BUV DESIGN TEAM

Mike NaughtonAaron McKibbenGabe CurrierWilliam Ortiz

Introduction

Task: To design and build a Basic Utility Vehicle (BUV) prototypeVehicle to be used in developing countries in rural areasUse many existing components Bottom line: Low cost – High durability

Customer Requirements

Cost as a kit $900 (less engine)Payload of 1000 lbsTop speed of 20mphRange of 100 milesWidth 4.4ft Ground clearance 8inFull safety equipment

Performance Requirements

Climb 10% slope at 6mph (full loaded)Engine dry in 3ft of waterBrakes lock two or more wheelsTow 385lb trailer w/ 50lb tongue wtAccess to brake when pushing in reverse

Front Suspension

Double A-armLeaf/solidCoil/solidMacPherson StrutTransverse leafNone

Criterion Wt Double

A-A

rm

Leaf/

Solid

Coil/S

olid

MacP

hers

on S

trut

Tra

nsvers

e

None

Cost 7 -1 -1 -1 -1 -1 D

Durability 10 1 1 1 1 1 A

Simplicity 8 -1 -1 -1 -1 -1 T

Load Capability 7 0 0 0 0 0 U

Maintenance 6 -1 -1 -1 1 0 M

Manufacturing 7 -1 -1 -1 -1 -1

Attach to Chassis 6 -1 0 -1 -1 -1

Light Weight 4 -1 -1 -1 1 -1Vibration Transfer to Chassis 4 1 1 1 1 1

Comfort 5 1 1 1 1 1

Safety 6 1 1 1 1 1

Handling 8 1 1 1 1 1Logical Failure Mode 6 1 1 1 1 1

Aesthetics 1 1 1 1 1 1

Compact 5 -1 0 -1 -1 0

Total + 7 7 7 9 7 0

Total - 7 5 7 5 5 0

Overall Total 0 2 0 4 2 0

Weighted Total -3 8 -3 17 8 0

Front Suspension

Best result for front suspension

MacPherson StrutHas good handling and low vibrationIt is durableEasy integration

Steering

Rack and PinionGo-kart4 WheelerRecirculating-ball

Criterion Wt Ra

ck a

nd

Pin

ion

Go

-ka

rt

4 W

he

ele

r

Re

cir

cu

latin

g

ba

ll

Cost 7 0 1 1 D

Durability 5 1 -1 1 A

Simplicity 8 0 1 1 T

Maintenance 9 1 1 1 U

Availability 7 -1 1 1 M

Replace ability 4 0 1 1

Lightweight 3 -1 1 -1

Aesthetics 1 1 -1 1

Attachment to vehicle 7 1 1 1

Low input force required to turn 10 1 -1 -1

Driver feedback 3 1 -1 1

Total + 6 7 9

Total - 2 4 3

Overall total 4 3 5

Weighted total 25 26 38

Steering

Best result for steering

4 WheelerSimple designEasy to maintainLow costEasy to handle

Brakes

Mechanical Cam BrakeMechanical Spread LeverMechanical Disc BrakeHydraulic ServoHydraulic SimplexHydraulic Disc Brake

Criterion Wt Me

ch

an

ica

l

Ca

m B

rake

Me

ch

an

ica

l

Sp

rea

d L

eve

r

Me

ch

an

ica

l

Dis

c B

rake

Hyd

rau

lic S

erv

o

Hyd

rau

lic

Sim

ple

x

Hyd

rau

lic D

isc

Bra

ke

Cost 7 1 1 1 1 1 D

Durability 8 -1 -1 -1 -1 -1 A

Simplicity 8 1 1 1 1 1 T

Performance 6 -1 -1 -1 -1 -1 U

Maintenance 6 -1 -1 -1 1 1 M

Availability for mass production 10 1 1 -1 0 0

Replace ability 7 1 1 1 1 1

Lightweight 2 1 1 -1 1 1

Lubrication 4 1 1 1 0 0

Attachment to vehicle 7 1 1 1 0 0

Input Force 9 -1 -1 1 -1 -1

Logical failure mode 7 -1 0 0 0 0

Total + 7 7 7 5 5

Total - 5 4 5 3 3

Overall total 2 3 2 2 2

Weighted total 9 16 10 7 7

Brakes

Best result for brakes

Mechanical Spread LeverSimple designTorque ranging from 3500lb.in. to 74000lb.inApplicable to many designsLow cost

Rear Suspension

MacPherson StrutDouble A-armSwing armTwo leaf over solid axleSolid axle with trailing arm and coil over shocksNone

Criterion Wt Ma

cP

he

rso

n

Str

ut

Do

ub

le A

arm

Sw

ing

Arm

Tw

o L

ea

f O

ve

r

So

lid

Axe

.

