MODELING AND ANALYSIS OF B-PILLAR -...

ISSN No: 2309-4893 International Journal of Advanced Engineering and Global Technology I Vol-03, Issue-08, August 2015

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MODELING AND ANALYSIS OF B-PILLAR

Mr. C.Venkataswamy B.Tech

Department of Mechanical

Engineering

Marri Laxman Reddy Institute

of Technology& Management

Hyderabad, T.S

[email protected]

Mr. T.Naganna M.Tech

Department of Mechanical

Engineering



Hyderabad, T.S

Mr. Nirmith Kumar Mishra M.Tech

Department of Aeronautical

Engineering



Hyderabad, T.S

[email protected]

ABSTRACT The design and development of an

automobile is a complex process. The Automobile

consists of number of parts; among them the

important ones are structural elements which form

the major skeleton/structure of the Automobile.

These elements need to be designed, developed and

analyzed with at most care, as many other parts are

assembled on them.

Automobile with major panels welded

together is called BODY IN WHITE or BLUE

BUCK. This consists of number of panels, one

among them is B-PILLAR. This is a structural

member as the sides of windshield on which doors

will be mounted.

This project work involves the surface

modeling of B-PILLAR using CATIA , the pre

processing is done in HYPERMESH and analysis of

B-PILLAR using different materials in ABAQUS

software’s.

1.1 Definition:

• An incomplete assembly of a vehicle

generally consisting of all the major panels

welded together and prior to prime and

paint processing.

• It is also called as BLUE BUCK.

1.2 Body Construction:

• Unitized construction

– Compact construction.

– Protects the occupants during

collision.

– Energy gets transferred

throughout the body when

collides.

• Body over frame construction

– Frame should hold all the major

parts and collide.

– Rubber mounts are used between

body and frame to reduce the

noise and vibration.

– Only local damage occurs.

The monocoque is currently the standard

structure for most cars made around the world in

high volume (100,000+per annum) production.

Constructed from pressed sheet steel, it combines

the function of both chassis and body in a three

dimensional structure. In its purest sense, the term

monocoque is applied to a structure which relies

entirely on its outer skin for strength.

Semi monocoques have stiffening members and

transverse frames supporting the skin or outer body

panel and are the accurate term to use when

describing the structure of most cars.

Whilst some panels are detachable such as

the doors, engine bonnet and the front wings, the

remainder of the outside surface plays a key part in

the structural integrity of the vehicle. With the

exception of the Jaguar E-type, there are probably no

true monocoques on the road today.

1.3 Objectives of Structural Design:

To make best use of material by arranging

for each member to support as near as

possible to its maximum load potential.

To make structure direct and continuous by

providing an unbroken path from the point

of application to point of reaction.

1.4 Classification- Body Shapes:

• Sedan – 4-6 persons,2/4 doors, stationary

window frame

– 2 door sedan/coupe

– Hard top- B pillars do not extend up

through the side windows

• Convertible – Vinyl roofs that can be lowered or

raised.

- 2/4 doors

• Lift back – Rear luggage compartment hatch type

door

– 3/5 door

• Station wagon – Roof which extends straight back

– 2/4 doors

– 9 passengers


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• Pick ups – Rear Cargo area

– 2/3/4 doors

• Vans – Tall roof

– 2-12 passengers

– Mini – full size vans

• Sports utility vehicles – Multi purpose vehicles

– Many passengers

– Aero dynamics is the common feature

for all the vehicles regardless of type of

vehicle.

2.1 Finite Element Methods

The Finite Element Methods were first

invented by structural engineers, who based

themselves on a strictly physical basis. However

mathematicians later discovered that FEM methods

could be classified as a subset of the Galerkin

Methods for the solution of PDE’s. This way the

method gained a broader mathematical foundation

which extended its use to many engineering

problems. Nevertheless this difference in the

engineering and mathematics points of view resulted

in two different interpretations which also affects the

way the method is used in practice.

