MECA0525: PERFORMANCE AND DYNAMICS OF VEHICLES

Prof. Pierre DUYSINX

University of Liège

Academic Year 2020-2021

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INTRODUCTION

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Course topics?

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Course target

◼ Ground Vehicle

◼ = vehicle whose motion is supported by the ground

◼ Conversely: boats whose travel is made on water and planes which travel in the air

◼ Guided vehicle v.s. non-guided vehicle

◼ Railway vehicle = guided vehicle

◼ Automobile = non-guided vehicle

◼ Road vehicles v.s. off-road and all-terrain vehicles

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Course target

◼ Course targets:

◼ Study the mechanisms in action in ground vehicles to create the motion and the mechanisms to control this motion

◼ Study of vehicle performance and dynamics is a key point:

◼ To state the vehicle design specifications

◼ To design and tailor better propulsion and suspension/ steering systems

◼ To understand the vehicle architecture and the design of its components

◼ Foundation of all vehicle courses and disciplines

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Course target

InternalCombustion

Engine

VehiclePerformance

and Dynamics

VehicleArchitecture & Components

EV, HEV and fuel cell vehicles

Vehicle Thermal Management

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Course target

◼ Generally preliminary design approach of vehicles

◼ System approach:

◼ Vehicle is considered as a system made of different sub-systems

◼ Each sub-system can be characterized with a variable level of fidelity and details, i.e. response curve or model based

◼ Major characteristics of ground and road vehicles: adherence forces generated by tyres interacting with the ground

◼ The vehicle dynamics follows from the knowledge of tyre forces

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Course target

◼ Tyre mechanics

◼ The vehicle control is mostly exerted through the forces generated at the contact patches between the tyres and the ground

◼ Knowledge and characterisation of the adherence forces is of a primary importance in performance and vehicle dynamics

◼ Aerodynamic loads:

◼ Second channel of interaction of the vehicle with its environment

◼ Introduction of basics of vehicle aerodynamics

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Course target

◼ Decomposition of the study of the vehicle motion into three topics:

◼ Performance ~ longitudinal motion

◼ Handling and turn ~ lateral equilibrium

◼ Comfort and road holding ~ vertical motion

◼ In addition, crash mechanics and crashworthiness is investigated to introduce safety aspects

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Course target

Longitudinal motion:Vehicle performance

Vertical motion: Road holdling and comfort

Turn and manoeuvre:Vehicle dynamics

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Vehicle performance

◼ Performance assessment

◼ Longitudinal dynamics

◼ Tractive forces

◼ Road loads

◼ Ability to accelerate, to brake and develop tractive forces (force at the hook), to overtake obstacle and develop work

◼ Evaluation of classical criteria as top speed, gradeability, acceleration and elasticity, braking distance…

◼ Evaluation of fuel / energy consumption and emissions

◼ Energy and environmental assessment

◼ Braking motion and stability

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Vehicle dynamics

◼ Handling and vehicle stability

◼ Study of the vehicle dynamics and stability

◼ Ability to take the turns or create manoeuvre

◼ Ability to resist to the action of external disturbances (stability)

◼ Ability to respond to driver command action (controllability)

◼ Steady state cornering: ability to develop lateral forces during a turn

◼ Understeer gradient

◼ Directional behaviour: time response of the vehicle facing manoeuvre, due for instance to wheel steering

◼ Roll over resistance

◼ Second order effects due to suspension and tyres: roll motion, wheel camber, compliance steer, etc.

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Road holding and comfort (MECA0492)

◼ Road holding

◼ Road holding: the ability of the vehicle to develop contact forces and so to keep control of the vehicle

◼ The road holding needs to include the ‘driver’ system into the control loop as well as the feedback signals perceived by the driver

◼ Comfort

◼ Ability of the vehicle to transmit and filter vibrations from the road and powertrain to the passengers and the payload

◼ Requires to model the driver, and his/her ability to absorb the vibrations as well as the road irregularities

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The vehicle – driver system

Véhicule

Performances

Tenue de route

Crash

Confort

Conditions de la route

Aérodynamiques

Freins

Volant

Accélérateur

Irrégularités de la route

Conducteur

Vue, et autres sens

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Course Layout

◼ Introduction et généralités◼ Équations du mouvement du véhicule rigide◼ Introduction à la mécanique du pneumatique

◼ Mouvement longitudinal et calcul des performances◼ Équations du mouvement longitudinal◼ Caractéristiques des motorisations (thermique et électrique)◼ Caractéristiques de la chaîne de transmission◼ Forces de résistance à l’avancement:

◼ Caractéristiques aérodynamiques◼ La résistance au roulement

◼ Calcul des performances◼ Stationnaires: Vitesse maximale, distance parcourue, pente maximale, ◼ Instationnaires: reprises (0-100, élasticité…).

