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Impostazione progettuale dell'autoveicolo

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A.A. 2023/24

2021/22

Impostazione progettuale dell'autoveicolo

L’insegnamento si propone di fornire agli allievi le conoscenze di base riguardanti la dinamica di un autoveicolo, con particolare riferimento alle principali prestazioni in termini di trazione e frenata, consumo energetico, comportamento direzionale e comfort. Sono oggetto di studio i sottosistemi principali dell'autotelaio (pneumatici, sospensioni, freni, sterzo e trasmissione, appendici aerodinamiche) di cui saranno analizzati in dettaglio: funzioni, soluzioni architetturali e costruttive più diffuse e saranno introdotte le metodologie per il loro progetto funzionale e l'analisi del loro effetto sul comportamento dinamico del veicolo (handling e comfort). Saranno inoltre introdotte le architetture elettriche, ibride e a fuel cell. Cenni sui sistemi attivi (ABS, ESP, TCS, Frenata rigenerativa,..).

Impostazione progettuale dell'autoveicolo

The course aims to provide students basic knowledge regarding the vehicle dynamics, with particular reference to the main performance in terms of traction and braking, energy consumption, directional behaviour and comfort. The main subsystems of the chassis are presented (tires, suspensions, brakes, steering and transmission, aerodynamic appendages) of which they will be analysed in detail: functions, most widespread architectural and construction solutions and the methodologies for their functional design and the analysis of their effect on the dynamic behaviour of the vehicle (handling and comfort). Electric, hybrid and fuel cell architectures will also be introduced. Notes on active systems (ABS, ESP, TCS, Regenerative braking,..).

Impostazione progettuale dell'autoveicolo

Conoscenza della dinamica longitudinale e laterale dell’autoveicolo e dei suoi principali componenti: pneumatici, freni, sospensioni, sterzo e trasmissione. Capacità di: - eseguire calcoli previsionali delle prestazioni dinamiche dell’autoveicolo; - prevedere il comportamento dinamico qualitativo di un autoveicolo in relazione alla sua architettura e all’impostazione/taratura di un suo sottosistema. Al termine del corso lo studente dovrà avere acquisito le seguenti competenze, relative ai sottosistemi del veicolo: - Costruzione dello pneumatico, comportamento longitudinale, laterale e combinato, resistenza al rotolamento. - Architetture powertrain, principali caratteristiche prestazionali e di consumo di carburante - Architettura e componenti del sistema frenanti, ripartizione della frenata. - Architettura dei sistemi di trasmissione. - Cinematica e componenti del sistema di sterzo e del sistema sospensione. - Criteri di dimensionamento e scelta powertrain elettrici e ibridi. - Modellazione del comportamento dinamico verticale delle sospensioni con approccio semplificato (quarter car model). - Modellazione e calcolo delle prestazioni longitudinali veicolo (velocità massima, consumo di carburante, risposta in accelerazione, in regime e in frenata) - Modellazione del comportamento dinamico laterale della vettura (accelerazione massima, angolo di rollio, trasferimento di carico, under/oversteering)

Impostazione progettuale dell'autoveicolo

• Knowledge of longitudinal and lateral dynamics of a motor vehicle and its basic components: tires, brakes, suspension, steering and transmission. • Ability to: - performing calculations about the dynamic performance of the vehicle; - predicting the trend of the dynamic behaviour of a vehicle in relation to its architecture and to the setting / calibration of a subsystem.

Impostazione progettuale dell'autoveicolo

Sono richieste conoscenze acquisite nell'ambito di: Analisi I, Fisica I, Meccanica applicata alle macchine, Disegno Meccanico.

Impostazione progettuale dell'autoveicolo

It is assumed that students attending this course already have basic knowledge and understanding of theoretical and applied mechanics, technical drawing and of fundamentals of differential and integral calculus.

Impostazione progettuale dell'autoveicolo

Forze e momenti agenti su un veicolo, forze di contatto pneumatico-strada, forze e momenti aerodinamici. Prestazioni longitudinali del veicolo, distribuzione dei carichi al suolo e trasferimento del carico, potenza richiesta per il movimento, potenza disponibile, scelta di i rapporti di trasmissione, le prestazioni massime (velocità, accelerazione, pendenza superabile); consumo di carburante, frenata e distribuzione della potenza frenante sulle ruote. Dinamica laterale del veicolo. Sterzo cinematico e modelli di base. Comportamento di sotto e sovrasterzo, influenza del vento trasversale. Sottosistemi del veicolo. Analisi funzionale e dettagli costruttivi dei più comuni sottosistemi veicolari (sospensioni, ammortizzatori, sistema di sterzo, sistema frenante,..) e loro comportamenti cinematici. Architetture e componenti per trazione anteriore, posteriore, integrale. Architetture e componenti per un veicolo elettrico, ibrido e a fuel cell. Architetture telaio, metodologie di progettazione e nuovi materiali. Cenni sui sistemi attivi, loro componenti e logiche di controllo: ABS, TCS, ESP, Frenata rigenerativa.

