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Transferability of Fracture Mechnaical Characteristics
Dlouhý, Ivo ; Lenkey, G. B. ; Pluvinage, G.
Comprehensive review of proved recent methods for transfer of fracture mechanical characteristics from smaller to standard specimen geometry is supplied thinking at the same time on transferability of these characteristics from laboratory experiments to real components. Application procedures for local approach, master curve methodology, toughness scaling models, dynamic fracture properties and notch sensitivity are workout and discussed.
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Master curve evaluation at static and dynamic conditions of loading (for cast ferritic steel and pressure vessel steels)
Dlouhý, Ivo ; Chlup, Zdeněk ; Holzmann, Miloslav
Various aspects of the master curve methodology have been investigated experimentally based on data obtained with different pressure vessel and container steel. A manganese cast steel has been utilised being considered for storage containers of spent nuclear fuel. Two locations of a segment of container cask, surface and midthickness, have been followed. Some results obtained with the RPV steel of VVER 1000 type and CrMo pressure vessel steel used in petrochemical applications have also been exploited. The applied mechanical testing procedures included: Standard fracture toughness tests at different temperatures using 1T bend specimen in order to determine fracture toughness - temperature diagrams, dynamic fracture toughness has been tested by using hydraulic test machine and drop weight tower. Pre-cracked Charpy specimens have also been tested. For each test technique larger sets of data have been generated in order to follow the statistical aspects. The investigations included procedures of reference temperature determination, both by the one and multitemperature methods, and the evaluation of the scale and constraint effects and the effect of loading rate. For static loading the multi- and single temperature methods of reference temperature determination have been tested with the same family of data. The transferability of results received on the small pre-cracked Charpy specimens was analysed and applied with good results.
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Validity of master curve for dynamic fracture toughness characteristics
Dlouhý, Ivo ; Lenkey, G. ; Holzmann, Miloslav
Master curve methodology have been investigated experimentally based on data obtained with cast ferritic steel being considered for storage containers of spent nuclear fuel. Standard pre-cracked specimens have been tested by means of instrumented drop weight tower, pre-cracked Charpy specimens by means of Instrumented impact tester. Different methodologies of reference temperature determination have been followed. Transferability of data from small pre-cracked specimens to standard ones has been also followed.
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Současné koncepce hodnocení křehkolomových charakteristik ocelí
Dlouhý, Ivo ; Holzmann, Miloslav ; Chlup, Zdeněk ; Kozák, Vladislav
Stručný přehled současného stavu v hodnocení křehkolomových charakteristik ocelí a kritický rozbor stávajících řešení pro popis pole napětí u čela trhliny jednoparametrovou elasticko-lineární a elasticko-plastickou lomovou mechanikou. Dvouparametrová lomová mechanika jako další vývojové stádium lomové mechaniky a dopady jejich poznatků na měření lomové houževnatosti. Základní (master) křivka pro popis lomové houževnatosti ocelí v tranzitní oblasti. Lokální přístup jako další koncepce lomové mechaniky, která s využitím mikromechanistických modelů porušování u čela trhliny umožňuje predikci globálních křehkolomových charakteristik a jejich transferabilitu z tělesa s trhlinou jedné geometrie na těleso jiné geometrie a velikosti.
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