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ABSTRACT
Automotive Design with economy, safety and aesthetics have been agreat challenge to design engineers. The safety of the passengers during
vehicle crashes can be ensured to a certain limit by using good bumpers.
A bumper is a shield, made of steel, aluminium, rubber, or plastic .It is a
horizontal bar fixed across the front or back of a motor vehicle to reduce
damage in a collision , but this proect is more inclined to off road
vehicles where It is not a safety feature intended to prevent inury to
occupants in the passenger cars but basically designed to protect the
hood, trunk, grill, fuel, exhaust and cooling system as well as safety
related e!uipment such as parking lights, headlamps and taillights in low
speed collisions during a rough road travel or "x" off road Driving..
In this work polystyrene coated steel bumper and a aluminium #$%& alloy
is compared with various factors by which the steel bumper has
advantages such as #etter 'trength, #etter Thickness, (ood towing
capacity and increasing the traction of the vehicles. The values of Impact
analysis are compared with the 'elected )aterial.
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CHAPTER 1
INTRODUCTION.
WHAT IS OFF ROAD DRIVING ?
• *++ *ADI-( is raggy , uneven or an activity that includes steering
/ehicles or called 'ports utility /ehicles dirt tracks, mountain paths or
desert trails. It is pursued on terrain such as sand, gravel, snow, mud,
rock, grassland, riverbeds 0'hallow or Dry water1, and other natural
terrain 2 away from unpaved surfaces.• *ff3roading is done in all3terrain vehicles 0AT/s1, both four3 and two3
wheel, like "x"4s, eeps, snowmobiles, dirt bikes, !uad bikes, rock
crawlers and sand rails.
HISTORY OF OFF ROADING
• A +renchman by the name of Adolphe 56gresse was awarded with the
design of the world4s first off3road model.
• 56gresse designed a track in the style of a caterpillar, with a flexible belt,
which could be modified to a ordinary car or truck .
• A conventional eep, would have four3wheel drive, high3ground clearance
and low gearing. -owadays, there is a mind3boggling variety of off3road
vehicles out there for those people who like going on dirt, to choose from
both solidly heavy3duty and all3purpose light3duty.• *ff3roading events like the Dakar ally and the #aa 7&&& being among
the most famous. These events are a test of both navigational
competence and vehicle resilience power.
OFF ROADING IN INDIA
https://www.google.co.in/search?safe=off&q=define+competence&sa=X&ved=0ahUKEwjv9ufD_pvLAhVTCo4KHaHRBKwQ_SoIITAAhttps://www.google.co.in/search?safe=off&q=define+competence&sa=X&ved=0ahUKEwjv9ufD_pvLAhVTCo4KHaHRBKwQ_SoIITAA
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• *ff3roading terrain, while 8adakh4s high3altitude desert offers e!ually
favourable conditions for the activity. *ut west in (uarat, the salt
marshes of the ann of 5utch make for a uni!ue off3roading experience.
• +ew *ff oad /ehicles opted for Indian oads7. )ahindra Thar
9. Toyota +ortuner
$. )itsubishi :aero 'port
ATTRIBUTES REQUIRED FOR OFF ROAD ING
• Heavy Duty Bumpers
• Ground Clearance
• Skid Plates
• Approach , brea!over " Departure A#$%es
• &hee% Art'cu%at'o#
• (o) E#* Tor+ue
• T'res
• H'$h ou#te* A'r I#tae
• Tow Points
• A Frame
1.1 WHAT IS A BUMPER
• A #umper is a shield made of 'teel, Aluminium, ubber, or :lastic
that is mounted on the front and rear of a passenger car.
• The e!uirement for new ustomised personal vehicles for
Adventure and other Activities have exponentially increased,
• A protective device which absorbs shocks and impeding contact.
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7.9 NEED OF A BUMPER:
• During low speed collision occurs, the bumper system absorbs the shock
to prevent or reduce damage to the car.
• The Truck;ar bumper is designed to prevent or reduce physical damage
to the front and rear ends of passenger motor vehicles in low3speed
collisions especially in *ff oading.
