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M.S Ramaiah School of Advanced StudiesPostgraduate Engineering and Management Programme (PEMP)

M.S.Ramaiah School of Advanced Studies

Postgraduate Engineering and Management Programmes (PEMP)#470-P Peenya Industrial Area, 4th Phase, Bengaluru-560 058

ASSIGNMENTModule Code AME 510

Module Name Structures, Safety and Impact.

Course M.Sc [Engg] in Automotive Engineering

Department Automotive and Aeronautical Engg.

Name of the Student Keerthiraj Shetty

Reg. No BBB0911019

Batch Full-Time - 2011

Module Leader Dr. Vinod K. Banthia

PO

STGRADUATEENG

INEERING

ANDMA

NAGEMENTPROG

RAMME

PEMP


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Structures, Safety and Impact.ii

Tel; 080 4906 5555, website: www.msrsas.org

Declaration Sheet

DelegatesName KEERTHIRAJ SHETTY

Reg No BBB0911019

CourseM.Sc.[ENGG] in Automotive

EngineeringBatch Full time 2011

Module Code AME 510

Module Title Structures, Safety and Impact.

Module Start Date 09-07-2012 Submission Date 04-08-2012

Module Leader Dr. Vinod K. BanthiaSubmission ArrangementsThis assignment must be submitted to Academic Records Office (ARO) by the submission date before 1730 hours

for both Full-Time and Part-Time students.

Extension requests

Extensions can only be granted by the Head of the Department / Course Manager. Extensions granted by any other

person will not be accepted and hence the assignment will incur a penalty. A copy of the extension approval must beattached to the assignment submitted.

Late submission Penalties

Unless you have submitted proof of Mitigating Circumstances or have been granted an extension, the penalties for a

late submission of an assignment shall be as follows: Up to one week late: Penalty of one grade (5 marks) One-Two weeks late: Penalty of two grades (10 marks) More than Two weeks late: Fail - 0% recorded (F2)All late assignments must be submitted to Academic Records Office (ARO). It is your responsibility to ensure that

the receipt of a late assignment is recorded in the ARO. If an extension was agreed, the authorization should be

submitted to ARO during the submission of assignment.

To ensure assignments are written concisely, the length should be restricted a limit indicated in the assignment

questions. Each participant is required to retain a copy of the assignment in his or her record in case of any loss.

Declaration

The assignment submitted herewith is a result of my own investigations and that I have conformed to the guidelines

against plagiarism as laid out in the PEMP Student Handbook. All sections of the text and results, which have been

obtained from other sources, are fully referenced. I understand that cheating and plagiarism constitute a breach of

University regulations and will be dealt with accordingly.

Signature of the

DelegateDate

Date stamp from

ARO

Signature of

ARO Staff

Signature of

Module Leader

Signature of

Course Manager


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Structures, Safety and Impact.iii

Attendance Details Theory Laboratory Fine Paid

(if any for shortage ofattendance)

Remarks

AssignmentMarks-Sheet (Assessor to Fill)

Part a b c d e f Total Remarks

A

B

C

Marks Scored for 100 Marks Scored out of 50

Result PASS FAIL

Written ExaminationMarksSheet (Assessor to Fill)

Q. No a b c d Total Remarks

1

2

3

4

5

6

Marks Scored for 100 Marks Scored out of 50

Result PASS FAIL

PMAR- form completed for student feedback (Assessor has to mark) Yes No

Overall Result

Components Assessor Reviewer

Assignment (Max 50) Pass Fail

Written Examination (Max 50) Pass Fail

Total Marks (Max 100) (Before Late Penalty) Grade

Total Marks (Max 100) (After Late Penalty) Grade

A+ A A- B+ B B- C+ C FAIL

100-

74-

69-

64-

59-

54-

49-

44-

Less than 40

IMPORTANT1. The assignment and examination marks have to be rounded off to the nearest integer and entered in the respective

fields

2. A minimum of 40% required for a pass in both assignment and written test individually3. A student cannot fail on application of late penalty (i.e. on application of late penalty if the marks are below 40,

cap at 40 marks)

Signature of Reviewer with date Signature of Module Leader with date

M. S. Ramaiah School of Advanced Studies

Postgraduate Engineering and Management Programme- Coventry University (UK)

Assessment Sheet

Department Automotive & Aeronautical Engineering

Course M.Sc.[ENGG] in Automotive Engineering Batch Full-Time 2011

Module Code AME 510 Module Title Structures, Safety and Impact

Module Leader Dr. Vinod K. BanthiaModule CompletionDate

04-08-2012

Student Name KEERTHIRAJ SHETTY ID Number BBB0911019


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Structures, Safety and Impact.iv

ABSTRACT____________________________________________________________________

The assignment deals with study of vehicle dynamics which is the study of vehicles

response to the force acting on the contact patch on tire and road. Different type of

moments and the lateral forces acting on the vehicle and the vehicles response to those

moments and forces while maneuvering is explained.

