MAJOR_ASSIGNMENT.PDF

7/27/2019 MAJOR_ASSIGNMENT.PDF

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Stefan WilliamsMay 2003

Mech 1540, Introduction to MechatronicsMajor Assignment due 16

th June

(Tutorial on 12th

June)

Please Read these Instructions Very Carefully

General: The Major Assignment is worth 50% of the final mark for Mech 1540

Introduction to Mechatronics. You are expected to spend 10-15 hours(including the tutorial times) on this assignment. The completed assignment

should be placed in the appropriate assignment box on the 3rd floor of themechanical engineering building by the due date. Please do not copy from

other students in this assignment. If copying is detected, then all suspectedparties will be given a zero mark. You have been warned. You may usematerial from other sources (books, the web, etc) but these sources must be

acknowledged.

Goals: The goal of this assignment is to apply what you have learned in thiscourse to the design of a mechatronic system. The intention is to get you tothink about what you have seen and to come up with an original design for a

practical system. The design should be sensible and considered. Emphasis isto be placed on system design and on clear concept. Technical information

should be no more extensive than that found in the lecture notes.

Directions: You are required to submit a written report detailing the design of

the mechatronic components (sensors, actuators, computers and controllers)of an engine management system for a small racing vehicle similar to thatdeveloped for the Formula Sae competition. A description of the vehicle andits operation are included here. The design report should consist of no morethan 10 pages including figures. You should assume that the mechanical

engineering design of the vehicle is complete and is as detailed in the

following description.



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The Report:

Your report should consist of the following sections (required headings areunderlined):

1. A Summary Description of the system. This should be approximately 1-2 pages, include a requirements analysis, functional and environment

specification, and an overall block-diagram showing how all thecomponents in the system relate to each other. Please focus on the

mechatronic components of the system.2. A Component Description in which specific hardware choices for the

actuators, sensors and other mechatronic components are made (4-5pages). In particular, you should provide:a) A considered choice for each of the actuators, and a description of

how they are controlled and powered.b) A considered choice for each of the sensors, how measurements

are acquired and processed to provide control information.c) Appropriate block diagrams that expand and explain how each

component (actuator, sensor, computer) relate to each other.3. A Process Description (or flow diagram) showing how the hardware

and software interact in sequence to achieve the desired function. Pay

particular attention to the detection and recovery from possible faults(2-3pages).

4. A brief summary of how well your design achieves the functional

specification and requirements laid down (fitness for purpose) (1 page).

Marks will be assigned according to the following breakdown:

1. Summary Description 10

2. Component Description 203. Process Description 10

4. Fitness for Purpose 55. Presentation 5

TOTAL 50



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The Formula SAE Car

The Formula SAE competition is for Society of Automotive Engineers (SAE)student members to conceive design, fabricate and compete with small

formula-style racing cars. Restrictions are placed on the car frame andengine so that the knowledge, creativity and imagination of the student are

challenged. Four cycle engines up to 610cc can be turbocharged orsupercharged to add a new dimension to the challenge of engine design. Thecars are built by a team of students over a period of one year and are taken toa host institution for judging and comparison with other competitors.

For the purpose of the competition, the students are to assume that amanufacturing firm has engaged them to produce a prototype car forevaluation as a production team. The intended sales market is the non-professional weekend autocross racer. Therefore the car must have very high

performance in terms of its acceleration, braking and handling qualities. Thecar must be low in cost, easy to maintain and reliable. In addition, the car’s

marketability is enhanced by other factors such as aesthetics, comfort anduse of common parts. The challenge to the design team is to design andfabricate a prototype car that best meets these goals and intents. Each

design will be compared and judged with other competing designs todetermine the best overall car.

The cars are judged in three different categories: static inspection andengineering design, solo performance trials and high performance trackendurance. These events are scored to determine how well the car performs.

