Notes-PPT - BE - EV - Sem I - Unit 5 - Frame - Chassis Design

BE_Sem I_ Modeling and
Simulation of EHV(402034MJ)
Unit 5 : Chassis / Frame Design
Syllabus
2
Prepared By Dr. A. R. Patil (9326273960) M. E. S. College of Engineering, Pune 01

Frame/Chassis Design
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 Introduction to body loads (Load cases and load factor, road loads),

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 Rolling Resistance:
 The rolling resistance of tires on hard surfaces is primarily caused by hysteresis in the tire
materials.
Fr = P *Crr ………………….(For Flat Road)
 Where P = Normal Load = M *g, Crr= Rolling Resistance Coefficient
𝑭 = 𝑪𝒓𝒓 ∗ 𝑷 ∗ 𝑪𝒐𝒔α ……………..(Rode with Slope α )

 The rolling resistance coefficient, Crr, is a function of tire material, tire structure, tire temperature,
tire inflation pressure, tread geometry, road roughness, road material, and presence or absence
of liquids on the road.
 For fuel saving in recent years, low-resistance tires for passenger cars have been developed.
Their rolling resistance coefficient is less than 0.01.
 In vehicle performance calculation, it is sufficient to consider the rolling resistance coefficient as
a linear function of speed. For the most common range of inflation pressure, the following
equation can be used for a passenger car on a concrete road
𝑽
𝑪𝒓 = 𝟎. 𝟎𝟏 ( 𝟏 + )
𝟏𝟓𝟎
where V is vehicle speed in km/h, and f0 and fs depend on the inflation pressure of the tire
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 Rolling Resistance:

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 Aerodynamic Drag:
 A vehicle traveling at a particular speed in air encounters a force resisting its motion. This
force is referred to as aerodynamic drag. It mainly results from two components: shape
drag and skin friction,
 Shape drag: The forward motion of the vehicle pushes the air in front of it. However, the air
cannot instantaneously move out of the way and its pressure is thus increased, resulting in high
air pressure. in addition, the air behind the vehicle cannot instantaneously fill the space left by
the forward motion of the vehicle. This creates a zone of low air pressure. The motion of the
vehicle, therefore, creates two zones of pressure that oppose the motion by pushing (high
pressure in front) and pulling it backwards (low pressure at the back) as shown in Figure below.
The resulting force on the vehicle is the shape drag. The name “shape drag” comes from the
fact that this drag is completely determined by the shape of the vehicle body.

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 Skin friction: Air close to the skin of the vehicle moves almost at the speed of the vehicle while air
away from the vehicle remains still. In between, air molecules move at a wide range of speeds.
The difference in speed between two air molecules produces a friction that results in the second
component of aerodynamic drag
 Aerodynamic drag is a function of vehicle speed V, vehicle frontal area, Af, shape of the vehicle
body, and air density, ρ:
𝟏
𝑭𝒘 = [ ρAf𝑪𝑫 (𝑽 − 𝑽𝒘 )𝟐 ]
𝟐
where 𝑪𝑫 is the aerodynamic drag coefficient that characterizes the shape of the vehicle body
and 𝑽𝒘 is component of the wind speed on the vehicle moving direction, which has a positive sign
when this component is in the same direction of the moving vehicle and a negative sign when it is
opposite to the vehicle speed.

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 Grading Resistance:
 When a vehicle goes up or down a slope, its weight produces a component that is
always directed in the downward direction. This component either opposes the forward
motion (grade climbing) or helps the forward motion (grade descending). In vehicle
performance analysis, only uphill operation is considered. This grading force is usually
called grading resistance
𝑭𝒈 = 𝑴𝒈 𝑺𝒊𝒏𝜶
 To simplify the calculation, the road angle, α, is usually replaced by the grade value, when the
road angle is small
H
Gradeibility i = = tan α ≈ sin α.
𝐿

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 Road Resistance:
 In some literature, the tire rolling resistance and grading resistance together are called
road resistance, which is expressed as
𝑭𝒓 = 𝑭𝒕 + 𝑭𝒈 = 𝑴𝒈 𝑪𝒓 𝑪𝒐𝒔α + 𝑺𝒊𝒏α
 When the road angle is small, the road resistance can be simplified as
𝑭𝒓 = 𝑭𝒕 + 𝑭𝒈 = 𝑴𝒈 𝑪𝒓 + 𝒊