In Part-A of the assignment a technical essay is given which includes introduction to

vehicle handling and also the understeer, oversteer characteristic of the vehicle. How the

understeer, neutral steer and oversteer characteristic is achieved by varying the lateral

load on front and rear part of the vehicle is explained. The effect of understeer gradientson vehicle turning radius is explained. The specific behavior required to maneuver in the

narrow lanes and also the latest electronic systems involved in vehicle stability is

explained.

Part-B of the assignment deals with the analytical calculation done to find out the

understeer gradient K value. The calculations are done by assuming standard equation

and also by cars technical and suspension data. After getting the understeer gradient

value, the cars behavior is analyzed at different maneuvering conditions.

In Part-C of the assignment, the car simulation is done by full vehicle analysis on

constant-radius cornering test to find out the K value, using ADAMS/Car software. The

K value obtained is compared with that of Part-B K value and commented on the

result comparison.


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Structures, Safety and Impact.v

TABLE OF CONTENTS_____________________________________________________________________

DECLARATION SHEET ................................................................................................. iiiABSTRACT .......................................................................................................................ivTABLE OF CONTENTS .................................................................................................... vLIST OF FIGURES ......................................................................................................... viiLIST OF TABLES .......................................................................................................... viii

NOMENCLATURE ..........................................................................................................ixPART-A .............................................................................................................................. 1CHAPTER 1 ....................................................................................................................... 1

1.1 Introduction to Vehicle Handling ...........................Error! Bookmark not defined.1.2 Understeer Vs Oversteered vehicle characteristics .Error! Bookmark not defined.1.3 Understeer Gradient and its significance ................Error! Bookmark not defined.1.4 Understeer gradient and turning radius ...................Error! Bookmark not defined.1.5 Manoeuvring in narrow lanes .................................Error! Bookmark not defined.1.6 Oversteer vehicle and stability control ...................Error! Bookmark not defined.

PART-B .............................................................................................................................. 4CHAPTER 2 ....................................................................................................................... 4

2.1 Introduction .............................................................Error! Bookmark not defined.2.2 Car specifications ....................................................Error! Bookmark not defined.2.3 Analytical equations to find Ku value...................Error! Bookmark not defined.2.4 Calculations.............................................................Error! Bookmark not defined.

2.4.1 Finding c and b values ................................Error! Bookmark not defined.2.4.2 Tire cornering stiffness Cf and Cr. ..............Error! Bookmark not defined.2.4.3 Tire cornering stiffness (Ktcs) ........................Error! Bookmark not defined.2.4.4 Wheel rate of front and rear wheels .................Error! Bookmark not defined.

2.4.5 Front and Rear suspension roll stiffness (Kf, Kr) ............Error! Bookmark not

defined.2.4.6 Load on front and rear wheels (Fzf, Fzr) ...........Error! Bookmark not defined.2.4.7 Second coefficient of cornering stiffness bf and br ...Error! Bookmark not

defined.2.4.8 Lateral load transfer stiffness (Kllt)................Error! Bookmark not defined.2.4.9 Tire patch length (p) ......................................Error! Bookmark not defined.2.5.1 Aligning torque stiffness (Kat).......................Error! Bookmark not defined.2.5.2 Steering system stiffness (Kst) .......................Error! Bookmark not defined.


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Structures, Safety and Impact.vi

2.5.3 Roll steer gradient (Krs) .................................Error! Bookmark not defined.2.5.4 Camber thrust gradient (Kct)..........................Error! Bookmark not defined.2.5.5 Lateral force compliance steer gradient (Klfcs) .............Error! Bookmark not

defined.

2.6 Comments on assumptions .....................................Error! Bookmark not defined.2.7 Final calculation and assumption tabulation ...........Error! Bookmark not defined.2.8 Analyzing car behavior at different maneuver ........Error! Bookmark not defined.2.9 Conclusion ..............................................................Error! Bookmark not defined.

PART-C ....12

CHAPTER 3 ..................................................................................................................... 153.1 Introduction to ADAMS/Car ..................................Error! Bookmark not defined.3.2 Building the vehicle for constant-radius cornering test .........Error! Bookmark not

defined.3.2.1 Steering system hard point and C.G settings ...Error! Bookmark not defined.3.2.2 Camber and Toe settings ..................................Error! Bookmark not defined.3.2.3 Caster setting ....................................................Error! Bookmark not defined.

