Ultrasonic Measurement and Destructive Tests

In order to allow both ultrasonic transmission experiments and tensile loading, the ultrasonic set-up was integrated into a small laboratory-scale tensile test stage (Fig. 25.9). The incentive for these experiments originated from the results of combined ultrasonic transmission and dynamic and quasi-static tensile tests of bonded steel tubes [14] and the data shown above. We wanted to test whether there is a correlation of any of the following parameters the second-order nonlinearity parameter y 2, the third-order nonlinearity parameter / 3, the distortion factor K, or the interaction force Fip to the destractively determined tensile strengths. 

Before the tensile test the samples were investigated by ultrasonic transmission measurements as described in Section 25.2. The peak power of the RF-car-rier pulse (again 10-30 cycles, center frequency 2.25 MHz) was swept from 0 up to 3.6 kW and back to zero. The transmitted ultrasonic signal was detected by a broadband receiver probe, recorded, and Fourier-transformed. The dependence of the resulting amplitude and phase spectra on the transmitting pulse power was recorded. Figs. 25.11 and 25.12 show the results obtained for two of the specimens, one with a weak and one with a strong bond of 5.5 and 

After the ultrasonic measurements the specimens were loaded until fracture to obtain the tensile strength. During the loading procedure nonlinear ultrasonic transmission measurements with an excitation peak power of 1.86 kW were carried out Figs. 25.13 and 25.14 show the results. The amplitudes of the transmitted waves of fundamental frequency (Fig. 25.13) and of the second and the third harmonic (Fig. 25.14) are plotted in arbitrary units as recorded by the receiver probe. The horizontal axis represents the number of measuring points 

5 MPa) and (b) a strong bond (tensile strength 32.5 MPa) are plotted versus the input RF pulse power. The amplitudes show hysteresis for the weak but not for the strong bond. 

The tensile strengths of the many samples examined are related to different ultrasonic measurement quantities. Fig. 25.15 a shows the distortion factor K as a function of tensile strength with the transmitting transducer excited at an RF peak power of 3.6 kW. The nonlinearity parameter (Fig. 25.15 b) in- 

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The suggested method is appropriately implemented at the practice. The cost and working hours of unit measurement of it is less than of any alternative method of destructive test and with respect to the authenticity inspection of Stress-Deformation the given method is inferior only to destructive testing. The method was successfully implemented while evaluation of service life of main pipe-lines sections and pressure vessels as well. Data of method and instrument are used as official data equally with ultrasonic, radiation, magnetic particles methods, adding them by the previously non available information about " fatigue " metalwork structure. 

It is perhaps less easy to excuse the lack of a chapter on non-destructive testing. The reason is a mixture of the fact that the major NDT techniques are, in the main only applied to a few particular rubber products and the realisation that to properly describe all methods would require a book, not a chapter. It is, however, worth remembering that it is not only ultrasonics, radiography, holography and so on which are non-destructive. A number of the more traditional rubber tests, for example electrical properties, many dynamic tests, hardness and dimensional measures leave you with the product intact. There are text books which deal with NDT techniques generally and. a comprehensive review of NDT of polymers by Gross in Handbook of Polymer Testing3. 

In this article, we introduce a recently developed ultrasonic spectroscopy method and review its application to polymeric studies. First, the principle of this ultrasonic spectroscopy is explained including the instruments and data analysis methods. Then, actual application of this measuring system is described for the characterization of solid polymers and the observation of phase transition phenomenon in liquid crystals and ferroelectric (VDF/TrFE) copolymer. Finally, the extension of this system to two-dimensional measuring and the application to non-destructive testing of CFRP (carbon fiber reinforced plastics) are discussed. 

Figure 16.6 shows the general yield and fast fracture loci for a pressure-vessel steel and an aluminium alloy. The critical flaw size in the steel is =9 mm that in the aluminium alloy is =1 mm. It is easy to detect flaws of size 9 mm by ultrasonic testing, and pressure-vessel steels can thus be accurately tested non-destructively for safety -vessels with cracks larger than 9 mm would not be passed for service. Raws of 1 mm size cannot be measured so easily or accurately, and thus aluminium is less safe to use. 

There have been a number of previous attempts to relate the appearance of higher harmonics in the transmission of ultrasound through bonded structures to the quahty of the bonds [2-9]. Commonly used is the so-called nonhnearity parameter y 2, a measure of the generation of only the second harmonic [2], and the distortion factor K which describes the complete nonlinear content of the response [7]. In this paper cahbrated measurements on samples consisting of two aluminum plates joined together by a thin epoxy layer are presented and discussed. The amphtudes and phases of the ultrasonic waves transmitted through the bond are considered. The measurements are related to the results of destructive tensile tests of the adhesive layer. 

The first real efforts to answer this question were made in the 1980s in the program for the inspection of steel components (PlSC), which was coordinated through the Council for the European Commission and the Organization for Economic Cooperation and Development (OECD) [11], Steel plates with known different types of defects (but of unknown size) were passed around NDE inspection teams in various countries, who carried out inspections in accordance with the requirements of the American Society of Mechanical Engineers (ASME) Code. The teams also used some advanced ultrasonic NDE techniques that were still undergoing research. The countries involved in the set of round-robin trials included various European countries, the USA and Canada. At the end of the tests, the steel plates were destructively examined so that the exact sizes of the defects could be measured. The measured defect sizes were then compared with what the NDE teams thought they had found. 

There are also a number of more sophisticated non-destructive techniques (NDT) which measure the frequency response of the bonded component part and can thus identify the presence (or absence) of adhesive in the joint. These NDT methods use ultrasonic testing, whereby high-frequency, highly directional sound waves analyse the adherends and find hidden internal flaws [2]. 

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