Modal Testing

During the 1980s the technology of modal testing became very widely practised in all those engineering disciplines where vibration and other dynamic phenomena affect the behaviour and performance of structures and machines. The techniques involved in carrying out a modal test were developed to a high degree of sophistication while the applications to which the results of these tests could be put became more numerous and more powerful. At the same time as the advantages of modal testing were being enjoyed by an increasing audience, some of the drawbacks of inexpert use of the technology were being learned and recorded. These experiences reinforced the need for a thorough understanding of fundamentals upon which modal testing is based, and of the detailed workings of the various phases and processes which make up a successful test. In this book, all the steps involved in planning, executing, interpreting and applying the results from a modal test are described in straightforward terms. Efforts are made throughout to ensure that the reader understands the physics of the various stages as well as (if not before) the mathematics.
This edition has brought the previous book up to date by including all the new and improved techniques which have emerged during the 15 years since the first edition was written. The more powerful applications are developed in more detail than previously and some new topics have been introduced, notable amongst which are the application of modal testing to rotating machinery and the use of the scanning laser vibrometer.

Chapter 1: Overview. 1. 1 Introduction to Modal Testing.
1. 2 Applications of Modal Testing.
1. 3 Philosophy of Modal Testing.
1. 4 Summary of Theory.
1. 5 Summary of Measurement Methods.
1. 6 Summary of Modal Analysis Processes.
1. 7 Review of Test Procedures, and Levels.
1. 8 Terminology and Notation.
Chapter 2: Theoretical Basis.
2. 1 Introduction.
2. 2 Single-Degree-of-Freedom (SDOF) System Theory.
2. 3 Presentation and Properties of FRF Data for SDOF System.
2. 4 Undamped Multi-Degree-of-Freedom (MDOF) Systems.
2. 5 MDOF Systems with Proportional Damping.
2. 6 MDOF Systems with Structural (Hysteretic) Damping - General Case.
2. 7 MDOF Systems with Viscous Damping - General Case.
2. 8 Modal Analysis of Rotating Structures.
2. 9 Complex Modes.
2. 10 Characteristics and Presentation of MDOF FRF Data.
2. 11 Non-sinusoidal Vibration and FRF Properties.
2. 12 Complete and Incomplete Models.
2. 13 Sensitivity of Models.
2. 14 Analysis of Weakly Non-linear Structures.
Chapter 3: Response Function Measurement Techniques.
3. 1 Introduction and Test Planning.
3. 2 Basic Measurement System.
3. 3 Structure Preparation.
3. 4 Excitation of the Structure.
3. 5 Transducers and Amplifiers.
3. 6 Analysers.
3. 7 Digital Signal Processing.
3. 8 Use of Different Excitation Signals.
3. 9 Calibration.
3. 10 Mass Cancellation.
3. 11 Rotational FRF Measurement.
3. 12 Measurements on Non-Linear Structures.
3. 13 Multi-point Excitation Methods.
3. 14 Measuring FRFs and ODSs using the Scanning LDV.
Chapter 4: Modal Parameter Extraction Methods.
4. 1 Introduction.
4. 2 Preliminary Checks of FRF Data.
4. 3 SDOF Modal Analysis Methods.
4. 4 SDOF Modal Analysis in the Frequency Domain (SISO).
4. 5 Global Modal Analysis Methods in the Frequency Domain.
4. 6 MDOF Modal Analysis in the Time Domain.
4. 7 Modal Analysis of Non-Linear Structures.
4. 8 Concluding Comments.
Chapter 5: Derivation of Mathematical Models.
5. 1 Introduction.
5. 2 Modal Models.
5. 3 Refinement of Modal Models.
5. 4 Display of Modal Model.
5. 5 Response Models.
5. 6 Spatial Models.
5. 7 Mobility Skeletons and System Models.
Chapter 6: Applications.
6. 1 Introduction.
6. 2 Comparison of and Correlation of Experiment and Prediction.
6. 3 Adjustment or Updating of Models.
6. 4 Coupled and Modified Structure Analysis.
6. 5 Response Prediction and Force Determination.
6. 6 Test Planning.
Notation.
Appendices: A Maths Toolkit.
1. Use of Complex Algebra to Describe Harmonic Vibration.
2. Review of Matrix Notation and Properties.
3. Matrix Decomposition and the SVD.
4. Transformations of Equations of Motion between Stationary and Rotating Axes.
5. Fourier Analysis.
References.
Index.