3.3 Post processing results ............................................Error! Bookmark not defined.3.3.1 Front and rear slip angle plot ...........................Error! Bookmark not defined.3.3.2 Lateral slip angle for front wheels ...................Error! Bookmark not defined.3.3.3 Lateral slip angle for rear wheels .....................Error! Bookmark not defined.3.3.4 Understeer gradient plot from post processing Error! Bookmark not defined.

3.4 Comparison of K value from calculation and simulation ...Error! Bookmark not

defined.3.4.1 Comments on results ........................................Error! Bookmark not defined.

3.5 Conclusion ..............................................................Error! Bookmark not defined.3.6 Module learning outcomes ...................................................................................... 17

REFERENCES ................................................................................................................. 18BIBLIOGRAPHY ............................................................................................................. 19


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Structures, Safety and Impact.vii

LIST OF FIGURES_______________________________________________________________________

Figure 1. 1 Understeer and Oversteer vehicle characteristics [2]. ...Error! Bookmark not

defined.Figure 3. 1 Car suspension assembly [12]. .......................Error! Bookmark not defined.

Figure 3. 2 Suspension and wheel base positioning [12]. .Error! Bookmark not defined.Figure 3. 3 Hardpoint modification [12]. ..........................Error! Bookmark not defined.Figure 3. 4 C.G height and fore, aft positions [12]. ..........Error! Bookmark not defined.Figure 3. 5 Camber and toe value settings [12]. ...............Error! Bookmark not defined.Figure 3. 6 Caster angle hardpoints [12]. ..........................Error! Bookmark not defined.Figure 3. 7 Constant radius cornering parameter setup [12]. ...........Error! Bookmark not

defined.Figure 3. 8 Constant radius cornering animation [12]. .....Error! Bookmark not defined.Figure 3. 9 Front wheel lateral slip angle [12] ..................Error! Bookmark not defined.Figure 3. 10 Rear wheel lateral slip angle [12]. ................Error! Bookmark not defined.Figure 3. 11 Understeer post processing plot [12] ............Error! Bookmark not defined.Figure 3. 12 Understeer gradient plot [12]........................Error! Bookmark not defined.Figure 3. 13 Characteristic speed plot [12]. ......................Error! Bookmark not defined.


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Structures, Safety and Impact.viii

LIST OF TABLES_______________________________________________________________________

Table 2. 1 Technical specifications [6]. ............................Error! Bookmark not defined.Table 2.2 Assumption table [7] ........................................Error! Bookmark not defined.Table 2. 3 Tabulation of calculation results and assumptions .........Error! Bookmark not

defined.Table 3. 1 Result table of understeer gradient

values...Error! Bookmark not defined.


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Structures, Safety and Impact.ix

NOMENCLATURE_______________________________________________________________________

ABS Antilock Braking System

CATIA Computer Aided Three dimensional Interactive Application

C.G Centre of gravity

ECS Engine Control System

ESC Electronic Stability Control


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M.S Ramaiah School of Advanced StudiesPostgraduate Engineering and Management Programme (PEMP)PART-A

CHAPTER 1

1.1 Introduction to crash pulse

A basic characteristic of a vehicle structural response in crash testing and model simulation is theCrash signature, commonly referred to as the crash pulse [1]. This is the deceleration time history

at a point in the vehicle during impact. In a frontal impact, the crash pulse at a point on the rocker

panel at the B-pillar is presumed to identify the significant structural behaviour and the gross motion

of the vehicle in a frontal impact. Other locations, such as the radiator and the engine, are frequently

chosen to record the crash pulse for component dynamic analysis. The nature of the crash pulse

response depends on the mass, structural stiffness, damping at that location, and on external

interactions from neighbouring components. Impact severity in rear collisions that can cause soft

tissue neck injuries are most commonly specified in terms of change of velocity. However, it has

been shown from real-world collisions that mean acceleration influences the risk of these injuries.

For a given change of velocity, this means an increased risk for shorter duration of the crash pulse.

The results from the crash tests reveal that, the similar changes of velocity can be generated with

various durations of crash pulses for a given change of velocity in rear impacts. Hence it plays an

important role in the design of automotive structure.

1.2 Characterisation of crash pulse

To fulfil the full scale dynamic testing of vehicle crashworthiness, mathematical models and

laboratory tests like Hyge sled or a vehicle crash simulator are frequently employed. The objective

of these tests is the prediction of changes in overall safety performance as vehicle structural and

occupant restraint parameters are varied. To achieve this objective, it is frequently desirable to

characterize or simplify vehicle crash pulses such that parametric optimization of the crash

performance can be defined. Crash pulse characterization greatly simplifies the representation of

crash pulse time histories and yet maintains as many response parameters as possible. The response

parameters used to characterize the crash pulse are those describing the physical events occurring

during the crash such as (maximum) dynamic crush, velocity change, time of dynamic crush,

centroid time, static crush, and separation (rebound) velocity [2]. A number of crash pulse

approximations and techniques have been developed for the characterization. These are divided into

two major categories according to whether or not the initial deceleration is zero, as follows [2].

