This module introduces the main design aspects of the vehicle bodywork considering the various functions involved. The areas covered include ergonomics, climatic, acoustical and vibrational comfort, layout of the structure and passive safety, and aerodynamics. The different aspects are analyzed introducing their physical models, along with the functional limitations and the normative constraints. The mutual interaction of the different aspects is underlined with the goal of understanding the the design of the vehicle body at system level. Each topic is introduced with a user-centric approach to evidence the requisites coming from the vehicle to passenger/driver interaction.

Students should acquire skills in the area of -postural ergonomics, -bodywork architecture, -noise and vibration, -passive safety and crash protection, -vehicle aerodynamics, -experimental techniques in wind tunnel and CFD (Computational Fluid-Dynamics).

Motor vehicle design, Fundamentals of machine design and drawing , Applied mechanics, Fluid mechanics, Mathematical analysis I and II.

1 - Introduction Prerequistes and functions of the motor vehicle from the bodywork point of view. 2 – Vehicle packaging Principles of postural comfort Principles of human vision Percentiles and manikins for packaging Main constraint to interior packaging coming from vehicle body structure: wheel arches, tunnel, firewall, pedals, underbody. Seating position and seat comfort Accessibility Direct and indirect visibility Manoeuvrability and command access. 3 – Vehicle structure Main vehicle structure architecture for hatchbacks and saloons, spiders, MPVs, commercial vehicles, lorry cabs. Reference load cases for design: loads coming from vehicle manoeuvres and obstacles, internal loads due to powertrain, suspensions and safety belts; loads on bodywork surface. Measurement of torsional stiffness. Estimate of minimum torsional stiffness due to vehicle functionality. Introduction to the analysis of thin walled structures: structural surface method. Structural surface method to analyse torsional and flexural behaviour of open and closed chassis architectures. Structural analysis of monocoque configuration: underbody types and evaluation of their torsional stiffness. H, I, X, ladder frame analysis. Influence of open or closed cross section beams. 4 – Acoustical and vibrational behaviour Principles of the physiology of the human ear and noise quality Noise and vibration transmission paths Vibration and noise sources Introduction of modal analysis and modal reduction Engine suspension 5 - Passive safety Definitions of preventative, active and passive safety Main injury criteria, HIC, tibia index, neck, viscous criteria. Role of restraint system and main parameters affecting the occupants accelerations during a crash. Crashworthiness requirements from EC and FMVSS Homologation vs. rating tests Crashes of small intensity: Insurance tests, tests on bumpers. 6. Introduction to vehicle aerodynamics Motivations 7. Air properties and governing equations Equations governing uncompressible and compressible fluids. Reynolds number and aerodynamic similarities Boundary layer and factors affecting its separation Reference system for aerodynamic forces Definition of aerodynamic coefficients. 8. Introduction to computational fluid-dynamics Numerical methods for equations of fluid motion. Calculation grid and their creations based on CAD geometry. Examples of turbulent flows. Surrounding conditions. Post processing of results and visualization. 9. Aerodynamic resistance Resistance to movement from friction and pressure Aerodynamic behaviour of simple bodies: plate, sphere, cylinder Flow structure around squat bodies Gauss and Stokes theorems Lift induced drag Influence of wake on drag - effect of rear vehicle body and underbody shape Aerodynamics of the wheel and the underbody Aerodynamic field around car body elements such as pillars, spoilers, dam 9. Aerodynamic effects on vehicle dynamics, to the comfort and engine cooling Aerodynamic noise. Stability with lateral wind. Lift decrease for high performance vehicles. Engine cooling Brake cooling 10. Experimental aerodynamics Automobile wind tunnels. Tests on scale models. Measurement of the aerodynamic forces and moments. Techniques for measuring the aerodynamic field (pressure, speed, heat cables, LDV, PIV). Measurement of aerodynamic noise. Analysis of air flows under the bonnet Road tests. 11. Aerodynamic development of vehicles Simultaneous development of aerodynamic shape, style and planning of the vehicle. Improvement of the shape and interaction with the style. Optimisation of the appendices. Reduction of the bodywork resistance.

The course is organised in lectures, classroom exercises, CFD laboratories, visits to experimental facilities. Lectures The lectures taught in the classroom are video-recorded and made available through Portale della Didattica. Exercises E1 Sizing the wheel arches and evaluation of the ground clearance in different load cases. E2 Evaluation of the torsional stiffness of a simplified underbody structure. E3 Modal analysis of simple flexible structure modelled by means of finite element method. Plot of mode shapes. Modal reduction Applicable examples of the calculus codes CFD. Instrumentation of measure for calibration. Measuring of pressure field on scale models.

Folders of notes are available for the students. Texts for further information : L. Morello, L. Rosti Rossini, G. Pia, A. Tonoli, “The Automotive Body”, Voll, I and II, Springer, 2011. J. Fenton, "Handbook of Vehicle Design Analysis", SAE, 1999 . W. Karwowsky, "Automotive Ergonomics", Taylor & Francis, 1993 . J. Happian-Smith e altri, "An Introduction to Modern Vehicle Design", SAE, 2002. T. Gillespie, "Fundamentals of Vehicle Dynamics", SAE, 1999. Hucho W. H. – Aerodynamics of Road Vehicles. Pope-Rae – Low Speed Wind Tunnel Testing W. F. Milliken and D. L. Milliken, Race car vehicle dynamics, Society of Automotive Engineers, 1995

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

Exam: Written test; Optional oral exam;

... The goal of the exam is to assess the following: - level of understanding of the topics treated during the lectures or the exercises - capability of demonstrating the knowledge about car body design and aerodynamics by means of: writing a technical report, sustaining a technical discussion, illustrating the solutions by means of graphical and mathematical tools Exam Procedure - The exam consists of a written exam composed of open questions regarding the topics illustrated in the lectures. The time allowed for the exam is 2 hours. The student cannot use any written material, like books, notes, etc. - The maximum score of the written exams is 27 - The maximum score of the exercise reports is 3. - The maximum score of the oral exam is 4 The reports have to be uploaded on Portale della Didattica before the written exam. The students who obtain at least 27/30 from written exam + exercise reports can proceed to the oral exam, which will take place after the correction of the written exam and publication of the results by means of the Portale della Didattica. - those who have obtained more than 27/30 from written exam + exercise reports and do not wish to make oral exam, the score is lowered to 27/30.

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.