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MECA-H411

Vibrations and acoustics

academic year
2021-2022

Course teacher(s)

Arnaud DERAEMAEKER (Coordinator), Patrick GUILLAUME, Jean-Louis MIGEOT and Steve Vanlanduit

ECTS credits

5

Language(s) of instruction

english

Course content

Vibrations :
The course studies the time dependent behavior of structures and systems excited by dynamic forces. The course starts with the analysis of systems with one, two and several degrees of freedom, with and without damping, and also deals with simple continuous structures (beams and bars) and more complex finite element models. The different sources of excitations for practical applications are described, together with a description of the effects and a discussion of possible design and remedial measures. Sensors, data acquisition and signal processing to measure vibrations experimentally are also presented.

Acoustics : The course provides a description of the fundamental phenomena of linear acoustics. Sound is defined and relevant equations describing sound propagation are derived as well as their fundamental solutions (plane waves, spherical waves). The course then discusses wave reflection and absorption, standing waves and resonances, guided propagation and silencers, refraction and diffraction and finally fluid structure interaction. The theoretical concepts are illustrated by various applications related to cars, aircrafts, wind turbines, loudspeakers and more.

Objectives (and/or specific learning outcomes)

The students will learn how to model time dependent dynamic behavior of structures. Emphasis is put on the ability to derive simple models from real complex structures and to compute their dynamic response due to different types of excitations. The students will also develop a deep understanding of the sources and effects of vibrations (positive or negative) on structures, as well as the practical guidelines for design modifications and remedial measures when vibration levels are excessive.

The students will develop an understanding of the fundamental quantities related to acoustics (pressure, intensity, power, impedance, levels) and the fundamental mechanisms of acoustics (propagation, attenuation, reflection, absorption, refraction, radiation, resonances, guided propagation, transmission, insulation).

Teaching methods and learning activities

The course consists in 36h of lectures (18 for vibrations / 18 for acoustics) which are taught by different means including regular and flipped classes. Supporting material includes videos and written material.
In addition, 12h hours of exercises are organized, combining Matlab and Actran (finite element) computations to illustrate the main concepts in structural dynamics, acoustics and vibroacoustics, and 12 additional hours are dedicated to a project in vibroacoustics.

Contribution to the teaching profile

This teaching unit contributes to the following competences:

  • In-depth knowledge and understanding of exact sciences with the specificity of their application to engineering
  • Reformulate complex engineering problems in order to solve them (simplifying assumptions, reducing complexity) 
  • Correctly report on research or design results in the form of a technical report or in the form of a scientific paper
  • Present and defend results in a scientifically sound way, using contemporary communication tools, for a national as well as for an international professional or lay audience

References, bibliography, and recommended reading

Vibrations :
Inman, D.J - Engineering vibrations. Prentice Hall, 3d Edition, 2007-Géradin M., Rixen D. Mechanical Vibrations - Theory and Application to Structural Dynamics. John Wiley & Sons, second edition, 1997

Acoustics : The course notes are very detailed and no additional reading is requested but the following book is recommended for students willing to dig deeper in the subject matter: Frank FAHY, Engineering Acoustics, Academic Press (2000).

Course notes

  • Podcast
  • Syllabus

Other information

Contacts

Arnaud Deraemaeker (arnaud.deraemaeker@ulb.be), Wout Weijtens (wout.weijtjens@vub.be), and Jean-Louis Migeot (jean-louis@migeot.eu)

Campus

Solbosch

Evaluation

Method(s) of evaluation

  • Project
  • Oral examination

The evaluation is based on an oral examination, and a project evaluation. The project evaluation consists in a written test before the examination session. The oral examination consists of two parts: the first part dealing with vibrations with Prof A. Deraemaeker and/or W. Weijtjens and the second part related to acoustics with Prof J.L Migeot.

Mark calculation method (including weighting of intermediary marks)

20% for the project, 80% for the oral examination (40% acoustics, 40% vibrations). The presence at the exercise sessions is compulsory. The professors may refuse the participation to the oral examination in case of unjustified absence at the exercise sessions.

Language(s) of evaluation

  • english

Programmes