Noncontact ultrasound studies of composite materials: new developments

Christopher Edwards; Theodosia Stratoudaki; Stephen Dixon; Stuart B. Palmer

doi:10.1117/12.385498

13 May 2000 Noncontact ultrasound studies of composite materials: new developments

Christopher Edwards, Theodosia Stratoudaki, Stephen Dixon, Stuart B. Palmer

Proceedings Volume 3993, Nondestructive Evaluation of Aging Materials and Composites IV; (2000) https://doi.org/10.1117/12.385498
Event: SPIE's 5th Annual International Symposium on Nondestructive Evaluation and Health Monitoring of Aging Infrastructure, 2000, Newport Beach, CA, United States

Abstract

Techniques are being developed worldwide for non-contact ultrasonic inspection of composite materials. These include laser generation and optical detection of ultrasound; both with interferometers and simpler beam deflection techniques, air coupled transducers are also used as generators and/or detectors of ultrasound. This paper compares the generation efficiency and damage thresholds of a range of different laser types: A fundamental Nd:YAG laser (1.06 micrometer), a TEA CO₂ laser (10.6 micrometer normally preferred for carbon- fiber reinforced composites) and a Nd:YAG laser with an Optical Parametric Oscillator (OPO) tunable up to 4 micrometer. The laser energy is absorbed with the optical absorption depth, the temperature rise is affected by the wavelength and laser pulse duration. It is essential to remain in the thermoelastic regime in order not to damage the material. A modified Michelson interferometer is used to detect the absolute displacement of the ultrasound. Optical beam deflection techniques and air-coupled transducers are also evaluated as detectors.

Citation Download Citation

Christopher Edwards, Theodosia Stratoudaki, Stephen Dixon, and Stuart B. Palmer "Noncontact ultrasound studies of composite materials: new developments", Proc. SPIE 3993, Nondestructive Evaluation of Aging Materials and Composites IV, (13 May 2000); https://doi.org/10.1117/12.385498

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