PSI - Issue 47

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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because they represent the buckling mode values as described previously. Meanwhile, the imperfection value of 100% and 300% has a lower ultimate strength value than the ultimate strength value based on the IACS-CSR method.

Table 3. The value of σ U / σ Y and σ U - FEM / σ U -IACS-CSR .

σ U - FEM / σ U -IACS-CSR .

σ U /σ Y

Type

Initial imperfection

Light 0.719 0.669 0.583 0.511 0.719 0.669 0.583 0.511

Medium

Heavy 0.972 0.948 0.846 0.684 1.010 0.842 0.808 0.717

Light 1.041 0.967 0.844 0.739 1.098 1.067 0.989 0.904

Medium

Heavy 1.039 1.013 0.904 0.731 1.136 0.947 0.909 0.807

2.5% 25% 100% 300% 2.5%

0.921 0.843 0.704 0.557 0.811 0.779 0.702 0.610

1.115 1.021 0.853 0.675 1.037 0.996 0.897 0.780

Short

25%

Long

100% 300%

Table 3 displays comparative data between the ratios of ultimate strength to yield strength and the ratio between ultimate strength based on FEM and ultimate strength based on IACS-CSR. As can be seen, the value of the imperfection will affect the value of the ultimate strength which will automatically affect the value of the ultimate strength ratio compared to the yield strength. This can be seen as an example in the comparison of the light model with the medium model, the ratios of ultimate strength to yield strength of the long light model with an initial imperfection geometric of 25% is greater than the long light model with 100% of initial imperfection geometric, which is 0.669 compared to 0.583. Also, it can be seen that the ultimate strength value in a model that has an imperfection value of 2.5% and 25% will tend to be greater in value than the ultimate strength value based on the IACS-CSR method. This can be seen in the graph where almost all models with imperfection values of 2.5% and 25% have an ultimate strength ratio of FEM and ultimate strength of IACS-CSR of more than one. In contrast, for all models with an imperfection value of 100% and 300%, the ultimate strength ratio of FEM and IACS-CSR is less than one.

Table 4. Summarized ratio between σ U (0.3β2tp) and σ U (20 mm).

Ratio between σ U (0.3β2tp) and σ U (20 mm)

σ U (MPa)

Initial imperfection geometrics

C 0 (mm)

Model

300% 300% 300% 300% 300% 300% 300% 300%

0.3β2tp

243.873 189.735 215.624 203.333 196.534 199.684 215.374 217.663

Short light

1.285

20

0.3β2tp

Long light

1.060

20

0.3β2tp

Short medium

0.984

20

0.3β2tp

Long medium

0.989

20

Based on data in Table 4, it is known that the initial imperfection geometric value of 300% for models with a slenderness plate value of more than 60 will have two variants to determine the initial imperfection geometric value. The first is based on the set equation which is a function of the slenderness of the plate with plate thickness. And the second is based on a constant value of 20 mm. In Table 5. The effect of the comparison between the two variations on the value of ultimate strength is given. It can be seen that for the medium model, both the short-medium model and the long-medium model have a ratio value between ultimate strength based on the equation and ultimate strength