2.1 Physical Interpretation:

The continous physical model is divided

into finite pieces called elements and laws of nature

are applied on the generic element. The results are

then recombined to represent the continuum.

2.2 Mathematical Interpretation:

The differetional equation representing the

system is converted into a variational form and

solved by the linear combination of a finite set of

trial functions.

2.3 FEM Notation

As the name suggests the FEM treat the

continuous problem domain as a collection of

individual finite elements. The problem parameters

are defined on each of the nodes of a typical element.

Let us now have a look to the key definitions of the

FEM notation.

• Dimensionality: The elements can be defined differently depending

on the problem context. Dimensionality indeed

expresses whether the element has 1, 2 or 3 space

dimensions.

• Nodal Points: Every element is described by its nodal points.

Frequently the nodal points are chosen to be the

corners of the element. However in case of non

linear geometries nodal points are also defined on

the edges.

• Geometry: This term is used to describe the domain on which

finite element discretization needs to be applied. It

can be smooth an regular (e.g. a rectangular plate),

or complex (e.g. surface of a machine part). The

geometry is defined by the placements of the nodal

points.

Fig Typical Finite Element Geometires

• Degrees of Freedom: The degree of freedom is the

number of ways in which the original problem

domain can change its state. In the case of the

continuous problem domain, the DOF is infinite,

because problem characteristics can be defined in

each point on the domain. In the discrete FEM

domain, instead, the DOF is limited by the number

elements, because problem characteristics can only

be defined on the nodal points.

• Nodal Forces: A set of nodal forces (or any other

actions depending on the problem) are defined on

each nodal point. From the mathematical point of

view this corresponds to the non-homogeneous right

hand side of the governing DE.

2.4 REQUIREMENT OF FINITE ELEMENT

ANALYSIS:

Finite Element Analysis makes it possible

to evaluate a detailed and complex structure, in a

computer, during the planning of the structure. The

demonstration in the computer of the adequate

strength of the structure and the possibility of

improving the design during planning can justify the

cost of this analysis work. FEA has also been known

to increase the rating of structures that were

significantly overdesigned and built many decades

ago.

3 Surface Modeling

3.1 A little history of Surface Modeling:

Surface modeling was developed in the

automotive and aerospace industries in the late

1970s to design and manufacture complex shapes.

Nurbs - nonuniform rational B-splines -- and cubic-

surface formats appeared early and remain the

primary spline and surface formats used throughout

the CAD industry. Nurbs and cubics are supported

by IGES (Initial Graphics Exchange Specification),

a neutral file format for exchanging data between

CAD systems.


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Nurbs and cubic formats are represented in a

computer by polynomial equations generated by a

CAD system, and onscreen through the location and

shape of curves and surfaces. For example, the

equation of a line, a first-degree polynomial, has this

form

Y = ax + b

The equation for a parabola, a second-degree

polynomial, has the form

Y = ax2 + bx + c

And the equation of a cubic spline, a third-degree

polynomial, looks like

Y = ax3 + bx2 + cx + d

The more terms in the polynomial equation, the

more "shape" the curve or surface.

The data structure of a Nurbs curve or

surface is comprised of points, weights, and

parameter values that define a control net which is

tangent to the curve or surface. The control net on a

Nurbs surface is a rectangular grid of connected

straight-line elements which define the tangency of

the surface at positions along the control net. The

points in the database which describe the control net

are not actually on the surface, they are at the

vertices of the control net. Weights in the Nurbs data

structure determine the amount of surface deflection

toward or away from its control point.

Cubic data structures use third-degree

polynomials that describe points actually on the

curve or surface. Therefore, the Nurbs control net is

an abstraction of the underlying surface, whereas the

cubic equation is the surface.

Fig. Examples of surface design

3.2TYPES OF CONTINUTY:

Continuity is a measure of how well two

curves or surfaces "flow" into each other.

