The objective of this course is to introduce to the design of a vehicle bodywork considering the main functional and regulatory constraints. The vast number of different topics require a system level interdisciplinary approach including ergonomics, noise and vibration, structure analysis and passive safety, aerodynamic simulation and testing.

Knowledge: Knowledge of Vehicle postural ergonomics, accessibility, direct and indirect visibility, structure solutions adopted for the of passenger cars and light duty vehicles and methods for the analysis of the stress and strain. Knowledge of the loads (external and internal) during operation and during crash events. Sources of noise and vibration, behavior of the vehicle structure under dynamic excitation. Human sensitivity to noise and vibration. Analysis of the aerodynamic and aero-acoustic field, simulation techniques using computational fluid dynamics and wind tunnel experimental measurements. Injury criteria, impact testing procedures following regulatory and rating procedures, structural solutions for crash energy dissipation. Restraint systems. Skills: Capability to define the vehicle packaging considering the occupants ergonomics, visibility, accessibility and structural constraints. Capability to setup a vehicle structure and analyze its main structural performances in terms of stiffness (torsional and bending), dynamic responses such as mode shapes, natural frequencies and frequency response functions. Analyze by finite element tools the response of the vehicle structure under the effect of the dynamic loads acting on it. Optimize the aerodynamic shape to reduce the drag and insure the functionality of the cooling and air conditioning system. Understand the main constraints coming from crashworthiness regulations and design or specify the subsystems dedicated to insure an adequate level of passive safety.

Motor Vehicle Design, Machine Design, Applied Mechanics, Fundamentals of Strength of Materials. Fluid mechanics, Numerical Modelling.

1 - Introduction (1,5 h) Prerequistes and functions of the motor vehicle from the bodywork point of view. 2 – Vehicle packaging (9) Ergonomics and posture 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 to the vehicle and to commands Direct and indirect visibility 3 – Structure (10,5 h) General vehicle structure architecture for different vehicle types and with different powertrains. Reference load cases: loads coming from manoeuvres and obstacles, internal loads due to powertrain, suspensions and safety belts; loads on bodywork surface. Simplified model of the car structure when subject to internal and external loads. Structural surface method to analyze torsional and flexural behavior 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 – Noise and vibration (10,5 h) Vibration and noise sources from powertrain, wheels, aerodynamic noise. Introduction to the dynamic behavior of the bodywork and modal analysis. Vibration response and attenuation. 5 – Passive safety (7,5 h) Injury criteria, HIC, tibia index, neck, viscous criteria. Role of restraint system and main parameters affecting the occupants accelerations during a crash. Crashes of small intensity: Insurance tests, tests on bumpers. High speed crash tests for homologation and rating. 6 - Introduction to vehicle aerodynamics (6 h) Equations governing uncompressible fluids. Limited laminar and turbulent layers Aerodynamic resistance from friction and pressure. 7 - Aerodynamic resistance (10,5h) Contributions to the aerodynamic resistance. Flow structure around squat bodies. Effect on consumption and performance. 8 - Aerodynamic effects on vehicle functionality (7,5h) Aerodynamic noise. Stability with lateral wind. Engine cooling Brake cooling. Soiling and dispersion of exhaust fumes. 9 - Experimental aerodynamics (7,5 h) Automobile wind tunnels. Tests on scaled models. Measurement of the aerodynamic and aerodynamic forces and moments. Techniques for measuring the fluid-dynamic variables (pressure, speed, heat cables, LDV, PIV). Measurement of aerodynamic noise. Measurement of air flows under the bonnet Road tests. 10 - Computational aerodynamics (9 h) Numeric methods for equations of fluid motion. Calculations grids and their creations based on CAD geometry. Turbulence models. Boundary conditions. Elaborations and visualization of the results.

The course is organised as follows: Lessons in classroom: (51 hours) Exercises in classroom: the exercises are organized in projects about the following topics: vehicle packaging, torsional stiffness evaluation of frames. Exercises in laboratory: CFD analyses will be performed in the Information Technology laboratories (23 hours). Visits: Wind Tunnel experimental facility, experimental facility for passive safety assessments (6 hours) In a.y. 2020/21 the lessons and exercises will be held in the form of virtual classooms by means of the BBB platform. All virtual classrooms will be recorded and made available on Portale della Didattica. A in the presence exercise session will be made available each week for a number of students according to the safety regulations and on the availability of classrooms.

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.