So

lid

axil w

ith

tra

ilin

g a

rm a

nd

co

il o

ve

r sh

ocks

Da

tum

No

Su

sp

en

sio

n

Durability 10 1 1 1 1 1

Cost 7 -1 -1 -1 -1 -1Vibration Transfer to Chassis 6 1 1 1 1 1

Integration to chassis 5 -1 -1 0 -1 -1 Availability for mass production 8 0 0 0 0 0

Compactness 5 -1 -1 0 -1 -1

Maintenance 6 0 -1 0 -1 -1

Handling 7 1 1 1 1 1

Simplicity 8 -1 -1 -1 -1 -1

Replacement 4 1 0 0 0 0

Light Weight 3 -1 -1 -1 -1 -1Load Capability 8 1 1 1 1 1

Logical Failure Mode 7 1 1 1 1 1

Aesthetics 1 1 1 1 -1 -1

Total + 7 6 6 5 5

Total - 5 6 3 7 7

Overall total 2 0 3 -2 -2

Weighted total 15 5 21 3 3

Rear Suspension

Best result for rear suspension

Swing armLow costSimple designLoad carrying

Best result for rear suspension

Swing armHonda 4 wheeler

Drive train

CVT with chainCVT with FNR gear boxHydrostatic transaxleManual transaxleManual gear box with clutch

Criterion Wt CV

T w

/ch

ain

CV

T w

/ F

NR

g-b

ox

Hyd

rosta

tic

tra

nsa

xle

Ma

nu

al tr

an

sa

xle

Ma

nu

al g

-bo

x

w/c

lutc

h

Cost 10 1 0 1 1 D

Avaliability 8 2 2 1 1 A

Efficiency 6 0 0 -1 0 T

Light weight 4 2 1 1 1 U

Durability 10 0 0 -1 0 M

Simplicity 7 1 0 -1 0

Maintence 8 1 0 0 0

Replacement 5 2 1 0 0Integration to chassis 7 1 1 0 0

Reverse? 3 -1 0 0 0

Vibration 6 0 0 1 0

Noise 3 -1 -1 1 0

Ease of operation 7 1 1 1 0

Total + 11 6 6 3

Total - 2 1 3 0

Overall Total 9 5 3 3

Weighted Total 44 34 8 22

Drivetrain

Best result for drive train

CVT with chainVery efficient Light weightSimple designLow cost

Chassis

Triangulated space frameUnit body constructionLadder frame

Criterion Wt Tri

an

gu

late

d

sp

ace

fra

me

Un

it b

od

y

co

nstr

uctio

n

La

dd

er

fra

me

Mat. Cost 8 0 -1 D

Manuf. Cost 10 0 -2 ABending Stiffness 6 0 0 T

Torsional Stiffness 9 1 1 U

Lightweight 5 1 1 M

Repair 9 1 -1

Integration of components 7 1 1

Aesthetics 2 0 1

Total + 4 4

Total - 0 4

Overall Total 4 0

Weighted Total 30 -12

Chassis

Best result for chassis

Triangulated space frameLow material costLow manufacturing costHigh strengthFairly simple design

Preliminary Design

Begin Final Design Process

Decided on final chassis designMaterial selectionConducted preliminary chassis analysis by handConducted advanced chassis analysis using ANSYSConstructed modelComplied all data

Final Chassis Design Sketch

Pro-E Drawing of Final Design

Shear & Moment Analysis

Chassis modeled as simple beamExternal forces modeled as distributed loads across beamReaction forces found at shock locationsShear force and bending moment diagrams plotted

Shear Force DiagramShear Force

-150.00

-100.00

-50.00

0.00

50.00

100.00

150.00

200.00

250.00

300.00

350.00

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00

x (ft)

V (lb

s)

V

Bending Moment DiagramBending Moment

-400.00

-350.00

-300.00

-250.00

-200.00

-150.00

-100.00

-50.00

0.00

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00

X (ft)

Mc

(lb ft

)

Mc

Bending-Moments by Parts

Simplified by 2-D analysis.(M/EI) diagram is drawn for each load, and the angle θ is obtained by adding algebraically the areas under the various diagrams. (EIθ = A1 + A2 + A3)(M/EI) diagram is drawn for each load, the tangential deviation t is obtained by adding the first moments of these areas about a vertical axis. (EIt = c1A1 + c2A2 + c3A3)

Areas and centroids of common shapes

When a bending-moment or (M/EI) diagram is drawn by parts, the various areas defined by the diagram consist of simple geometric shapes, such as rectangles, triangles, and parabolic spandrels.

The bending-moment results

ANSYS Analysis Steps

Model in Pro-EngineerImport to ANSYSAdd constraintsAdd loadsRun solutionAnalyze results

Loads and Constraints

Maximum Stress Area

Comparison of the two analysis

Analytically we obtained a bending-moment of 341.27 lbs-ft at the cargo area inner weld joints, considering point loads and 2-D analysis. ANSYS we obtained a stress of 3111 psi at the seating area weld joints, considering distributed loads and 3-D analysis.

BUV Model

Scale: 1 inch = 1 footThe model helped the group make recommendations for improvements.

Recommendations

Add 1 foot to the cargo areaAdd additional support under seating areaChanges to front of chassis to accommodate steering linkages

Questions?