Programme
The programme is divided in two days:
Thursday 20 sep. 2012 from 8h30 until 19h00 and Friday 21 sep. 2012
from 8h30 until 18h00.
Course programme
- Introduction
Overview of modal analysis applications.
- Modal analysis theory
Basic assumptions. Single and multiple degree of freedom systems. Undamped systems, proportionally and generally viscously damped systems. Frequency response function approach. Natural frequencies, damping factors, residues, modal vectors, modal participation factors, modal mass, modal stiffness, modal scaling. Demonstrations.
- Digital signal processing
Signal types, Fourier transforms: definition and properties, related transforms. Sampling and A/D conversion, leakage errors and windows, aliasing errors and filters. Autocorrelation and autopower. Crosscorrelation and crosspower. Averaging. Frequency response function estimation: H1, H2 and Hv, coherence function. Demonstrations.
- Instrumentation
Excitation systems, excitation hammers. Force transducers, motion transducers, transducers mounting, calibration. Measurement and analysis systems. Laser vibrometers.
- Excitation techniques
Signal types: random, sine, pulse. Signal performance and limitations. Application on linear and non-linear systems. Multiple input/output testing.
- Demonstration and discussion
Aim of the test, test set-up, suspension, selection of equipment, mounting of transducers, calibration, excitation set-up, hammer excitation test, shaker excitation test, frequency response function measurements.
- Modal parameter estimation
Review and principles, frequency and time domain methods, single and multiple degree of freedom systems, local and global estimates, system order estimation tools, stability diagram, some specific methods: least squares complex exponential, least squares complex frequency domain, least squares frequency domain. Interpretation of results. Demonstration.
- Modal model validation
Error sources, non-linearities, modal assurance criterion, mode overcomplexity, mode colinearity, frequency response function synthesis.
- Use of modal parameters
Principles and application areas of the use of modal parameters in trouble shooting, forced response estimation, sensitivity analysis and structural dynamics modification and assembly.
- Linking analysis and test
Correlation between numerical and experimental models, model matching, model updating. Using numerical model information for improved test set-up design.
- In-operation modal analysis techniques and case
studies
Operating mode analysis, output-only modal analysis, running mode analysis.
- Visit "Vehicle technology and lightweight construction"
Laboratory
