modeling and analysis of b-pillar -...
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ISSN No: 2309-4893 International Journal of Advanced Engineering and Global Technology I Vol-03, Issue-08, August 2015
1079 www.ijaegt.com
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
Mr. T.Naganna M.Tech
Department of Mechanical
Engineering
Marri Laxman Reddy Institute
of Technology& Management
Hyderabad, T.S
Mr. Nirmith Kumar Mishra M.Tech
Department of Aeronautical
Engineering
Marri Laxman Reddy Institute
of Technology& Management
Hyderabad, T.S
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
ISSN No: 2309-4893 International Journal of Advanced Engineering and Global Technology I Vol-03, Issue-08, August 2015
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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.
ISSN No: 2309-4893 International Journal of Advanced Engineering and Global Technology I Vol-03, Issue-08, August 2015
1081 www.ijaegt.com
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.
ISSN No: 2309-4893 International Journal of Advanced Engineering and Global Technology I Vol-03, Issue-08, August 2015
1082 www.ijaegt.com
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
ISSN No: 2309-4893 International Journal of Advanced Engineering and Global Technology I Vol-03, Issue-08, August 2015
1083 www.ijaegt.com
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
ISSN No: 2309-4893 International Journal of Advanced Engineering and Global Technology I Vol-03, Issue-08, August 2015
1084 www.ijaegt.com
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:
ISSN No: 2309-4893 International Journal of Advanced Engineering and Global Technology I Vol-03, Issue-08, August 2015
1085 www.ijaegt.com
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
ISSN No: 2309-4893 International Journal of Advanced Engineering and Global Technology I Vol-03, Issue-08, August 2015
1086 www.ijaegt.com
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
ISSN No: 2309-4893 International Journal of Advanced Engineering and Global Technology I Vol-03, Issue-08, August 2015
1087 www.ijaegt.com
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