Use to check the ship stability while launch from a platform at certain angle

Created on 2020.06.19 236 views
A ship’s launching is one of the important processes representing the beginning of a ship’s life in water. The launching operation is a vital process since the launching stage is a time consuming process, as well as involves high costs . A successful launching floats the ship safely on the water in an equilibrium condition. Basically, there are two kinds of ship launching which are commonly practised ; the longitudinal or the side ship launching . In restricted waters such canals and rivers which are associated with less longitudinal strength for the ship [4], the side launching is normally chosen instead of the longitudinal method. The ship side launching is a hectic and dynamic process as it also involves six degrees-of-freedom of a ship’s motion responses, as well as the process of putting the ship into the water. Ye presented a theoretical solution in the form of a numerical method in which the motion of a side launching ship is set to three degrees-of-freedoms . The ship side launching method is vulnerable to some serious risks as reported by Hak , such as structural damages or capsizing due to abrupt heeling once the ship falls into the water. By applying the gravitational concept, a ship commences to slide down the platform and launches into water. When ship falls into the water, she returns to an upright Fitriadhy and Malek / Journal of Mechanical Engineering and Sciences position after experiencing instability which is caused predominantly by her rolling motions. Conceptually, the ship side launching method has two different launching ways; the first way is by launching the ship by sliding it into the water, while the second method is by sliding the ship on a platform so that it inherently falls into the water. To ensure a safe launching process, therefore, a comprehensive study on the ship side launching method is necessary to avoid the aforementioned serious risks. In this paper, the authors propose a ship side launching analysis by applying the second method using the Eulerian and Langrangian approach. The commercial ABAQUS software 2018 version is used to do the analysis. Several parameters such as various inclination angles 16.7° and lengths of sliding platforms with respect to the ship's length (d/L) were taken into consideration to identify the ship’s launching performance. Some probes were placed in the computational domain to measure the maximum free surface water elevation (water splashing) as the ship falls into the water. The parametric studies put forward here are aimed at providing an insight into their dependencies on the tipping time during launching. In addition, the maximum value of Under Keel Clearance (UKC) and the characteristics of the ship’s motions responses i.e., roll and heave motions are presented in the simulation results. With regards to the results, this work will provide a prominent insight into a more realistic model of the ship side launching simulation compared to the empirical approach. Due to the insufficient number of published manuscripts discussing the ship side launching simulation, we do hope that the current paper would become a valuable literature reference in the future.
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