PSI - Issue 19

Giovanni M. Teixeira et al. / Procedia Structural Integrity 19 (2019) 175–193 Author name / Structural Integrity Procedia 00 (2019) 000–000

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loads directly, Radaj et al. (2006). The British Standards (in particular BS7608), Eurocode 3 (Aygul et al. (2013)) and IIW (Hobbacher et al. (2016)) are examples of design codes that support the use of nominal stresses. The notch stress (or notch strain) method and fracture mechanics are examples of local approaches whereas the hot spot and structural stress methods, although sometimes referred as a local approach (Reibenwein (2016)), work as a link between those two, Radaj et al. (2006). The advantages and disadvantages of every method are profusely discussed in the literature and therefore are not included in this paper.

Nomenclature σ s , ∆σ s

structural stress, structural stress range

σ m σ b

membrane stress bending stress

τ s , ∆τ s τ m , τ b τ z , ∆τ z f´, m´ F, M

shear structural stress, shear structural stress range

in-plane shear stress

transverse shear stress, transverse shear stress range line forces and line moments in local coordinate system forces and moments in global coordinate system element edge length between the grid points

l t

component thickness

∆σ e ∆S s

effective structural stress range equivalent structural stress range

r

bending ratio

m

fatigue crack growth exponent

I(r) C,h m n G(f)

dimensionless parameter derived from fracture mechanics

master SN curve parameters

n th spectral moment

one-sided power spectral density

H i (f) Q(f) d n , d s p(S R ) A

transfer function

dynamic response matrix quadratic Mises operator

directional vectors

probability density function of stress range

Z, R, Q, x m D 1 , D 2, D 3

constants of Dirlik´s PDF constants of Dirlik´s PDF expected peak rate irregularity factor rate of zero crossings

E[P]

γ

n 0

+

T

exposure time

k, b

SN curve parameters

The increasing popularity of the structural stress methods (the Verity® Method in particular) stems from the need of accuracy, usability and consistency in the fatigue evaluation of welded joints from finite element analysis (FEA) results. The Volvo method was the first to work with structural stresses derived from nodal forces and moments. The paper published by Fermèr et al. (1998) provides further details and some numerical examples. A comprehensive comparison between the two methods (Verity® and Volvo) is also available in the literature, Wei et al. (2013). The next paragraphs will shortly summarize the main features of the Verity® method for the benefit of understanding the contribution of the present research.