The Effect of Notch Depth on CTOD Values in Fracture Tests of Structural Steel Elements

Abstract In elements of steel structures working at low temperatures, there is a risk of appearance of brittle fracture. This risk is reduced through the use of certified materials having guaranteed strength at a given temperature. A method which is most frequently used to determine brittle fracture...

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Bibliographic Details
Published in:Polish Maritime Research
Main Authors: Kowalski, Jakub, Kozak, Janusz
Format: Article in Journal/Newspaper
Language:English
Published: Walter de Gruyter GmbH 2018
Subjects:
Online Access:http://dx.doi.org/10.2478/pomr-2018-0058
https://content.sciendo.com/view/journals/pomr/25/2/article-p85.xml
https://www.sciendo.com/pdf/10.2478/pomr-2018-0058
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Summary:Abstract In elements of steel structures working at low temperatures, there is a risk of appearance of brittle fracture. This risk is reduced through the use of certified materials having guaranteed strength at a given temperature. A method which is most frequently used to determine brittle fracture toughness is the Charpy impact test, preformed for a given temperature. For offshore structures intended to work in the arctic climate, the certifying institutions more and more often require Crack Tip Opening Displacement (CTOD) tests instead of conventional impact tests, especially for steel and welded joints of more than 40 mm in thickness in the case of high-strength steel, and more than 50 mm for the remaining steels. The geometry of specimens and the test procedure are standardised; however, these standards provide some margin for specimen notch depth. The paper analyses the effect of notch depth difference, within the range permitted by the standards, on the recorded CTOD values of a given material. The analysis was performed via numerical modelling of destruction of specimens with different notch geometries and further verification of the obtained numerical results in laboratory tests. The calculations were carried out at the Academic Computer Centre in Gdansk.