Location

Snowbird, UT, USA

Start Date

1-1-1999 12:00 AM

Description

In the ultrasonic NDE of layered materials and structures, such as bonded joint, coating, and in particular the composite material, the surface or Lamb wave velocity or the reflection and transmission coefficient are measured, to determine for examples, the elastic constants, the anisotropy and the integrity of the materials, etc. A commonly used technique to determine locally the surface or Lamb wave velocity V g is based on the measurement of the reflection minima or the transmission maxima at oblique incidence of the test sample. It is supposed that at the critical incident angle θ c where the reflection coefficient appears the minima, the surface or Lamb waves are favorably generated and V g =V o/sinθ c where V 0 is the wave speed in coupling liquid. So, the determination of the reflection function is essential and important. In general, the acoustic reflection or transmission coefficient of a layered medium depends on the wave incident angle θ, the wave frequency ƒ and the orientation angle φ if the material is anisotropic. To obtain the whole information of this reflectance function R(θ,φ,ƒ), one needs to insonify the structure at varying incident and orientation angles and do the frequency spectroscopy using the wide-band transducer.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

18B

Chapter

Chapter 5: Engineered Materials

Section

Composites

Pages

1289-1296

DOI

10.1007/978-1-4615-4791-4_165

Language

en

File Format

application/pdf

Share

COinS
 
Jan 1st, 12:00 AM

Measurement of Reflectance Function for Layered Structures Using Focused Acoustic Waves

Snowbird, UT, USA

In the ultrasonic NDE of layered materials and structures, such as bonded joint, coating, and in particular the composite material, the surface or Lamb wave velocity or the reflection and transmission coefficient are measured, to determine for examples, the elastic constants, the anisotropy and the integrity of the materials, etc. A commonly used technique to determine locally the surface or Lamb wave velocity V g is based on the measurement of the reflection minima or the transmission maxima at oblique incidence of the test sample. It is supposed that at the critical incident angle θ c where the reflection coefficient appears the minima, the surface or Lamb waves are favorably generated and V g =V o/sinθ c where V 0 is the wave speed in coupling liquid. So, the determination of the reflection function is essential and important. In general, the acoustic reflection or transmission coefficient of a layered medium depends on the wave incident angle θ, the wave frequency ƒ and the orientation angle φ if the material is anisotropic. To obtain the whole information of this reflectance function R(θ,φ,ƒ), one needs to insonify the structure at varying incident and orientation angles and do the frequency spectroscopy using the wide-band transducer.