In each event, the manufacturing firm has specified minimum acceptableperformance levels that are reflected in the scoring criteria. More information

on the Formula SAE comptetion can be found at the following websites:

http://www.aeromech.usyd.edu.au/sae

http://www.sae.org/students/formula.htm

http://www.sae-a.com.au/formula_sae

Figure 1 - The University of Sydney's 2001 Formula SAE car



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For the purposes of this assignment you are to assume that you have joinedthe team as part of the newly formed mechatronic engineering group. Yourresponsibility is to identify and design mechatronic systems that could be usedto enhance the car and aid in its development, tuning and operationalperformance. In particular, you should consider ONE of the following system

enhancements and design its interface with the existing mechanical system:1. Engine management unit – an Engine Management Unit (EMU) is

designed to regulate the fuel air mixture in the vehicle’s engine. Inputstypically consist of the throttle position, engine speed, temperature and

exhaust levels. Outputs include timing characteristics and control of thefuel valves. The current EMU on the Formula SAE car is implementedopen loop with tuning performed off-line on a dynamometer that measures

engine performance under various operating conditions. More advancedsystems also monitor wheel speeds, braking effort and emissions to further

refine the engine settings and adapt to changing driving conditions – some

even adaptively change the EMU behaviour by monitoring engineperformance. Propose a design for the EMU that incorporates feedback

and demonstrate how this will lead to improved engine performance.

www.efitechnology.com/engcontrol.html

www.sts.sae.org/membersonly/techinfo/servicetech/oxygen13-17.pdf

www.simcar.com/literature/sae950417/sae950417.htm

2. Telemetry system – tuning of the engine can be done using a

dynamometer to measure engine performance off of the track. However,important information relating to the performance of the car itself should

also be collected during vehicle operation. This includes such things assteering angles, throttle position and resulting accelerations of the vehicle,wheel speeds and stresses in the suspension and other components. In

high performance race cars this information is monitored during the race tomonitor the system performance and optimize the race plan. Propose a

telemetry system for the Formula SAE vehicle. Consider the pros andcons of designing a system to be used solely during testing versus onethat might be used during the race itself.

www.howstuffworks.com/champ-car7.htm

http://www.plextek.co.uk/pages/brochure/f1.pdf



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3. Drive by wire – Traditional road vehicles, including the Formula SAE car,

rely on mechanical linkages between the steering, throttle and brakes andthe devices they control. There has been a significant amount of workrecently on the development of drive by wire systems, similar to thosefound in advanced fighter aircraft. These systems work by replacing

conventional mechanical control systems with sensors that monitor thepedal positions and send this information to an engine control module. By

eliminating the mechanical elements and transmitting a vehicle's throttleposition electronically, drive-by-wire greatly reduces the number of moving

parts in the throttle system. This can lead to greater accuracy, reducedweight, and, theoretically, reduced service requirements. Design a driverby wire system suitable for the Formula SAE car.

www.edmunds.com/news/innovations/articles/43033/article.html

www.daimlerchrysler.com/specials/sidestick/sidestick1_e.htm

www.citroen.com/site/htm/en/technologies/tomorrow/drivebywire

4. Anti-lock brakes – Anti-lock brakes are designed to minimize the skid in a

wheel during hard braking. A skidding wheel (where the tire contact patchis sliding relative to the road) has less traction than a non-skidding wheel.By keeping the wheels from skidding while the vehicle slows down, anti-lock brakes provide a twofold benefit: the car will stop faster, and the driverwill be able to steer while stopping. Anti-lock braking systems monitorvehicle speed when the brakes are applied. A sudden deceleration in

wheel speed is often an indication that the wheels have locked up and arebeginning to skid. A controller dynamically adjusts braking pressure to

keep the wheel from locking up. Propose an anti-lock braking system

appropriate for the Formula SAE vehicle.

auto.howstuffworks.com/anti-lock-brake.htm

http://autorepair.about.com/library/weekly/aa052001a.htm

www.intel.com/design/mcs96/designex/2351.htm

5. Active suspension – A typical suspension system consists of a springand damper in parallel. The spring exerts a force proportional todisplacement while the damper exerts a force proportional to the rate ofchange of displacement. The parameters for these two components areselected based on the characteristics of the vehicle, anticipated operating

conditions and desired performance of the suspension system. Stiffersuspension is often appropriate for high speed applications but causessignificantly more vibration to be transmitted to the driver. Active

suspension systems dynamically adjust the stiffness and dampingconstants to minimize disturbances to the vehicle. This can result in

improved vehicle handling and performance. Propose an activesuspension system to be used with the Formula SAE vehicle.

