Ultrasonic pulse velocity

The pulse velocity approach is best done in a transmission mode with the pulse created on one side of a concrete member and detected on the other side. It can be used at corners or in a reflective mode if necessary, but it loses effectiveness and interpretation gets harder. The impact-echo technique can be used with pulse generator and detector side by side as the echo is reflected back from defects. 

Estimating concrete strength from ultrasonic measurements using a PUNDIT is a well tested technique. Recent developments have meant that the technique can also be used in reflection mode as an assessment of condition as well as in the more traditional transmission mode for strength estimation. 

The collection of ultrasonic data is relatively slow due to the need to collect the data from point locations. The results often give a relative condition only and as such a good knowledge of the structure is necessary. As with many non-destructive tests it is often necessary to calibrate the findings from limited targeted intrusive work. 

The surface of the structure to be investigated needs to be smooth in order to get sufficient energy into the concrete. Whereas gel couple methods such as the pundit require a smooth surface the dry couple transducers can accommodate a certain amount of roughness and therefore less surface preparation is necessary. 

On many sites external noise sonrces may interfere with the instrument and this should be discussed to avoid wasted trips to site. Many factors such as traffic movement and general site noise should not affect the instrument as the frequency wonld be ontside the recording range of the equipment. Needle guns are a source of interference which wonld affect the technique. 

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The use of ultrasonic pnlse velocity is documented in BS EN12504-4 2000 Testing Concrete. Determination of ultrasonic pulse velocity . 

Condition Evaluation of Concrete Bridges Relative to Reinforcement Corrosion. Vol. 4 Deck Membrane Effectiveness and a Method for Evaluating Membrane Integrity. Investigates membrane performance and effectiveness to develop a nondestructive test to evaluate in-place membranes. An ultrasonic pulse velocity method was developed. Conclusions indicate that properly installed and maintained preformed membrane systems reduce chloride intrusion. 143 pages. SHRP-S-326, 15... 

Ultrasonic pulse Velocity Porosity, mineralogy, strength In situ non-damaging Physical decay... 

Hola, J. and Moczko, A., The analysis of destruction process of selected structures of concrete using ultrasonic pulse velocity and acoustic emission (in Polish). Ph.D. Thesis, Institute of Building Science, Technical University of Wroclaw, Wroclaw, December 1984. 

In general a thickness measurement using ultrasound is done by measuring the time of flight of the ultrasonic pulse and calculating the thickness of the objeet multiplying the time and the known constant sound velocity in the material. 

Phase Velocity Measurements of Polybutadiene Composites Using Ultrasonic Pulses , Rept No BRL-1908 (1976)... 

The discussion above that led to Eqs. (4.2.6 and 4.2.7) assumes that the no-slip condition at the wall of the pipe holds. There is no such assumption in the theory for the spatially resolved measurements. We have recently used a different technique for spatially resolved measurements, ultrasonic pulsed Doppler velocimetry, to determine both the viscosity and wall slip velocity in a food suspension [2]. From a rheological standpoint, the theoretical underpinnings of the ultrasonic technique are the same as for the MRI technique. Flence, there is no reason in principle why MRI can not be used for similar measurements. 

Instrumentation for revealing the presence of bulk quantities of concealed drugs will differ from those developed to find evidence of minute quantities on surfaces. Bulk detection is concerned with amounts ranging from grams to kilograms [4], Bulk detection is done by manual inspection, X-ray, CT scans, and acoustic inspection. X-ray or CT scanners used as bulk detectors have sensitivity of 2-10 g, and suspect items are subsequently confirmed by chemical analysis. Hand-held acoustic inspection instruments such as the Acoustic Inspection Device (AID) and the Ultrasonic Pulse Echo (UPE) developed by Pacific Northwest National Laboratories/Battelle, can be used for analysis of cargo liquids in sealed containers of various sizes within seconds [5]. The acoustical velocity and attenuation of multiple echoes returned to the instrument is evaluated by software which compares the data to the shipping manifest. 

The acoustic velocity of SiC has been measured using both ultrasonic resonance [1] and ultrasonic pulse echo techniques. The latter has resulted in the appearance of CVD-SiC diaphragms in commercially available speakers [2]. 