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 Vehicle Acceleration Force:
 According to Newton’s second law, vehicle acceleration can be written as
𝒅𝑽 𝑭𝒕 − 𝑭𝒓
=
𝒅𝒕 δ𝑴
where V is the speed of the vehicle, Ft is the total tractive effort of the vehicle, Fr is the total resistance, M
is the total mass of the vehicle, and δ is the mass factor that equivalently converts the rotational inertias
of rotating components into translational mass.
 Acceleration Force :
𝒅𝑽
Fa = M*a =M *
𝒅𝒕

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 Inertia Force:
 According to Newton’s second law, vehicle acceleration can be written as
𝒅𝑽 𝑭𝒕 − 𝑭𝒓
=
𝒅𝒕 δ𝑴
where V is the speed of the vehicle, Ft is the total tractive effort of the vehicle, Fr is the total resistance, M
is the total mass of the vehicle, and δ is the mass factor that equivalently converts the rotational inertias
of rotating components into translational mass.
 Acceleration Force :
 Nominal vehicle power requirements are typically based on vehicle acceleration

requirements, usually specified as the time to accelerate from 0 to 100 km/h (62 mph) or
from 0 to 60 mph. Under these conditions, the maximum available torque and power of
the propulsion system are likely to be required.
𝒅𝑽
Prepared By Dr. A. R. Patil (9326273960) Fa = M*a =M *
M. E. S. College of Engineering, Pune 01
𝒅𝒕
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 Internal Friction:
 If ‘Pf’ is power lost due to internal friction, then force to overcome internal friction is
𝑷𝒇
𝑭=
𝑽
 Accessories Force :
 If ‘Pac’ is power required to run the accessories (Ac, power steering etc.) then force is
𝑷𝒂𝒄𝒄
𝑭= 𝑽

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 Vehicle Dynamics,
 In the longitudinal direction, the major external forces acting on a two-axle vehicle
include the rolling resistance of the front and rear tires Frf and Frr, which are represented
by rolling resistance moment, Trf and Trr, aerodynamic drag, Fw, climbing resistance, Fg
(Mg sin α), and tractive effort of the front and rear tires, Ftf and Ftr. Ftf is zero for a rear-
wheel-driven vehicle, whereas Ftr is zero for a front-wheel-driven vehicle.
 The dynamic equation of vehicle motion along the longitudinal direction is expressed by
𝒅𝑽
𝑴 = (Ftf + Ftr) − (Frf + Frr + Fw + Fg)…………………..(a)
𝒅𝒕
where dV/dt is the linear acceleration of the vehicle along the longitudinal direction and M is the
vehicle mass. The first term on the right-hand side of Equation (a) is the total tractive effort and the
second term is the resistance

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 To predict the maximum tractive effort that the tire–ground contact can support, the
normal loads on the front and rear axles have to be determined. By summing the
moments of all the forces about point R(center of the tire–ground area), the normal load
on the front axle Wf can be determined as
𝐝𝐯
𝐌𝐠𝐋𝐛 𝐂𝐨𝐬α − (𝐅𝐭𝐟 + 𝐅𝐭𝐫 + 𝐅𝐰 𝐡𝐰 + 𝐌𝐠𝐡𝐠 𝐒𝐢𝐧α + 𝐌𝐡𝐠 )
𝐖𝐟 = 𝐝𝐭
𝐋
 Similarly, the normal load acting on the rear axle can be expressed as
𝐝𝐯
𝐌𝐠𝐋𝐚 𝐂𝐨𝐬α + (𝐅𝐭𝐟 + 𝐅𝐭𝐫 + 𝐅𝐰 𝐡𝐰 + 𝐌𝐠𝐡𝐠 𝐒𝐢𝐧α + 𝐌𝐡𝐠 )
𝐖𝐫 = 𝐝𝐭
𝐋

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 The maximum tractive effort that the tire–ground contact can support (any small
amount over this maximum tractive effort will cause the tire to spin on the ground) is
usually described by the product of the normal load and the coefficient of road
adhesion, μ, or referred to as frictional coefficient in some of the literature
𝑭𝒕𝒎𝒂𝒙 = μ* Wf
𝑳𝒂 − 𝒇𝒓 𝒉𝒈 − 𝒓𝒅
μ𝑴𝒈𝑪𝒐𝒔
𝑭𝒕𝒎𝒂𝒙 = 𝑳
𝟏 − μ𝒉𝒈 /𝑳