www-control.eng.cam.ac.uk/gww/what_is_active.html

e-www.motorola.com/webapp/sps/site/application.jsp?nodeId=02M0ylfWcbfM0ym4PgS8



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6. Vehicle dynamics controller – a vehicle dynamic controller monitors the

motion of the vehicle and adjusts braking, and sometimes steering, of thefour wheels independently to assist in controlling the dynamics of thevehicle. The car assists the driver in maintaining control of the vehicleduring hard cornering or during loss of traction. This technology effectively

combines advances in Anti-lock braking with traction control systems toimprove vehicle handling and control. Propose a vehicle dynamics

controller design suitable for the Formula SAE vehicle and show how it willimprove vehicle performance.

www.kraftfahrzeugtechnik-heute.de/k/en/esp/index_flash.jsp

www.abs-education.org/ishs/techindex.html

www.subaru.net/prototype/vdc.html

You should research your chosen system and consider alternatives

appropriate to the Formula SAE vehicle. In particular, pay attention not onlyto the technical merit of your solution but consider its appropriateness from afinancial perspective as well. More information regarding these systems can

be found at the websites supplied above. Consider this a starting point for theresearch and not a comprehensive source of information. Texts relating to

these systems are also available in the library. The appendix at the back ofthis handout contains the design report for the University of Sydney’s 2001Formula SAE entry detailing the major components of the car.



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Appendix A: University of Sydney Formula SAE 2001

Design Report

The following report details the design of the 2001 University of SydneyFormula SAE vehicle. It details the design criteria and provides a high leveloverview of major components of the system.



USYD FORMULA SAE 2001

En g i n e e r e d t o W i n ManualFSAE-006

USYD FSAE DESIGN REPORT

An overview of the University of Sydney’s Formula SAE Race Car Design. Outlining

detailed characteristics of the final product and reasons for design methodology andapplication.

Produced By:

Denis MesarosTeam LeaderUSYD FSAE 2001

Date: 20th September 2001 Signed:

Approved By:Paul McHughTeam Adviser

School of Aerospace, Mechanical,Mechatronic Engineering.

Date: 20th October 2001 Signed:

Implementation Date: 2/11/2001

Approved Document The Original of this document has been signed




USYD FSAE Design Report Issue 1, 21/05/03FSAE-006 Approved Page 2 of 10

TABLE OF CONTENTS

GENERAL OVERVIEW OF DESIGN.................................................................................................................................3

R ELIABILITY ...............................................................................................................................................................................3 SAFETY........................................................................................................................................................................................3 LOW WEIGHT..............................................................................................................................................................................3 SIMPLE ALL R OUND ..................................................................................................................................................................3 HIGH OVERALL PERFORMANCE...............................................................................................................................................3 EASY ACCESS .............................................................................................................................................................................4 EASE OF MANUFACTURE ..........................................................................................................................................................4 LOW COST ...................................................................................................................................................................................4

DESIGN OF THE CHASSIS ...................................................................................................................................................5

OVERALL FRAME DESIGN CONSIDERATIONS........................................................................................................................5 TUBE SIZES AND MATERIALS USED ON THE FRAME...............................................................................................................5 BODY CONSTRUCTION...............................................................................................................................................................5

ERGONOMICS..............................................................................................................................................................................5 DESIGN OF SUSPENSION SYSTEM..................................................................................................................................6

OVERALL SUSPENSION DESIGN CONSIDERATION .................................................................................................................6 FINAL SUSPENSION SPECIFICATIONS......................................................................................................................................7

DESIGN OF BRAKING SYSTEM ........................................................................................................................................7

OVERALL BRAKE DESIGN CONSIDERATIONS........................................................................................................................7 BRAKE DESIGN SPREADSHEET.................................................................................................................................................8

DESIGN OF POWER-TRAIN SYSTEM .............................................................................................................................9

DIFFERENTIAL............................................................................................................................................................................9 I NLET ...........................................................................................................................................................................................9 E NGINE COOLING.......................................................................................................................................................................9 FUEL SYSTEM DESIGN...............................................................................................................................................................9

FINAL PRODUCT .................................................................................................................................................................. 10

FRONT VIEW.............................................................................................................................................................................10 R EAR VIEW...............................................................................................................................................................................10





General Overview of DesignThe design of the University of Sydney’s Formula SAE Racecar has been governed by the following criteria’s we

set for ourselves.

