Vehicle Frame system

SRI KRISHNA COLLEGE OF ENGINEERING AND TECHNOLOGY
DEPARTMENT OF MECHATRONICS ENGINEERING
Session: Vehicle Frame
11/24/2020 16MT323 CAE LABORATORY 1
MODULE 1

SESSION OBJECTIVES
 On the completion of this session, the students might
be able to understand,
 Right selection of frame for vehicle construction.
 Types of load act on vehicle frame.
 What materials are used for frame construction?

Topics
 Introduction
 Function of Frame
 Frame construction
 Basic chassis frame Types
 Other frame construction
 Loads act on Frame

INTRODUCTION
What is Frame?
 Frame is the main part of chassis on which remaining part of chassis are
mounted.
 The frame is supported by wheel & tyre assembly.

FUNCTION OF FRAME
Function of Frame:
 To form the Basic structure of vehicle
 To withstand accelerating & Braking torque
 To accommodate suspension system
 To carry the other parts of the vehicles & its passenger.
 To resist the effect of centrifugal forces when cornering a curve.
 To withstand bending and twisting stresses due to fluctuating rear & Front
axle

FRAME CONSTRUCTION
In order to provide a good
resistance to bending & Torsional
effect, the frame section are made
of proper form
Types of cross section :
 Channel Section
 Box Section
 Tubular Section
 I Section

FRAME CONSTRUCTION
Channel Section :
 Channel section is good for high bending
resistance
 Mainly used for long section of frame
construction.

FRAME CONSTRUCTION
Box Section :
 Have high Bending & Torsional
resistance
 Used in very short section of frame
construction.

FRAME CONSTRUCTION
Tubular section :
 Have high Torsional resistance
 Used in three wheelers, Scooters, Pick-
Up’s
 Tata Ace

FRAME CONSTRUCTION
I or H Beam section :
 Flange is called horizontal portion
 Vertical portion called Web
 As per Beam theory I shaped section is
a very efficient form for carrying both
bending & Shear loads in the plane of
web

TYPES OF CHASSIS FRAME
Types of Chassis Frame :
 Conventional Frame
 Semi Integral Frame
 Integral Frame

Conventional Frame :
 Non load carrying Frame.
 Because all the loads are transferred to
the suspensions by frame
 Not suited for resist Torsional load.
 Total frame is mounted on the wheel
axle.
 This arrangement makes the body
completely isolated from the deflection
 It is mostly used in heavy vehicle &
Trucks The curved upward portion on rear & Front
used to accommodate the movement of axle
due to springing & Kept the chassis height as
low

Simple structure Conventional Frame :

Semi Integral Frame :
 Load is transferred to body structure
also.
 Little heavy
 Half of the frame is fixed in the front
end on which the engine gear box and
front suspension is mounted.
 This type of construction is still followed
in European & American cars
Rubber body mounting are replaced
by stiff mounting

Integral Frame :
 Chassis less construction
 Followed by most of the passenger cars.
 Very suit full for mass production of
vehicle.
 No separate frame & All the assembly
units are attached to the body of the
vehicle.
 Heavy side members are eliminated &
Cross members are combined with floor
of the body
 This types are called weight less
construction

Integral Frame :
 Stresses are evenly distributed
throughout the structure.
 Have good torsional & Bending
resistance.

OTHER FRAME CONSTRUCTION
Some important chassis frame :
 Ladder Frame
 Tabular Space frame
 Monocoque Frame
 ULSAB Monocoque
 Backbone Frame
 Aluminum Space frame
 Carbon Fiber

Ladder Frame :
 The ladder frame is simplest & oldest of design.
 It consists merely of two symmetrical rails
 It provides good bending resistance because of its continuous rails from front
to rear.
 Poor resistance to torsion

Tubular space Frame :
 Tubular space frame chassis employs
dozens of circular section tube.
 Positions in different directions to
provide mechanical strength against
force from anywhere.
 Frames are made by welding tubes &
Formed a very complex structure
 Generally used in sports car, which
required high strength.

Tubular space Frame :
Advantage :
1. Very strong in any direction compared
with ladder chassis & Monocoque
chassis :
Disadvantage :
1. Very complex
2. More costly
3. More time required to built
4. Impossible for robotized production
Who use it ?
 Ferrari, Jaguar Xj220.