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 Vehicle Road-Load Coefficients from EPA Coast-Down Testing :
 Significant testing is conducted by vehicle manufacturers for the various regulatory agencies. In
addition to fuel economy and emissions data, the EPA in the United States requires the manufacturers
to supply data on vehicle road-load coefficients based on the “coast-down” test. In this test, the
vehicle is allowed to coast down from 120 km/h in neutral, and three coefficients are generated to
simulate the rolling, spinning, and aerodynamic resistances.
 The vehicle road-load force Fv as a function of speed, is defined as follows:
Fv =A + Bv + Cv 2
 where v is the vehicle speed in m/s, and the A, B, and C coefficients are determined from the coast-
down test.
 Typically,
 coefficient A correlates to the rolling resistance
 coefficient C to the aerodynamic drag.

 Coefficient B relates to the spinning or rotational losses and tends to be relatively small
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 Total Motive Force:
 Fm required to accelerate the vehicle is the sum of the acceleration, load, and climbing
forces and is given by
Fm = Fa + Fv + Fc
we can express the motive force as
dv
Fm = M∗ +A + Bv + Cv 2 + Mg sinα
dt
 The motive force describes the force required for linear motion. The motive torque Tm is
the torque required at the drive axle and is obtained by multiplying the motive force by
the wheel radius r, thus relating the linear motion to rotating motion
Tm = Fm* r

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 Total Motive Force:
 Fm required to accelerate the vehicle is the sum of the acceleration, load, and climbing
forces and is given by
Fm = Fa + Fv + Fc
we can express the motive force as
dv
Fm = m∗ +A + Bv + Cv 2 + mg sinα
dt

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 Motive Torque:
 The motive force describes the force required for linear motion. The motive torque Tm is
the torque required at the drive axle and is obtained by multiplying the motive force by
the wheel radius r, thus relating the linear motion to rotating motion
Tm = Fm* r
 From Newton’s second law of motion for a rotating system, we can express torque as
dω
T=J*α=J∗
dt
 where J is the moment of inertia, and ω and α are the angular speed and acceleration.

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 Axle Torque:
 In addition to the motive torque to move the vehicle, we must also consider the torque
to spin the rotating parts within the drivetrain. This is represented by a drive-axle
referenced moment of inertia, Jaxle . Thus, the total torque required at the drive axle
Taxle is the sum of the motive torque and the torque required to accelerate Jaxle :.
Taxle =Tm +Jaxle * αaxle
where αaxle is the angular acceleration.
 By substituting value of Tm and v = rω
dv d𝑉
 Taxle = m∗ +A + Bv + Cv 2 + mg sinα + J ∗ 𝑟 ∗
dt dt

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 Traction Torque:
 The traction torque 'Tt ′ is the torque developed on the output shaft of the IC engine or
electric motor. The maximum traction motor or engine torque and power are typically
specified by the manufacturer. These values are the maximum traction power and
traction torque available on the shaft of the motor or engine. The traction torque is
directly geared to the drive-axle torque. The powertrain gearing ratio ‘Ng’ is specified by
the manufacturer in the case of most cars. The gearing and transmission efficiency ′ηg ′
can significantly impact the required motive torque. The axle torque is related to the
traction torque Tt, when motoring, as follows
Taxle = Ng *ηg * Tt
𝟏 dv d𝑽
Tt = m∗ +A + Bv + Cv 2 + mg sinα + J ∗ 𝒓 ∗
Ng *ηg dt dt
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 Regenerative Braking of the Vehicle:
 The energy used to brake or slow down a vehicle in a conventional vehicle is dissipated
as heat in the braking system and lost to the vehicle. An electric vehicle can capture or
regenerate the energy and store it on the vehicle. The traction motor can develop a
negative torque, up to the rated value in the forward direction, which reverses the flow
of power such that the kinetic energy of the vehicle is converted to negative
mechanical power on the rotor shaft, and subsequently converted to electrical power
by the machine, which is used to recharge the battery. This is the principle of
regenerative braking, as shown in Figure (b)
Ng * Tt
Taxle =
ηg