• *ff oading #umpers are not typically designed to be structural
components that would significantly contribute to vehicle
crashworthiness or :assenger;occupant protection during front or rear
collisions.
• During a head on crash. The forward or the front side of the #umper folds
progressively and creates enough 'pace for the :assenger.
•
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7.$ CLASSIFICATION OF BUMPERS
PLASTIC BUMPER - )ost modern cars use a reinforced thermoplastic
bumper, as they are cheap to manufacture, easy to fit and absorb more
energy during a crash.
BODYKIT BUMPER - )odified cars often now have a full body kit
rather than ust a front and rear bumper. These kits act as a skirt around
the entire body of the car and improve performance by reducing the
amount of air flowing underneath the car and so reducing drag.
CARBON FIBER BUMPER- arbon fibre body work is normally the
thing of super3cars, but many a car companies, and specialist modifiers,
are starting to use it for replacement body part on everyday cars.
STEEL BUMPER & ALUMINIUM BUMPER- This material worked
well, as it was very strong in a crash, 'teel bumpers are very heavy and
dented performance. Aluminium #umpers are light and have good
strength to weight ratio, but not strong as 'teel as car engine design has
improved, steel bumpers have pretty much shifted to off roading trucks.
Depending on the re!uirement of 'teel or Aluminium , the bumpers are
manufactured
7." COMPONENTS OF A BUMPER
There are different shapes, models and system for vehicle #umpers.
onventional models have corrugated open section areas for installing
some car elements and increasing bending strength of the bumper. )ain
parts of the conventional bumper systems are depicted.
• Fas!a: bumper fascia should have good aerodynamic and aesthetically
pleasing to the consumer but in *ff roading #umpers they are replaced
with 'teel or Aluminium.
• E"#$% a's($'#$s= energy absorbers are designed to absorb a portion of
the kinetic energy from vehicle collision. Its types include foam,
honeycomb and mechanical ones.
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several times the weight of foam and honey comb absorber, they receive
limited usage.
• R#!")($!"% '#a*= )ain key component of the bumper and helps to
absorb the kinetic energy and give protection to the rest of the vehicle.
onfiguration of common bumper
7.> MATERIAL PROPERTIES RE+UIRED FOR DESIGN
'trength
Toughness
Ductility
?eldability
Durability.
)alleability
7.@ DEFINITION OF THE PROPERTIES
• S,$#"%, = the strength re!uired to cause permanent plastic deformation3
IB8D strength but till this point metal is undergoing elastic
deformation. Application of further load or stress will cause plastic
deformation and until the material can no longer withstand the stress
applied and ruptures, this point is called C8TI)ATB strengthCltimate strength of 'teel 3""& ):a
Cltimate strength of Aluminium 3$9& ):a
• T(%"#ss: defined as the work re!uired to deform one cubic inch of the
metal till it factures or it is the resistance of a material to being broken in
two,
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suffer impact or for components where a fracture would be catastrophic
0pressure vessels, aircraft. Automotive parts1.
F($ E/= If a load is suddenly applied to a piece of mild steel and then to a
piece of glass the mild steel will absorb much more energy before failure
occurs. Thus, mild steel is said to be much tougher than a glass.
D,!0!,: Ductility is a measure of how much strain a given stress
produces and also property of a material enabled to drawn out into thin
wire on application of the load. )ild steel is a ductile material. The wires
of gold, silver, copper, aluminium, etc. are drawn by extrusion or by
pulling through a hole in a die due to the ductile property. The ductility
decreases with increase of temperature.
:ercent Blongation 0Bl1=
• W#0a'!0!,: ?elding is a process by which two materials, usually
metals, are permanently oined ,It is induced by a combination of
temperature, pressure, and metallurgical conditions .It is simply a
measure of how easy it is to make a weld in a particular material without
cracks. ?eldability is not a fixed parameter for a given material, but will
depend on oint details, service re!uirements, and welding processes and
facilities available.
