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| MECA0062-1 | Vibration Testing and Experimental Modal Analysis
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| Duration : | 30h Th, 30h Pr |
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| Credits/ECTS : |
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| Holder(s) : | Jean‑Claude Golinval |
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| Language : | French language |
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| Course contents : | Vibration sensors: displacement, speed, acceleration. Signal analysis: power spectral density, discrete Fourier transform, FFT algorithm, digital spectrum analyzers, aliasing and leakage phenomena. Excitation methods in vibration: types of excitation signals (impact, sine sweep, pseudo-random, etc.), electrodynamic exciter, impulse hammer. Theoretical background of modal analysis: transfer function, receptance, mobility, impedance, Bode diagram, Nyquist diagram, development of the dynamic influence coefficient matrix in terms of poles and residues. Identification methods: phase separation and phase resonance methods, identification of modal parameters on the basis of the frequency or impulse response functions, 1 DOF-method(peak picking, circle fitting) and multi-DOF methods, influence of residual terms, multiple excitation. Introduction to model updating methods in linear elastodynamics. Diagnosis of the mechanical state of a machine through vibratory measurements. |
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| Course objective : | The aim of the course is to train students to use vibration measurement equipment in laboratories, to acquire, process and exploit the vibratory signals as well as modal identification methods, comparison techniques between theoretical and experimental results and parametric correction methods for structural models on the basis of experimental results. |
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| Workshops : | The lab sessions are organised in groups and upon appointment only.
The first session is led by a member of staff from the Vibrations and Identification of Structures department. It is aimed at allowing students to familiarise themselves with the measuring equipment available in the laboratory. During the following sessions, students work independently on a real lattice-work type of structure or an airplane.
An individual report has to be handed in within a set deadline to be agreed upon with the students. It must include:
1. the detailed description of the measurements made in the laboratory on the test structure,
2. the development and application of two modal parameter identification methods (modes and frequencies, depreciation) of the structure based on the experimental results obtained,
3. the construction and exploitation of a model through the finite elements of the structure tested in the MATLAB environment,
4. the qualitative and quantitative comparison between theoretical and experimental results.
The lab sessions are OBLIGATORY. Any unjustified absence may lead to the refusal of participation in the final exam. |
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| Organization : | The course includes 30 hours of theoretical lectures and 30 hours of practical work.
It is organised in the first or second semester according to a timetable to be agreed upon with the students. |
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| Written notes : | The course notes are handed out during lectures. |
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| Assessment : | The exams are organised in June (1st session) and September (2nd session).
A. WRITTEN EXAM
The practical work is the subject of a report which replaces the written exam.
B. ORAL EXAM
The oral exam consists of an oral presentation relating to the practical work. |
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| Contacts : | Jean-Claude Golinval (JC.Golinval@ulg.ac.be) |
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