1. Reliability

2. Safety3. Low Weight4. Simple All Round

5. High Overall Performance6. Easy Access7. Ease of Manufacture

8. Low Cost

A brief rundown of each design objective is given below.

Reliability

From our observations of last years contest we made the conclusion that reliability was clearly the most important

design component of the car. On our return from the 2000 competition, the team sat together and made a list ofwhat we thought were the key lessons to learn from our observations and research. The outcome of that list

provided the grounds to decide what to focus on in our designs. We immediately decided that RELIABILITY wasour first design priority. We want to have a car that is engineered to last and to be reliable in all components. Wefound that many Australian teams had many technical problems with their cars last year and things kept breaking

down. Hence we wanted to make sure our car does not break down and competes with its full potential.

Safety

Safety is important in any project. Our high regard to health and safety has seen that our second design objective isto ensure the car is structurally sound and that driver safety is paramount. We have carefully followed all SAE

Rules and guidelines in terms of required roll-hoop design and side impact design and in most cases exceededminimum requirements for driver safety. Our designs give reassurance to the driver that their safety is not

compromised and that safety has been factored into the design of the car.

Low Weight

An obvious design feature if one expects to perform well. We have designed the car so that every component has been optimised to the bare minimum mass possible . Although the above two factors has ensured that our carweight is slightly more then what we budgeted for. Our initial target was approximately 200kg total mass (not

including driver), although our final mass is slightly over 250kg. The reason for this is that the frame has beenslightly over engineered to ensure a stiff frame in all locations has been attained and that the frame remains reliableunder the most severe tests. We could have decreased mass; although as mentioned earlier we wanted to make sure

that the car is reliable and safe hence decided to keep it as it is.

Simple All Round

Keep it simple is the key. Another outcome of our observations in last year’s competition was that the car should be designed to be simple. We therefore designed the car to be simple in every aspect including frame, suspension,

braking, engine, steering and body shell. You will find that there are no complex components in our design.Everything on the car serves a purpose and does so with the minimum complexity. The result of keeping ourdesigns simple is that reliability remains and there are less complex problems to solve when bugs appear. It is clear

to see that our car has one mission and that is what its been designed for – (to compete well in the competition).We have omitted any added complexities such as electric controlled gearing, ABS, Turbo-charging and Engine-Reworking to ensure the car remains simple. The less complex our car and components is, the lesser the chance of

something failing during competition

High Overall Performance

To be competitive our car must be designed to perform well in all events. Our suspension, brakes, chassis andengine have been designed and adapted so that the car performs well primarily in acceleration, braking, cornering

and fuel economy. Our intake and exhaust have been designed such that the engine has maximum volumetric





efficiency and the chassis is designed to consider suspension kinematics and load transfer. The weigh distributionwas factored in so that the car has symmetry of weight distribution and a low centre of gravity with respect to ourdesigned roll centres.

Easy Access

Our car has been designed so that every component in the car is positioned so that there is easy access to it shouldany work need to be made to it. You will find that every major component in the racecar can be accessed directlywithout having to remove any other major component. For example, our diff can be removed and inserted easily

just by removing one bar; our entire engine can be removed easily and accessed easily should any work berequired on it easily just by removing the roll-hoop bracing and ancillaries. By making the car easily accessible,this further adds to ease of maintenance and ease of operation.

Ease of Manufacture

It is important that our racecar is easy to manufacture. Our team is one of the only teams in Australia to entirely build the racecar on our own. We have had to learn how to weld, lathe, machine and more to be able to have thesatisfaction of building our racecar entirely ourselves with no other assistance. To do so our designs had to ensure

that we could manufacture what we were designing. We used DFM (Design for Manufacture) & DFA (Design for

Assembly) techniques to ensure that our car was easily manufacturable and also easily assembled. As an added benefit, by making the car easily manufacturable using DFM & DFA, we found that we could keep the costs down

at the same time and also adapt our simplicity and reliability objectives as well. Our DFM & DFA methods hasalso kept the number of parts to a minimum and therefore reduced the chances of things failing.

