Servizi per la didattica
PORTALE DELLA DIDATTICA

Motor vehicle mechanics

02SQLQD, 02SQLNE

A.A. 2022/23

Course Language

Inglese

Course degree

Master of science-level of the Bologna process in Ingegneria Meccanica (Mechanical Engineering) - Torino
Master of science-level of the Bologna process in Ingegneria Meccanica - Torino

Course structure
Teaching Hours
Lezioni 53
Esercitazioni in laboratorio 27
Tutoraggio 29
Teachers
Teacher Status SSD h.Les h.Ex h.Lab h.Tut Years teaching
Galvagno Enrico   Professore Associato ING-IND/13 53 0 27 0 2
Teaching assistant
Espandi

Context
SSD CFU Activities Area context
ING-IND/13 8 B - Caratterizzanti Ingegneria meccanica
2022/23
The subject is addressed at providing the knowledge and capabilities for mathematical and dynamic modelling of passenger vehicles and main automotive systems.
Automotive industry is a typical career opportunity for graduates in Mechanical engineering. Working in this context requires at least a basic comprehension of the motor vehicle mechanics subject. The knowledge of main chassis systems (i.e. suspension, steering, powertrain/transmission and tyre) from one hand and the understanding of vehicle dynamic behaviour during braking, traction, cornering and when travelling on rough roads on the other hand, are the basis for vehicle design and virtual validation, early integration of passive or active chassis systems and experimental assessment of vehicle dynamic performance, just to cite some possible fields of application. In this general framework, the subject is addressed at providing the knowledge and capabilities for modelling passenger car dynamics and for the functional design of automotive systems. Thanks to an extensive use of modelling and simulation, the tutorial part of the course allows the students to apply said knowledge and understanding by letting them put their hands on the fundamentals of the discipline, thus verifying, in a virtual but realistic environment, the theoretical aspects explained during the lectures. Different methods and rules of thumb for fast evaluation of alternative design solutions on vehicle dynamic performance will be given during the course for building lifelong skills and foster critical thinking and creativity.
Knowledge related to the dynamic behaviour of motor vehicles and of chassis subsystems such as suspension, steering and braking devices. Capability of modelling and analysing the behaviour of road vehicles with the analytical and numerical methods and simulation softwares provided during the semester.
At the end of the semester the students will be able to: - use analytical tools for evaluating the longitudinal, lateral and vertical dynamic behaviour of a motor vehicle; - analyse the main chassis subsystems such as transmission, suspension, steering, tyres and braking devices and understand their effect on vehicle dynamics; - model the chassis subsystems and simulate typical vehicle tests used for handling, ride comfort and traction/braking analysis; - apply the analytical and numerical methods for choosing vehicle design parameters (e.g. anti-roll bar stiffness, roll centre height, toe and camber angles); - discuss and support a vehicle design choice to achieve given technical specifications; - apply simple methods to predict the effect of vehicle parameters change on its dynamic behaviour.
Attendance of this module requires fluent spoken and written English as a necessary pre-requisite: all lectures and tutorials, and all study material will be in English. It is assumed that students taking this subject already have knowledge and understanding of analytical and applied mechanics, vibrations, technical drawing, machine design, Matlab software and of fundamental of differential and integral calculus.
It is assumed that students attending this subject already have knowledge and understanding of mathematical analysis, theoretical and applied mechanics, mechanical system dynamics, technical drawing, machine design and Matlab programming language. Attendance to this module requires fluent spoken and written English since all lectures and tutorials, and all study material are in English.
• Tyre dynamics: slip and slip angle, longitudinal and side forces, transient behaviour, Pacejka magic formula • Longitudinal dynamics - driving: power required for motion, maximum slope, acceleration and speed. Transmissions for ICE: manual and non-manual transmissions (AMT, DCT, AT). Differentials. • Longitudinal dynamics - braking: ideal and real braking distribution, efficiency, main components of braking systems, ABS. Regenerative braking. • Lateral dynamics: single track model, kinematic and dynamic equations. Vehicle directional behaviour and stability. Analysis of steady state and transient motion. Effects of longitudinal and lateral load transfer. Roll bars. • Suspensions: analysis of main components and architectures. Kinematic gradients and analysis of the influence on lateral dynamics. Roll behaviour. Anti-dive, anti-lift and anti-squat characteristics. • Spring and shock absorber design: driving comfort and drivability. • Hybrid architectures: parallel, series, EVT and dual mode transmissions.
