Microstructural and Defect Characterization in Ceramic Composites Using an Ultrasonic Guided Wave Scan System

Ultrasonics: A Technique of Material Characterization

“…The low intensity and high frequency ultrasonic waves are applied for medical diagnosis, acoustical holography, material characterization etc. The low intensity ultrasoud measurements provides a good diagnosis of material property and process control in industrial apllication (Alers, 1965;Green,1973;Lowrance, 1975;Renolds, 1978;Teagle, 1983;Smith, 1987;Varry, 1987;Thompson,1996;Jayakumar, 1998;Kumar, 2001;Raj, 2003;Roth, 2003;Blodgett, 2005).…”

NDE for Characterizing Oxidation Damage in Reinforced Carbon‐Carbon

“…Multiple mode excitation is likely due to the use of broadband transducers and the existence of multiple plate wave modes is confirmed by the complicated nature of the signal. 8 Ultrasound was coupled to the material via elastic coupling pads. The distance between sending and receiving transducers was 2.5 cm.…”

“…In a future investigation, the effect of the slot and oxidation on other ultrasonic parameters that can be derived from broadband ultrasonic guided wave signals will be considered. 8,10 X-ray Computed Tomography X-ray computed tomography (CT) was used to provide additional images of the oxidation damage and study oxidation in the naturally-cracked RCC sample, without destructive sectioning. 9 This SmartScan Model 100 (CITA Systems, Inc., Pueblo, CO) system utilizes a Feinfocus FXE-160 (COMET AG, Flamatt, Switzerland) microfocus x-ray source to produce very high resolution imaging of samples, approaching 0.025 mm, in the CT mode of operation.…”

Characterization of C/Enhanced SiC Composite During Creep-Rupture Tests Using an Ultrasonic Guided Wave Scan System

“…The guided wave method discussed in this article utilizes the total (multi-mode) ultrasonic response, does so in a scanning configuration, and employs specialized signal processing routines to extract parameters of the time-and frequency-domain signals. 8 These parameters have proven to be sensitive to changes in microstructural conditions and to the presence of defects, [6][7][8] and appear promising at monitoring degradation in CMCs. 9 Ultrasonic guided waves through the material thickness are generated when the ultrasonic wavelength is on the order of the thickness of the material being interrogated.…”

“…One method showing promise for characterizing distributed microdamage is the ultrasonic guided wave technique. [6][7][8][9] In particular for CMCs, prior studies conducted at NASA GRC have shown ultrasonic guided waves to be successful for characterizing matrix cracking and stiffness degradation in SiC/SiC materials. Advantages of the guided wave technique include 1) the sample under test does not have to be immersed in fluid (as for most conventional ultrasonic characterization), 2) the method requires access to only one side of the sample, and 3) the method is potentially applicable to components with curved surfaces.…”