PSI - Issue 75

Carl-Fredrik Lind et al. / Procedia Structural Integrity 75 (2025) 519–529 Carl-Fredrik Lind et al./ Structural Integrity Procedia (2025)

525 7

, , w i k M k i    define a local ik l as ik l   i k x x . When creating ik l also create the unit . Then, assume that the element normal vector (unit vector) of the element that , i k belong to is

. w i i M W M   . Then,

i k x x x x   k i

i



vector

k

( k i,k F n i  e

)

, e i k n . The actual local-coordinate forces can then be constructed as , y i F   i

and

known as

, x i M   i k M i . The stresses then calculated as follows:

1



l

l

     



ik

ik

    

F F

, y i            , x i 6

M M

( ) k

i   k

  

  

1

3 6



(10)



 

l

l

t

t

2

  

, x k  

, y k   

ik

ik

6 3

all the , w i M ) and then they averaged over k to gain a length average i  .This yields a more accurate result. However, if the goal is to be conservative, a more conservative version can be chosen max( ( )) i i k k    . Doing this for all nodes i , yields an associated structural stress i i W   . We then calculate an associated lifespan for each node i N using Eq. (9) with i  . The last step is grouping the nodes that belong to the weld line based on their distance to each other, creating groups 1 2 , ,..., m C C C where m is the number of groups. It should be the case that if this is not true, then the nodes that belong to the set should be flagged, since these will not provide reliable results and should be analysed with other methods in detail. Then, for each group w C , the life is defined as below:   min , w C i w i N N i C   (11) 5. Finite Element Model Several models have been analysed in this study, among which the finite element shell model of the T-joint is described. In this analysis, the meshing was performed in Hypermesh, the solver was Abaqus, and Ansa-Meta was used as a post-processor. The dimension of the model, along with the applied load and boundary conditions, is explained in Fig. 5. The weld is modelled with beam elements connecting the baseplate to the stiffener. Two FE-mesh models of the same weld were made, one with a solid tetrahedron mesh (3D-elements) and the other with quadratic shell elements (2D). ( ) i k  are calculated (a total number

Figure 5.Finite element shell of T-joint model.