Modeling the high cycle fatigue behavior of T-joint fillet welds considering weld-induced residual stresses based on continuum damage mechanics

Numerical analysis of low cycle fatigue for welded joints considering welding residual stress and plastic damage under combined bending and local compressive loads

“…Lautrou et al 24 predicted the fatigue crack initiation lives of S355NL steel welded joints with a twoscale damage model considering the welding residual stresses and obtained a satisfactory result. Lee et al 25 predicted the fatigue lives of T-joint welds in the case of multiaxial high cycle fatigue (HCF) by virtue of a nonlinear multiaxial HCF damage model. In their prediction, the welding residual stress was considered as an important factor to obtain an accurate result.…”

Fatigue life prediction for butt‐welded joints considering weld‐induced residual stresses and initial damage, relaxation of residual stress, and elasto‐plastic fatigue damage

“…In the structural integrity evaluation, fatigue failure becomes one of the dominant concerns. Existing studies have revealed that there are mainly three factors impacting the fatigue property of welded joints: (a) the welding residual stresses, (b) local plastic deformation resulting from the welding process, and (c) the interaction between residual stresses and fatigue damage during cyclic loadings. Some approaches have been proposed to address one or two influencing factors .…”

“…Consequently, there is an imminent urge to develop a method to comprehensively consider the weld‐induced residual stresses, initial damage, as well as the interactive relationship between the fatigue damage and residual stresses, when evaluating the fatigue property of welded structures. The continuum damage mechanics (CDMs) could be a suitable candidate because of its advantageous ability for describing the mechanical performance of a deteriorated material and for calculating the progressive damage by developing damage‐coupled constitutive model and thermodynamics‐based damage evolution laws . Do et al developed a nonlinear damage cumulative model, based on the CDM approach.…”

“…cumulative plastic strain during the entire welding period; q f , q r , front and rear heat sources; Q V , thermal generation per unit volume; Q, heat source power; R, stress ratio; R ν , the triaxiality function; δS D , surface density of microcracks and intersections of microvoids; δS, area of cross section cutting the representative volume element (RVE); δS R , effective area of resistance, δS R = δS − δS D = δS(1 − D); S ij, min , S ij, max , minimum and maximum values of the ijth components of the deviatoric stress tensor; T, instant temperature; t, time; U, voltage of the welding process; v, welding velocity; z 0 , initial z-coordinate of the applied heat source; α, expansion coefficient of material; α ij , S ij , deviatoric part of back stress and stress; γ k , material parameters in kinematic hardening rule; δ ij , Kronecher delta; ε ij ; ε e ij ; ε p ij , total strain, elastic strain, and plastic strain; ε p ij : , evolution of plastic strain; η, welding arc efficiency; λ, heat conductivity of material; λ : , plastic multiplier; ν, Poisson's ratio of material; ρ, density of material; ∇, spatial gradient operator; σ e , effective stress; σ a , amplitude of fatigue loading; σ eq , von Mises equivalent stress; σ eqmax , maximum equivalent stress during the welding process; σ eq, max , maximum equivalent stress during fatigue loading; σ H , hydrostatic stress; σ H, m , mean hydrostatic stress; σ max , maximum cyclic stress; σ ij , Cauchy stress; σ l0 , fatigue limit of material; σ u , ultimate value of tensile stress; σ x , axial normal residual stresses in x-direction; σ y , axial normal residual stresses in y-direction; σ ′ y , yield stress the dominant concerns. Existing studies have revealed that there are mainly three factors impacting the fatigue property of welded joints [1][2][3][4][5][6] : (a) the welding residual stresses, (b) local plastic deformation resulting from the welding process, and (c) the interaction between residual stresses and fatigue damage during cyclic loadings. Some approaches have been proposed to address one or two influencing factors.…”

“…Some approaches have been proposed to address one or two influencing factors. [4][5][6] However, it is very difficult to completely consider all the three factors simultaneously. Residual stresses during the welding process significantly influence the fatigue behaviour of welded structures.…”