Ultrasonic and X-ray computed tomography characterization of progressive fracture damage in low-porous carbonate rocks

This paper studies the fracturing process in low-porous rocks during uniaxial compressive tests considering the original defects and the new mechanical cracks in the material. For this purpose, five different kinds of rocks have been chosen with carbonate mineralogy and low porosity (lower than 2%). The characterization of the fracture damage is carried out using three different techniques: ultrasounds, mercury porosimetry and X-ray computed tomography. The proposed methodology allows quantifying the evolution of the porous system as well as studying the location of new cracks in the rock samples. Intercrystalline porosity (the smallest pores with pore radius < 1 μm) shows a limited development during loading, disappearing rapidly from the porosimetry curves and it is directly related to the initial plastic behaviour in the stress–strain patterns. However, the biggest pores (corresponding to the cracks) suffer a continuous enlargement until the unstable propagation of fractures. The measured crack initiation stress varies between 0.25 σp and 0.50 σp for marbles and between 0.50 σp and 0.85 σp for micrite limestone. The unstable propagation of cracks is assumed to occur very close to the peak strength. Crack propagation through the sample is completely independent of pre-existing defects (porous bands, stylolites, fractures and veins). The ultrasonic response in the time-domain is less sensitive to the fracture damage than the frequency-domain. P-wave velocity increases during loading test until the beginning of the unstable crack propagation. This increase is higher for marbles (between 15% and 30% from initial vp values) and lower for micrite limestones (between 5% and 10%). When the mechanical cracks propagate unstably, the velocity stops to increase and decreases only when rock damage is very high. Frequency analysis of the ultrasonic signals shows clear changes during the loading process. The spectrum of treated waveforms shows two main frequency peaks centred at low (~ 20 kHz) and high (~ 35 kHz) values. When new fractures appear and grow the amplitude of the high-frequency peak decreases, while that of the low-frequency peak increases. Besides, a slight frequency shift is observed towards higher frequencies.

Correlation between ultrasonic nondestructive inspection and wheel test of 34 retreaded tires. Interim report.

National Highway Traffic Safety Administration, Office of Research and Development, Washington, D.C.

Report of pre and post road test ultrasonic inspection results on 134 passenger tires: final report.

National Highway Traffic Safety Administration, Washington, D.C.

The development of an apparatus for cutting tooth structure by means of ultrasonic vibrations. research progress report.

"Project no. NM 008 015.08"

Guidelines for ultrasonic inspection of hanger pins /

"July 2004."

A semi-automated pulse-echo ultrasonic system for inspecting tires. Interim report.

National Highway Traffic Safety Administration, Office of Research and Development, Washington, D.C.

Ultrasonic inspection of ten retreaded tires and thirty-two casings. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Evaluation of a K. J. Law Model 8300 Ultrasonic Roughness Testing Device. Final report.

Federal Highway Administration, Washington, D.C.

Application study of ultrasonic nondestructive inspection for tire compliance testing. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Ultrasonic detection of overbuffing in retreaded tires. Interim report.

National Highway Traffic Safety Administration, Office of Research and Development, Washington, D.C.

The influence of ultrasonic vibrations upon the physical features of activated sludge.

Thesis (M.S.)--University of Illinois.

Operator, organizational, and intermediate (direct support and general support) maintenance manual (including repair parts and special tools list) : processor, passive signal ultrasonic MX-9443()/FSS-9(V), FSN 6350-228-2548; receiver, passive signal ultrasonic ....

"July 1974."

Quantitative assessment of aortic sclerosis using ultrasonic backscatter

Background. The development of therapeutic interventions to prevent progressive valve damage is more likely to limit the progression of structural damage to the aortic valve with normal function (aortic sclerosis [ASC]) than clinically apparent aortic stenosis. Currently, the ability to appreciate the progression of ASC is compromised by the subjective and qualitative evaluation of sclerosis severity. Methods: We sought to reveal whether the intensity of ultrasonic backscatter could be used to quantify sclerosis severity in 26 patients with ASC and 23 healthy young adults. images of the aortic valve were obtained in the parasternal long-axis view and saved in raw data format. Six square-shaped 11 X 11 pixel regions of interest were placed on the anterior and posterior leaflets, and calibrated backscatter values were obtained by subtracting the regions of interest in the blood pool from the averaged backscatter values obtained from the leaflets. Results. Mean ultrasonic backscatter values for sclerotic valves exceeded the results in normal valve tissue (16.3 +/- 4.4 dB vs 9.8 +/- 3.3 dB, P < .0001). Backscatter values were greater (22.0 +/- 3.5 dB) in a group of 6 patients with aortic stenosis. Within the sclerosis group, the magnitude of backscatter was directly correlated (P < .05) with a subjective sclerosis score, and with transvalvular pressure gradient. mean reproducibility was 2.4 +/- 1.8 dB (SD) between observers, and 2.3 +/- 1.7 dB (SD) between examinations. Conclusion: Measurement of backscatter from the valve leaflets of patients with ASC may be a feasible means of following the progression and treatment response of aortic sclerosis.