PSI - Issue 14

Filin V.Yu. et al. / Procedia Structural Integrity 14 (2019) 758–773 Filin V.Yu, Ilyin A.V. / Structural Integrity Procedia 00 (2018) 000–000

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1. Hydrocarbon fields of the Russian sea shelf and the Northern Sea Route Recently in Russia great efforts are undertaken to develop the Far North and other offshore hydrocarbon fields and set the Northern Sea Route for regular use as it is the shortest way by sea between European and Asian countries. The main part of the hydrocarbon resources and reserves of the Russian Arctic Shelf is concentrated in the Barents (with Pechora) and Kara seas. These resources and reserves are mainly represented by gas. Another source of hydrocarbons is Caspian Sea. Gas comes to Europe from Russia by subsea pipelines, new lines are under construction. Nowadays another actual task should be solved to transport liquified natural gas (LNG) from Yamal peninsula to East Asia through the eastern part of the North Sea Route. So, the objects of interest and at the same time sources of ecological accidents are subsea pipelines, nuclear ice breakers, offshore platforms and terminals, icegoing tankers (including LNG) and freighters and other large-size critical welded structures made of high-strength low-alloyed steel predominantly operated in the conditions of low climatic temperatures, heavy ice loads, wind and waves and probable earthquake hazard. Their safe operation needs to be guaranteed within the design service life. It means that the following problems must be solved:  Required properties of hull materials (critical fracture resistance and cold resistance) need to be stated without extra reserve but at the same time with no error to the unsafe side,  The maximum allowable flaws in welded structures shall be set for known materials and nondestructive inspection procedures,  Flaws in structures found during construction or while in service shall be assessed following a certain calculation procedure. These problems are qualitatively solved in many investigations telling what is good what is bad but the quantitative estimation is needed for a relatively wide range of strength properties and it may be given in terms of fracture mechanics.

Nomenclature 

contour around the crack tip specific fracture energy



specific energy of plastic deformation specific energy of forming new surfaces

 pl

 f 

load line displacement

crack tip opening displacement, CTOD



Kronecker’s delta

 ij

strain hardening exponent

  

bend angle

Poisson’s ratio

relative ligament width elastic energy of the body





 stress (  ij ) HRR stress components as per Hutchinson, Rice and Rosengren  b bending stress component  t tensile stress component  Y yield strength  geometry parameter A reduced flaw size a crack depth a 0 initial crack depth da crack extension B characteristic size of a specimen