PSI - Issue 47

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Muhammad Imaduddin Hanif et al. / Procedia Structural Integrity 47 (2023) 125–132 Hanif et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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Before performing calculations using the FEM method, it is necessary to simplify the model of the stiffened panels that make up the hull structure. The 1/2+1/2 bay-1/2+1/2 span model was chosen because it is one of the simplest modelling that can be done to shorten the analysis time. After that, the variation of the geometry of the stiffened panel was carried out. There are three variations of the model based on its geometry. The three models are varied based on the value of 2 . One model has a value 2 less than 60, one model has a value of about 60, and the last one has a value far exceeding 60. The 2 = 60 mm value is used as a reference because in severe conditions there is a change in the value of the initial imperfection geometric where if the value 2 = 60 mm will refer to the function formula that has been set, but if it exceeds 2 = 60 mm then the imperfection value will have a constant value of 20mm. Furthermore, the three models will be further distinguished into two based on the span/bay ratio. Therefore, a total of six models will be formed which will be referred to as the short light model, short medium model, short heavy model, long light model, long medium model, and long heavy model. All described dimensions in Figure 3 are in mm.

t f = 17 w f =100

t f = 16 w f = 100

t f = 90 w f = 15

h w = 383 t w = 12

h w = 334 t w = 9

h w = 235 t w = 10

t p = 25 w p = 880

t p = 25 w p = 8

t p = 18.5 w p = 880

t p = 12.5 w p = 880

span = 2610

span = 5220

Short light model

Short medium model

Short heavy model

Long light model

Long medium model

t f = 17 w f =100

t f = 16 w f = 100

t f = 90 w f = 15

h w = 383 t w = 12

h w = 334 t w = 9

h w = 235 t w = 10

= 235 = 10

t p = 25 w p = 880

t p = 18.5 w p = 880

t p = 12.5 w p = 880

610

span = 2610

span = 5220

ight el

Short medium model

Short heavy model

Long light model

Long medium model

Long heavy model

Figure 3. Light, medium, and heavy types of the idealized geometries.

The used formula to calculate the initial imperfection geometric on the stiffened panel is shown in Table 1 which refers to Adiputra et al. [2023].

Table 1. Deformation of initial imperfection on the designed structure. Buckling Mode

0 = 0 0 = 0 ℎ

Nomenclature 0 = /1000 0 = 2 /10

Initial imperfection geometric Formula

Column Buckling Mode

Torsional Buckling Mode

Local Buckling Mode 0 = 0 B 0 is the maximum geometric initial imperfection geometric for column and torsional buckling. L represents the length of the model. C 0 is the maximum initial imperfection geometric for local buckling. 0 and 0 themself represent the maximum value of the initial imperfection geometric. Boundary conditions in this modeling can be seen in Figure 4. To apply continuous conditions to the longitudinal and transverse edges, all edges are set to be uniform. In this modeling, the transverse frame was not modeled. Instead, its contribution was model as a fix boundary condition along the attached elements. At both ends of the nodes in the opposite direction, an initial displacement of 7.5 mm will be given to each. In addition, the center point of the plate is also regulated so that it does not experience initial displacement.

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