[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)

No abstract available

[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] 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

No abstract available

[en] There are opinions that the eddy current non-destructive evaluation (NDE) reached its limits and the applicability of this method is phasing out, being replaced by new, improved techniques. These views cannot be further from the truth; similar outlooks were expressed for ultrasonic and radiographic techniques, and they were proven wrong by the arrival of phased array ultrasonic waves and digital radiography methods, respectively. The emergence of pulsed and remote field eddy current as more capable methods than conventional eddy current testing, along with improved signal and image processing algorithms, are only few supporting examples for this NDE technique. Moreover, the use of solid-state sensing devices instead of coils allows inspections for minute, deeply buried discontinuities. In this paper, the feasibility of using solid-state sensors in eddy current testing for detection of cracks initiated from the alodine fasteners holes in a three-layer specimen is provided as an example. This NDE task is approached by employing the pulsed eddy current inspection method, along with a giant magneto-resistive (MR) sensor pick-up. Detection of cracks under installed fasteners is a challenge due to the defect orientation and the masking effect of the fasteners. The induced eddy currents flow within the adjacent lap joint layers, as well as inside the conductive fastener; therefore, reducing the current density around the crack. (author)

[en] In this paper the author after having indicated the methods used in nondestructive testing presents 4 of these methods - X-ray and gamma radiography - ultrasonic testing - eddy current - acoustic emission

No abstract available