Location

La Jolla, CA

Start Date

1-1-1993 12:00 PM

Description

The increased use of composite materials and adhesively bonded joints has resulted in the need for the development of inspection techniques appropriate for multi-layered structures. Normal incidence ultrasonic pulse-echo imaging has been and continues to be a principal technique for the detection of interface condition. Ideally, only a single reflection from each interface in the layered structure would be received and the ultrasonic image would be based upon a single parameter intrinsic to the material, such as the reflection coefficient. The reflection coefficient is, in turn, primarily determined by the relative change in ultrasonic impedance across the interface. In the absence of a complete inversion procedure by which the reflection coefficient may be calculated from pulse echo-data, the reflected signal amplitude is used to form the ultrasonic image. Unfortunately, the reflection amplitude, as indicated in Figure 1(a), often decreases rapidly due to the presence of reflective, overlying interfaces.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

12A

Chapter

Chapter 3: Interpretive Signal Processing and Image Analysis

Section

Imaging and Inversion Methods

Pages

827-834

DOI

10.1007/978-1-4615-2848-7_105

Language

en

File Format

application/pdf

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Jan 1st, 12:00 PM

An inversion approach to ultrasonic imaging through reflective interfaces in multi-layered structures

La Jolla, CA

The increased use of composite materials and adhesively bonded joints has resulted in the need for the development of inspection techniques appropriate for multi-layered structures. Normal incidence ultrasonic pulse-echo imaging has been and continues to be a principal technique for the detection of interface condition. Ideally, only a single reflection from each interface in the layered structure would be received and the ultrasonic image would be based upon a single parameter intrinsic to the material, such as the reflection coefficient. The reflection coefficient is, in turn, primarily determined by the relative change in ultrasonic impedance across the interface. In the absence of a complete inversion procedure by which the reflection coefficient may be calculated from pulse echo-data, the reflected signal amplitude is used to form the ultrasonic image. Unfortunately, the reflection amplitude, as indicated in Figure 1(a), often decreases rapidly due to the presence of reflective, overlying interfaces.