No abstract available

[en] Crack initiation and growth in the Charpy V-notch test are investigated for controlled deflections of the specimen applied both by slow bending and by impact. Charpy test specimens were deformed to various deflections, heat-tinted to mark the crack extensions, and broken apart at low temperature to allow measurement of the crack extensions. These measurements provide estimates of crack initiation as defined by various criteria. The loading point at which crack initiation occurs depends on the particular definition being used for ''initiation,'' but in all cases it is well before the maximum load is reached. When initiation is defined as the first observable micro-initiation away from the ductile blunting of the notch root, the experimental results are in good agreement with computer modeling predictions

[en] Ultrasonic and eddy current testing devices are compiled to a building unit. As the ultrasonic testing device works according to the electrodynamic transducer principle, the test coils of both test equipment can be arranged centrally to each other and be alternately connected. A control device and measured value processing unit are used for this. (RW)

[en] As an effort to enhance the reliability and accuracy of the instrumented impact testing, a new pendulum type of test apparatus has been designed and constructed at the Technical Research Centre of Finland (VTT). The new tester contains several novel features which help to avoid the drawbacks of the normal designs and which make the impact testing more reliable and appropriate from the fracture mechanics point of view. For that purpose the tester is equipped with a fully computerized data acquisition system and an optical COD measuring device. The latter has been developed and constructed through the co-operation between Materialpruefungsanstalt (MPA) and VTT. In the new testing facility the determination of fracture toughness is based on the application of the optical COD measuring device. In this paper testing equipment and procedures are described and discussed. (orig./HP)

[en] NDT begins to adapt and use the most recent developments of digital signal and image processing. We briefly sum up the main characteristics of NDT situations (particularly noise and inverse problem formulation) and comment on techniques already used or just emerging (SAFT, split spectrum, adaptive learning network, noise reference filtering, stochastic models, neural networks). This survey is focused on ultrasonics, eddy currents and X-ray radiography. The final objective of end users (availability of automatic diagnosis systems) cannot be achieved only by signal processing algorithms. A close cooperation with other techniques such as artificial intelligence has therefore to be implemented. (author). 20 refs

[en] The drastic operating conditions to which fast reactor cladding is subjected necessitate very elaborate tests. Sensitive and specific non-destructive tests were developed for this purpose, for example ultrasonic and eddy current testings and metrological diameter and thickness measurements. Appropriate selection methods based on amplitude, phase and frequency analysis of the signals were established. The results obtained show up various categories of defects which respond to the test as a function of the characteristics of the methods used. The validity of such a classification implies adequate technical examination facilities and a thorough knowledge of the tube manufacturing range

[en] In this study, evaluation of acoustic emission signals characteristics for the post weld heat treated (PWHT) multi-pass weldment and weldment was dealt. Charpy standard specimens were taken from the lowest, middle and highest regions of the weld block. Pre-crack was made using the repeated load. Four point bend and AE tests were conducted simultaneously. Regardless of the specimens, AE signals were absent within elastic region and produced in the process of plastic deformation. AE signals for all specimens were not emitted after the maximum load. Value of signal strength for the all PWHT specimens was lower than that of the weldment. Besides, relations of plastic deformation zone size and accumulated AE counts for the PWHT specimens were more simple compared with the weldment. In case of the PWHT specimen, particles on the fractured surface decreased prominently compared with the weldment due to PWHT. From these results, it can be concluded that PWHT was effective in reducing the AE sources for the weldment

[en] A setup is described for measuring the velocity, wavelength, and frequency of the waves arising on the surface of draining liquid films. The contactless measurement technique is based on ultrasonic probing of a liquid film through the wall of a pipe, reception of the reflected signals by two acoustical sensors, and statistical computer processing of the data acquired. 3 refs., 4 figs

[en] The combination of the automatic testing system ALOK with a controlled probe in the form of a phased array device is a possibility to meet the high requirements on the test method with regard to the statements of the test as well as the requirements on the reduction of operation and preparation times. The system's applications are not limited to the testing of reactors in nuclear technology (basic tests and recurring tests of the RPV and other primary circuit components); they are also of great importance in the non-nuclear sector e.g. the testing of pipelines, of reactors in the chemical field and of offshore structures as well as tests of components in the field of production. The modularity of the system permits an adaptation to the particular testing task with the possibility of using different manipulation and hardware systems. (orig./DG)

[en] An improvement of the axial resolution in us-impulse-echo testing is reached by suitable signal processing. Two techniques can be given that yield an improvement by retention of the usual us-impulses. However in both the cases i.e. the inverse filtering and spectroscopy the limitation is valid that the ratio of the two superseded impulses must not higher than about 14dB. (DG)