PSI - Issue 5

Jung Min Sohn et al. / Procedia Structural Integrity 5 (2017) 935–942 Aditya Rio Prabowo et al. / Structural Integrity Procedia 00 (2017) 000 – 000

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penetration and the earliest contact was presented by the over deck-collision. Tendency of the resultant force was found to increase from the initial impact approximately until 0.225 s for the shell and deck-collisions. This increment was considered to match with the internal energy.

Bulbous bow penetrates the lower part of the struck ship Striking bow penetrates the upper part of the struck ship

Deck-collision

Over deck-collision

Shell-collision

Fig. 5. The resultant forces for different collision model based on the target location.

After passing this time point, the internal energy showed less increment than before 0.225 s. As related to the energy in previous discussion, the resultant force drastically went down for the shell and deck-collisions in time range 0.225 – 0.25 s which was found the calculations, this time range was the initial failure of the lower part as the bulbous bow had successfully penetrated the lower part of the struck ship. The shell-collision decreased later than the deck collision since the initial impact of two ships occurred later for both the internal energy and resultant force. Effect of the location was significant in this work as the over deck-collision on the upper location produced the earliest timing for both the initial impact and tendency reduction. The initial impact began approximately in 0.01 s which was the shortest gap from the initial location to the initial impact. Reduction occurred after passing 0.15 s as the bulbous bow breached the lower part of the struck ship. In the same timing, the initial energy observed experience remarkable reduction, the increment of the internal energy for this collision model being not significant before 0.15 s. The time point during the energy and force shows a major increment or reduction which is considered as the shift-state point in this work. It can be initially concluded that the bulbous bow delivered the most significant impact to the struck ship during side collision. 4.3. Damage extent After a contact took place between the striking and struck ships, crushing process on the side structure was simulated. In this situation, damages on the structure are found different for each location. Until the collision is ended, the shell-collision, produced damage on the upper and lower structures. The interaction of the upper deck and bulbous bow of the striking ship with the side structure was produced. This crushing behavior was also spotted on the deck collision which both the upper and lower parts were successfully penetrated. However, on the over deck-collision , remarkable damage on the upper structure was not produced in the end of collision. This result directly becomes a verification of the resultant force which is presented in Fig. 5. It is obtained from damage extent and displacement contour in Figs. 6 to 8 that there is no damage on the upper part of the struck ship in the end of collision. Tendency of the damage extent of the over deck-collision is different than other models which produced damage on the both parts of the struck ship. The energy in the over deck-collision was not significantly increasing as in the two first models since the crushing process of the side structure was only focused on the lower structure by the striking ship’s bulbous bow. Furthermore, due to geometric characteristics of the striking ship, a contact between the upper deck of the striking