POSITION (G0)

This type of continuity between

curves implies that the endpoints of the curves have

the same X,Y, and Z position in the world space.

This is the minimum requirement for obtaining G0.

• TANGENT (G1)

This type of continuity between curves implies that

the tangent CVs must be on one line.

• CURVATURE (G2)

This continuity type impacts the third CV of the

curve. All three CVs have to be considered in order

to maintain a smooth curvature comb.

If a curvature comb does not have a smooth

transitional line. In order to improve the curvature

comb, manually modify the position of the three

CVs that constitute the G2 continuity.

Fig Curvature Continuity

3.3 Bezier Curves:

The following describes the mathematics

for the so called Bezier curve. It is attributed and

named after a French engineer, Pierre Bezier, who

used them for the body design of the Renault car in

the 1970's. They have since obtained dominance in

the typesetting .

Consider N+1 control points pk (k=0 to N) in 3

space. The Bezier parametric curve function is of the

form.


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3.4 Bezier Surface:

The Bezier surface is formed as the

Cartesian product of the blending functions of two

orthogonal Bezier curves.

Fig Beizer curves

Where Pi,j is the i,jth control point. There

are Ni+1 and Nj+1 control points in the i

and j directions respectively.

The corresponding properties of the Bezier

curve apply to the Bezier surface.

- The surface does not in general pass

through the control points except for the

corners of the control point grid.

- The surface is contained within the

convex hull of the control points. Along the

edges of the grid patch the Bezier surface

matches that of a Bezier curve through the

control points along that edge. Closed

surfaces can be formed by setting the last

control point equal to the first. If the

tangents also match between the first two

and last two control points then the closed

surface will have first order continuity.

While a cylinder/cone can be formed from

a Bezier surface, it is not possible to form a

sphere.

Fig Biezier surfaces

3.5 CLASS ‘A’ SURFACING:

‘A' Class surfacing and its importance:

A class surfaces are those aesthetic/ free form

surfaces, which are visible to us (interior/exterior),

having an optimal aesthetic shape and high surface

quality.

Mathematically class A

surface are those surfaces which are curvature

continuous while providing the simplest

mathematical representation needed for the desired

shape/form and does not have any undesirable

waviness.

Products are not only designed considering the

functionality but special consideration is given to its

form/aesthetics which can bring a desire in ones

mind to own that product. This is only possible with

high-class finish and good forms. This is the reason

why in design industries Class A surface are given

more importance.

3.6Analyzing A Class Surface:

Highlight is the behavior of the form or Shape of

a surface when a light or nature reflects on it. This

reflection of light or nature gives you an

understanding about the quality of surface. This

reflection required should be natural, streamline and

with uniformity

Fig .Example for A-class surface

Class A refers to those surfaces, which are

CURVATURE continuous to each other at their

respective boundaries. Curvature continuity means

that at each "point" of each surface along the

common boundary has the same radius of curvature.

4.0 B-PILLAR MODELING IN CATIA


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Denoting the automobile body structural

member on the sides of the windshield as the A-

pillar, and the successive vertical supports are

named after a successive letter in the alphabet (B-

pillar, C-pillar etc.).With the introduction of

monocoque design in automobiles, supporting

pillars have become increasingly important, and

nearly every visual break in a modern vehicle

contains a supporting pillar.

Fig. PILLAR

Originally developed for performance cars

such as Maserati in the early 1950’s, space frames

resembled a ‘cage’ of welded tubes onto which a

non-structural body shell was attached. The space

frame, unlike the monocoque, relied on an internal

tubular cage or frame to provide all the load

bearing qualities of the vehicle.

On current models such as the Fiat

Multipla, outside panels assist only in the crash

worthiness of the structure, with the possible

exception of the roof panel which provides some

lateral stiffness. Current Space frames can be

constructed from either aluminum or steel extrusions

and can readily take advantage of technology such

as composite panels and high-strength adhesive

bonding. Major savings can be achieved of around

30 to 40% in the frame weight.