Impostazione progettuale dell'autoveicolo

- The vehicle: definition, reference systems, degrees of freedom, characteristic quantities. - Tire mechanics Limits of the Coulomb friction model in tire-road contact, hypothesis of flexible wheel on rigid ground. Effect of tire stiffness, inflation pressure and vertical load on contact patch dimension and average pressure. Structure of a tire and manufacturing process. Brush model in conditions of simple longitudinal and lateral slip: stress distribution in the contact footprint, trends of the ground forces and of the self-aligning moment and sensitivity to the vertical load and the wheel-road friction coefficient. Steering axis position and its effects on straight driving stability and on sensitivity to the limit adhesion condition. Linearized behavior: dependence of cornering stiffness and longitudinal slip stiffness on vertical load. Cornering stiffness of an axle. Combined slip and interaction between longitudinal and lateral force. Empirical models, ply steer and conicity. Losses in a pneumatic tire: drift losses, slip losses and hysteresis. - Longitudinal dynamics of the vehicle Estimation of the center of gravity position (longitudinal and vertical) with dedicated experimental tests. Traction: motion equations, vertical loads and load transfers, resistances to the motion of a vehicle at constant speed. Estimation of the loss coefficients by coast-down test. Power available from the powertrain and inertial power. Kinetic energy and translating apparent mass of a vehicle. Electric motors (operating quadrants, efficiency) and thermal engines for motor vehicles (specific consumption maps, efficiency, E-line, fuel consumption calculation). Transmission: components for a 2WD vehicle. Why a gearbox? Ideal traction hyperbola and characteristic traction force on the wheels for stepped and stepless transmission. Range of transmission ratios typical for automotive gearbox: example of a 6-speed DCT and 8-speed AT. Classification of transmissions, schemes and constructional drawing (MT, DCT, AT, CVT). Maximum slope that can be overcome by a vehicle equipped with different drivetrain layouts: FWD, RWD, ideal AWD, fixed torque distribution AWD. Optimized torque distribution ratio for a given grip condition. Effect of adherence conditions and torque distribution factor on performance. Epicyclic gears and their use as differentials between wheels and axles. Performance: acceleration, elasticity, gear ratio to maximize acceleration. Criteria for the selection of the minimum and maximum transmission ratios and of the intermediate ratios of a gearbox: geometric and progressive ratio selection (theory and numerical exercise). - Braking mechanics Dynamic loads under braking. Ideal braking and braking with wheels locking on a single axle. Constant deceleration curves. Real braking with fixed brake force distribution. Braking efficiency. Graphic check of axle locking when the vehicle loading and grip change. Fixed distribution between the braking forces of the two axles: friction utilization and braking efficiency. Brake system design specifications. Braking correctors (pressure reducing valve, with fixed and variable calibration), EBD. Verifications required by ECE 13 regulations. Stopping time and distance of a vehicle. Approval limits for service and emergency braking. Components of a passive hydraulic braking system: brake booster and tandem master cylinder. Characteristic curve pressure-Force. Brake boost gain. Effect of the degree of vacuum on p-F, F-stroke characteristics. Response delay and speed of manoeuvre execution: Emergency Valve Assist, Hydraulic Brake Assist. Active systems that act on the brakes: ABS (layout, low and high level control logic). - Lateral dynamics of a vehicle Kinematic and dynamic steering. Bicycle model: kinematic and dynamic analysis of steady-state motion during cornering. Understeer and sideslip angle equation and related gradients. Linear lateral dynamics: steady-state cornering response for understeering, neutral and oversteering vehicles; gains of curvature, yaw rate, lateral acceleration and sideslip angle; critical speed, instability and balance in counter-steering. Nonlinear lateral dynamics: axle nonlinearity effect; understeer characteristic and real vehicle attitude; sensitivity to the driving torque, load transfers and setting of the anti-roll bars.

