PSI - Issue 57

Inge Lotsberg et al. / Procedia Structural Integrity 57 (2024) 569–580 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

573

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3. Finite element analysis of fillet welded doubling plates

3.1. Finite element models

The quadratic doubling plate with rounded corners in Fig. 2 is selected for analysis. The analysis model of a part of the plate is shown in Fig. 4 which is made symmetric about the center plate of the test specimen. Three analyses were performed with 20-node solid elements using different element meshes. One analysis was performed using 8 node shell elements. Both these elements are higher order elements as their stiffness are based on a quadratic displacement function. The analyses were performed with the Abaqus program (2021). The element mesh for the three solid models is shown in Fig. 5. There are two elements over the thickness of the doubling plate and the fillet weld is modelled by four elements. There is a thin gap below the doubling plate as there are separate nodes on the doubling plates and the main plate below the doubling plate that are not connected to simulate a small gap between the plates in the area inside the fillet welded region. The finite element models are described in Table 1. The fillet welds in the shell element model are simulated by orthogonal shell elements of thickness two times the main plate thickness as recommended for analysis of eccentric lug plates in DNV-CG-0129 (2021). Reference is made to Fig. 6 which shows a typical connection between a longitudinal stiffener and a transverse frame where a lug plate is welded to the transverse frame after the stiffener has been installed and is thus eccentric relative to the transverse plate. The height of these shell elements in the analysis model is equal to the distance between the mid layers of the doubling plate and the main plate.

75 mm

Doubling plate 150 x 150 mm

Fillet weld

t D = 10 mm

Unit load 1.0 MPa

Main plate

t = 20 mm

800mm

Boundary conditions for symmetry

Fig. 4. Part of plate analyzed by finite elements.

Table 1. Finite element models. Analysis no Type of element

Number of elements over the main plate thickness

Width of element

Length of element in the main stress direction

1 2 3 4

20-node solid 20-node solid 20-node solid 8-node shell

1 4 4 1

t t t t

t t

0.5t

t