• Course introduction. (1.5h) • Mechanics of pneumatic tyre (12h): main functions and objectives, tyre structure and manufacturing process, limits of single point contact tyre model with Coulomb friction, brush model, slip and slip angle, longitudinal, side forces and self-aligning moment, camber thrust, combined slip, power dissipation, transient behaviour (relaxation length), causes of asymmetry (ply steer and conicity), effect of rubber hardness and contact pressure on static friction coefficient, Pacejka magic formula. Tutorial #1 (3h): Analysis and simulation of the tyre brush model and the Pacejka magic formula tyre model implemented in Matlab/Simulink. Interpretation of the different curves and application to realistic driving conditions. • Vertical dynamics (10.5h): Introduction to ride comfort and road holding: definitions, objectives and frequency range. 4DOF vehicle model: time and frequency domain response. 2DOF pitch and bounce model, design criteria for suspension stiffness based on mode shapes and natural frequencies. Wheelbase filtering. Suspension damping selection criteria: optimal damping for 1DOF and 2DOF quarter car models. Effect of damping and unsprung mass on road holding and ride comfort. Nonlinear damping. Road profile description: deterministic and stochastic. Road classification according to ISO 8608, road profile PSD conversion in time domain and effect of vehicle speed. Vehicle response to random vibrations. Road profile generation from PSD using Matlab. Hints on the effect of vibration on health, comfort, perception and motion sickness. Tutorial #2 (3h): Modelling and simulation of the 2dof linear quarter car model with different excitations. Matlab/Simulink model implementation, modal analysis and simulation of the system response in time and frequency domain. Tutorial #3 (3h): Simulink model of a 2dof quarter car model with nonlinear shock absorbers. Estimation of the transfer function for a nonlinear system with Matlab. Analysis of a Matlab implementation of a 4dof vehicle model: natural frequencies and modes for the undamped system. Effect of damping on the oscillation frequencies and damping factors. Computation of FRFs. System response to road profile irregularities with stochastic approach: from displacement PSD of the road profile to PSD of the sprung mass acceleration. Input delay and wheelbase filtering. • Lateral dynamics (13.5h): Vehicle trajectory control methods. Single and double-track model assumptions. Kinematic and dynamics steering. Single track model: equations of motion. Understeer and sideslip angle equations. Curvature of the centre of gravity trajectory. Steady-state cornering: understeer and sideslip angle vs lateral acceleration, handling gains (curvature, yaw rate, lateral acceleration and sideslip angle) vs vehicle speed. Critical speed and tangent speed. Stability derivatives and stability analysis of the single-track model. Synthesis of lateral vehicle dynamics. Aerodynamic drag and downforce. Yaw moment contributions due to different longitudinal forces on the two sides of the car. Torque vectoring due to differentials. Lateral load transfer for a car on rigid suspensions and considering roll motion. Suspension stiffness and roll stiffness. Roll axis. Roll dynamics, anti-roll bars and load transfer distribution between the axles. Lateral force characteristic of and axle and the effect of roll stiffness and roll centre height. Axle lateral force characteristics from tyre data. Effect of roll-steer, roll-camber, static toe and camber on axle cornering stiffness. Tutorial #4 (4.5h): Analysis and simulation of the Single-Track vehicle model in Matlab/Simulink. Steady-state cornering, root locus, frequency response (Bode plot). Completion of simulink model with state-space block, simulation of: ramp steer, step steer and sweep steer. Simulation of car drift with counter-steer control. Tutorial #5 (1.5h) Analysis and simulation of a double-track model in Simulink including roll dynamics. • Suspensions and Steering (4.5h): analysis of main components and architectures. Kinematic gradients, kinematic suspension setup, instant centre of rotation, roll centre and pitch centre, anti-dive/lift during braking, anti-squat/lift during acceleration. Jacking forces and moments. Suspension testing K&C. Power steering systems (Hydraulic, Electro-Hydraulic and Electric), steering column and actual steering ratio. • Longitudinal dynamics - driving (4.5h): Vehicle acceleration on a road with longitudinal slope: normal forces on the axles. Conventional thermal vs electric powertrain. Power required for motion, traction diagram and the need for a start-up device and a power converter, transmission gear ratio selection, maximum speed, acceleration, car elasticity. Maximum slope at slow constant speed considering the available friction: FWD, RWD, AWD constant torque split and AWD with ideal torque split. Transmissions for conventional powertrains: manual and non-manual transmissions (AMT, DCT, AT, CVT). Torque converter and friction clutch. Tutorial #6 (3h): Matlab script for the design of transmission ratios of an electric car with multi-speed transmission. Simulink model for the simulation of longitudinal dynamics with different drive trains (FWD, RWD, AWD, Ideal AWD). • Differentials (4.5h): ideal, real (with friction), self-locking differentials. Effect of differentials on longitudinal and lateral dynamics. • Longitudinal dynamics - braking (3h): ideal and real braking distribution, efficiency, main components of braking systems, ABS and EBD. Regenerative braking. Tutorial #7 (3h): Matlab script for the preliminary design of a conventional hydraulic braking system. Simulation of emergency braking manoeuvres using pressure limiting valve and EBD. • Group project (6h): group division and assignment of the different tasks. Presentation of the commercial software for vehicle dynamics simulation. Aim of the project and deliverables. • Guided Tour of the Vehicle Dynamics Lab in the Mechanical Laboratory (1.5h). Description and analysis of automotive components (clutches, flywheels, manual and automatic gearboxes, differentials), research test benches (dual clutch transmission, braking system, suspension), static driving simulator.
