Peter Avitabile

Modal Testing (eBook, ePUB)

A Practitioner's Guide

• Format: ePub

Produktbeschreibung

The practical, clear, and concise guide for conducting experimental modal tests Modal Testing: A Practitioner's Guide outlines the basic information necessary to conduct an experimental modal test. The text draws on the author s extensive experience to cover the practical side of the concerns that may arise when performing an experimental modal test. Taking a hands-on approach, the book explores the issues related to conducting a test from start to finish. It covers the cornerstones of the basic information needed and summarizes all the pertinent theory related to experimental modal testing. Designed to be accessible, Modal Testing presents the most common excitation techniques used for modal testing today and is filled with illustrative examples related to impact testing which is the most widely used excitation technique for traditional experimental modal tests. This practical text is not about developing the details of the theory but rather applying the theory to solve real-life problems, and: Delivers easy to understand explanations of complicated theoretical concepts Presents basic steps of an experimental modal test Offers simple explanations of methods to obtain good measurements and avoid the common blunders typically found in many test approaches Focuses on the issues to be faced when performing an experimental modal test Contains full-color format that enhances the clarity of the figures and presentations Modal Testing: A Practitioner's Guide is a groundbreaking reference that treats modal testing at the level of the practicing engineer or a new entrant to the field of experimental dynamic testing.

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Produktdetails

• Verlag: John Wiley & Sons
• Seitenzahl: 544
• Erscheinungstermin: 8. September 2017
• Englisch
• ISBN-13: 9781119222958
• Artikelnr.: 52552247

Autorenporträt

PETER AVITABILE is Professor Emeritus at the University of Massachusetts Lowell, the co-director of the Structural Dynamics and Acoustic Systems Laboratory, and the former President for the Society for Experimental Mechanics. In addition, he is the Associate Editor of the Handbook for Experimental Structural Mechanics. He has written hundreds of papers and articles on analytical and experimental modal analysis techniques, including the Modal Space article series published in SEM's Experimental Techniques.

Inhaltsangabe

Preface xv

About the CompanionWebsite xix

Part I Overview of Experimental Modal Analysis using the Frequency Response Method 1

1 Introduction to ExperimentalModal Analysis: A Simple Non-mathematical Presentation 3

1.1 Could you Explain Modal Analysis to Me? 6

1.2 Just what are these Measurements called FRFs? 10

1.2.1 Why is Only One Row or Column of the FRF Matrix Needed? 13

1.3 What's the Difference between a Shaker Test and an Impact Test? 17

1.3.1 What Measurements do we Actually make to Compute the FRF? 18

1.4 What's the Most ImportantThing toThink about when Impact Testing? 21

1.5 What's the Most ImportantThing toThink about when Shaker Testing? 22

1.6 Tell me More AboutWindows; They Seem Pretty Important! 24

1.7 So how do we get Mode Shapes from the Plate FRFs? 25

1.8 Modal Data and Operating Data 29

1.8.1 What is Operating Data? 29

1.8.2 So what Good is Modal Data? 33

1.8.3 So Should I Collect Modal Data or Operating Data? 34

1.9 Closing Remarks 36

2 General Theory of Experimental Modal Analysis 37

2.1 Introduction 37

2.2 Basic Modal AnalysisTheory - SDOF 38

2.2.1 Single Degree of Freedom System Equation 38

2.2.2 Single Degree of Freedom System Response due to Harmonic Excitation 40

2.2.3 Damping Estimation for Single Degree of Freedom System 42

2.2.4 Response Assessment with Varying Damping 43

2.2.5 Laplace Domain Approach for Single Degree of Freedom System 46

2.2.6 System Transfer Function 47

2.2.7 Different Forms of the Transfer Function 48

2.2.8 Residue of the SDOF System 49

2.2.9 Frequency Response Function for a Single Degree of Freedom System 49

2.2.10 Transfer Function/Frequency Response Function/S-plane for a Single Degree of Freedom System 51

2.2.11 Frequency Response Function Regions for a Single Degree of Freedom System 51

2.2.12 Different Forms of the Frequency Response Function 53

2.2.13 Complex Frequency Response Function 53

2.3 Basic Modal AnalysisTheory - MDOF 56

2.3.1 Multiple Degree of Freedom System Equations 57

2.3.2 Laplace Domain for Multiple Degree of Freedom System 66

2.3.3 The Frequency Response Function 68

2.3.4 Mode Shapes from Frequency Response Equations 68

2.3.5 Point-to-Point Frequency Response Function 71

2.3.6 Response of Multiple Degree of Freedom System to Harmonic Excitations 72

2.3.7 Example: Cantilever Beam Model with Three Measured DOFs 75

2.3.8 Summary of Time, Frequency, and Modal Domains 83

2.3.9 Response due to Forced Excitation using Mode Superposition 87

2.4 Summary 89

3 General Signal Processing andMeasurements Related to Experimental Modal Analysis 93

3.1 Introduction 93

3.2 Time and Frequency Domain 93

3.3 Some General Information Regarding Data Acquisition 96

3.4 Digitization of Time Signals 97

3.5 Quantization 97

3.5.1 ADC Underload 98

3.5.2 ADC Overload 100

3.6 AC Coupling 100

3.7 SamplingTheory 101

3.8 Aliasing 103

3.9 What is the Fourier Transform? 105

3.9.1 Fourier Transform and Discrete Fourier Transform 107

3.9.2 FFT: Periodic Signal 108

3.9.3 FFT: Non-periodic Signal 108

3.10 Leakage and Minimization of Leakage 109

3.10.1 Minimization of Leakage 111

3.11 Windows and Leakage 111

3.11.1 RectangularWindow 112

3.11.2 HanningWindow 116

3.