Ma00#a'!0!,: )alleability of a material is its ability to be flattened into
thin sheets without cracking by hot or cold working. Aluminium, copper,
tin, lead, steel. are malleable metals. ability to plastically deform and
shape a material by forging, rolling or by any other method of applying
pressure. #eing easy to beat into a thin sheet is the literal meaning.
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CHAPTER 2
During the 7%%&s, sport utility vehicles 0'C/s1 became the fastest growing
segment of the auto industry. In 7%%%, 'C/ sales reached almost 7% of the
total light vehicle market and the mix of 'C/s on the road was about E.F.
demand for new and customised personal vehicles were increasing at an
exponential rate with the increase in buying power of customers. As these 'C/s
were being used for different purposes namely in #attle fields, allies,
adventure , *ff oading etc. ?hen these trucks; 'C/s were driven on these
purposes they re!uired additional accessories or Cpgradation for #etter safety
of the truck as well as the passengers in the vehicle, ease of movement, (ood
towing capacity and increasing the traction of the vehicle.
'o this :roect is more narrowed down to design, model and manufacture a cold
rolled steel bumper for off road vehicles which can improve the above
mentioned factors. +inally this is done=
Stress -Stra'# curve o. '%*
stee%
Stress -Stra'# curve o.
A%um'#'um
:*#8B) DB+I-ITI*-
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7. )aterial 'election
9. )odelling of the #umper
$. :roduction.
OB3ECTIVE OF THE PRO3ECT
• To determine the thickness of the -B? *++ *AD #C):B
• To design a -B? #C):B by )odeling in Cnigraphics -G E
• To carry out static analysis and impact Analysis on the -ew #umper to
and validate the results with the existing bumper in Impact Analysis.
9.9 METHODOLOGY
onceptual Design of the #umper
)odelling of the #umper
Development of (eometry from the
Bxisting #umper
)aterial 'election for the #umper
)echanical :roperties )eshing of (eometry
'imulation of the part
Impact 'trength for Bnergy Absorption Analysis of the esults
+inal )aterial selected from result
comparison
/alidation of the +inal bumper
esults and onclusion
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CHAPTER 4
REVIEW OF LITERATURE
• arbon composites meets most of the e!uirements like high strength to
weight atio , rashworthiness and high stiffness to weight ratio, but
according to A0#" 3(" et.al H various aerodynamic shapes and structures
couldn4t be used due to high cost, )ore materials, composites and alloys
will used as materials in future. +urther analysis on environmental impact
can be done using the 8ife ycle Assessment software and carbon
calculator tools.
• Design, fabrication and testing of steel and composite bumper 0using
glass fibre material1 are completed and also composite bumper is
analysed and compared with steel bumper. K.C!"a$as5 #,.a0 has
discussed that fuel efficiency of the vehicle has increased as the weight
of the composite bumper is less compared to 'teel bumper.
• old3rolled and hot3dip galvanized steel grades with up to 7"&& ):a
tensile strength can be cold formed with conventional press forming and
roll forming methods. 3a"-O0() S6#$0# #,.a0 high strength and ultra high
strength sheet steels are today used successfully for weight reduction and
increased safety in applications such as door impact beams, bumper
reinforcements, and seat constructions.
The study of automotive bumper was done on designs namely, basic
bumper design with steel, with the attachment of foam and with the
attachment of honeycomb. P$a7##" K*a$89 #,.a0 concluded that
carbon fibre gives high strength to weight ratio in comparison with steel
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and dissipates energy. The basic design with front part as a foam absorbs
the energy and ensures the pedestrian safety.
• S,a C. Da7!s8; found from 'urvey that 'C/s are safer than cars
because they are generally larger 0considered a weight advantage in
crashes with other vehicles1, higher 0improved visibility1, and more
rugged 0a vehicle that can climb mountains and cross streams of water
will surely be more than ade!uate on a city street1.According to crash
statistics indicate that large vehicles provide more protection than small
vehicles in crashes, there is no methodology to compare crash test results
across vehicle models in different size categories.