Credits 8: 80 classroom hours (53 lecture hours, 27 tutorial hours). Theoretical lectures are supported by examples and applications. Tutorials will focus on using and developing software partly provided as course material to analyse vehicle dynamics and main subsystem characteristics. Students are required to apply knowledge to working context problems and to interact with the tutor, especially when setting the solution. The tutor will assist students during the tutorial class hours, supporting students in their learning progression and clarifying their doubts. Attendance to both lectures and tutorials is strongly recommended, being vital to achieve the expected learning outcomes. Neither intermediate formal checks of the learning process nor reports on projects are programmed. The teacher and the tutor are available weekly during the teaching period in order to meet students for explanations; please contact them by e-mail.
Credits 8: 81 classroom hours (54 lecture hours, 27 tutorial hours), lab visit 1.5 hours. - Theoretical lectures are supported by examples and applications. - Tutorials will focus on using and developing models, partly provided as course material, to analyse vehicle dynamics and main subsystem characteristics. Students are required to apply knowledge to working context problems and to interact with the tutor, especially when setting the solution. The tutor will assist students during the tutorial class hours, supporting students in their learning progression and clarifying their doubts. - A group project is scheduled in the last two weeks of the teaching period. A commercial software for the simulation of virtual test driving of automobiles and light-duty vehicles will be used. The project aims at verifying the key aspects of vehicle dynamics discussed during the lectures with realistic car models and manoeuvres, thus giving the students the opportunity to gain more sensibility on the effect of vehicle parameters changes. The project will be developed in small groups of students (4-5 people each group). Each group will receive different car setups (parameters), for investigating their effects on handling, ride and longitudinal performance, and objectives to be pursued with a proper selection of these parameters. Each group is required to draw up a slide presentation. A presentation session will be scheduled for the week following the end of the teaching period, where the groups are asked to show and discuss the results of the group project. All the members of the group should actively partecipate in this results discussion. - A guided tour of the Vehicle Dynamics Lab in the Mechanical Laboratory is planned during the last month of the didactic period (may). The visit is focused on: automotive components: clutches, flywheels, manual and automatic gearboxes, differentials; research test benches: dual clutch transmission, braking system, suspension; static driving simulator. Students will be divided into small groups of 4-5 people and each visit will last approximately 1.5 hours. Attendance to both lectures and tutorials is strongly recommended to achieve the expected learning outcomes. Participation in the group project is mandatory and will be evaluated from 0 to 4 points. A dedicated Slack workspace is available to facilitate the communication between the students and the teachers and to share additional learning material. The students are encouraged to use Slack workspace to ask questions instead of using email. The teacher and the tutor are available weekly during the teaching period in order to meet students for explanations.
• M. Guiggiani, "The Science of Vehicle Dynamics", Springer, 2016. • H.B. Pacejika, "Tire and Vehicle Dynamics", Butterworth-Heinemann, 2012. • G. Genta, L. Morello, "The automotive Chassis", Volume 1 and 2, Springer, 2009. Lectures notes on specific topics and other material are available on the course page. Tutorials: texts of problems and Matlab/Simulink codes are provided on the website before the tutorials. Students should either download or print the files.
• M. Guiggiani, "The Science of Vehicle Dynamics", Springer, 2016. • H.B. Pacejika, "Tire and Vehicle Dynamics", Butterworth-Heinemann, 2012. • G. Genta, L. Morello, "The automotive Chassis", Volume 1 and 2, Springer, 2009. Lectures notes on specific topics and other material are available on the course web page. Tutorials: texts of problems and Matlab/Simulink codes are provided on the website before the tutorials. Students should either download or print the files.
Modalità di esame: Prova scritta (in aula); Prova orale facoltativa; Elaborato progettuale in gruppo;
Exam: Written test; Optional oral exam; Group project;