Impostazione progettuale dell'autoveicolo

Impostazione progettuale dell'autoveicolo

Impostazione progettuale dell'autoveicolo

Le 60 ore saranno suddivise, in base alla numerosità del corso, tra lezioni in aula ed esercitazioni in aula/laboratorio/laib. Gli argomenti teorici presentati durante le lezioni sono accompagnati da esempi e applicazioni. Le esercitazioni permettono allo studente di verificare la comprensione degli argomenti trattati a lezione e di implementare le tecniche di calcolo proposte. In relazione alla numerosità del corso potranno essere effettuate esercitazioni di laboratorio/laib, in cui agli allievi è richiesto di impostare la soluzione dei problemi proposti attraverso l’utilizzo di software. OPZIONALE: In relazione alla numerosità del corso potranno essere assegnati dei Progetti/Tesine da svolgere in piccoli gruppi (4-5 persone massimo) che saranno valutate in sede di esame, anche attraverso una presentazione ai docenti e compagni di corso.

Impostazione progettuale dell'autoveicolo

Credits 6: 60 classroom hours (48 lecture hours, 6 tutorial hours and 6 computer lab). Theoretical lectures are supported by examples and applications. During specific tutorials, students are required to apply knowledge to working context problems. The tutor will provide materials and frames for solutions. However, students are asked to interact with each other and 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. The teacher and the tutor are available weekly during the teaching period in order to meet students for consultation; please contact them by e-mail.

Impostazione progettuale dell'autoveicolo

- Testi di riferimento M. Guiggiani, Dinamica del veicolo, Città Studi. G. Genta, Meccanica dell’autoveicolo, Levrotto & Bella. - Testi di approfondimento G. Genta, L. Morello, The Automotive Chassis Volume 1: Components Design, Springer. Milliken W. F., Milliken D. L., Race Car Vehicle Dynamics, SAE International. Saranno fornite dispense su specifici argomenti e altro materiale didattico (immagini, schemi) durante lo svolgimento dell’insegnamento e consultabili attraverso il portale della didattica.

Impostazione progettuale dell'autoveicolo

Suggested readings M. Guiggiani, The Science of Vehicle Dynamics: Handling, Braking, and Ride of Road and Race Cars, Springer. G. Genta, L. Morello, The Automotive Chassis Volume 2: System Design Further readings G. Genta, L. Morello, The Automotive Chassis Volume 1: Components Design, Springer. Naunheimer, H., Bertsche, B., Ryborz, J., Novak, W., Automotive Transmissions, Fundamentals, Selection, Design and Application, Springer. Lectures notes on specific topics, exercises and other material are available on the subject page. Tutorials: texts of problems and Matlab/Simscape codes are provided on the course website before the lectures.

Impostazione progettuale dell'autoveicolo

Modalità di esame: Prova scritta (in aula); Prova orale facoltativa; Elaborato progettuale in gruppo;

Impostazione progettuale dell'autoveicolo

L’esame, della durata indicativa di 1 ora, è costituito da domande scritte a risposta multipla (almeno 20) e la valutazione massima è pari a 27/30. Ulteriori 5 punti (per raggiungere la valutazione di 30 e lode) possono essere ottenuti: con il Progetto/tesina (se assegnata e presentata prima della fine del corso) o con un esame orale su tutto il programma del corso.

Impostazione progettuale dell'autoveicolo

Exam: Written test; Optional oral exam; Group project;

Impostazione progettuale dell'autoveicolo

The examination consists of a written test, duration 1 h 30 min, closed book, composed of three questions, each related to a different topic covered during the course. The single question can be and open question or could require the solution of an exercise. The exam aims at evaluating the understanding of the topics covered during the course and the ability to apply tools and methods appropriate for the analysis, prediction and modeling of the dynamic behavior of a vehicle. The maximum mark is 30/30 with merit (cum laude). Usually, a few days after the written test, students are called for a review of their papers, in which examiners inform the students on grading criteria, and they can report any problems with the interpretation of the document. Computers, telephones and any printed documentation are not allowed during the written test. Further details on exam rules are reported on the official page of the course on the teaching portal.

Impostazione progettuale dell'autoveicolo

Modalità di esame: Prova orale facoltativa; Prova scritta a risposta aperta o chiusa tramite PC con l'utilizzo della piattaforma di ateneo Exam integrata con strumenti di proctoring (Respondus); Elaborato progettuale in gruppo;

Impostazione progettuale dell'autoveicolo

L’esame, della durata indicativa di 1 ora, è costituito da domande scritte a risposta multipla (almeno 20) e la valutazione massima è pari a 27/30. Ulteriori 5 punti (per raggiungere la valutazione di 30 e lode) possono essere ottenuti: con il Progetto/tesina (se assegnata e presentata prima della fine del corso) o con un esame orale su tutto il programma del corso.

