PSI - Issue 41

Ilham Widiyanto et al. / Procedia Structural Integrity 41 (2022) 274–281 Widiyanto et al. / Structural Integrity Procedia 00 (2022) 000 – 000

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The results obtained from the experimental results were compared with theoretical analysis using the methods commonly used to design the cylinder pressure hull of a deep-diving manned submersible ABS2012 and CCS2013 to determine the strength and stability of the cylinder shell. The experimental and theoretical results are then compared with FEM using ABAQUS/CAE software. In this study, the mesh size used is 2.5 mm. The analysis uses linear perturbation in ABAQUS/CAE with the first five request modes. The results obtained are that there are five eigenmodes. The following simulation is a nonlinear simulation using the first eigenmode. The method used in nonlinear buckling is the RIKS Method. The imperfection used is 0.2 times the model's thickness.

l std ( × 10 (mm) 6.22

Table 1. Measured data dimension for all tested specimens (Zhu et al., 2018) D max (mm) D min (mm) D ave (mm) D std (mm)

-3 )

l ave (mm) 49.67 75.70 98.82 150.76 202.29 349.89

D ave /t ave (mm) 111.40 111.14 110.68 108.11 109.49 108.49

l ave /D ave (mm)

LR1.0 LR1.5 LR2.0 LR3.0 LR4.0 LR7.0

101.73 101.77 101.82 101.75 101.30 101.82

101.46 101.36 101.35 101.33 100.80 101.48

101.60 101.58 101.60 101.62 100.73 101.55

0.135 0.205 0.235 0.210 0.250 0.170

0.49 0.75 0.97 1.48 2.01 3.45

6.46 6.94 6.02 6.24 6.34

According to the study (Zhu et al., 2018), the worst geometric imperfections can cause the fastest reduction in buckling load, but the worst defects are unknown. Therefore, the first eigenmode of linear buckling is often considered the worst defect. The distribution of shell thickness variations is determined by a mapped field section assignment is also considered. The arc length method is used for imperfections. Table 2 shows the input arc-length method.

Table 2. Arc length method input Parameters Initial arc length (mm) Minimum arc length (mm) Maximum arc length (mm)

Value

0.1

0.00001

0.5 100

Number of iterative

Material properties 304 stainless steel based on research flat tensile specimens were designed and tested from Chinese Standard (GB/T228.1-2010). The cross-sectional area of the specimen is measured to get the value of young's modulus ( E ). This value can be calculated using the following formula: = , for < (1) and, = √( − 1) , for ≥ (2) Where E is Young's modulus, n and k are strain hardening, is yield strength based on 0.2% of actual stress. The material is assumed to be elastic-perfectly plastic. Based on the experiments conducted by (Zhu et al., 2019). The material properties of 304 stainless steel are yield stress =323.18 MPa, and Young's modulus E = 176.05 GPa. In this study, the cylinder shell has no constraint when subjected to uniform pressure. One end is completely fixed, and one is fixed, but the only axial movement is permitted. The incremental external pressure in this Finite Element Analysis (FEA) was 1 MPa was applied to the entire area of the cylindrical shell. Experiments were carried out to obtain material property values. Based on theoretical analysis, the calculation result of buckling load on CCS2013 is 4.50 MPa, and ABS2012 is 3.60 MPa. The results of the comparison of the nonlinear buckling experiment and simulation results taken from Zhu et al. (2018), can be seen Fig 2. The critical buckling load value in the experiment is 4.56 MPa. While the nonlinear buckling simulation results with FE analysis, it is 4.02 MPa.