Acoustic Emission and Durability of Composite Materials [Hardcover]

In this book, two kinds of analysis based on acoustic emission recorded during mechanical tests are investigated.

In the first, individual, analysis, acoustic signature of each damage mechanism is characterized. So with a clustering method, AE signals that have similar shapes or similar features can be group together into a cluster. Afterwards, each cluster can be linked with a main damage. The second analysis is based on a global AE analysis, on the investigation of liberated energy, with a view to identify a critical point. So beyond this characteristic point, the criticality can be modeled with a power-law in order to evaluate time to failure.

Introduction ix

Chapter 1. Acoustic Emission: Definition and Overview 1

1.1. Overview 1

1.2. Acoustic waves 8

1.2.1. Infinite medium: volume waves 8

1.2.2. Semi-infinite medium: surface waves 9

1.2.3. Guided waves 9

1.2.4. Anisotropic medium and wave attenuation 10

1.3. The sensors and acquisition system 12

1.4. Location of sources 16

1.5. The extracted descriptors from the AE signal 21

1.5.1. Time domain descriptors 22

1.5.2. Frequency domain descriptors 26

1.5.3. Time–frequency analysis 30

1.6. The different analyses of AE data 32

1.6.1. Conventional analysis: qualitative analysis 32

1.6.2. Multivariable statistical analysis: application of pattern recognition techniques 42

1.7. Added value of quantitative acoustic emission 55

Chapter 2. Identification of the Acoustic Signature of Damage Mechanisms 59

2.1. Selection of signals for analysis 59

2.2. Acoustic lS: