• 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.

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.

- 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.

Il corso non è inseribile dagli studenti di ingegneria dell'autoveicolo causa sovrapposizione con corso obbligatorio di Motor Vehicle Design.

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.

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.

Lecture notes;

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

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.

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.