PSI - Issue 5

Jung Min Sohn et al. / Procedia Structural Integrity 5 (2017) 943–950 Aditya Rio Prabowo et al. / Structural Integrity Procedia 00 (2017) 000 – 000

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Fig. 3. Magnitude of the internal energy during penetration of the indenter. Solid black line highlights crushing progress on the bottom structure.

Structural failure progress is presented in Fig. 3 which indicates penetration of the conical indenter taking place until space between the second and third transverse floors in impact time 0.5 s. Approximation of the damage length reaches 5 m in longitudinal direction. Damage extent and stress contour on the bottom structure are presented in next discussion. Confirmation of the failure sequence in the internal energy is successfully verified with the damage extent in Fig. 4. In the end of grounding impact, the conical indenter almost reached the third floors with a gap between them of 0.6 – 0.7 m. Stress contours were observed similar for each target with the highest stress occurred on the bottom part. However, in the center girder grounding, the highest stress magnitude was also experienced by the longitudinal stiffener. Further penetration will make the initial structural failure occurring in these components.

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(a) (c) Fig. 4. Damage extent and von Mises’ stress contour s on the penetrated zone for each target: (a) center girder, (b) side girder and (c) inner shell. (b)

Attention should be given after grounding to the center and side girders of the bottom structure. Tearing opening on these precise locations will present a possibility for lubrication oil or waste of two tanks (left and right sides of the side girder) to come out and contaminate water territory. Mitigation process of the grounded ship is also influenced volume of a spilled oil or waste. Larger volume of a spilled cargo (in this case is oil) from side girder case than a direct contact to space between two girders possibly occurs as content of two tanks can come out during the girder is crushed.