to run some sessions in the CAE suite, to introduce you to engineering simulation using Solid Works Cosmos FEA.
In the spring term we will look at Matlab Simulink.

Please attend the sessions indicated below in Smeaton 105

If you need to swap session YOU must find someone to swap with.

CAE Lab week - - Students - - Topic

Link to FEA Introductory Examples

Week commencing 8th Nov 2010 - The originally time tabled session Tuesday 9th 10 - 12 is now for Clive Williams to take the entire class in Smeaton 104

W/c 15th Nov 2010 - ......................
Tuesday 16th November 10.00 - 12.00 in Smeaton 104 Family names beginning A - F: FEA 1
Friday 19th November 9.00 - 11.00 G - O: FEA 1 This and remaining sessions in Smeaton 105

Friday 26th Nov 2010 - 9.00 - 11.00...................... P - Z: FEA 1

Friday 3 Dec 2010 - ..................... A - F: FEA 2

Friday 10 Dec 2010 - ...................... G - O: FEA 2

Friday 17 Dec 2010 - ...................... P - Z: FEA 2

Matlab Simulink sessions
Slots are on Tuesdays 2.00 - 4.00pm

W/c Mon 24th Jan 2011 - ...................... A - M: Matlab Simulink 1, Smeaton 105

W/c Mon 31st Jan 2011 - ...................... N - Z: Matlab Simulink 1, Smeaton 105

W/c Mon 7th Feb 2011 - ...................... A - OM: Matlab Simulink 2, Smeaton 104

W/c Mon 14th Feb 2011 - ...................... N - Z: Matlab Simulink 2, Smeaton 104

Honda Engine Weights and Measurements
Engine capacity: 163 cc.
Cylinder head gasket thickness: 1.15 mm
Height of piston below cylinder block deck at tdc: 0.3 mm
Cylinder bore: 67.88 mm
Piston od: 67.67 mm
Piston (including rings) mass: 172.4 gm
Gudgeon pin mass: 41.3 gm
Gudgeon pin dimensions: 18mm od, 14 mm id, 54mm length.
Gudgeon pin to connecting rod little end bearing diametral clearance: approx. 0.01 mm
Gudgeon oin hardness (1 kg load): 759 vpn
Gudgeon pin surface roughness, Ra: 0.01 micro m
Connecting rod cap surface roughness, Ra: 0.014 micro m
Connecting rod mass: 151.9 gm, (little end 44 gm, big end 107 gm)
Connecting rod length between centres: 84 mm, big end bore: 30 mm, little end bore 18 mm
Connecting rod big end clearance with crankshaft big end journal: 0.04 - 0.063 mm.
Valve lift: 5.65 mm
Valve spring mass: 4.9 gm
Valve spring free length: 30.3 mm (5.25 coils)
Valve spring wire diameter: 1.8 mm
Valve spring , od of coil: 19.8 mm
Rocker mass: 15 gm
Pushrod mass: 12 gm
Pushrod diameter: 2.9 mm (3.9 mm dia ball on end)
Pushrod length: 132.6 mm
Cam follower mass: 17.6 gm
Valve and collet mass: 31 gm
Inlet and exhaust throat diameters: 23 mm
Mass of water to fill the cylinder head: 18 gm
Pull to turn over engine with only piston and rings in place: about 8 N at a radius of 87.5 mm
Crankshaft mass: 1.7 kg
Camshaft mass: 504.5 gm
Piston rings (compression) 0.95 mm wide; 2.3 mm deep; 9 mm gap; mass: 3.7 gm.
Carburettor jet: 70S
Carburettor main body diameter: 18 mm, venturi diameter: 12 mm
Engine block micro-hardness (200gm): 92 Vickers
Connecting rod micro-hardness (200gm): 110 Vickers

Note: The lecture programme may be varied somewhat according to student feedback, however the hand in dates for the assignments can not be changed - you should be aware that late submission of an assignment results in a zero mark unless you have valid extenuating circumstances.

Return to Introduction.

7 Suggested Books - General Design:
1. ** 'Mechanical Engineering Design Notes - Theme: Automotive Engines', by David Grieve, 2008, ISBN: 978-0-9560037-0-6.
2. ** 'Mechanical Engineering Design', by J E Shigley and C R Mischke, 5th Ed., McGraw Hill.
3. 'Engineering Design', by Dieter, McGraw Hill, 1989.
4. 'Total Design', by S Pugh, Addison Wesley, 1991.
5. 'Case Studies in Engineering Design', by C Matthews, Arnold, 1998.
6. 'Mechanical Behaviour of Materials', by N E Dowling, Prentice - Hall, 1993.
7. 'Composites - Design Manual', by J A Quinn, J A Quinn Associates, Liverpool, L25 4SY, 2002.
8. ** 'Mechanical Design', by Peter R N Childs, Arnold, 1998.
9. 'Machine Elements in Mechanical Design', by R L Mott, Prentice - Hall Inc., 3rd ed. 1999.
10. 'Design of Machinery', by R L Norton, McGraw - Hill International Editions, 1999.
11. 'The Engineering Design Process', A Ertas and J C Jones, John Wiley and Sons, 1993.
12. 'Engineer's Toolkit - Engineering Ethics', by C Mitcham and R S Duvall, Prentice Hall, 2000.
13. 'An Engineer's Responsibility for Safety, Safety by Design', The Hazards Forum, 1996, ISBN: 0 9525103 1 6.
14. 'Modern Ceramic Engineering - Properties, Processing and Use in Design', D W Richerson, CRC Taylor and Francis, 2006, ISBN: 1-57444-693-2
Specifically about Engines / Vehicles:
Web site
Excellent animations of a wide variety of engines by Matt Keveney.
Web Site How Stuff Works - Auto
15. 'The Motor Vehicle, Newton, Steeds and Garrett, various editions.
16. 'Bosch Automotive Handbook', H Bauer(Ed.), Published by Bosch, distributed by SAE, 2000.
17. 'Gasoline Fuel-Injection Systems L-Jetronic', Technical Instruction, Bosch, 1999, ISBN: 3-934584-29-2.
18 'Engines, an Introduction', J L Lumley, Cambridge University Press, 1999, ISBN: 0-521-64489-5.
19. 'Internal Combustion Engines', C R Ferguson and A T Kirkpatrick, John Wiley and Sons, 2nd Ed. 2001, ISBN: 0-471-35617-4. The publishers web site has some useful Java applets.
20. 'The Romance of Engines', by T Suzuki, Society of Automotive Engineers, Inc., 1997.
21. 'R-2800 - Pratt & Whitney's Dependable Masterpiece', by G White, SAE, 2001.
Resources on Propellers, Water Jets and Resistance.
Resources on Propellers, water jets and resistance
Under Water Vehicles:
22. 'An Introduction to ROV Operations' by G Last and P Williams, Oil Field Publications Ltd.
23. 'Handbook for ROV Pilot Technicians', by C Bell, M Bayliss, R Warburton, Oil Field Publications Ltd.
24. 'Submersible Vehicle Design Systems', by E E Allmendinger, 1990.
25. 'Design Aspects of Under Water Intervention Systems', by J G Hawley, M L Nuckols, G T Reader, I J Potter, Pub. Kendall Hunt, 1996.
Useful Reference:
26. 'Without Hot Air', by David J C MacKay, 2009. Free online: A lot of useful information on energy.
27. 'Roark's Formulas for Stress and Strain', by W C Young, 7th Ed. McGraw Hill.
** Indicates the text includes tables / charts from Raimondi and Boyd for plain bearing design.

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David J Grieve, 25th January 2011.