Pulse echo ultrasonic test

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. 

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... 

This paper deals with the control of weld depth penetration for cylinders in gold-nickel alloy and tantalum. After introducing the experimental set-up and the samples description, the study and the optimization of the testing are presented for single-sided measurements either in a pulse-echo configuration or when the pump and the probe laser beams are shifted (influence of a thermal phenomenon), and for different kind of laser impact (a line or a circular spot). First, the ultrasonic system is used to detect and to size a flat bottom hole in an aluminium plate. Indeed, when the width of the hole is reduced, its shape is nearly similar to the one of a slot. Then, the optimization is accomplished for... 

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... 

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). 

Ultrasonics. The most widely used nondestmctive test method for explosion-welded composites is ultrasonic inspection. Pulse-echo procedures (ASTM A435) are appHcable for inspection of explosion-welded composites used in pressure appHcations. 

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. 

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. 

With a test sample on the optically flat top surface of the bar, the pulse echo train is reduced in amplitude. This attenuation is owing to the refraction of part of the ultrasonic wave into the test sample at the frequency used. The ratio of successive peak amplitudes may be measured on the oscilloscope and expressed in decibels loss per echo. From this, the loss per echo with no sample on the bar can be substracted to give a value Adb which is related to the mechanical shear impedance of the sample. Rapid changes can be conveniently monitored by a recorder which follows the peak signal of a selected echo. 

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 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. 

PVDF is generally an ideal material for transducers operating at frequencies above 0.5 MHz in hydrophones and pulse echo probes for medical and nonmedical testing. A 64-element linear array transducer has been produced that, operating at 5 MHz, offers a wide-bandwidth pulse response, sharp ultrasonic field distribution, and a high energy conversion efficiency. 

Delaminations reduce the time required for the reflected signal to arrive at the surface in pulse-echo setups (also shown in Fig. 2.6) which have both the transmitting and detecting transducers on the same side of the test sample. The same method can distinguish between flaws at different depths. A slightly different ultrasonic resonance method utilizes the fact that delaminations reduce the sample stiffness and hence produce a resonant frequency shift. 

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. 

Ultrasonic Pulse Echo Contact Impedance Testing... 

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. 

Image quality indicators (IQIs) were fabricated for use in development and acceptance testing of the ultrasonic inspection system. Silicon nitride test uars (3.5x4.5x50 mm) with known internal voids, characterized by microfocus radiography, are being utilized to benchmark the pulse-echo imaging capability. 

FIGURE 7. Basic ultrasonic test principle, (a) Pulse echo setup (b) oscilloscope display. 

J. L. Rose, M. J. Avioli, and R. Bilgram, A feasibility study on the nondestructive evaluation of an adhesively bonded metal to metal bond An ultrasonic pulse echo approach, Br. J. Non-Destr. Test, 25, 67 (1983). 

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. 

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