Pulse approximations with non-zero initial deceleration like, ASW, ESW and TESW. Pulse approximations with zero initial deceleration like, FEWSA, TWA and BSA.


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Structures, Safety and Impact.2

1.3 Structure design affecting the crash pulse

Some of the studies have shown that in some existing cars, the concept of increasing the mass is

coupled with stiffening the structural components, component design variation and also the

modification in wheelbase length, bumper height, track width and over hanging size indicating that,

size or geometry may affect at least as much as mass [3]. The study included full vehicle MADYMO

model on 1995 model Ford Explorer at 56kmph frontal barrier crash of vehicle, using a mid size

hybrid III dummy as driver [4].Five simulations were conducted, where the first had rear, side and

frame masses uniformly scaled so that it is 20 percent less massive than the baseline case, the second

with the mass values scaled down by 10 percent, the third being the baseline case, and the fourth and

fifth with masses scaled up by 10 and 20 percent, respectively [4]. The results obtained on plots are

as shown in figure 1.1

Figure 1.1 Simulation plots [4].

Simulation results [4]:

The acceleration pulses as measured on the driver side door sill and on the drivers thorax are shown

in figure 1.1 plot A and plot B respectively. In both plots, the curve with the highest peak represents

the lightest vehicle and the lowest curve represents the heaviest vehicle.

From figure 1.1 plot A, it is evident that the peak acceleration in the lighter two cases occurs near the

first peak at 45ms and the peak acceleration in the heavier cases occurs closer to 60ms. This peak

shifting may account for non-uniform behaviour when observing any peak acceleration criteria as it

changes over different vehicle designs.

A second behaviour is seen in figure 1.1 plot B, where the thoracic peak acceleration does not follow

a linear trend from the heaviest to the lightest vehicle, but there is an unexpected higher value on the

default case acceleration curve. It shows that although the vehicle is responding as expected, dummy

interactions with different body parts or vehicle components designs can cause significant changes in


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the model response. These nonlinearities in crash pulse data, demonstrate that dummy contact or

non-contact with a particular vehicle structure can produce sharp changes in dummy response as the

independent variables are manipulated.


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PART-B

CHAPTER 2

2.1 Introduction to rear impact (whiplash) of vehicles

Basically majority of the tests were conducted to investigate the effect and results, on vehicle and itsoccupant, which are caused due to frontal impact of the automobiles, due to its high severity in

collision and also due to frequent collision frequency. However, even slower speed rear end impacts

can also cause the occupant debilitating neck and back injuries, because of whiplash of the neck. To

prevent the extension of the neck during whiplash, head rests are provided in the back rest of the

seats. Euro NCAPs is the one to perform the first rear impact (whiplash) test, which showed nearly

80% of the seats tested need to be improved [5]. It performed the sled test on the dummy and found

the severity on the spine part damage, and gave ranking accordingly in which it found only 20% of

the seats had less whiplash. Whiplash is not uncommon in frontal and side impact accidents, but

more often occurs in low speed, rear end collisions in urban environments. Based on sled test rating

Volvo XC60, Alfa Romeo Mito, Volkswagen Golf VI, Audi A4 and Opel Insignia are the cars which

received Euro NCAPs best score with a good or green result [5]. Figure 2.1 shows the whiplash in

rear end collision of vehicles.

Figure 2. 1 whiplash in rear collision [5].

Similarly in this chapter, the neck injury criteria is studied from the results obtained by simulation of

standard dummy in rear impact car collision models using LS-Dyna and MADYMO softwares.

2.2 Modelling of rear end collisions

The idea of modelling rear end collision is carried out by placing two car models, one behind the

other with some assumed distance between them, so that there is considerable amount of impact on

neck region of occupant inside car during rear collision. In order to carry out crash analysis the given

standard car.key file of single car model is imported to LS-Dyna working environment, which is

duplicated and positioned one behind the other, so that the rear car will hit the front stationary car


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during rear collision analysis. The rear car is positioned at an assumed distance of 100mm from the

front car to get the quick rear impact effect when velocity is assigned for collision as shown in figure

2.2.

Figure 2. 2 car positioning for simulation [6].

Now by using this full car models, if the analysis is done then the computational time required to

get the results will be very high, hence the idea to reduce computational time is by reducing the size

of model by deleting some elemental mass from front and rear car models without affecting the

physics of problem.

2.2.1 Reducing car model size

Initially the given car model is made up of number of rigid, solid, shell and beam elements. Hence to

reduce the size, front portion of front car and rear portion of rear car is deleted.To carry out this, the car models are cropped in LS-Dyna work space accordingly by deleting the

elements and nodes. The figure 2.3 shows that the front portion, from windshield portion of front car is

deleted.

