Subject: VEHICLE NVH TESTING (A.A. 2021/2022)
Unit Vehicle NVH Testing
To be chosen by the student (lesson)
Provide advanced experimental methods for NVH (Noise Vibration and Harshness) and comfort issues in the automotive field.
Processing of experimental vibro-acoustic data in an autonomous way for the identification of the main sources of noise and vibration in vehicles.
Use of advanced instrumentation for the experimental characterization of the NVH impact of vehicles.
Provide experimental tools for taking into account the NVH issues within the vehicle design (design for NVH).
• Design for NVH: main concepts.
• The physics of sound, definition of the main acoustics properties, frequency analysis, noise propagation in free field and confined areas, instrumentation.
• Noise generation and propagation in mechanical systems for automotive applications. Sound insulation and sound absorption. Sound quality for vehicles.
• Introduction on experimental vibration testing.
• Experimental modal analysis: procedure, signal processing, transducers, estimation techniques, validation, MAC.
• Vibration signature of i.c. engines (waterfall plot, order tracking).
• Closed-loop vibration analysis: random sine, shock testing. Accelerated life testing.
• Transfer Path Analysis
• Lab testing. NVH experimental tests in operational conditions: Noise measurements in the passenger compartment, acceleration measurements, pass-by measurements.
• Lab testing. Experimental test with shut down vehicle: acoustic isolation tests, experimental modal analysis with impact hammer and electrodynamic skater of a BIW, FRF test for dynamic stiffness evaluation.
• Lab testing: MIMO testing in vibrating table.
The course includes: theoretical lectures made with the aid of multimedia systems. The didactic material is uploaded before each lecture on the platform “Dolly” (http://dolly.ingmo.unimore.it); training and laboratory activities related to the realization of technical reports on vibro-acoustic testing of vehicles, experimental modal analysis of a chassis, accelerated life testing; technical seminars by specialists and educational visits at local companies. Due to COVID restriction, lessons will be in streaming mode or videorecording mode. Deliverables are: technical reports regarding the experimental tests carried out in the laboratories; a speech of 15 minutes regarding one experimental technique explained during the course.
The exam includes an oral test. The oral exam, for testing the understanding and application of the course content, consists of two parts: a 15-minute oral speech regarding one experimental technique explained during the course, to be held in the classroom; an oral test regarding the course contents. The exam is passed if the score of each test is at least sufficient. The final mark is the arithmetic mean of the marks obtained in the two tests.
Knowledge and understanding: through lectures and technical seminars by specialists, students learn the experimental NVH both in terms of testing set up and processing, and develop the ability to think out and implement original ideas and problem solving skills even in a Research & Development contest.
Applying knowledge and understanding: through the practical exercises and laboratory activities related to NVH testing, students learn how to apply the knowledge gained, even in new and unfamiliar multidisciplinary fields.
Making judgments: through the engineering project development, in team, and the discussion with the teacher, students develop the ability to integrate knowledge and handle complexity, and formulate judgments even on the basis of incomplete or limited information, reflecting on social and ethical responsibilities linked to the application of their knowledge and judgments.
Communication skills: through the work in team and the discussion with the teacher, students develop the ability to critically communicate, especially using the engineering technical language, technical information, ideas, problems and solutions to both specialist and non-specialist.
Learning skills: the activities described allow students to develop the skills necessary to autonomously deepen technical topics, in order to effectively face professional challenges or to undertake further studies.
Per lo studio/For study
Mechanical Vibrations (6th Edition), Singiresu S. Rao, ISBN-13: 978-0134361307.
Noise and Vibration Analysis: Signal Analysis and Experimental Procedures, Anders Brandt, ISBN: 9780470746448.
István L. Ver, Leo L. Beranek, Noise and Vibration Control Engineering: Principles and Applications, 2nd Edition, Wiley, ISBN: 978-0-471-44942-3, 976 pages, December 2005.
Malcolm J. Crocker, Handbook of Noise and Vibration Control,Wiley, ISBN: 978-0-471-39599-7, 1584 pages, October 2007
Per l’approfondimento personale dei contenuti/For the personal deepening of contents:
Random Vibration and Shock Testing, Wayne Tustin.
Vibration monitoring, testing, and instrumentation, Clarence W. de Silva.
Vibration damping of structural elements, C. T. Sun, Y. P. Lu
Passive vibration isolation, Eugene I. Rivin
Vibration damping, control, and design, Clarence W. de Silva
Vibration: fundamentals and practice, Clarence W. de Silva
Modal analysis, Jimin He and Zhi-Fang Fu