72860 - Transport Systems Design M

Learning outcomes

The student will learn the basic elements for the functional design of propulsion systems of road and rail vehicle. All topics are therefore developed not only in theory but also, and above all, for practical purposes. To this aim, lessons are supplemented by classroom exercises and visits to major transport companies of the territory.

Course contents

The student who accesses this teaching has assimilated the basic knowledge concerning Transport Economics and Technique, having usually taken the corresponding exam during the first three years. For students that have not taken the corresponding exam, an introductory part of 12 hours of lectures is planned, in which the basic concepts necessary to attend the course profitably are recalled.

The student also knows how to use computer applications of the Office family (Excel, Powerpoint, Word) and is able to generate PDF files. All classes are held in Italian. The comprehension of Italian language is therefore a necessary prerequisite to successfully attend the course and to be able to use the educational material provided.

Topics include the following:

- General notions. Definition of transport system. Performance of land vehicles. Functional and systemic design of transport vehicles.

- Elements of locomotion mechanics. Equation of motion. Resistance to motion. Testing of models. Diagram of traction. Mechanical characteristic.

- Active and passive safety in the automotive sector. Insights on passive safety: design and development of devices, historical evolution of the air bag and seat belt.

- Engine. Study of the propulsion system in general. Components of drive systems of land vehicles. Ideal mechanical characteristic. Propulsive stability. Motor selection.

- Thermal engines. General principles of functioning. Efficiency, torque and power of the engine piston and of the turbine engine and their comparison. Outline of external combustion engines. Alternative internal combustion engines; Theoretical and real cycles, comparison of various types of engine and particular problems connected to their use in land vehicles: regulation, motion reversal, starter, exhaust brake, boost, pollution. Notes on the Wankel engine. Outline of gas turbines and their use in motor vehicles. Characteristic curves of the various types of engine.

- Electric motors. General principles of functioning. Characteristics equations, performance, power limits. Commutator motors. Asynchronous motor. Synchronous motor. Linear motor. Characteristic curves of the various types of engine. Classical and electronic adjustment. Electrical motors. Outline of rolling multi power. Notes on electric braking. Vehicles with an electric motor.

- Transmission. General overview. Transmission components: mechanical joints (elastic, universal, homocynetic, friction); hydraulic coupling; gearing (differential, gearbox); modulators (manual gearbox and hydraulic converter). Modulating transmissions for road and rail vehicles: mechanical, hydrodynamic, hydrostatic, electric, mixed. Comparison between different types of transmission.

- Wheel. Features of the pneumatic tire and the wheel train. Adherence. Notes on experiments.

- Braking. Generality. Adhesion curves. Correctors braking. Braking distance. Braking devices of road and rail vehicles. Elementary calculations relating to braking system.

- Steering. Steering kinematics: band footprint of road vehicles with two or more axes. Dynamical steering condition - oversteering and understeering; critic speed. Steering devices of motor vehicles.

- Unconventional land systems. Outline of air-cushion vehicles and a magnetic sustentation.

- Reconstruction of the dynamics and kinematics of road accidents.

- Active and passive safety in rail traffic.

- Tutorials. The functional design of the drive system (motor, transmission, drive wheels) of road vehicles (cars, trucks, busses, electric cars). Design of the braking and steering a road vehicle. Design of a continuous system.

Readings/Bibliography

G. Genta, Meccanica dell'Autoveicolo;

Evaristo Principe, Nozioni sui veicoli FS per viaggiatori;

Evaristo Principe, Nozioni sui veicoli FS per trasporto merci;

A. Orlandi, Meccanica dei Trasporti;

L. Piano, La sicurezza passiva degli autoveicoli.

Teaching methods

The arguments are developed in:

• n° 12+24 teaching hours;
• n° 24 classroom exercises, in which numerical exercises concerning the topics dealt with in the course are discussed.

Assessment methods

The assessment consists in an interview, in which the candidate is asked to answer three questions, basically on three main areas of the course: technology and economy of transport, mechanical traction, electric traction.

The vote, expressed in thirties, is the sum of the votes in tenths for the three mentioned areas. The foundations of transport economics, the correct knowledge of concepts related to the ideal propulsive characteristic and to the internal mechanical characteristics of the various types of analyzed engines, and finally the modalities of application to concrete cases constitute sufficient conditions to obtain a sufficient mark.

The candidate is allowed to replace one of the three questions by composing a short dissertation analyzing one of topics dealt with in the lectures. The dissertation must consist in a paper of 10-15 pages and a powerpoint presentation of 4-6 slides, to be sent to esame.trasporti@gmail.com at least 3 days before the examination date. The presentation will be illustrated in about 10 minutes during the examination on the teacher's PC. Original contributions to the topic, appropriate exposure technique and language competence will be positively evaluated.

The candidate is also allowed to replace another of the three questions by answering a written test provided by the teacher and through the exhibition of the collection of the numerical exercises discussed in exercise classes, which the candidate will have provide as a typewritten report including calculations, graphs and all necessary theoretical explanations.

The achievement by the student of an organic comprehension of the topics dealt with in the course together with their critical use, the possession of an expressive and appropriate language will be evaluated with excellent marks. The merely mechanical and mnemonic knowledge of the subject, a non sufficiently articulated synthesis and analysis ability and the use of a non completely appropriate language, although correct, will result in discrete evaluations. Theoretical gaps and inappropriate language - albeit in a context of minimal knowledge of exam material - will lead to votes that will not exceed sufficiency. Theoretical gaps, inappropriate language, lack of orientation within the bibliographic materials offered during the course can only result in negative evaluations.

Teaching tools

Educational visits to production and maintenance centers (Ducati, Maserati, Lamborghini, wind tunnel, ...) are possible depending on the encountered interest, as well as specialized seminars from professionals working in the study field.

Office hours

See the website of Mattia Strangi