Wisnu Wardhana

Strength Analysis and Sea-Fastening Design of Container Crane Structure for Heavy Lifting Sea Transportation

This paper discusses heavy-lifting sea-transportation of 831-ton container-crane in Indonesia from Surabaya to Kupang. Structural strength analysis is carried out to ensure the safety of the crane during the transportation process. The purpose of this analysis is to design the sea-fastening construction capable of redistributing the excessive stress that might occurred, to avoid structural failure. The first step is to model the crane structure and barge under certain various drafts. This is important because selection of the proper draft will determine the suitable righting moments of barge and hence to ensure good stability. The selected drafts under investigation are taken between 0.25 T to 0.75 T. The result of the structural strength calculation shows that the static load is found around 8150 kN. Loads due to motion of barge for heave, roll, and pitch motions are 116 kN, 7424 kN, and 232kN, respectively. Location of the high stress due to the motion is identified at the bottom of the crane structure so that the design of sea-fastening constructions will be concentrated in the vicinity of this position. The values of Unity Check after fitting the sea-fastening construction are reduced to 0.940, 0.704, and 0.702, respectively. It is concluded that the structure of container crane under such sea-fastening design is proven to be capable of overcoming the loads during transportation process.

Vibration Analysis on the Dog Leg Subsea Pipeline due to Internal Fluid Flow

Internal fluid flow can affect a vibration on the dog leg subsea pipeline due to bend in the pipe structure. This study was done by varying fluid speeds which flows inside of piping system to obtain a pipe safety limitation due to internal flow. The results showed that the vibration occurred in the piping is still within safety tolerance, and distribution of maximum stress occurred at 900 bend. Therefore, it was recommended to add the buffer support installed in the middle of span to reduce amplitude at the longest segment.

Measurement of propeller-induced cavitation noise for ship identification

Acoustic cavitation noise caused by propeller is used in many underwater applications as one of the ships noise signatures. This paper reports characterization process done by measuring the cavitation noise generated by a propeller in a cavitation tunnel. The cavitation tunnel used for the measurement is of the K16B type belonging to the Indonesian Hydrodynamic Laboratory, Surabaya, Indonesia. The experiment is done using a B-series four-blade bronze propeller (diameter 23cm) using a hydrophone placed in the tunnel at window section (60x90)cm2 of the measurement section (400x85x85)cm3. Some of the solutions to get accurate and reliable measurement results include calibration measurement and minimizing acoustic noise system and environment. Preliminary process has been done to analyse the characteristics of the measurement results in the time-frequency domain, with the objective being to detect when and which type of cavitation noise occurs in any kind of condition. Measurement outcomes in the form of acou...