Figure 2. 3 front car front end deleted [6].


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After reducing size of front car, the rear car size is reduced by deleting the element and nodes in the

same way. The figure 2.4 shows the rear portion deleted from A- pillar portion of rear car.

Figure 2. 4 rear car rear end deleted [6].

After deleting some of the masses from front and rear portion of the car, the C.G of the vehicle is

varied hence to compensate that mass, an arbitrary mass should be added to front and rear car to

maintain their original C.G. This process of adding the mass is done in HYPERMESH software.

2.2.2 Location of C.G and mass

The method of adding the mass to properly locate the C.G is done in HYPERMESH. Following are

the data given, which is used to properly locate C.G and mass as shown in table 2.1.Table 2. 1 Table of C.G location and mass.

Velocity

(kmph)

Front

end mass

(kg)

Front end C.G Rear end

mass

(kg)

Rear end C.G

- - X(mm) Y(mm) Z(mm) - X(mm) Y(mm) Z(mm)

36.88 374.12 -784.39 0 -499.58 430.30 -2824.49 0 -521.05

Once the frontal and rear portions of the cars are deleted, it is then imported to hypermesh working

environment. Here the car models are checked for proper geometry clean-up to remove all the

unwanted free nodes and positioned properly to add mass.

To locate the C.G, a node is created at a certain distance from both front and rear portion of car cut

sections. These locating distances are calculated as follows,

Front car

Distance of front cars C.G = front car length + distance between carfront end C.G distance

= 3700mm +100mm784.39mm


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Distance of front cars C.G = 3015.61mm.

Therefore front car C.G coordinates are, x = 3015.61, y = 0, z = 499.92

Rear car

Distance of rear cars C.G = rear car length + distance between car= 2824.49mm +100mm

Distance of rear cars C.G = 2924.49mm.

Therefore rear car C.G coordinates are, x = 2924.49, y = 0, z = 521.05

The C.G coordinates obtained from calculation is used to locate C.G in HYPERMESH and to that

particular C.G node the given front end and rear end mass is allocated as mentioned in table 2.1.

the figure 2.5 shows the mass added to the C.G point and also the C.G location with respect to axis

coordinates.

Figure 2. 5 C.G location and mass added [7].

2.2.3 Rigid body creation

After locating the C.G and applying mass to that C.G point, the rigid body creation is done so that

whatever the elements have been removed will be compensated back by assigning the rigid body

connection to the front and rear portion of the both cars.

Figure 2.6 shows the rigid body allocation for the front car.

Figure 2. 6 front end rigid body creation [7].


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Similarly the rigid body allocation to the rear end portion of the rear car is done from the rear end mass

nose as shown in figure 2.7.

Figure 2. 7 rear end rigid body creation [7].

The final modeling of both the cars with C.G location, mass defining and rigid body allocation are asshown in figure 2.9. Now this model is carried to LS-Dyna and carried out the simulation.

Figure 2. 8 final modeling of car models [7].

2.3 Boundary conditions applied

In order to simulate the rear collision following are the boundary conditions applied,

2.3.1 Defining Parts and applying material property

The car model is having many components out of which some are rigid, shell, solid and beams.

Some particular elements are chosen and given the Linear plastic characteristics so that they plastic

behavior in the collision. Some of the parts selected for plastic behavior from front and rear cars are

front, rear, rear left of window glass etc.

2.3.2 Set IDWhen the model containing two cars is imported from HYPERMESH it will be a single entity, hence

they are separated as two models naming as front and rear car by selecting all the nodes and

elements by picking the areas option in the software. The ID set given for cars as Set-ID 841 for rear

car and Set-ID 842 for front car. The part set given for rear car is Set-Part 849 and that of front car is

Set-Part 850.


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2.3.4 Defining contact

The contact between both cars had to be defined to let the program know which parts are going to hit

each other. The type of contact between the rear and front car is selected as, automatic Surface to

Surface contact because, Surface to Surface contact algorithm establishes contact, when the surfaceof one body penetrates the surface of another. Single surface contact is not chosen because we are

defining the slave and master for the cars. Also in single surface collision, impact will be

concentrated only at certain point and stress as well deformation will be minimal. Since rear

collision is having large surface area of contact, Surface to Surface contact is chosen.

Also while defining contacts, the master type and slave type in between the cars are selected. Front

car is selected as master and rear car as slave.

Figure 2. 9 contact type defining [6].

Figure 2.9 shows the contact type defined between two cars. The slave section type (SSTYP) and

master section type (MSTYP) are selected as 2 and also the master section ID (MSID), slave

section ID (SSID) are set 842 and 841.