Monocoque Frame: (Single shell or
Single hull)
 Monocoque is the one piece structure
which defines the over all shape of the
car.
 99% cars are made by this
construction.
 Chassis are made by welding of several
pieces (Spot Welding)
 Monocoque is made of steel

Spot Welding :
 Two plates are connected by resistance
to electric current flow & work piece are
held together under pressure exerted
by electrodes.
 Robots can used in production of
Monocoque frame – Mass production is
achieved.

Advantage :
 Large Space efficiency
 More crash production
 Cheap for mass production
Disadvantage :
 It is very heavy
 Impossible for small volume production

ULSAB Monocoque :Ultra light steel
auto body
 Traditional steel Monocoque are more
heavier. So in 90’s car makers want to
replace with ULSAB.
 Car makers choose aluminum.
 The auto body is made of “Hydroform
parts” – Sandwich steel
 It is new technique to shaping material
into desired shape. As an alternative to
conventional pressing.

Hydroform Technology :
 Hydroform is the cost effective way of
shaping ductile metals such as
aluminum, brass & low alloy steel &
Stainless steel into light weight.
 Structurally stiff & strong pieces.

Advantage :
 Stronger & Lighter than conventional
Monocoque frame by without increasing
production cost.
 Compare with conventional Monocoque
it is 36% lighter & 50% stiffer.
Disadvantage :
 Not strong enough than tubular frame.
 Not suits for sports car.
Who use it :
 Opel Astra, BMW 3 –series, Audi A8

Backbone chassis:
 Colin Chapman is the inventor for
backbone chassis
 It is a strong backbone connects the
front axle & rear axle to provide nearly
all mechanical strength.
 The whole drivetrain, engine &
Suspension are connected to the both
ends of the backbone.
 Made of glass fiber.
 Very much suits for small sports car

Advantage:
 Good crash protection
 High Space efficient
 Hand made – suits for low volume
production.
 Disadvantage :
 Does not provide protection against
side impact or crash.
Who use it?
Lotus Esprit,
TVR, Marcos – British sports car
manufacturer

Carbon frame Monocoque:
 Carbon fiber is found in aircraft,
superbikes, spaceships, racing cars,
because of its superior rigidity to
weight.
 The mechanical advantages:
 High stiffness
 High tensile strength
 Low weight
 High chemical resistance
 High temperature tolerance
 Low thermal expansion

Advantage:
 The lightest & Stiffest chassis
Disadvantage :
 Most expensive
Who use it?
Ferrari f50, Bugatti EB11055.

Aluminum space Frame:
 Made up by vacuum die casting
method.
 Audi 8 is the first mass production car
made by aluminum space frame
 Audi 8 is 40% lighter than the BMW
740I

Vacuum Die casting:
 Reduce the porosity in the casting
 Produce the high quality parts in high
volume

Advantage:
 Lighter than Monocoque
Disadvantage:
 Still expensive

LOADS ON CHASSIS FRAME
Loads on chassis Frame:
1. Loads of short duration: When a
vehicle crossing a broken patch of
road, it is acted upon by heavy &
suddenly applied loads of short
duration. This loads results in
longitudinal torsion.
2. Combined loads of moment any
duration: These loads occurs while
negotiating curve, applying brakes,
striking pits on roads

3. Inertia loads: These loads are applied
on the vehicle due to application of
brake for short period.
- This loads tends to bend the side
member in the vertical plane.
4. Impact Load: These loads are applied
during collision of vehicle with another
object. It results in general collapse.

5. Load due to road chamber: Side
wind,and cornering force while taking a
turn. It results in lateral bending of side
member.
6. Load due to wheel impact with road
obstacles: May cause particular wheel
to remain obstructed the other wheel
tends to move forward. It will tend to
distort the frame to parallelogram shape

7. Static Load: Load due to chassis
parts like engine, steering, gearbox,
fuel tank, body etc. are constantly
acting on the frame
4. Overloads: The load of the which is
loaded beyond the specified design load
is known as overloads

Materials for Frame:
The various steels are used for conventional pressed frame are mild sheet,
carbon steel sheet, and Nickel alloy steel.
The composition of sheet nickel alloy steel is given as follows:
Carbon : 0.25 – 0.35%
Manganese : 0.35 – 0.75%
Silicon : 0.30%
Nickel : 3%
Phosphorus : 0.05%
Sulphur : 0.5%

END

Vehicle Frame system

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