Ultrasonic testing pulse-echo technique

Ultrasonic Testing of Concrete with Fast Imaging Pulse-Echo-Technique. 

Due to the outer circumference of the silo, about 25 meters, a non- or rarely destructive testing method was needed for the localization. Because the building was still in use, it was only accessable from the exterior side. We chose the ultrasonic pulse-echo-technique as an appropriate way of doing the testing. 

Hillger, W. Inspection of Concrete by Ultrasonic-Pulse-Echo-Technique, In Proceedings of the European Conference on Non Destructive Testing, Nice 1994, pp. II59-II63... 

Povey, M.J.W., Wilkinson, J.M. 1980. Application of ultrasonic pulse-echo techniques to albumen quality testing - a preliminary report. Br. Poult. Sci. 21, 489-495. 

The two major techniques in ultrasonic testing arc the pulse-echo mode and the through-transmission mode. In pulse-echo mode, the same transducer is used to emit and receive ultrasonic waves and requires access to only one side of the structure inspected (Fig. 12). The pulse-echo technique is effective on the near side skin laminate only, and the sensitivity decreases as a function of depth [29]. With the through-transmission mode, access to both sides of a structure is required as an emitter probe is placed on one side and a receiver on the other (Fig. 13). This technique measures the signal amplitude of ultrasonic waves transmitted through the material tested and is more sensitive to small defects than the pulse-echo mode. The detection of flaws throughout the whole depth of a... 

The pulse-echo technique is the most popular of the three basic ultrasonic, nondestructive testing techniques. The pulse-echo technique is very useful in detecting flaws and for thickness measurement. 

Tattersall, A.G., 1973, "The Ultrasonic Pulse-Echo Technique as Apphed to Adhesion Testing", J. Phys. D Appl. Phys, Vol. 6, pp819-832. 

Tattersall, H.G., 1973, The Ultrasonic Pulse-Echo Technique as Applied to Adhesion Testing, J. Appl. Phys.D., 6, 819-832. 

The common civil engineering seismic testing techniques work on the principles of ultrasonic through transmission (UPV), transient stress wave propagation and reflection (Impact Echo), Ultrasonic Pulse Echo (UPE) and Spectral Analysis of Surface Waves (SASW). 

In most ultrasonic tests, the significant echo signal often is the one having the maximum ampHtude. This ampHtude is affected by the selection of the beam angle, and the position and direction from which it interrogates the flaw. The depth of flaws is often deterrnined to considerable precision by the transit time of the pulses within the test material. The relative reflecting power of discontinuities is deterrnined by comparison of the test signal with echoes from artificial discontinuities such as flat-bottomed holes, side-drilled holes, and notches in reference test blocks. This technique provides some standardized tests for sound beam attenuation and ultrasonic equipment beam spread. 

The resonance frequency technique has been used for determining the adiabatic Young s moduli in dependence on test temperatures up to 1000 °C. The shear moduli were measured by the pulse-echo ultrasonic technique. The bulk moduli were determined by synchrotron radiation diffraction. The temperature-dependent Young s and shear moduli are plotted in fig. 7. 

The Barker code pulse compression technique is a special ultrasonic testing method that compresses the ultrasonic pulse through the use of a special class of binary code called the Barker code [49], The pulse compression techique can be used to overcome the limitations of the traditional pulse-echo techique and is useful in testing materials that cause high attenuation. 

The oldest techmque for obtaining the ultrasonic transmission characteristic of a material as a function of the frequency is manual tuning of a conventional pulse echo measuring instrument. Of course, tunable and wide-band transmitter and receiver are required to carry out this technique. However, a narrow-band transducer had to be selected according to the test frequency and consequently this techmque is clumsy and rarely used outside the laboratory. 

Rose, J.L. and J.J. Ditri, Pulse-echo and through transmission Lamb wave techniques for adhesive bond inspection. British Journal of NOT, 34(12), 1992. GogUo, L. and M. Rossetto, Ultrasonic testing of adhesive bonds of thin metal sheets. NDT E International, 32 323-331,1999. 

However, it appears that none of the non-destructive tests currently employed directly correlate with any critical failure property. Most industrial test techniques such as through-transmission and pulse-echo ultrasonics, sonic vibration techniques. X-ray radiography, thermal inspection methods, holography, liquid penetrants, etc. basically attempt to find defects in the joint. Such defects may arise from several sources. Some defects arise from porosity, cracks or voids in the adhesive layer or at the interface and are typically filled with air they will simply be referred to as voids in the present discussions. However, during the service life of the joint such voids may fill with water which makes them far more difficult to detect since, for example, water has a much higher acoustic, impedance than air. Also, zero-volume voids, or debonds, may occur when the adhesive and substrate are in contact but no... 

Nondestructive testing. An ultrasonic inspection technique is available for the detection of flaws in plate, piping, and tubing. The water-immersed pulse-echo ultrasound equipment has been adapted to highspeed use. Eddy-current, dye-penetrant, and radiogr.aphic inspection methods are also used as required. The inspected materials have included Inconel, austenitic stainless steel, INOR-8, and the Hastelloy and other nickel-molybdenum-ba.se alloys. 

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