2.3.5 Velocity generation

To simulate a rear-end collision, the striking car (rear) was given an initial velocity. The struck car

(front) is standing still during simulation. The initial velocity simulates that the striking car is driving

with a certain velocity before hitting the struck car. The velocity of magnitude 36.88kmph, as

mentioned in table 2.1 is given in terms of mm/s2 i.e. (10244.44 mm/s2) for the slave car which is

nothing but the rear car. The velocity data fed into the LS-Dyna in the positive x - direction is as

shown in figure 2.10


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Figure 2. 10 initial velocity data fed [6].

2.3.6 Simulation time length

The simulation time step is decided by the length of the collision time in a normal rear end collision.

The time set for simulation is basically given in terms of milliseconds. Lesser the time step lesser

will be the computational time. After study of some of the thesis, where they have conducted lot of

trials using time steps for simulation in milliseconds, for rear end collision, a standard value of 150

milliseconds is assumed as termination time for simulation [8]. The termination time data fed into

software is as shown in figure 2.11.

Figure 2. 11 simulation time steps [6].

2.4 Crash pulse plot

After assigning all the boundary conditions, the simulation is carried out and the crash pulse is

generated. The severity of crash in the rear end collision is as shown in the figure 2.12. The plot of

acceleration verses time is plotted where we can find the high acceleration in the drivers cabin.

Figure 2.13 shows the acceleration pattern obtained randomly with some peak acceleration and very

low acceleration. This peak value depends on the time period of collision and also the severity of

collision with high hitting velocity.

It is seen that the peak acceleration value obtained is around 100mm/s at a time period of 28 th

milliseconds of the simulation time.


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Figure 2. 12 rear end collision [7].

Figure 2. 13 crash pulse plot [6].

2.4.1 Energy plot

The plots of kinetic energy, internal energy and total energy are shown in the figure 2.14. As like the

physics behind crash phenomena, the total energy remains unchanged, and only the transformation

of energy takes place on this impact, as per the plots shown.

During collision the car comes and hit with given velocity, due to which the kinetic energy will be

decreased from high level to low level.

Same way before collision the system is not disturbed by any external excitations or forces hence the

internal energy will be zero and will increase gradually with the collision time. But total energy will

remain almost constant.


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Figure 2. 14 energy plot [6].

2.5 High neck acceleration time

The simulation to get the neck acceleration of the driver in the driver compartment is done by

assuming a standard dummy from the library of MADYMO software. This is done by modifying the

dummy seat with a standard seat dimension of a selected car. Initially the crash pulse generated in

the drivers compartment due to rear collision from LS-Dyna simulation is imported to MADYMO

and the software is run for the partial run period of 149milliseconds. The figure 2.15 shows the

MADYMO simulation results showing the peak neck acceleration plot along with NIC plot.

Figure 2. 15 neck acceleration and NIC plot [6].

The plot shows that the x- axis is plotted for the time for simulation in milliseconds and y-axis as

NIC and linear acceleration of dummy during simulation. The graph shows the peak acceleration of

point, which means that the dummy head is experiencing so much acceleration during collision. The


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acceleration magnitude obtained as 1150m/s2, exactly at 104th milliseconds. The other plot also

shows the NIC value of the dummy neck at the same 104 th milliseconds of simulation. It is also seen

that the NIC value of 1100 is obtained during collision.


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PART-C

CHAPTER 3

3.2 Environment modeling on MADYMO

The simulation to find any sort of criterion or finding acceleration in MADYMO is done byimporting whatever the crash pulse generated in LS-Dyna simulation. This is done because whatever

the dummy we select on different sled test we require will have their own default crash pulse values,

hence in order to simulate the rear collision in MADYMO, the crash pulse generated from in LS-

Dyna from part-B is imported. The crash pulse data from LS-Dyna will be having the time of

simulation list and particular acceleration value to that particular instant of time of simulation. This

data is obtained for the acceleration in only x-direction which is in m/s2 hence the value is converted

to mm/s2, and then imported to MADYMO. It is also seen that the co-ordinates in LS-Dyna and

MADYMO are in opposite direction hence, whatever the direction of magnitude of crash pulse data

obtained from Dyna is reversed and then fed into MADYMO. The crash pulse data is fed into

MADYMO in LOAD.SYSTEM_ACC option, as shown in figure 3.1.

Figure 3. 1 X,Y data importing to MADYMO [9].

Once the crash pulse data is set, the proper seat dimension data is fed by selecting a car of choice.

The seat dimensions are selected from SUV class, Land Rover series as mentioned in table 3.1.

Table 3. 1 seat dimension table [10].

Head rest Seat back Seat cushion

Height(mm) Width(mm) Height(mm) Width(mm) Height(mm) Width(mm)

152.7 305.4 610 350 508 350


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The seat dimensions from the table 3.1 is fed into MADYMO in terms of meters. The dimensions

fed into the software are as shown in figure 3.2.