Low Cost

We wanted to ensure our car was valued in the reach of a typical autocross enthusiast. Our targeted market

suggested that the maximum cost should not exceed $60000 AUD. Hence our designs needed to ensure that wekept within this limit. Our actual aim was to make the one prototype worth no more than $50 000 AUD so that inactual industry competit iveness our car will be attractive to buyers as being the best value for money.

Below is our final Racecar Design as designed using solid modelling software (SolidWorks®). The model gives anaccurate presentation of what our final Racecar design looks like.





Design of the Chassis

Overall Frame Design Considerations

The chassis is a space frame design where all tube members meet at nodal points. This was chosen over other

chassis types such as monocoque chassis do to its ability to retain high efficiency without difficult design andmanufacturing processes. The space frame construction ensures that all tubes are in ether tension or compressionmaking the most efficient use out of the material. We decided to use Chromoly 4130 tubing for our tube material

since its strength in tension is superior to mild steel. Althoughit’s higher difficulty to weld and treat than mild steel theexpertise on the team was sufficient enough to make use of the

higher tensile properties of the material. This allowed theframe to have increased stiffness without the added weight. Theframe was designed to take into account the geometries of the

suspension components and the dimensions required by theengine and drive train. With those constraints, along with theconstraints of the 2001 Formula SAE design and safety rules,

the above chassis was designed to meet all interfacing needs

and at the same time efforts were made to minimise weightwhere possible. As a first year team reliability was a

strongpoint we aimed for and thus the frame does has minorover-engineering in areas based on the fact that adding a fewmore grams wont hurt when reliabili ty is critical.

Tube sizes and materials used on the frame.

-Alternate tubing sizes were used for the side impact members. Under the alternate tubing requirements the tubesmust have a minimum wall thickness of 2.1mm and must show equivalency to the sizes given for mild steel. Thealternate tube size was calculated using the solver function with in Microsoft Excel. The solver allowed the tube

dimensions to be optimised in relation to size and we ight and resulted in a tube size that possessed increasedstrength in compression and tension, with a decrease in weight compared to the mild steel tube sizes given.

- Calculations were performed which indicated that the use of Chromoly Steel provided a significant increase instrength (tension) over the use of mild steel. This arises, as the tensile strength of Chromoly steel is significantlylarger than for mild steel. It must also be noted that the density of chromoly and mild steel is the same, indicating

that tubes with the equivalent size will have the same weight. These factors indicate that the use of Chormoly steelwill yield a frame that is the same weight as mild steel but with an increased strength. It is no wonder most professional racecar manufacturers use this material for their racecars.

Body construction

- The body comprises of Aluminium panels, a fibreglass nose cone and a single fibreglass side pod. Thealuminium panels are used on the outer skin of the vehicle in the side impact regions. These are simple, light -weight and provide a safe barrier around the middle body region of the driver. The fibreglass side pod is located on

the left hand side of the vehicle around the radiator. The purpose of the side pod is to provide an air inlet to directthe flow of air into the radiator. The side pod is constructed of fibreglass, which is relatively lightweight and issimple and easy to construct, especially when multiple components are made. The use of fibreglass also allows

repairs to be easily performed. The fibreglass nose cone provides a cover for the front section of the vehicle that isdurable and aesthetically pleasing. Both the nose cone and the side pod are attached to the frame via Oddie ¼ turnfasteners, which allow for fast and easy attachment and removal of the component. This allows for easy access to

the components covered by these body members.

Ergonomics

The instrumentation, seating and controls were all designed with the utmost attention being paid to ergonomicfactors. This was conducted in order to develop the best possible interaction between driver and vehicle, which iscrucial in the development of a race vehicle.