• G.N. RADU8s guide to safe and
common sense off oad Driving , he talks about )ag ?heels.
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9.1 G#(*#,$! M(#0
• (eometric )odel is divided into
0a1.9D proection drawings
0b1.?ireframe )odelling
0c1.'urface )odelling
0d1.'olid )odelling
F%o) chart o. Geometr'c
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• C("s,$,!(" () 'as! %#(*#,$! ('@#,s= In the very first step the
designer creates simple and basic geometric shapes and elements by
using options like points, lines, and circles.
• T$a"s0a,!("s () ,# sa6#s a" #0#*#",s= In the second step the
designer uses options like scaling, rotation and other related
transformations of the geometric shape and elements.
• C("s,$,!(" () ,# %#(*#,$! *(#0= During the last step the
designer makes use of various commands to that option which causes
integration of the obects or shapes sometimes called elements of the
geometric model to form the desired structure and shape.
• The onstruction can be saved in a file or location using a standard
0$D1 file format.
• (eometric modelling plays a maor role in cost by cutting down the
capital investment by creating in $d than physically.
• The )odels design or created can be directly used in )anufacturing
computer numerical control.
• +inite elemental analysis also accept these $D models to find out the
'tress, Thermal, Deflection etc.
WIREFRAME MODELLING
The word KwireframeL means a wire that is bent to follow the obect
edges to generate a model.
)odel consists entirely of points, lines, arcs and circles, conics, and
curves.
The obect is not recorded as a solid but the vertices that define4s the
boundary of the obect, or the intersections of the edges of the obect
boundary are recorded as a collection of points and their connectivity.
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• haracteristics of ?ireframe modelling
♦ 'imple and straight forward in concept
♦ Displays less information than re!uired
♦ Ambiguous display of real obects will be created.♦ e!uires more user strain or effort to install the re!uired data.
• ?ireframe is divided into Analytical and 'ynthetic entities.
• This format cannot be used to calculate dynamic properties and
complex shapes curves cannot be modelled.
• /irtual edges are not provided.
SURFACE MODELLING
A surface model is a set of faces.
A surface model consists of wireframe entities that form the basis to
create surface. It contains the definitions of 'urface, edges and vertices.
Bliminates ambiguity and non3uni!ueness present in wireframe
models.
A wireframe model can be extracted from a surface model surface
model by deleting or blanking all surface entities deleting or blanking
all surface entities.
(ive4s the )odel a touch of better visualization and :resentations were
the obect looks very ealistic.
F'$ure o. )'re.rame
&'re.rame
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It creates a surface (eometry for - )achining.
:roperties related to 'urfaces like eflectivity, colour and roughness
can be demonstrated and assigned.
'hape design and representation of complex obects such as car, ship ,and airplane bodies as well as castings.
It doesn4t provide useful information about the interior property of the
model as it is only 'urface construction.
'urface )odelling cannot be used to find out or calculate dynamic
properties.
SOLID MODELING
• It4s a three dimensional advanced (eometric modelling.
• 'olid :arts of an obect can be represented through solid modelling.
• The $D *bect can be viewed in wire frame, in turn wire frame for
better visualisation can be seen in 9D and $D.
• (iving surface :roection to the wire $D views of geometric models
makes the obect appear solid on the screen and this is called as solid
modelling.• 'olid )odelling is basically represented by volume.
• )ost importantly The solid modelling method is based upon the Mhalf3
spaceM concept.
• The boundary of the model differentiates the inside and outside of the
modelled obect.
• 'olid modelled obect stores both the geometric and topological data.
• Through 'olid modelling we can verify whether the 9 obects occupy
the same space or not.
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• 'olid modelling improves the Design !uality and improvises the
visualization and has very good potential for functional automation
and integration.
• Csing volume information =• weight or volume calculation, centroids,
• moments of inertia calculation,
• stress analysis 0finite elements analysis1,
• heat conduction calculations,
• dynamic analysis, 2 system dynamics analysis.
