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Project

Design of Floodlight Pole for

Playground Table of Contents

1. Problem description

2. Design Spiral3. Assumptions4. Selection of Geometry5. Pole material properties6. oad and !i"tures

#. $es% information&. 'on(ergence tests ) Plots*. +esults ) Plots1,. 'onclusion

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Problem definition & Design Objective

Aim of t%e pro-ect is to design a floodlig%t pole to be installed in aplayground of /0. Pole is 1, metre %ig% and %as to able tobalance a dead load of 2, g at t%e top and s%ould %a(e enoug%strengt% to support a maintenance person for t%e person to be able

to climb to t%e top for maintenance purposes

%e ob-ecti(e is to design a model %ic%

• s able to sustain %ig%er le(els of bending moment• %as lo er fle"ural stress induced by t%e bending moment• %as least deflection at free end• %as a factor of safety bet een 1.5 and 3• reasonable costs of production

Assumptions

%ese are t%e assumptions t%at e %a(e ta en in t%e design1. $aterial ill remain in elastic region2. Applied loads remain constant in direction and magnitude3. All cross sectional plane remains plane during ending4. Ground is assumed to be rigid

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Design Spiral

Selection of Geometry7e started t%e design process by considering a %ollo circular crosssection it% base outer radius 12, mm8 top outer radius 5, mm andt%ic ness 5 mm. After multiple iterations8 considering ourre9uirements8 e finally settled on a design it% base outer radius *,

mm8 top outer radius 4,mm and t%ic ness 5 mm. %is design ga(e usa !oS:2.1.

'onsidering ot%er cross sections it% same cross sectional area ast%e pre(ious design8 e analysed octagonal cross sections it%circular and octagonal %oles respecti(ely.

ased on t%e calculations ;s%o n in t%e ne"t page<8 e selected t%edesign it% %ollo circular cross section as it %ad t%e least flexuralstress !ig!est factor of safety among t%e t%ree designsconsuming same amount of material.

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Pole material properties 7e ould li e to select a material based on t%e follo ing properties

• =ptimum material strengt%•

>ase of manufacturability• >ase of maintenance• A(ailability• 'ost of material8 manufacturing and maintenance

After careful consideration of (arious materials and t%eir properties8e decided t%at t%e pole s%ould be made of gal(ani?ed steel.

!ollo ing are t%e properties of gal(ani?ed steel

"ame# Gal(ani?ed Steel$odel type# inear >lastic sotropic

%ailure criterion# $a" (on $ises Stress

ield strengt!# 2.,3*43e@,,& BmC2Tensile strengt!# 3.56*,1e@,,& BmC2'lastic modulus# 2e@,11 BmC2

Poisson(s ratio# ,.2*$ass density# #&#, gBmC3

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)oads and %ixtures7e %a(e 4 loads to consider in t%e design process.

%ey are

Self*+eig!t $ass of t%e pole is 154.2&& g and is assumed to act at its centre ofmass and t%e force is ,-,./0. "

Dead load at t!e topt accounts for t%e lig%t fi"tures at t%e top of t%e pole and is ta en to be 2,g and t%e force is ta en to be .00 " .

+eig!t of maintenance personDesign %as to be strong enoug% to support a maintenance person of 65

g and t%e force is considered to be 1-0 " .

Drag force of 2indPole %as been designed to it%stand strong %urricanes it% inds speedsaround 5, mBs.

Drag force :1

2×ρ × A×C d ×u

2

ρ – Density of air : 1.225 gBm 3

A – =rt%ograp%ic pro-ected area : 1.3 m 2

u E 7ind (elocity

' d E Drag coefficient ;Depends on geometry< : ,.4#n t%e orst case scenario it% ind speeds of 5, mBs8

drag force turns out to be 34-/-34 " %ic% acts on t%e top most pointperpendicular to t%e a"is of t%e pole.

%ixturesPole %as been grounded using a circular base plate of inner radius &5 mmand outer radius 14, mm and plate is fi"ed using & bolts of 2, mmdiameter and 2# t%reads per inc% ;tpi<.

$es! 5nformation

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$es! type Solid $es% ; etra%edral<6acobian points 4 PointsTotal "odes &##2#Total 'lements 4426#$aximum Aspect 7atio8A79 2*.116

: of elements 2it! A7 ; 4 ,.2&

: of elements 2it! A7 < ,0 2.#3: of distorted elements ,

Time to complete mes! ,& seconds

Convergence testsTest

"o/

"o/ of 'lements "o of "odes $ax Stress

8$Pa9

$ax

Displacement8cm9

$ax Strain $in %OS

1. 1#*42 32&53 #6.26 21.&1 3.12e F ,,4 2.#2. 2*1#6 5&&#* &6.5* 25.,4 3.5&e F ,,4 2.43. 3&4** &,4&4 *1.36 25.2& 3.&4e F ,,4 2.2

4. 4426# &##2# *#.21 2#.6& 3.66e F ,,4 2.1

Plots

0 50000 1000000

50

100

150

Max Stress

Max Stress (MPa)

No of Nodes

Max Stress (Mpa)

0 50000 1000000

10

0

!0

Max Displace"ent (c")

Max Displace"ent (c")

No of Nodes

Max Displace"ent (c")

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0000 #0000 $0000 %0000 1000000

1

!

Min F&S

Min F&S

No of Nodes

Min FoS

0 50000 1000000

1

!#5

Max Strain

Max Strain

No of Nodes

Max strain ( e'00#)

'onclusions

7e %a(e designed a floodlig%t pole it% %ollo circular polefulfilling t%e necessary design re9uirements.

ibliograp%y• GA >PS Data points for pole geometry• Drag Coefficient 8Wikipedia:The Free Encyclopedia. 7i imedia

!oundation8 nc8 7eb8 accessed on 25.1,.2,15%ttps BBen. i ipedia.orgB i iBDrag coefficient• =urricane 2ind velocities 8%ujita Scales9 8Wikipedia:The Free

Encyclopedia. 7i imedia !oundation8 nc8 7eb8 accessed on25.1,.2,15%ttps BBen. i ipedia.orgB i iB!u-ita scale

• Structure of a report8 Hni(ersity of +eading8 7eb8 accessed on

25.1,.2,158%ttps BB .reading.ac.u BinternalBstudyad(iceBStudy+esourcesB>ssaysBstaFstructuringreport.asp"