Impostazione progettuale dell'autoveicolo

Exam: Optional oral exam; Computer-based written test with open-ended questions or multiple-choice questions using the Exam platform and proctoring tools (Respondus); Group project;

Impostazione progettuale dell'autoveicolo

The exam aims at evaluating the understanding of the topics covered during the course and the ability to apply tools and methods appropriate for the analysis, prediction and modeling of the dynamic behavior of a vehicle and it will be exclusively in writing through the University Exam platform integrated with proctoring tools (Respondus and lockdown browser). The duration of the exam is 120 min. The exam consists of three sections relating to three course topics. The weight of each section is approximately one third of the total score. Each section will be composed of a certain number of questions which may fall into the following types: open, multiple choice, calculated numbers. The relative weight of each question will be explicitly indicated in the text. For each open question you will be asked to answer on paper and upload a photograph taken with the webcam for each written sheet. It is recommended to use one or more A5 landscape sheets to answer questions. It is necessary to verify that the quality of the uploaded images is adequate. For each numerical question, you will be asked to first report the number relating to the solution requested and in the immediately subsequent question a photo of the procedure followed to arrive at the solution. If the numerical result was wrong but the procedure is correct, the score achieved would be half the score associated with the question. Material admitted during the examination: an identification document, twenty white A4 sheets, pens and ruler and the official course form downloadable from the teaching portal (Exam folder). The use of the personal calculator is forbidden; only use the calculator available through the Exam platform. It is not allowed to consult notes or books or to use forms other than the official one. The smartphone must remain off for the duration of the test, facing the screen downwards and resting on the desk. It must be clearly visible during the environment check phase by Respondus. It can be turned on again after exiting the examination procedure to load the documents in the Elaborati section. During the accreditation phase on respondus it is essential that you clearly show in the video the desk and all the environment around you, rotating the camera 360 °, up and down. The time available for the exam will be counted from the moment you have completed this preliminary procedure. A multiple answer question was added in the last section of the exam to allow you to withdraw. Remember that it is still necessary to stay connected and comply with the examination rules for the duration of the test. Once the exam is finished, it is requested to upload within 15 minutes in the Elaborati section of the teaching portal the scan, in a single pdf file, of the sheets already loaded through the exam platform. Rename the file indicating the exam date, your surname and name before uploading it to the portal, respecting the following format: Exam_dd_mm_yyyy_Surname_Name.pdf In this phase, you can turn on and use your smartphone to photograph your papers with adequate quality. - Introductory Virtual Classroom 15 min before the scheduled start of the exam, the teacher will activate a VC to briefly introduce the test. After that you will be able to access the automatic exam procedure. - Support Virtual Classroom During the exam, a support VC will be active, accessible with a special button visible for the duration of the online exam. - Correction of examination and optional papers view The examination will be corrected based on the answers given and the material uploaded during the online exam session with active respondus and browser lockdown. The processed section alone does not allow you to acquire the score of the question and will be consulted only in special cases. As soon as the correction is complete, the test results will be published on the personal page as provisional results. The optional viewing of the papers will be possible upon request of the individual students via email and by agreeing with the owner an online meeting in the days immediately following the publication of the results.

Impostazione progettuale dell'autoveicolo

Modalità di esame: Prova scritta (in aula); Prova orale facoltativa; Prova scritta a risposta aperta o chiusa tramite PC con l'utilizzo della piattaforma di ateneo Exam integrata con strumenti di proctoring (Respondus); Elaborato progettuale in gruppo;

Impostazione progettuale dell'autoveicolo

L’esame, della durata indicativa di 1 ora, è costituito da domande scritte a risposta multipla (almeno 20) e la valutazione massima è pari a 27/30. Ulteriori 5 punti (per raggiungere la valutazione di 30 e lode) possono essere ottenuti: con il Progetto/tesina (se assegnata e presentata prima della fine del corso) o con un esame orale su tutto il programma del corso.

Impostazione progettuale dell'autoveicolo

Exam: Written test; Optional oral exam; Computer-based written test with open-ended questions or multiple-choice questions using the Exam platform and proctoring tools (Respondus); Group project;

Impostazione progettuale dell'autoveicolo

The exam has the same purpose and in mixed mode will also be based exclusively on the University Exam platform. In-presence students, as well as those connected remotely, will use their personal PC to take the exam by accessing the University Exam platform. The criteria, rules and procedures are therefore the same as those specified in the previous section, dedicated to the remote examination method.

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