Figure 3. 2 seat dimension fed [9].


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3.6 Module learning outcomes

This module is intended to familiarize with the more complex aspects of vehicle dynamicsand their use and to develop skills in using simulation software to investigate and improve

performance of vehicle.

Use of bicycle model to investigate vehicle handling is well taught. Using theoretical knowledge and simulation, how to improve vehicle and driver performance

is understood.

The lab session instructions, on how to use simulation software, including validation ofresults is efficiently taught and well understood.

The module notes data helped in modelling an existing vehicle, run a simulation to validatethe model and then investigate various changes with the goal of optimizing the vehicles

performance.


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The module helped in gaining the knowledge of most important vehicle dynamics estimationand vehicle control problems. In particular, the main expected learning outcome is how the

control algorithms of longitudinal Anti-Lock Braking Systems, Traction Control Systems,

Cruise Control Systems, Yaw Control Systems, Roll-Over Prevention systems, and verticaldynamics Active and Semi-Active Suspensions systems, play an important role in controlling

vehicle stability.

The module also helped in estimating road friction, yaw rate and road grades, whichsimplified the calculations involved in calculating the understeer gradient values.

The module helped in understanding the concept of acceleration, braking and corneringperformance of the vehicle.

Difference between understeer and oversteer behavior of the vehicle is understood. The concept of center point and Ackermans steering is understood. Effect of variation in bump steer, roll steer, caster angle, camber angle and toe angles are

studied.

REFERENCES______________________________________________________________________________

[1] How do understeer and oversteer work? (The math and the

physics)http://www.physicsforums.com/showthread.php?t=505028

[2] Understeer_Oversteer: http://en.wikipedia.org/wiki/Understeer_and_oversteer.[3] Handling Characteristic of Road vehicles:

http://www.thecartech.com/subjects/auto_eng2/Handling_characteristics_of_road_vehicles.htm

[4] Thomas D. Gillespie, - Fundamentals of Vehicle Dynamics.

[5] OVERSTEER -http://www.oversteer.org.uk/2012/07/vauxhall-adam-odd-name-interesting-

car.html

[6] Volkswagen Passat Alltrack 1.8TSIautomobile technical data :

http://www.carfolio.com/specifications/models/car/?car=266783

[7] Autobuildindia_handling_test.pdf (SECURED).

[8] Dr. S.R. Shankpal- FT-11 AME-508, Vehicle Dynamics, handling and Simulation-Module

Notes.

[9] Thomas D. Gillespie: CarSimData Manual, Version 5.

[10] Tire_dimension calculator: bndtechsource.ucoz.com/index/tire...calculator/0-20 - United States.

[11] Neha Ravi Dixit - Evaluation of Vehicle Understeer Gradient Definitions thesis.
http://www.physicsforums.com/showthread.php?t=505028http://www.physicsforums.com/showthread.php?t=505028http://www.physicsforums.com/showthread.php?t=505028http://www.oversteer.org.uk/2012/07/vauxhall-adam-odd-name-interesting-car.htmlhttp://www.oversteer.org.uk/2012/07/vauxhall-adam-odd-name-interesting-car.htmlhttp://www.oversteer.org.uk/2012/07/vauxhall-adam-odd-name-interesting-car.htmlhttp://www.oversteer.org.uk/2012/07/vauxhall-adam-odd-name-interesting-car.htmlhttp://www.carfolio.com/specifications/models/car/?car=266783http://www.carfolio.com/specifications/models/car/?car=266783http://www.carfolio.com/specifications/models/car/?car=266783http://www.oversteer.org.uk/2012/07/vauxhall-adam-odd-name-interesting-car.htmlhttp://www.oversteer.org.uk/2012/07/vauxhall-adam-odd-name-interesting-car.htmlhttp://www.physicsforums.com/showthread.php?t=505028


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[12] ADAMS/CarMultibody Dynamic Software tool.

[13] Bridgestone TyresWheel alignment centre, west of chord road Rajajinagar, Bengaluru.

BIBLIOGRAPHY______________________________________________________________________________

1.

Evaluation of Vehicle Understeer Gradient Definitions thesis, byNeha Ravi Dixit.2. FT-11 AME-508, Vehicle Dynamics, handling and Simulation-Module Notes, by Dr. S.R.

Shankpal.

