A phenomenological Wake Oscillator Model (WOM) is studied to capture the coupling effects between the fluid and the structure. The Vortex-Induced Vibration (VIV) phenomenon is modelled to describe the motion imposed by the lift forces on the structure. The influence of the aspect ratio parameter (L/D) was introduced into the model to characterize the VIV phenomenon for finite cylinders. The proposed model captured the basic features of the VIV such as the amplitude of vibration, frequency, and lift coefficient by coupling the structural equation to the wake equation. Predictions of the WOM are discussed and compared with the experimental data in order to establish a relationship describing VIV as a factor of aspect ratios.
School of Mechanical Engineering, University of Western Australia, Crawley, WA, Australia
School of Ocean Engineering, Universiti Malaysia Terengganu, Terengganu, Malaysia
Department of Mechanical Engineering, University of Maine, Orono, USA
Oil and gas transportation in subsea operation continues to the extreme depth. Harsh environment in deep water lead to a challenge for especially pipeline design. The pipelines are operated at high pressure and high temperature in order to be able to transport the crude oil from the well to the end termination of loading. Such condition, the pipelines are subjected to axial compressive forces which will cause the pipelines to expand, consequently the pipelines tend to buckle for certain size and distance from the initial of pipeline. The sleeper is one of method to control the pipeline expansion by insertion of bar underneath the pipeline. The sleeper results initial imperfection for pipeline which forms a curvature. The magnitude of curvature is designed comply with DNV OS F101 where the design load will accommodate the combination load works on pipeline and the curvature configuration will validate by using ANSYS 14.
Department of Aeronautics, Automotive and Ocean Engineering,Mechanical Engineering, Universiti Teknologi Malaysia, Malaysia
One of reinforcement bar treatment during delivery transportation is to bend up or buckle in the middle of the bar. This treatment will undermine the strength of the reinforcement bar on buckle region due to its mechanical properties have been changed and no longer within specification. An important point of this study is to knowing the rate of change of mechanical properties, especially strength. Concrete reinforcing steels are bent with nine variations of the bending angle starting from the angle ( α ) of 20o , 40o , 60o , 80o , 100o , 120o , 140o , 160o , and 180o. The data obtained indicated that the yield strength and ultimate tensile strength increases and decreasing the ductility. The increasing percentage of the yield strength is 14% and the tensile strength is 7%. The maximum decreased elongation is 13.42% (α = 180º) from 24.67% (α = 0º) and the reduction of area is decreasing 1.93 %.
Teknik Mesin - Universitas Riau, Kampus Bina Widya Panam 28293 Pekanbaru, Riau Indonesia.
The oil and gas exploration and production activities in deep sea are now on a steady increase globally. Therefore, it is necessary to design a cost effective and safe system for these operations. The main objective of this research is to design a Floating Production, Storage and Offloading (FPSO) vessel suitable for operation even in extreme meteorological and oceanographic conditions. In order to achieve this, the effects of extreme environmental loads on the vessel have been evaluated in terms of the maximum responses in surge, heave and pitch modes of motion. Furthermore, an interactive programme, the Principal Dimensions Programme (PD Prog) has been designed to accurately evaluate and optimise the principal particulars based on the required storage capacity and response analyses. Results show that the vessel length, which is directly proportional to the cube root of the cubic number (the overall volume), is a measure of the critical wavelength. Close to the critical wavelength in extreme metocean condition, the vessel could be subjected to several billions Newton meter of Wave Bending Moment. This design technique, in addition to the numerous useful data obtained, helps to ensure good performance during operation and so reduces downtime, and increases uptime, safety and operability of the vessel even under extreme metocean conditions.
Department of Naval Architecture, Ocean and Marine Engineering, University of Strathclyde, Glasgow, United Kingdom.