Tarbell, J.M., Gunishan, J.R, Geselowitz, D.B., Rosenberg, G Shung, K.K., and Pierce, W.S. 1986. Pulsed ultrasonic Doppler velocity measurements inside a left ventricular assist device. ASME J. Biomech. Eng. 108 232-238. 

In the 12 years since the first edition I have been fortunate to continue to work with many knowledgeable and experienced engineers and specialists on the committees of NACE, the Corrosion Prevention Association, Concrete Society, Institute of Corrosion, the Transportation Research Board and CEN. I must specifically acknowledge Andrew Trafford of Aperio who kindly supplied a lot of useful information as well as photographs about radar, radiography, pulse velocity, ultrasonic and impact-echo techniques. My thanks also go to my publisher, and to Nick Clarke whose helpful suggestions strengthened the first draft of the book considerably. 

The contact method can be used to obtain the complete set of stiffness constants for samples with much smaller dimensions. In this method [3,5], a piezoelectric ceramic transducer, bonded to one surface of the sample, generated a beam of pulsed 10 MHz elastic waves that was subsequently received by another transducer bonded to the opposite surface. The wave velocity was calculated from the transit time of the ultrasonic pulse measured on a gated time interval counter. Longitudinal and transverse waves were generated using two different types of transducers. 

Often an acousto-optic switch is used, for example, for argon lasers and cw dye lasers [648]. Its basic principle is explained in Fig. 6.6. A short ultrasonic pulse with acoustic frequency / and pulse duration T 1 //s is sent nit = to through a fused quartz plate inside the laser resonator. The acoustic wave produces a time-dependent spatially periodic modulation of the refractive index n(t,z), which acts as a Bragg grating with the grating constant A = Cs//, equal to the acoustic wavelength A where Cg is the sound velocity. When an optical wave Eocos((ot — k r) with the... 

No single crystal elastic constant data for cerium were found by the writer This probably reflects the difficulty of obtaining suitable single phase crystals. The most complete and systematic investigation of the polycrystalline elastic properties of cerium was conducted by Rosen (1969a). He used an ultrasonic pulse technique employing a frequency of 10 MHz to measure sound velocities in spectrographically pure (99.9 + %) metal and corrected the acoustic path... 

Rosen (1971) is the only investigator known by the writer to have measured the temperature dependence of the elastic properties of ytterbium. Using an ultrasonic pulse technique (10 MHz) to determine acoustic wave velocities in polycrystalline ytterbium Rosen obtained the results given in figs. 8.85 and 8.86. He corrected the acoustic wave path length for thermal expansion. The values of E, G and d increase smoothly with decreasing temperature and approach the... 

Various electromagnetic and acoustic techniques are used for nondestructive examination of concrete. These include radar for locating delaminations, radiography for mapping the rebar network, ultrasonic techniques like pulse velocity and PUNDIT, which can estimate concrete strength and quality and find defects like voids, honeycombing, crack.s, etc. All of these techniques require. specialized equipment and most require specialists to operate and interpret them. Figure.s 4.18(a) and (b) illustrate the equipment and use of pulse velocity and impact echo. 

In this paper a method is described to measure accurately the three-dimensional geometry of the isolated, working canine heart during the cardiac cycle. Times of flight of ultrasonic pulses are measured with high accuracy for many directions through the object under study. These transmissions times are then used to reconstruct the ultrasound velocity distribution in the plane of measurement. 

Interaction between ultrasound and tissue can be characterized by a number of parameters like speed of propagation, attenuation, absorption coefficients etc. As ultrasound velocity is characteristic for a particular tissue the possibility is opened for ultrasound velocity tomography. The principles hereof and implications for medicine have been described by Greenleaf et al. (1975). In ultrasound velocity tomography transmitters and receivers are positioned around the object under study. Times of flight of ultrasonic pulses from transmitter to receiver are measured accurately. By rotating the transmitters and receivers in a plane around... 

With ultrasound velocity tomography the local speed of ultrasound in a cross section of the subject under study is computed from a large set of ultrasound transmission times. These calculations (reconstructions) are based upon a model that describes the propagation of ultrasound in a medium. In its simplest form the ultrasonic pulses are supposed to travel along straight pathways from transmitter to receiver. The measured transmission times depends on the velocity distribution v(jc, y) in the plane of reconstruction ... 

Papadakis, E.P. (1967) Ultrasonic phase velocity by the pulse-echo overlap method. J. Acoust. Soc. Am., 42, 1045-1051. 

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