Sustainability studies will support the development of drillship design. One primary aspect to be explored during the design stageis the global structural responses due to the excitation of head sea waves. This paper presents the global structural response analysis by implementing the so called quasi-static approach and the effect for ultimate strength. In this respect, a motion analysis should be first carried out to obtain the coupled heave and pitch motion data for a range of regular wave frequency.The next step is performing the quasi-static computation for a number of wave frequencies, where the magnitudes of heave and pitch motions are considered important. After accomplishing RAO of shear force and bending moment calculation, further analysis is obtained the extreme global structural responses by implementing the spectral approach. It will be inputed to Global Finite Element Model (FEM) to get the ultimate condition of drillship material. Final results of the global analysis indicates the ultimate condition is exceeded on 12 meter wave height by the Structural Stress output of 585 Mpa.
Marine Technology Post-Graduate Program, Institut Teknologi Sepuluh Nopember(ITS), Surabaya, Indonesia
Department Of Ocean Engineering, Institut Teknologi Sepuluh Nopember (ITS), Surabaya, Indonesia
Wave response motion and dynamic stability of the new generation Round Shaped FPSO structure in ocean environments is required to be investigated properly to ensure the safety and the operability of this new proposed model. The main objective of this research is to predict the wave induced motion response of the designed Round Shaped FPSO. In this study, the motion response of the Round Shaped FPSO is simulated by diffraction potential theory with Morison heave damping correction method. To ensure the validity of the simulated results, wave tank experiment in the model scale 1:110 was conducted. Upon completed the experiment, the time series data are converted by fast Fourier Transformation method to obtain the response amplitude, RAO of Round Shaped FPSO in 6 degree of freedom measured in the experiment. In the comparison, both the experimental result and numerical result are agreed between each other in this research. Based on the simulation results, it is observed that wave response characteristic and the dynamic stability of the Round Shaped FPSO is good in most of the ocean environment.
Department of Aeronautics, Automotive and Ocean Engineering, Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, Malaysia
Ocean and Aerospace Research Institute, Indonesia
Department of Transportation and Environmental Systems, Hiroshima University, Japan
National Research Institute of Fisheries Engineering (NRIFE), Japan
Centre for Marine Technology and Engineering (CENTEC), Instituto Superior Técnico, Universidade de Lisboa, Portugal
Department of Materials, Manufacturing and Industrial Engineering, Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, Malaysia
Exposure to environmental conditions at sea for a floating structure is inevitable. Environmental conditions that wave forces are the most important of them have a big impact on floating structures as well. Due to the nature of semi-submersible Platforms that they are exposed to the wave forces, therefore minimizing of tension force in mooring lines and choosing an appropriate mooring system always has been discussed. This article investigate the tension force on mooring lines of a semi-submersible platform when that it has been exposure to 0, 45 and 90 degrees of sea wave direction with the environmental conditions of the Caspian Sea with using Flow-3d (version10.0.1) software. Also the seven symmetric mooring systems in the form of 4 and 8 numbers of mooring lines’ systems have been used to choosing the best modes.
Department of Ocean Engineering, Amirkabir University of Technology, Tehran, Iran
Department of Marine Sciences and Technology, Science and Research Branch, Islamic Azad University, Tehran, Iran
Department of Ocean Engineering, Khalij-e Fars University, Bushehr, Iran