LADDER FRAME The ladder type frame consists of two C section side members with weldedin tubular cross members The ladder frame is so called because it resembles a ladder with two side rails and a number of cross beams ID: 573653
Download Presentation The PPT/PDF document "TYPES OF CHASSIS FRAMES" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
TYPES OF CHASSIS FRAMESSlide2
LADDER FRAME
The
ladder type
frame
consists
of two
C
section side members with welded-in tubular cross-
members.
The
ladder
frame is
so called because it resembles a ladder with two side rails and a number of cross beams.
Originally seen on almost all vehicles, the ladder frame was gradually phased
out due to invention of better frames.Slide3
ADVANTAGES OF LADDER FRAME
The greatest advantage of the ladder frame is its adaptability to accommodate a large
variety
of body shapes and types.Bodies ranging from flat platforms, box vans andtankers to detachable containers can all be easily attached to ladder frames.Ladder frames exhibit good bending strength and stiffness.The open channel section provides easy access for attaching brackets and components.Slide4
DISADVANTAGES OF LADDER FRAME
The ladder frame exhibits poor
resistance to torsion or warping if simple, perpendicular
cross members are used. Also, the vehicle's overall height will be higher due to the floor pan sitting above the frame instead of inside it.If the open sections are replaced by closed box sections then the torsional stiffness is greatly
improved.
However
, the strength of the joints becomes critical as
the maximum
bending on all members occurs at the joints
and
the attachment
of brackets
becomes more
complex.Slide5
CRUCIFORM FRAMES
The cruciform
frame is
made of two straight
beams placed perpendicular to each other.
The cruciform frame overcomes the poor torsional stiffness of the ladder frame.
Here the torsional loads gets cancelled among the cross members and the side frame bears only bending loads.Slide6
ADVANTAGES
It overcomes the weak torsional stiffness of ladder frame.
When combined with a ladder frame, it can effectively take bending and torsional loads.
The cross beams at the front and rear not only assist in carrying the torsion moment but also assist in carrying the lateral loads from the suspension mounting points.Slide7
DISADVANTAGES
The maximum
bending occurs at the joint hence joint design becomes critical
.Since cruciform frame is used along with a ladder frame, it shares some of the disadvantages of ladder frame such as increased vehicle’s overall height.Slide8
SPACE FRAME
The frames described
earlier are
all essentially 2-dimensional or at
least their
depth is very much less than their length and breadth
.
Adding
depth to a frame
considerably increases
its bending strength and stiffness (i.e. truss type bridges
).
3-dimensional
Space
frames have
been used for specialist cars such as sports racing
cars.
This
type of vehicle design can be used for low volume production with G.R.P.
bodies.Slide9
ADVANTAGES
Like a truss,
a space frame is strong because of the inherent rigidity of the
triangle.Space frames can be used to span large areas with few interior supports.In a spaceframe chassis, the suspension, engine, and body panels are attached to a skeletal frame of tubes, and the body panels have little or no structural function.Due to the depth of the frame, it is more stiffer to bending and torsional loads than the two dimensional frames.
All the bending and torsional loads and the lateral loads are effectively resolved into tension and compression loads on the tubes.Slide10
DISADVANTAGES
A drawback of the
spaceframe
chassis is that it encloses much of the working volume of the car and can make access for both the driver and to the engine difficult. In this type of structure it is imperative to ensure all planes are fully triangulated so that the beam elements are essentially loaded in tension or compression.Due to the welded joints some bending and torsion restraints will occur at the joints, but to rely on these restraints will render the structure far less stiff
.Slide11
INTEGRAL STRUCTURES
The modern mass-produced passenger car is almost exclusively produced with sheet
steel pressings
spot welded together to form an integral structure. This is a structure where the component parts provide both structural and other functions. The depth of a structure such as a space frame, can improve the stiffness and in the integral structure the whole side frame with its depth and the roof are made to contribute to the vehicle bending and torsional stiffness.Slide12
ADVANTAGES
It is
stiffer in bending and
torsion.
It
is of lower weight than when using a chassis and
separate body
.
It
can be produced with lower
cost.
I
t
produces a quieter car for the passengers
.Slide13
DISADVANTAGES
Integral body
is geometrically very complicated and the detailed stress distribution
can only be determined by the use of Finite Element methods. The stress distribution within the structure is not only a function of the applied loads but also of the relative stiffness of the many components.During an impact the body will crumple completely beyond repair, whereas in a body-on-frame, only the body will be damaged and the chassis can be reused.Slide14
THANK YOU