Design of Suspension SystemOverall Suspension Design Consideration

The suspension system is a double wishbone, with non-equal and non-parallel arms. The suspension geometry wasdesigned and analysed in bump and roll in order to give the optimal camber gain to maximise grip. The car uses an

inboard type suspension system front and rear, with pushrod-actuated coil over dampers, adjustable in rebound andcompression. Aluminium bell cranks connect the pushrod and shocks. The uprights and wheel assembly wheredesigned to reduce unsprung mass, whilst maintaining low cost and reliability. The entire suspension system was

CAD modelled and FEA analysis was performed in order to optimise components and the entire suspension

system. The front suspension was designed to help give the best handling characteristics. A caster angle of 7°

together with King Pin Inclination of 0° where used as they give desirable camber effects in steering. The steering

rack was located to eliminate bump steer. Below are some illustrations of designs of suspension components andgeometries.

Rear Suspension System Front Suspension System

Illustrated below are stress analysis results showing the stress contours acting under maximum loadings with adegree of safety factors. Alongside these results are pictures of actual manufactured components.

Some stress results for the bell crank design and wheel hubs.





The suspension geometry was simulated and optimised using the SusProg3D®. Assembly and cut out views of therear and front wheel assemblies are shown below respectively.

Final Suspension Specifications

Type: Double Wishbone, non-parallel, unequal length

Pushrod actuated DNM coil-over dampersConstruction: 4130 Chromoly A -arms and pushrodsWheels: 13” x 5.5” Auscar

Tyres: Yokohama A032R 175/60 R13 Wet & Dry Approved Race TyresWheel Base: 1760mmFront Track: 1315mm

Rear Track: 1225mm

Front Caster: 7°

King Pin Inclination (KPI): 0°

Scrub radius: 14mmCaster Trail: 20mmFront roll centre height: 25mm

Rear roll centre height: 40mm

Design of Braking SystemOverall Brake Design Considerations

Our braking system incorporated the Dual hydraulic circuit (2 master cylinders) as required by the SAE Rules. Weare using four wheel braking, due to our differentia l design. The negative side to this is that we increase theunsprung mass of the suspension assembly. Although reliability, safety, easy access and braking performance is

upheld by doing so

Our car is designed to stop in 33m, with factor of safety in the friction coefficient between pad and disc. The pedal

effort requirement is 65kg. (50 front and 15 rear).

Rear Wheel &Brake Assembly

Front Wheel &

Brake Assembly





The brake design based on the uniform pressure assumption (Norton V5):

Where •T- Braking torque •F- Axial force on disc

•um- Friction coefficient between pad and disc.•r i,r o- inner and outer disc radius respectively

•At- area factor

•N- number of friction surfaces

The force analysis completed on the our car, assuming a deceleration of 1.2 g’s, approximately 70% rearwardCOM, weight of driver and car approximated at 350kg. Hence moments were taken about the front and rear wheelsto find the reaction torque. This torque is then inserted into the uniform pressure equation and the axial force is

found. The results were placed in a spreadsheet and the solver function was used to come to an optimised

condition for braking design requirements as shown below.

Brake Design Spreadsheet

The space within the wheel proved to be a governing factor thatdetermined the maximum disk diameter and calliper size. As can be

seen in the diagram on the right, there is minimal clearance betweenthe calliper and wheel. By searching existing motorcycle brakes wefound a unit that perfectly matched our design requirements .

The disc front and rear was sourced from a CBR900 rear disc unit. R o-110mm, R i-75mm. Front callipers are adual piston floating calliper with Piston f 30mm, pad area 44.6cm2. Rear callipers are also dual piston floating

Preliminary Brake Design for SAE car

Brake for SUFSAE

Values Description

Fixed FrontPad force 30858.06637 Force of pad on disc

Ro (m) 0.11 outer disk diameter Required pedal effort (N) 321.4381914 Using ME's

Ri (m) 0.075 inner disk diameter (front) Required pedal effort (Kg) 32.76638037

Rir (m) 0.1 inner disk diameter (rear)

vehicle mass (kg) 350 Rear Master cylinder Diameter (m):mc 0.015 Pad Force 11250.79797