◼ Consommation◼ Performance en freinage

◼ Comportement en virage◼ Mouvement vertical et confort◼ Dynamique des crashs

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Course Layout

◼ Introduction et généralités ◼ Mouvement longitudinal et performances◼ Comportement en virage

◼ Équilibre latéral en régime établi◼ Théorie d’Ackerman - Jeantaud◼ Théorie avec dérive des pneus◼ Théorie avec dérive des pneus et roulis

◼ Équilibre dynamique latéral◼ Modèle simplifié et équations linéarisées en lacet et dérive◼ Influence du roulis, du carrossage, etc.◼ Stabilité du mouvement transitoire

◼ Mouvement vertical et confort◼ Dynamique des crashs

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Course Layout

◼ Introduction et généralités

◼ Mouvement longitudinal et performances

◼ Comportement en virage

◼ Mouvement vertical et confort◼ Dynamique des suspensions

◼ Mesure du confort

◼ Modèles simplifiés du véhicule en pompage et tangage◼ Fréquences propres

◼ Comportement sur une route à profil sinusoïdal

◼ Influence des masses suspendues

◼ Dynamique des crashs

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Course Layout – Practical works

◼ Supervised exercises & Labs (P. Duysinx & Denis Trillet, assistant)

◼ Exercises◼ Solved analytical and numerical examples during the class

◼ Performance, ◼ Steady state cornering, ◼ Comfort.

◼ Assessment: Homeworks

◼ Computer works◼ Write your own computer simulation (in Matlab or in Python)

◼ Consumption assessment against driving cycles,◼ Vehicle stability using time response.

◼ Supervised work◼ Assessment : Reports + Defense during oral exam

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Projects and Labs

◼ Lab: Chassis dynamometer◼ Tests

◼ Acceleration and elasticity

◼ Introduction to normalized fuel consumption tests

◼ Deliverable: Report

◼ Company visits◼ Not planned this year because

of COVID

19

◼ Seminars ◼ Real life fuel consumption by Dr M. Belhabib (Ford Motor Company)

◼ Development process of the suspension of a passenger car by Dr E. Tromme (Toyota Motor Europe)

◼ Influence of the differential(s) and 4W by P. Sachettini (JTEKT-Torsen)

Course layout – Lab works

Chassis Dynamometer

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MECA0525 - Agenda

◼ Lectures and exercises

◼ Thursday 13:45-17:30

◼ From 4/2 till 13/05

◼ In red and orange codes: in vision conferences using LIFESIZE MECA0525 Perfo & Dyn Vehicles

◼ https://call.lifesizecloud.com/1937521

◼ In yellow and green code: in presence teaching @Institute Mécanique et Génie Civil B52, room +2/441

◼ Labs (Chassis dyno)◼ Thermodynamic Labs (B49)

◼ Group of 3-4 students

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Exam & Assessment

◼ Continuous Assessment◼ Homework 1-4: Exercises + Computer Projects (Matlab)

◼ Lab Report

◼ Defense during exam session

◼ Exam in June (Oral exam)◼ One question about theory

◼ Discussion and sub questions

◼ Weighting factors:◼ Theory during exam: 55%

◼ HW and Projects + Lab reports: 30%

◼ Project defense during exam: 15%

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Lecture notes & Contact

◼ Copies of slides are available on web site:

◼ www.ingveh.ulg.ac.be

◼ Cours >> MECA0525

◼ MyUliege

◼ Podcast of the lessons◼ Live-recordings of LIFESIZE Sessions

◼ Off-line podcasts of lessons and exercise sessions when available

◼ Summary of the available recordings on the website

◼ www.ingveh.ulg.ac.be

◼ Cours >> MECA0525

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Lecture notes & Contact

◼ Lecture notes: textbook in French (update February 2021)

◼ Reference textbook:

◼ T. Gillespie. « Fundamentals of Vehicle Dynamics », 1992, Society of Automotive Engineers (SAE)

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References

◼ T. Gillespie. « Fundamentals of vehicle Dynamics », 1992, Society of Automotive Engineers (SAE)

◼ J.Y. Wong. « Theory of Ground Vehicles ». John Wiley & sons. 1993 (2nd edition) 2001 (3rd edition).

◼ W. Milliken & D. Milliken. « Race Car Vehicle Dynamics », 1995, Society of Automotive Engineers (SAE)

◼ G. Genta. « Motor Vehicle Dynamics – Modeling and Simulation. World Scientific. 1997.

◼ W.H. Hucho. « Aerodynamics of Road Vehicles ». 4th edition. SAE International. 1998.

◼ R. Bosch. « Automotive Handbook ». 5th edition. 2002. Society of Automotive Engineers (SAE)

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Contact

◼ Prof. Pierre DUYSINX

◼ Email p.duysinx@uliege.be

◼ Tel: 04 3669194

◼ Room: 0/514 (B52)

◼ Mr Denis TRILLET (assistant)

◼ Email: dtrillet@uliege.be

◼ Tel: 04/3669273

◼ Room 0/512 (B52)

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