3. Fundamentals of Vehicle Dynamics, SAE, Warren dale, PA, 1992by Gillespie T. D.4. CarSimData Manual, Version 5 by, Thomas D. Gillespie.5. http://www.rearwheeldrive.org/rwd/rwdlist.html, retrieved on 1-7-20126. http://www.ford-trucks.com/specs/2003/2003_expedition_1.html, retrieved on 2-7-20127. http://www.carfolio.com/specifications/models/car/?car=2667838. http://www.trackpedia.com/wiki/Oversteer9. http://www.motortrend.com/roadtests/exotic/1202_2013_ferrari_f12_berlinetta_first_look/10.http://www.google.co.in/search?hl=en&safe=active&q=oversteer+and+manoeuvring+on+nar

row+lanes&oq=oversteer+and+manoeuvring+on+narrow+lanes&gs_l=serp.3...18084.23947.

0.24558.14.14.0.0.0.0.627.2686.4j2j5j1j0j1.13.0...0.0...1c.4c62kKg-IQU

11.http://www.volkswagen.co.in/en/models/newpassat/gallery.html
http://www.carfolio.com/specifications/models/car/?car=266783http://www.carfolio.com/specifications/models/car/?car=266783http://www.trackpedia.com/wiki/Oversteerhttp://www.trackpedia.com/wiki/Oversteerhttp://www.motortrend.com/roadtests/exotic/1202_2013_ferrari_f12_berlinetta_first_look/http://www.motortrend.com/roadtests/exotic/1202_2013_ferrari_f12_berlinetta_first_look/http://www.google.co.in/search?hl=en&safe=active&q=oversteer+and+manoeuvring+on+narrow+lanes&oq=oversteer+and+manoeuvring+on+narrow+lanes&gs_l=serp.3...18084.23947.0.24558.14.14.0.0.0.0.627.2686.4j2j5j1j0j1.13.0...0.0...1c.4c62kKg-IQUhttp://www.google.co.in/search?hl=en&safe=active&q=oversteer+and+manoeuvring+on+narrow+lanes&oq=oversteer+and+manoeuvring+on+narrow+lanes&gs_l=serp.3...18084.23947.0.24558.14.14.0.0.0.0.627.2686.4j2j5j1j0j1.13.0...0.0...1c.4c62kKg-IQUhttp://www.google.co.in/search?hl=en&safe=active&q=oversteer+and+manoeuvring+on+narrow+lanes&oq=oversteer+and+manoeuvring+on+narrow+lanes&gs_l=serp.3...18084.23947.0.24558.14.14.0.0.0.0.627.2686.4j2j5j1j0j1.13.0...0.0...1c.4c62kKg-IQUhttp://www.google.co.in/search?hl=en&safe=active&q=oversteer+and+manoeuvring+on+narrow+lanes&oq=oversteer+and+manoeuvring+on+narrow+lanes&gs_l=serp.3...18084.23947.0.24558.14.14.0.0.0.0.627.2686.4j2j5j1j0j1.13.0...0.0...1c.4c62kKg-IQUhttp://www.google.co.in/search?hl=en&safe=active&q=oversteer+and+manoeuvring+on+narrow+lanes&oq=oversteer+and+manoeuvring+on+narrow+lanes&gs_l=serp.3...18084.23947.0.24558.14.14.0.0.0.0.627.2686.4j2j5j1j0j1.13.0...0.0...1c.4c62kKg-IQUhttp://www.google.co.in/search?hl=en&safe=active&q=oversteer+and+manoeuvring+on+narrow+lanes&oq=oversteer+and+manoeuvring+on+narrow+lanes&gs_l=serp.3...18084.23947.0.24558.14.14.0.0.0.0.627.2686.4j2j5j1j0j1.13.0...0.0...1c.4c62kKg-IQUhttp://www.google.co.in/search?hl=en&safe=active&q=oversteer+and+manoeuvring+on+narrow+lanes&oq=oversteer+and+manoeuvring+on+narrow+lanes&gs_l=serp.3...18084.23947.0.24558.14.14.0.0.0.0.627.2686.4j2j5j1j0j1.13.0...0.0...1c.4c62kKg-IQUhttp://www.google.co.in/search?hl=en&safe=active&q=oversteer+and+manoeuvring+on+narrow+lanes&oq=oversteer+and+manoeuvring+on+narrow+lanes&gs_l=serp.3...18084.23947.0.24558.14.14.0.0.0.0.627.2686.4j2j5j1j0j1.13.0...0.0...1c.4c62kKg-IQUhttp://www.google.co.in/search?hl=en&safe=active&q=oversteer+and+manoeuvring+on+narrow+lanes&oq=oversteer+and+manoeuvring+on+narrow+lanes&gs_l=serp.3...18084.23947.0.24558.14.14.0.0.0.0.627.2686.4j2j5j1j0j1.13.0...0.0...1c.4c62kKg-IQUhttp://www.motortrend.com/roadtests/exotic/1202_2013_ferrari_f12_berlinetta_first_look/http://www.trackpedia.com/wiki/Oversteerhttp://www.carfolio.com/specifications/models/car/?car=266783


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