Location

Snowbird, UT, USA

Start Date

1-1-1999 12:00 AM

Description

Composites are a material class for which nondestructive material property characterization is as important as flaw detection. Fiber reinforced composite laminates often possess strong in-plane elastic anisotropy attributable to the specific fiber orientation and layup sequence. Many of these elastic anisotropies may be investigated using ultrasound [1–6], among which angular measurements are often used. Hsu et al [3,4] used angular scan of acousto-ultrasonic signals to investigate fiber reinforced composite laminates. By placing and rotating two contact transducers on the same side of crossedplied composite laminates, the angular dependence of the acousto-ultrasonic signal was measured and found to have good correlation with the fiber orientation of the sample. Angular measurement of normal-incident shear wave has also been used to detect errors in layup sequence and ply orientation in both green (before cured) and cured composites [4–6]. The transmitted signals of normal incident shear wave in a “crossed polarizer” configuration were found to be particularly sensitive to ply misorientation and layup sequence in a laminate. For green composites, sandwiched between aluminum delay lines, EMATs (electro-meganetic transducer) were used so that the problem of changing coupling condition during the angular scan was avoided. This technique was believed to hold good potential as a practical NDE tool for detecting layup errors during the manufacturing process [5].

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

18B

Chapter

Chapter 5: Engineered Materials

Section

Composites

Pages

1385-1392

DOI

10.1007/978-1-4615-4791-4_178

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Development of Motorized Azimuthal Scanners for Ultrasonic NDE Of Composites

Snowbird, UT, USA

Composites are a material class for which nondestructive material property characterization is as important as flaw detection. Fiber reinforced composite laminates often possess strong in-plane elastic anisotropy attributable to the specific fiber orientation and layup sequence. Many of these elastic anisotropies may be investigated using ultrasound [1–6], among which angular measurements are often used. Hsu et al [3,4] used angular scan of acousto-ultrasonic signals to investigate fiber reinforced composite laminates. By placing and rotating two contact transducers on the same side of crossedplied composite laminates, the angular dependence of the acousto-ultrasonic signal was measured and found to have good correlation with the fiber orientation of the sample. Angular measurement of normal-incident shear wave has also been used to detect errors in layup sequence and ply orientation in both green (before cured) and cured composites [4–6]. The transmitted signals of normal incident shear wave in a “crossed polarizer” configuration were found to be particularly sensitive to ply misorientation and layup sequence in a laminate. For green composites, sandwiched between aluminum delay lines, EMATs (electro-meganetic transducer) were used so that the problem of changing coupling condition during the angular scan was avoided. This technique was believed to hold good potential as a practical NDE tool for detecting layup errors during the manufacturing process [5].