Modalità di esame: Test informatizzato in laboratorio; Elaborato progettuale in gruppo;

Exam: Computer lab-based test; Group project;

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The exam requires the student to know the following topics - vehicle packaging considering the occupants ergonomics, accessibility and structural constraints. - Direct and indirect visibility according to EU and SAE regulations, - Capability to determine the quasi static longitudinal, lateral and torsional loads acting on the vehicle in operating conditions. - Capability to determine the internal loads from suspensions and powertrain. - Knowledge of the main a vehicle structure architectures of passenger cars and their main structural performances. - Capability to analyze the load distribution in frames and box structures under the effect of bending and torsional loads. - Knowledge about the dynamic responses and human sensitivity to vibration, modal analysis and modal reduction, natural frequencies and frequency response functions. - Injury criteria, impact testing procedures following regulatory and rating procedures, structural solutions for crash energy dissipation and estimation of their characteristics. Role of the restraint systems. - Optimize the aerodynamic shape to reduce the drag and insure the functionality of the cooling and air conditioning system. - Wind tunnel testing and measurement techniques to evaluate different aerodynamic performances. - Methodologies for the analysis of the aerodynamic performances by means of Computational Fluid Dynamic tools. The aim of the exam is to verify if and in what measure the learning outcomes are consistent with the expected ones as described above. The exam is conceived to verify the knowledge acquired in the field of the vehicle packaging and visibility, vehicle structure, noise and vibration, aerodynamics, aerodynamic testing and computational fluid dynamics. The exam is also aimed to verify the capability of the student to elaborate the given knowledge and elaborate it to obtain results and allow to take personal decisions in the field of vehicle body design. This is obtained by the evaluation of the exercise reports prepared during the semester. Additionally one part of the written exam is devoted to numerical exercises. Exam rules and procedure Written exam The written exam will consist in an online written test performed in LAIB or on paper in classroom with 30 multiple choice questions on the theory and 5 short numerical questions about the exercise classes. They will be split as follows: Multiple choice: CBD: 14 questions, 1 correct answer per question, 1 marks per correct answer, -0.5 marks per wrong answer, 0 marks per no answer AERO: 16 questions, 2 correct answer per question, 0.5 marks per correct answer, -0.25 marks per wrong answer, 0 marks per no answer Numerical questions Multiple choice: CBD: 5 questions, 2 marks if the result is within 2% tolerance, 0 marks if out of tolerance interval. Aero: no numerical questions The result of multiple-choice questions and numerical exercise sums to a maximum of 40 points. This result will be rescaled to a max written score of 27/30. Multiple choice questions and numerical questions will be grouped in one session. The written score is one, including the CBD and Aero parts that are not evaluated separately. During the exam • exchange information among you is not permitted by any means. To this end the application will activate the video-camera and we and the system itself will detect activities not strictly related to answering the questions. • use of cell phone is forbidden and you will be asked to leave it far from your desk. • use of any written material is forbidden as well. • numerical computations can be done just by a simple scientific calculator or by means of the scientific calculator available in the Exam web interface. • Scrolling up/down between questions is possible. Exercise reports The CBD and Aero repots are discussed orally with the team and will be evaluated as follows. CBD: 3 reports, max 3 marks for the 3 reports, reports are compulsory. AERO CFD: 1 report, 0 marks, report is compulsory. AERO work group: 1 report, 3 marks, optional Reports are due 1 week before the exam. This means that the reports have to be submitted one week before the exam call that will be attempted first by one of you. If you are the first of your team to attempt the exam in the second call, then your team has to submit the reports one week before the second call. Note2: the team members that attempt the exam in later calls have not to resubmit the reports. Note 3: if you already submitted the reports in previous academic years and had them evaluated, you do not need to resubmit them this a.y. A max of 6 marks can then be reached from CBD reports or Aero workgroup discussion. These marks are added to the written score. The result is saturated at 30. Laude can be obtained with additional oral examination. We ask you then to upload in the “Elaborati” section of CBD&Aero Portale della Didattica webpage your project reports. Frontpage must include all the names of the team members. CBD: Submit just one report per group in pdf format with following file naming convention: Sxxxx-Syyyyy-Szzzz.pdf Where xxxx, yyyy, zzzz are the student IDs of each team member. • .doc or other formats will not be evaluated. • Files sent by email will not be evaluated. Oral exam Optional oral examinations in presence will be possible just for cumulative written+reports scores higher or equal to 25 or in cases left to the teacher's decision, such as an unclear result of the written. The oral examination consists in a number of at least three questions covering the course program for a further assessment of the expected learning outcomes. The student will be asked to answer giving priority to quantitative arguments, graphical representations, and analytical reasoning. The oral examination can lead to an increment as well as a reduction of the score obtained in the written.

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.