Front Calliper piston diameter:fcp 0.03 Required Pedal Effort 168.7619696

Rear Calliper piston diameter: rcp 0.025 Required pedal effort (Kg) 17.203055

Number of pistons front 2

Number of Pistons rear 2

Length b/w pivot and pushrod 50

Length b/w pivot and foot 300

Variable

Friction coefficient :U_1 0.3 Between pad and disk

deceleration (m2/s) :a 11.799367 100km/hr to 0 in 33m

Wheel base (m) :xt 1.73 between front and rear wheels

COM height (m) :y 0.39 height of centre of mass

friction coefficient :U_2 1.2027897 Longitudinal force between tire and roadangle of pad contact (radians) :B Front 0.6981317 Enter chosen angle

angle of pad contact (radians) :Brear

Hydraulic Mechanical Advantage (Front 16

Hydraulic Mechanical Advantage (Rear) 11.111111

Pedal mechanical advantage 6

)(

)(

3

233

33

io

io

t

r r

r r FA N T

−

−

= µ

Caliper

Clearance

Upright/hub assembly





calliper with Piston f 25mm, pad area 14.5cm2. We are using dual master cylinders with Bore f 5/8”. The remotereservoirs are raised above the height of the callipers, which will remove possibility of brake fluid flow back.

The pedal effort biased is made through the use of a bias bar, which distributes the foot load to front and rearcylinders as required. By rotating the bar the pedal effort is distributed in the ratio of pushrod distances from thecentre of the bar.

Design of Power-Train System

Differential

The Differential is a Japanese Specification Limited Slip Ball Type Competition Differential. It has been adaptedfrom a front wheel drive Mitsubishi Mirage Cup Mivec Car. Originally, the differential was in a transversemounted gearbox and had an extremely high preload, which was tuned for a 140kW, 1000kg vehicle. This all had

to be modified and adapted to suit a rear wheel drive vehicle with much less power, and less than one third themass. Tuning of the differential is very important to allow maximum traction under acceleration and braking,whilst not compromising vehicle turn-in when entering or exiting a corner.

Inlet

The standard Honda CBR-600 engine has a carburettor at each cylinder, and draws air from a settling chamberlocated after the air filter. This has been thrown out as we opted for electronic fuel injection to maximize performance. The entire inlet had to be redesigned to accommodate the mandatory restrictor of 20mm in diameter,

and to house the injectors.

The inlet has been tuned to match the exhaust to improve engine efficiency over a particular rev band. The tuning

of the inlet was performed by implementing Helmholtz resonance tuning. The entire inlet manifold and pipesconstitute a mathematical model that should create peaks in efficiency at chosen revs. The inlet is manufacturedfrom an all aluminium construction featuring a carbon fibre inlet restrictor, which is a venturi design to minimize

losses.

Engine Cooling

The engine cooling is performed through a heat exchanger that has a puller fan mounted on the back. The radiatorhas been selected by using thermodynamic equations that allow us to select a size that suits “worst case scenario”.

The size allowable has a factor of safety to ensure that the engine will never overheat whilst the system functionswithin reasonable operating conditions. The radiator design is a cross-flow, finned tube heat exchanger. The driveroperates the puller fan by a toggle switch, so that the engine does not loose valuable power whilst on the track.

Clear images of the above components can be seen in the final product section on the next page.

Fuel System Design

The fuel system has been implemented as an efficient, low weight, low cost and performance oriented design. Aconfined space within the engine bay meant that the actual fuel tank features a complex shape that effectively

limits the overall system’s capacity to approximately 5.5 litres. Aluminium was selected as the primary fuel tankmaterial both due to its superior strength to weight ratio combined with its ease of manufacturability for thiscomplex shape. Baffles were designed and incorporated into the fuel tank design in order to minimise the

possibility of fuel splash and therefore fuel surge during the acceleration, braking and cornering cycles.

In line with SAE regulations the fuel system features screw type fittings on the high-pressure side of the fuel pump

as well as braided hoses for all fuel lines. This lowers the possibility of catastrophic damage to the fuel system inthe advent of an accident or mechanical failure, as well as providing improved aesthetics.




Final Product

Below are some pictures of the final product that has been designed (without body panels in place).

Front View

Rear View

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