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 Traction Motor Characteristics:
 , the rated conditions of speed, torque, and power are the conditions for which the machine
is designed, either continuously or intermittently with time. The conditions also depend on
various environmental conditions, such as ambient and coolant temperatures. When
discussing the electric powertrain, the rated conditions are typically for the maximum torque
or power output
 The electric motor can be characterized by two modes of operation, constant-torque mode
and constant-power mode
 In constant-torque mode, which is a low-speed mode, the machine can output a constant rated rotor
torque T𝒓(𝒓𝒂𝒕𝒆𝒅) and the rotor power P𝒓 increases linearly with speed. Thus, the rotor torque T𝒓 and rotor
power P𝒓 are limited as follows:
T𝒓 =T𝒓(𝒓𝒂𝒕𝒆𝒅) and P𝒓 = T𝒓(𝒓𝒂𝒕𝒆𝒅) ∗ ω𝒓
where ω𝒓 is the angular frequency or speed of the rotor. This condition holds until the rated speed
ω𝒓(𝒓𝒂𝒕𝒆𝒅) of the machine defined by
P𝒓(𝒓𝒂𝒕𝒆)
ω𝒓(𝒓𝒂𝒕𝒆𝒅) =
Prepared By Dr. A. R. Patil (9326273960) T𝒓(𝒓𝒂𝒕𝒆𝒅)
M. E. S. College of Engineering, Pune 01
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 Traction Motor Characteristics:
 In constant-power mode, which is a high-speed mode, when operating above the rated speed,
the machine can output a constant rated power P𝒓(𝒓𝒂𝒕𝒆𝒅) and the available rotor torque
decreases inversely with rotor speed
P𝒓(𝒓𝒂𝒕𝒆)
P𝒓 =P𝒓(𝒓𝒂𝒕𝒆𝒅) and T𝒓(𝒓𝒂𝒕𝒆𝒅) =
ω𝒓(𝒓𝒂𝒕𝒆𝒅)

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 Vehicle Structure/Chassis/Frames
 Chassis for a car is analogous to the skeleton for a human body. Chassis, also known as
‘Frame’, is the foundation structure of any car that supports it from underneath. The purpose
of the chassis is to bear the weight of the car in its idle and dynamic states.
• Function of Chassis :
• Supports or bears the load of the vehicle body.
• Provide the space and mounting location for various
aggregates of vehicle.
• Supports the weight of various systems of the vehicle
such as engine, transmission etc.
• Supports a load of passengers as well as the luggage.
• Withstands the stresses arising due to bad road
conditions.
• Withstands stresses during braking and acceleration of
Prepared By Dr. A. R. Patil (9326273960) M. E. S. Collegethe vehicle.Pune 01
of Engineering,
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 Classification of Vehicle Structure/Chassis/Frames
• According to the fitting of the engine:

• Full-forward
• Semi-forward
• Bus chassis
• Engine at back
• Engine at the center.
• According to the number of wheels fitted in the vehicles and the number of driving wheels:
• 4 x 2 drive chassis – It has four wheels out of which 2 are driving wheels
• 4 x 4 drive chassis – It has four wheels and all of them are driving wheels
• 6 x 2 drive chassis – It has six wheels out of which 2 are driving wheels
• 6 x 4 drive chassis – It has six wheels out of which 4 are driving wheels

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• Full-forward
• This type of chassis consists of an engine fitted in front of the driver seat or driver cabin. It is
commonly used in cars and old models of TATA trucks.
• The driver cannot see the road just in front of the front tires because he sits behind the engine
quite far off from the front axle.
• To help the driver to see as close to the wheels as possible, the slope is provided at the
mudguard. Moreover, passengers or goods cannot be carried in a portion of the chassis where
the engine is fitted.
• Semi-forward
• This chassis, the engine is mounted in such a way that half of it is placed in the driver
compartment and half out of the driver compartment.
• These extra passengers or luggage can be placed in the portion of chassis thus saved.
• Semi forward chassis are used in standard Bedford pick-ups and Tata-Mercedez trucks.