Extrusions are an important feature of the

space frame as they represent a departure from the

reliance of conventional manufacture on pressed

sheet steel as a means of achieving body stiffness

and strength. The total tooling costs associated with

either aluminium or steel extrusions in vehicle

Production are around half that of pressings.

Space frames are more labour intensive

than the welded steel monocoque due a greater

number of parts required in constructing the body.

Fig Inputs from the Styling team to Create B –

Pillar, in the form of A – Surfaces and wire frame

Geometry as shown in the picture.

Fig By Using Catia, Generative Shape Design work

Bench, we Created B-Pillar

Fig: Pillar Integration with the BIW Assembly

http://en.wikipedia.org/wiki/Monocoque


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5.0 ANALYSIS OF B-PILLAR

Preprocessing (Hyper mesh software)

o Create or import the model

geometry

o Mesh the geometry this can be

done by using HYPERMESH

software

Fig MESH OF B-PILLAR IN HYPERMESH

5.1 STRESS ANALYSIS OF B-BILLAR USING

TWO DIFFERENT MATERIALS

5.1.1 IMPORTING THE MODEL:

1. Choose Utility Menu > File > Import >

model A Window appears.

2. In the window select the file with extension

.inp

3. Click on ok.

Fig FEA MODEL IMPORTED FROM

HYPERMESH TO ABAQUS

5.1.3 DEFINE MATERIAL PROPERTIES:

(MAGNESIUM)

To define material properties for the analysis, these

steps are followed:

1. Choose Property Module > Material

Manager > The Define material properties

like Young’s Modulus, poisons ratio,

Density and so on depending on application

analysis..

2. Section Manager> To define the section of

the existing FE model

3. Section Assignment Manager> To assign

the section for defined in previous case to

the particular FE section.

4. Enter the Young’s Modules of 45000 and

the Poisson’s ratio of 0.35 in the dialog box

appeared and clicks ok in Material manager

and density value of 1820 kg/m3 in the box

and click ok.

5.1.4 DEFINE THE SOLUTION TYPE:

1. Choose STEP MODULE > STEP

MANAGER > Static, General> The step

dialog box appears and remaining options

keep as default and click ok.

5.1.5 APPLY LOADS:

1. Choose Load Module > Load Manager >

Create Load > Under Mechanical

option, Concentrated Load > 2. Pick the nodes on the end of the key by

using box option in the pick option box and

Enter Pressure value of 3500N in the

column specified in the Y-Direction and

click OK.

3. Constraint the nodes in all the directions.

By using

4. Choose Load Module > Create Boundary

Condition > Mechanical >

Displacement/Rotation 5. Pick the nodes on another end of the key by

using box option in the pick option box and

fix the nodes in six directions.

6. Below picture shows the Loads and

Boundary Conditions.

Fig B-PILLAR AFTER APPLYING LOADS ON

IT

5.1.6 SOLVE THE MODEL: Choose Job Module

> Job Manager > Create > Job1 > Continue. And

press ok. Go to job manager again and select the

Submit option by selecting the job1.

5.1.7 REVIEW THE DEFORMED RESULTS:


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1. Choose Visualization Module > Results >

Field Output > Step/Frame. It shows step

information in the model. Select the

appropriate step in which we are interested

to view results.

2. Choose Results> Field output, S

(Stresses)> S22 for Y-Component of

Stresses and click Ok. The stresses in Y-

Direction are displayed.

3. Choose Results> Field output> U

(Deflection) > U22 for Deflection in Y-

Component and click Ok. The

deformations in Y-Direction are displayed.

4. Choose Results> Field output, S

(Stresses) > Mises and click Ok. The

Vonmises stresses will be displayed.

5. Choose Results> Field output> U

(Deflection) > Magnitude and click Ok.

