PSI - Issue 19

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

177

3

2. The Verity® Method The primary motivation for structural stress methods (also known as geometric stress methods) is the elimination of self-balanced peak stresses that arise at notches as weld toes (see Fig. 1). The decomposition of an arbitrary notch stress can be accomplished as indicated in Fig. 1. In Equations 1 and 2 the bending and membrane stresses are the components that balance the external loads and therefore chosen to compose the structural stresses. The forces f x , f y , f z , and moments m x and m y need to be represented in the local coordinate system as indicated in Fig. 2. For an open ended weld line the system of equations shown in Equation 4 are used to extract the forces f along the weld line from the forces F output in the global coordinate system from a finite element analysis. Similar system of equations is available for closed weld lines and for cases where second order finite elements are employed.

y f 6m t t   f 6m t t   2 2

x       m b s

(1)

s m b     

y  

x

(2)



f

 

(3)

Z

Z

t

Fig. 1. Decomposition of the local finite element stresses.