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• Bus chassis
• To allow the driver to see the road just in front of the front wheels as well as to make driving easier
and trouble-free especially in the congested areas, full forward chassis was modified by mounting
the engine completely inside the driver cabin.
• In addition to providing an extra clear view of the road in front of the front wheels, it provided an
increased floor area to accommodate three extra seats.
• Engine at back
• In this chassis, the engine is fitted at the rear of the vehicle thus saving a lot of space at the front
eliminating long propeller shafts and providing a clear view of the road at the front.
• This system is used in popular vehicles like Renault, Daulphine, and Volkswagen. The engine is also
mounted at the rear end of the chassis in imported Leyland Double Decker Buses.
• In this chassis fix up of controls like gear shift lever, oil, and fuel gauge, the accelerated linkage is
very complicated. Moreover natural draft of air to the radiator due to forward motion of the
vehicle is also missing.
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 Engine at the center
 In this chassis, the engine is fitted in the centre.
 its centre under the chassis to remove defects of the engine fitted at the rear chassis and to use the
complete floor of the space.
 This chassis was used in Royal Tiger Wordmaster busses previously plied in Delhi by Delhi Transport
Undertaking.

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 Types of Vehicle Structure/Chassis/Frames :
 Ladder Frame Chassis:

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 Ladder Frame Chassis:
 Named after the shape it replicates, the ladder-frame chassis is one of the oldest chassis types. This
chassis is characterized by two long heavy beams that are supported by two smaller ones. Its quality
of being easily manufactured not only made it contemporarily popular but also eased the way for its
mass production. Since ladder frame chassis is significantly heavy it’s usually used for vehicles that
transport heavy material.
 Benefits
 Easy to manufacture and easy assembling of the car over it.·
 Heavy and strong tensile strength.
 Drawbacks
 Poor cornering ability due to weak torsional rigidity
 Its heaviness doesn’t make it suitable for performance cars and hatchbacks.
 Application:
 Heavy commercial vehicles such as trucks and buses mainly use the ladder-type chassis structure.
However, some light commercial vehicles like pickup trucks also use the ladder-type.
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 Backbone Chassis:

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 Backbone Chassis:
 Similar to the ladder frame chassis, the backbone chassis is also named after the shape it reflects. The
hollow rectangular cross-section and a cylindrical tube passing through it connecting the front and rear
suspension, like a backbone. The cylindrical tube surrounds the driveshaft. You can find backbone chassis
in one of the most popular cars, Skoda Rapid.
 Benefits
 Its crafting allows better contact between the half axle and ground making it preferable for off-
roading.
 A cylindrical tube covering the driveshaft saves it from any damage while off-roading.
 The structure’s torsional toughness is relatively more supple than ladder chassis.
 Drawbacks
 In case the driveshaft fails, the whole chassis needs to be dismantled as the driveshaft is covered
with the cylindrical tube of the chassis.
 The
Prepared manufacture
By Dr. of backbone
A. R. Patil (9326273960) chassis
M. E. S.is costly
College and increases
of Engineering, Pune 01 the overall cost of the car.
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 Monocoque Chassis:

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 Monocoque Chassis:
 Monocoque is French for ‘single shell’. This unibody frame is named after its structural outlook. The
monocoque frames were firstly used in ships, next in aeroplanes, and manufacturers took quite a while to
find them pertinent for cars as well. A monocoque is like an endoskeleton of a car crafted by fitting chassis
and complete basic frame in a single unit. Monocoque chassis is the most popularly used chassis as of
now given its number of advantages over the other two types of chassis.
 Benefits
 Best torsional rigidity
 Its cage-like design makes it relatively safer.
 Easy to repair.
 Drawbacks
 The amalgamation of frame and chassis makes it fairly heavy.
 The production of monocoque chassis on a small scale isn’t financially plausible, thereby it can
prove
Prepared fairly
By Dr. A. R. Patilcostly for
(9326273960) the cars that are produced
M. E. S. in small
College of Engineering, numbers.
Pune 01
39
 Tubular Chassis:

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 Tubular Chassis:
 A three-dimensional derivative of ladder chassis, Tubular chassis are mainly used in performance cars given their
excellent safety. Rarely seen in passenger cars, tubular chassis is much stronger than ladder chassis and they
popularised the utilization of stronger structure underneath the doors to accomplish more consolidated strength.
 Benefits
 Comparatively better rigidity for the chassis of the almost same weight
 Nice ratio of rigidity and weight making a car strong while being light-weighted.
 Highly preferred for race cars
 Drawbacks
 Tubular chassis are quite complex in design, conclusively they can’t be manufactured by conventional methods.
 They are very time-consuming in production, and can’t be mass-produced.
 Not suitable for passenger cars and the tubular chassis elevates the doors a bit making it slightly hard to access the cabin
 Application:
 Some
Prepared By Dr.racing vehicles
A. R. Patil and All-Terrain vehiclesM.use
(9326273960) E. S.tubular
College frame designs.
of Engineering, Pune 01
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Skateboard chassis :

