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MECA-H411

Vibrations and acoustics

année académique
2021-2022

Titulaire(s) du cours

Arnaud DERAEMAEKER (Coordonnateur), Patrick GUILLAUME, Jean-Louis MIGEOT et Steve Vanlanduit

Crédits ECTS

5

Langue(s) d'enseignement

anglais

Contenu du cours

!Note! : ULB (Prof A. Deraemaeker and J.L Migeot) is in charge of this course every other year (2021-2022 for example), VUB (Prof P. Guillaume and S. Vanlanduit) the other academicyears (2020-2021 for example). For information related to the VUB course, please refer to VUB website

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.

Objectifs (et/ou acquis d'apprentissages spécifiques)

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).

Méthodes d'enseignement et activités d'apprentissages

The course consists in 36h of lectures (18 for vibrations / 18 for acoustics) which are taught with the principle of flipped classes. Students are expected to be acquainted with the proposed learning material in the form of videos or written material before joining the class where interactive activities are organized based on the learning 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 au profil d'enseignement

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

Références, bibliographie et lectures recommandées

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).

Support(s) de cours

  • Podcast
  • Syllabus

Autres renseignements

Contacts

Arnaud Deraemaeker (aderaema@ulb.ac.be), Jean-Louis Migeot (Jean-Louis.Migeot@ulb.ac.be)

Campus

Solbosch

Evaluation

Méthode(s) d'évaluation

  • Projet
  • Examen oral

The evaluation is based on an oral examination which consists in two parts: the first part dealing with vibrations with Prof A. Deraemaeker and the second part related to acoustics and the presentation of the vibroacoustics project with Prof J.L Migeot

Construction de la note (en ce compris, la pondération des notes partielles)

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.

Langue(s) d'évaluation

  • anglais

Programmes