Assessment Achieved learning outcomes will be assessed by means of a final exam, consisting of a written test and of an optional oral part. The exam is based on an analytical assessment of student achievement of the "expected learning outcomes" described above. In order to properly assess such achievement, the examination consists of a written test, lasting indicatively 1 h 30 min, closed book, composed of three questions, each focused on one of the topics seen during the lectures. The exam aims at evaluating the ability of the students to deal with the dynamic behaviour of vehicle systems, starting from the model definition and ending with the system analysis. In particular, the test aims at assessing knowledge, communication skills and ability to use tools and method taught in the lectures for analysing and modelling components, subsystems and vehicle longitudinal and lateral dynamics. The optional oral part aims at assessing the knowledge of the software used during the tutorials, discussing both the model structure and the results from the simulations. Moreover also the student ability to explain the effects of parameter variations on the results will be assessed. Grading criteria The final maximum obtainable mark is 30/30 with merit (cum laude) and is formed by the sum of the mark achieved in the written test (0 ÷ 28) plus the mark of the optional oral test (-3 ÷ +5). The oral part can be taken only if the mark of the written part is at least 18. Each answer to the three questions usually is evaluated from 0 to a maximum of 9 or 10 points, for a total of 28 available points. The oral consists in a discussion and can also lead to loss of points: the oral score can vary from -3 up to +5 points. A few days after the written test, students are summoned for a review of the written output, in which examiners inform the student on grading criteria, and receive any student appeal supported by appropriate explanations. In the same day, students who chose to take the oral part will be examined. During the semester, students are given an example of the final test, with discussion of the solution and hints on common errors and evaluation criteria. Computers, mobiles, electronic devices and any printed documentation are not allowed.
Gli studenti e le studentesse con disabilità o con Disturbi Specifici di Apprendimento (DSA), oltre alla segnalazione tramite procedura informatizzata, sono invitati a comunicare anche direttamente al/la docente titolare dell'insegnamento, con un preavviso non inferiore ad una settimana dall'avvio della sessione d'esame, gli strumenti compensativi concordati con l'Unità Special Needs, al fine di permettere al/la docente la declinazione più idonea in riferimento alla specifica tipologia di esame.
Exam: Written test; Optional oral exam; Group project;
Assessment The learning tests (written, oral and group project) aims at evaluating the ability of the students to deal with the dynamic behaviour of vehicle systems, starting from the model definition and ending with the system analysis. In particular, the test aims at assessing knowledge, communication skills and ability to use tools and method taught in the lectures for analysing and modelling components, subsystems and vehicle longitudinal, lateral and vertical dynamics. The achievement of the expected learning outcomes will be assessed by means of a group project and a final exam, consisting of a written test and an optional oral part. The written test, lasting indicatively 2 h, closed book, is composed of three questions, each focused on one of the topics presented during the lectures. The optional oral exam will focus on the tutorial part of the course that involved the usage of commercial softwares (e.g. Matlab and Carmaker) for the analysis through simulation of the vehicle dynamics. The student ability to implement simple models, set and run simulations, analyse the results, understand models implemented by others and link the theoretical aspects with the modelling and simulation of vehicle dynamics, will be assessed. The evaluation of the group project is based on the presentation and discussion of the results of each group tasks. The ability to analyse and comment the simulation results of vehicle dynamics tests will be evaluated with the aim of supporting the design choice and highlighting the effect of parameter changes. The project work is mandatory for students who attended the second semester of the academic year. 2021/22 and subsequent. For the other students the assessment will be limited to the written (compulsory) and oral (optional) tests. Grading criteria The final maximum obtainable mark is 30/30 with merit (cum laude) and is formed by the sum of the marks achieved in the written test (0 ÷ 24) plus the mark of the group project (0÷4) plus the mark of the optional oral test (-4 ÷ +4). The oral part can be taken only if the mark of the written part is at least 18. Each answer to the three questions of the written test usually is evaluated from 0 to a maximum of 10 points, the total score is then saturated to 24. The oral consists in a discussion and can also lead to loss of points: the oral score can vary from -4 up to +4 points. A few days after the written test, students are summoned for a review of the exam, in which the examiners make each student's written exam available to check for corrections. In the same day, students who chose to take the oral part will be examined. During the semester, students are given an example of the final test, with discussion of the solution and hints on common errors and evaluation criteria. Computers, mobiles, electronic devices and any printed documentation are not allowed.
In addition to the message sent by the online system, students with disabilities or Specific Learning Disorders (SLD) are invited to directly inform the professor in charge of the course about the special arrangements for the exam that have been agreed with the Special Needs Unit. The professor has to be informed at least one week before the beginning of the examination session in order to provide students with the most suitable arrangements for each specific type of exam.
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