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 skateboard chassis : A popular feature of many of today's electric vehicles (EVs) is the
skateboard chassis or platform that looks like a skateboard that carries the vehicle's battery and electric
motors. It also allows for x-by-wire technology. This skateboard chassis is a flat platform with four wheels
that, while it looks like a skateboard, holds all the electric motors and the battery pack.
 Benefits
 manufacturers can build nearly any kind of vehicle they want on top of the platform, as the size and shape of
the chassis can easily be varied to meet different requirements Nice ratio of rigidity and weight making a car
strong while being light-weighted.
 can be custom configured fairly cheaply if the auto-maker wanted to place a motor on each of the four wheels
for higher performance or give the vehicle more power by slotting it into the front or back axle.
 saves the auto manufacturer time and money, as a new vehicle platform does not need to be designed from
the bottom up. Vehicle makers can simply modify the skateboard platform to fit whatever is desired in a new
vehicle.
 For drivers, the platform gives vehicles lower centers of gravity as the battery is closer to the ground. Additionally, the
skateboard chassis allows for much more interior space, as the hood space (if there even is a hood) can be used for
storage.
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 Strength and Stiffness,

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 Frame building Problems and frame components,
 Chassis frame is the basic frame work of the automobile. It supports all the parts of the
automobile attached to it. It is made of drop forged steel. All the parts related to
automobiles are attached to it only. All the systems related to automobile like power
plant, transmission, steering, suspension, braking system etc are attached to and
supported by it only
 The Functions of the Chassis frame
 To carryall the stationary loads attached to it and loads of passenger and cargo carried in it .
 To withstand torsional vibration caused by the movement of the vehicle
 To withstand the centrifugal force caused by cornering of the vehicle
 To control the vibration caused by the running of the vehicle
 To withstand bending stresses due to rise and fall of the front and rear axles
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 Types of Chassis frame,
 There are different types of chassis frame sections
 Channel section
 Box section
 Tubular section
 The conventional frame is also known as Non-load carrying frame. In this types of frame ,
the loads on the vehicle are transferred to the suspension by the frame which is the main
skeleton of the vehicle. The channel section is used in long members and box section in
short members. Tubular section is used now-a-days is three wheelers, scooters, matadors
and pickup vans. The frames should be strong enough to bear load while sudden brakes
and accidents.

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 Various loads acting on the Chassis frame,
 The loads acting on the chassis frame are as follow
 Vertical bending: The force acting on an automobile due to the vertical load is called vertical bending.
This force accommodates the weight of the body and passengers sitting inside the vehicle.
 Longitudinal torsion: The longitudinal torsion acts on a vehicle when one wheel is lifted and the other
wheels are grounded as shown in the figure. This tends to twist the frame; this results in a torsional effect.
 Fore and aft loading: When the vehicle is suddenly accelerated or brakes are applied suddenly, forces
start acting on the frame of the vehicle. During braking the forces act on the front side of the frame and
during accelerating the forces act on the rear side of the frame.
 Impact loads: When the vehicle strikes a solid structure it causes the frame to collapse, or lose shape.
These types of sudden loads are known as impact loads. This also means that the vehicle has met with
an accident.
 Overloading: Overloading again is a type of vertical load which is due to excess weight on the vehicle.

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 Frame Defect,
 Defects in frames and body generally occur due to severe impacts on rough roads and
collision with other objects or vehicles.
 Depending upon the nature of collision, the defects of the following kinds may occur.
• Misalignment in horizontal and/or vertical plane.
• Twisting of main frame and/or sub-frames.
• Buckled main frame and/or sub-frames.
• Bent side members and/or dumb iron.
• Broken or loose gusset plates and rivets..

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 Frame Defect Check,
 Whenever the vehicle is subjected to a major collision, the frame alignment must be
checked. A visual check generally reveals major misalignment, but in case this fails to
indicate the defect, the frame check is conducted as follows
 a) Wheel Base Check. The front wheels are set in the straight-ahead position and the
wheelbase on each side is checked
 (b) Alignment. To verify parallelism of the rear wheels with each other, a cord or straight
edge is held against the rear wheel. Then the front wheel is turned until it is parallel with
the cord. The clearance (if any) between the wheel and cord should be the same on
both sides
(c) Plumb-line Check. A plumb line is dropped from the outside of each fixed shackle of
the spring to give eight chalk marks on the floor.
49
 Frame Defect Check,

50

51
 Understructure Design:
 An understructure platform is also called underbody platform where is a

platform that can be divided into three sections which are
 The front section that is designed support for the steering system.
 The mid-section is the main structure of the vehicle that will be a structure
protected the battery of the EV and also support the full weight of the passenger
and some other components.
 The rear component is the support for the drivetrain system.

