PSI - Issue 14

Ilyin A.V. et al. / Procedia Structural Integrity 14 (2019) 964–977 Author name / Structural Integrity Procedia 00 (2018) 000 – 000

966

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local RWS , a fragment of inherent RWS field in WTZ

res

 R reactive RWS originating as a response on limitation of displacement of structural members being welded  Rb base curve parameter  r fatigue limit  Y yield stress  ( a ) correction function for small crack kinetics  х 0 angular displacement after welding A macro geometry parameter of a welded joint accounting for its type, dimensions of welded elements and weld seam and the type of loading (tension or bending) a crack depth a 0 depth of initial micro crack a c crack depth criterion da / dN crack growth rate а 1 , а 2 , а 3 coefficients for A determination depending on the type of loading (tension or bending) b reinforcement width С constant for a certain material in the crack growth rate equation d reference structural size of material E modulus of elasticity f loading frequency H height of an attached element h reinforcement height k coefficient in the function  ( a ) related to the reference structural size of material d K I SIF at Mode I loading  K SIF range (nominal, related to an applied load) K Id SIF for a crack in the design (service) stress field K Imax SIF in a cycle corresponding to the maximum applied load K op SIF in a cycle corresponding to the start of crack opening K IR SIF for a crack in a reactive RWS field K Ires SIF component related to residual stress for a crack in an inherent RWS field K Iscc critical SIF under static load in a corrosion medium K ef effective SIF Δ K ef effective SIF range determined by  K and r K th threshold SIF value ( K th ) 0 threshold SIF value obtained at standard test with r = 0 (  K th ) 0 threshold SIF range at r = 0 K t stress concentration factor K s structural stress concentration factor K w “ technological ” stress concentration factor K eq reduced “ technological ” stress concentration factor K  strain concentration factor m S-N-curve exponent determined by the type of welded joint and thickness of its load-transmitting part N number of cycles [ N ] admissible number of loading cycles for a structure n safety factor determined as a function of the ratio “residual cyclic life / total cyclic life ” N i cyclic life at Stage 1 fatigue N i 0 mean estimate of N i N c cyclic life at Stage 2 fatigue N c 0 mean estimate of N c Q exponent in K eq accounting for cyclic asymmetry q exponent for a certain material in the crack growth rate equation