The deformations are displayed

Fig MAXIMUM DEFLECTION IN B-PILLAR

(MAGNESIUM)

Fig MAXIMUM STRESS IN B-PILLAR

(MAGNESIUM)

Fig DEFLECTION ALONG Y-DIRECTION

(MAGNESIUM)

Fig STRESS ALONG Y-DIRECTION

(MAGNESIUM)

5.2 DEFINE MATERIAL PROPERTIES:

(ALUMINIUM)

To define material properties for the analysis, these

steps are followed:

1. Choose Property Module > Material

Manager > The Define material properties

like Young’s Modulus, poisons ratio,

Density and so on depending on application

analysis..

2. Section Manager> To define the section of

the existing FE model

3. Section Assignment Manager> To assign

the section for defined in previous case to

the particular FE section.

4. Enter the Young’s Modules of 70000 and

the Poisson’s ratio of 0.33 in the dialog box

and density value as 2700 kg/m3 in the box

and click ok.

5.2.1 DEFINE THE SOLUTION TYPE:

1. Choose STEP MODULE > STEP

MANAGER > Static, General> The step


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dialog box appears and remaining options

keep as default and click ok.

Fig MAXIMUM DEFLECTION IN B-PILLAR

(ALUMINIUM)

Fig MAX IMUM STRESS IN B-PILLAR

(ALUMINIUM)

Fig DEFLECTION ALONG Y-DIRECTION

(ALUMINIUM)

Fig. STRESS ALONG Y-DIRECTION

(ALUMINIUM)

5.3 ADVANTAGES OF ALUMINIUM

Light Weight:

Aluminium is a very light metal with a

specific weight of 2.7 g/cm3, about a third that of

steel. For example, the use of aluminium in vehicles

reduces dead-weight and energy consumption while

increasing load capacity. Its strength can be adapted

to the application required by modifying the

composition of its alloys.

Corrosion Resistance;

Aluminium naturally generates a protective

oxide coating and is highly corrosion resistant.

Different types of surface treatment such as

anodising, painting or lacquering can further

improve this property. It is particularly useful for

applications where protection and conservation are

required.

Reflectivity:

Aluminium is a good reflector of visible

light as well as heat, and that together with its low

weight, makes it an ideal material for reflectors in,

for example, light fittings or rescue blankets.

Ductility:

Aluminium is ductile and has a low melting

point and density. In a molten condition it can be

processed in a number of ways. Its ductility allows

products of aluminium to be basically formed close

to the end of the product’s design.

Recyclability :

Aluminium is 100 percent recyclable with

no downgrading of its qualities. The re-melting of

aluminium requires little energy: only about 5

percent of the energy required to produce the

primary metal initially is needed in the recycling

process.

6.0 Conclusion


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The maximum stress experiencing along B-

pillar is 378 Mpa

The peak stresses are observed along the

ribs of the B-pillar.

The deflection of the aluminium is 10.3

which is far less than the deflection of

magnesium i.e., 16.0.

So, aluminium is preferred rather than

magnesium

The Design is safe from the obtained stress

378 Mpa value which is less than yield

stress of the aluminium i.e. 414 Mpa.

CAD/CAM is fast becoming a necessity

and it is a must, in order to scope up with

the huge demand that existing now and it’s

exponential growth analysis software like

ABAQUS are very much useful as evident

by this project where the deflection’s and

the different mode shapes are generated for

its adaptability under conditions.

BIBILOGRAPHY

Finite Element analysis -

Desai & Able

Applied Finite Element Analysis -

SEGERLIND . L. J

The Finite Element Methods In

Engineering - S.S.RAO

Website www.steamengines.com

CAD/CAM by MIKEL P.GROOVER

CATIA V5 by shauntickoo

Introduction to Finite Elements in

Engineering: Tirupati.R. Chandrupatla

Ashok D.BAQUS manual

http://www.steamengines.com/

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