doi: 10.1111/j.1460-2695.2006.01084.x Significance of the elastic peak stress evaluated by FE analyses at the point of singularity of sharp V-notched components G. MENEGHETTI 1 and P. LAZZARIN 2 1 Department of Mechanical Engineering, University of Padova, Via Venezia 1–35131 Padova, Italy, 2 Department of Management and Engineering, University of Padova, Str. S. Nicola 3–36100 Vicenza, Italy Received in final form 16 June 2006 ABSTRACT The paper presents an expression useful to estimate the notch stress intensity factor (NSIF) from finite element analyses carried out by using a mesh pattern with a constant element size. The evaluation of the NSIF from a numerical analysis of the local stress field usually requires very refined meshes and then large computational effort. The usefulness of the presented expression is that (i) only the elastic peak stress numerically evaluated at the V-notch tip is needed and no longer the whole stress–distance set of data; (ii) the adopted meshes are rather coarse if compared to those necessary for the evaluation of the whole local stress field. The proposed expression needs the evaluation of a virtual V-notch tip radius, i.e. the radius which would produce the same elastic peak stress than that calculated by FEM at the sharp V-notch tip by means of a given mesh pattern. Once such a radius has been theoretically determined for a given geometry, the expression can be applied in a wide range of notch depths and opening angles. Keywords elasticity; finite element analysis; notch stress intensity factor; stress intensity factor; V-notches. NOMENCLATURE a = crack length, V-notch depth or component’s reference dimension d = adopted finite element size ρ = notch tip radius ρ ∗ = virtual notch tip radius r, θ = polar coordinates K I = mode I Stress Intensity Factor K V I = mode I Notch Stress Intensity Factor for a sharp V-notch σ r , σ θ = stress components in a polar frame of reference σ g = nominal stress on the gross section σ max = linear elastic maximum principal stress at the tip of a rounded notch (exact stress) σ peak = linear elastic peak stress calculated by FEM at the sharp V-notch tip by means of a given mesh pattern 2α = opening angle of the V-shaped notch INTRODUCTION Notch stress intensity factors (NSIFs) play an important role in static strength assessments of components made of brittle or quasi-brittle materials and weakened by sharp V-shaped notches. 1–8 This holds true also for components made of structural materials undergoing high cycle fatigue Correspondence: P. Lazzarin. E-mail: plazzarin@gest.unipd.it loading 9,10 as well as for welded joints both under tension or bending loading 11–16 and multiaxial loading. 17 In plane problems, the Mode I NSIF for sharp V-notches can be expressed by means of the Gross and Mendelson’s definition 18 : K V 1 = √ 2π lim r → 0 (σ θ ) θ =0 r 1−λ1 , (1) where (r, θ ) is a polar coordinate system centred at the notch tip as shown by Fig. 1, σ θ is the stress component c  2006 Blackwell Publishing Ltd. Fatigue Fract Engng Mater Struct 30, 95–106 95