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• Csing volume an d boundary in formation=
• (eneration of - codes,
• obotic and assembly simulation.
• DI++BB-T '*8ID )*DB88I-( TB
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o PARAMETRIC MODELLING= :arametric is a term used to describe
a dimension4s ability to change the shape of model geometry if the
dimension value is modified.
o F#a,$#-'as# is a term used to describe the various components of amodel. +or example, a part can consists of various types of features such
as holes, grooves, fillets, and chamfers.
o +eature3based, :arametric 'olid )odelling system represents the
progression of (eometric modelling.
o In parametric modeling, dimensions control the model.
o Design intent is how your model will react when dimension values are
changed.
o
+eature3based, parametric solid modelling eliminated the direct use of common geometric primitives such as cone, cylinder, sphere, etc, since
these primitives only represent low3level geometric entities. In designing
and manufacturing mechanical parts, one would always refer to
mechanical features.
o :arametric modeler software also provides tabular views of the
components 0parts list, door schedule, window schedule, etc.1 and
maintains their association with other views of the model. If a component
is edited graphically, the list is updatedO if a component is edited on thelist, the graphic views are updated.
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SAMPLE MODEL OF A STEEL BUMPER
FRONT /IE& OF A BU0ER
ISOETRI1 /IE& OF A
BU0ER
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MODELLING APPROACHES
There are two Different Approaches in creating a '*8ID )*DB8
o T(6 D(" A66$(a
o B(,,(* U6 A66$(a
TOP DOWN MODELLING:
o Bither volume or areas are considered to complete on single
solid part.
o ombination of these 'olid parts in a fashion finishes the final
'hape
o The volumes or areas that you initially define are called
primitives.
o :rimitives are located and oriented with the help of the working
plane.
o The combinations used to produce the final shape are called
#oolean operations.
o ?hen you create a 93D primitive, a modeling tool usually
defines an area, along with its underlying lines and key points.
o ?hen you create a $3D primitive, a modeling tool usually
defines a volume, along with its underlying areas, lines and key
points.
TO0 DO&N ODE((ING
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BOTTOM UP MODELLING:
o Bither points or lines will be oined to complete the solid part.
o 8ow level programming systems usually adopts with bottom3up
modeling
o #ottom3up design is the traditional method. ou first #s!%" and
model parts, then insert them into an assembly and use mates to position the parts.
2!D pr'm't'ves '#c%u*e recta#$%es, c'rc%es,
tr'a#$%es, a#* other po%y$o#s
3!D pr'm't'ves4 b%ocs, cy%'#*ers, pr'sms,
spheres, a#* co#es5
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BOTTO U0 ODE((ING
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CHAPTER ;
;.1 MATERIAL SELECTION:
1. G$a# () (0 $(00# s,##0 CRCR99.
2. G$a# () A0*!"!* B 4.
;.2 STEEL VERSUS ALUMINIUM
• 'teel has higher density than Aluminium.• 'teel4s modulus of elasticity is greater than Aluminium.
• Aluminium has to have better thickness than 'teel to maintain its
stiffness property.
• 'teel is twice stronger than AluminiumO this strength role plays a critical
part during a collision or an impact action.
• Aluminium is almost three times costlier than 'teel in India.
• )aterial :roduction of 'teel and Aluminium , 'teel has an advantage
because Aluminium sheet :roduction is less
• Aluminium is complex to weld when its weldability is compared to 'teel
• Aluminium doesn4t have good 'tretch apability compared to 'teel this
property can be inferred from the 'tress3'train curve (raph.
• 'teel does have a very good preserving !uality, even after number of
load cycles, whereas Aluminium will be affected with +atigue and
eventually be destroyed.• Drilling holes of Aluminium is very intricate as compared to 'teel.
• +inally 'teel is easier to work under die;press and tooling. 'ecurity with
Aluminium needs much more engineering because itPs more prone the
shear, less tolerance to temperature change.
• 'o 'teel is a #etter )aterial than Aluminium to Design, model and
)anufacture #umpers for *ff oad Driving.
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