52
 FMEA (Failure Mode and Effects Analysis)
 Failure Modes and Effects Analysis (FMEA) is a systematic, proactive method for
evaluating a process to identify where and how it might fail and to assess the
relative impact of different failures, in order to identify the parts of the process that
are most in need of change.
 FMEA includes review of the following:
 Steps in the process
 Failure modes (What could go wrong?)
 Failure causes (Why would the failure happen?)
 Failure effects (What would be the consequences of each failure?)
 A few different types of FMEA analyses exist, such as:
 Functional
 Design
 Process
53
 Ground rules : The ground rules of each FMEA include a set of project selected procedures; the
assumptions on which the analysis is based; the hardware that has been included and excluded
from the analysis and the rationale for the exclusions. The ground rules also describe the indenture
level of the analysis (i.e. the level in the hierarchy of the part to the sub-system, sub-system to the
system, etc.), the basic hardware status, and the criteria for system and mission success. Every
effort should be made to define all ground rules before the FMEA begins; however, the ground
rules may be expanded and clarified as the analysis proceeds. A typical set of ground rules
(assumptions) follows:
 Only one failure mode exists at a time.
 All inputs (including software commands) to the item being analyzed are present and at nominal values.
 All consumables are present in sufficient quantities.
 Nominal power is available

54
 Benefits :Major benefits derived from a properly implemented FMECA effort are as follows:
 It provides a documented method for selecting a design with a high probability of
successful operation and safety.
 A documented uniform method of assessing potential failure mechanisms, failure modes
and their impact on system operation, resulting in a list of failure modes ranked
according to the seriousness of their system impact and likelihood of occurrence.
 Early identification of single failure points (SFPS) and system interface problems, which
may be critical to mission success and/or safety. They also provide a method of verifying
that switching between redundant elements is not jeopardized by postulated single
failures.
 An effective method for evaluating the effect of proposed changes to the design
and/or operational procedures on mission success and safety.
 A basis for in-flight troubleshooting procedures and for locating performance monitoring
and fault-detection devices.
 Criteria for early planning of tests.
55
 Retrofitting
 Electric Vehicle Retro-fitment means to convert existing petrol or diesel run vehicles into
an electric vehicle.
 The process involves changing the original engine and other related components and a
new alternative energy source to be transplanted into the existing vehicle body.
 It can either be an additional system added to the existing vehicle motor or to
completely replace the existing engine with a new motor and drivetrain.
 All other components remain the same on the vehicle, which makes it easier to replace
or repair parts like suspension, brakes, headlights, etc.
 Conversion planning can pay even greater dividends:
 Chassis—Purchase, preparation, removal of internal combustion engine parts
 Mechanical—Motor mount fabrication, motor installation, battery mounts, and other mechanical
parts fabrication and installation
 Electrical—High-current, low-voltage, and charging system components and wiring
 Battery—Purchase and installation of batteries

56
 Retrofitting

57
 Retrofitting and its associated Problems.
 Challenges to the widespread adoption of EVs
 Inadequate charging infrastructure.
 Risk of grid overload.
 High-carbon grid profile.
 Finite critical minerals and rare earth metals.
 Smart and flexible charging.
 Smart energy management for effective EV load management.
 Battery monitoring, analytics and recycling.
 the higher cost of retrofit electric powertrains,
 falling prices of electric batteries leading to a fall in the prices of new EVs. This leads to
buying a new EV easier for the end customer vis-à-vis retrofitting an old ICE vehicle
 Range anxiety
 Lack of charging infrastructure
 Battery quality

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BE_Sem I_ Modeling and

Prepared By Dr. A. R. Patil (9326273960) M. E. S. College of Engineering, Pune 01

Prepared By Dr. A. R. Patil (9326273960) M. E. S. College of Engineering, Pune 01

Prepared By Dr. A. R. Patil (9326273960) M. E. S. College of Engineering, Pune 01

𝑭 = 𝑪𝒓𝒓 ∗ 𝑷 ∗ 𝑪𝒐𝒔α ……………..(Rode with Slope α )

Prepared By Dr. A. R. Patil (9326273960) M. E. S. College of Engineering, Pune 01

Prepared By Dr. A. R. Patil (9326273960) M. E. S. College of Engineering, Pune 01

Prepared By Dr. A. R. Patil (9326273960) M. E. S. College of Engineering, Pune 01

Prepared By Dr. A. R. Patil (9326273960) M. E. S. College of Engineering, Pune 01

Prepared By Dr. A. R. Patil (9326273960) M. E. S. College of Engineering, Pune 01

Prepared By Dr. A. R. Patil (9326273960) M. E. S. College of Engineering, Pune 01

Prepared By Dr. A. R. Patil (9326273960) M. E. S. College of Engineering, Pune 01

 Nominal vehicle power requirements are typically based on vehicle acceleration

Prepared By Dr. A. R. Patil (9326273960) M. E. S. College of Engineering, Pune 01

Prepared By Dr. A. R. Patil (9326273960) M. E. S. College of Engineering, Pune 01

Prepared By Dr. A. R. Patil (9326273960) M. E. S. College of Engineering, Pune 01

Prepared By Dr. A. R. Patil (9326273960) M. E. S. College of Engineering, Pune 01

Prepared By Dr. A. R. Patil (9326273960) M. E. S. College of Engineering, Pune 01

 The vehicle road-load force Fv as a function of speed, is defined as follows:

 coefficient A correlates to the rolling resistance

 coefficient C to the aerodynamic drag.

Prepared By Dr. A. R. Patil (9326273960) M. E. S. College of Engineering, Pune 01

we can express the motive force as

Prepared By Dr. A. R. Patil (9326273960) M. E. S. College of Engineering, Pune 01

we can express the motive force as

Prepared By Dr. A. R. Patil (9326273960) M. E. S. College of Engineering, Pune 01

Prepared By Dr. A. R. Patil (9326273960) M. E. S. College of Engineering, Pune 01

where αaxle is the angular acceleration.

 By substituting value of Tm and v = rω

Prepared By Dr. A. R. Patil (9326273960) M. E. S. College of Engineering, Pune 01

Prepared By Dr. A. R. Patil (9326273960) M. E. S. College of Engineering, Pune 01

T𝒓 =T𝒓(𝒓𝒂𝒕𝒆𝒅) and P𝒓 = T𝒓(𝒓𝒂𝒕𝒆𝒅) ∗ ω𝒓

Prepared By Dr. A. R. Patil (9326273960) M. E. S. College of Engineering, Pune 01

• According to the fitting of the engine:

Prepared By Dr. A. R. Patil (9326273960) M. E. S. College of Engineering, Pune 01

Prepared By Dr. A. R. Patil (9326273960) M. E. S. College of Engineering, Pune 01

 In this chassis, the engine is fitted in the centre.

Prepared By Dr. A. R. Patil (9326273960) M. E. S. College of Engineering, Pune 01

Prepared By Dr. A. R. Patil (9326273960) M. E. S. College of Engineering, Pune 01

 Easy to manufacture and easy assembling of the car over it.·

 Heavy and strong tensile strength.

 Poor cornering ability due to weak torsional rigidity

Prepared By Dr. A. R. Patil (9326273960) M. E. S. College of Engineering, Pune 01

Prepared By Dr. A. R. Patil (9326273960) M. E. S. College of Engineering, Pune 01

 Best torsional rigidity

 Its cage-like design makes it relatively safer.

 The amalgamation of frame and chassis makes it fairly heavy.

Prepared By Dr. A. R. Patil (9326273960) M. E. S. College of Engineering, Pune 01

 Highly preferred for race cars

 They are very time-consuming in production, and can’t be mass-produced.

Prepared By Dr. A. R. Patil (9326273960) M. E. S. College of Engineering, Pune 01

Prepared By Dr. A. R. Patil (9326273960) M. E. S. College of Engineering, Pune 01

 The Functions of the Chassis frame

 To withstand torsional vibration caused by the movement of the vehicle

 To withstand the centrifugal force caused by cornering of the vehicle

 To control the vibration caused by the running of the vehicle

 There are different types of chassis frame sections

Prepared By Dr. A. R. Patil (9326273960) M. E. S. College of Engineering, Pune 01