A Method of Dynamic Response Analysis Based on Laplace Transform for Fully Symmetric Floating Platform
- Ruimin Wang (Ocean University of China) | Zhenqiang Jiang (Powerchina Huadong Engineering Corporation Limited) | Zhe Tian (Ocean University of China) | Hongchao Lu (Ocean University of China) | Xujie Wang (Ocean University of China) | Fushun Liu (Ocean University of China)
- Document ID
- International Society of Offshore and Polar Engineers
- The 29th International Ocean and Polar Engineering Conference, 16-21 June, Honolulu, Hawaii, USA
- Publication Date
- Document Type
- Conference Paper
- 2019. International Society of Offshore and Polar Engineers
- transfer function, Laplace transform, complex exponential decomposition, floating platform, dynamic response
- 3 in the last 30 days
- 12 since 2007
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Dynamic response analysis is becoming an essential part in the stage of structural design and is significant to the safe operation of floating platforms during the service life. In this paper, a method of dynamic response analysis for fully symmetric floating platforms is proposed, which is based on Laplace transform and complex exponential decomposition. Two numerical examples are used to investigate the performance of the proposed method. Compared with the traditional New-mark-β method, the proposed method is more efficient.
With the increase of population and the development of the society, the demand for resources is rising sharply. As a result of the extensive exploitation and consumption of land resources, people turned their attention to the vast ocean which contains abundant resources including petroleum, mineral and marine wind energy. Gradually, the coastal countries of the world have been engaged in the development of marine energy, and the design and use of platforms is an essential part closely related to oil exploitation. As oil production is moving from shallow water to deep-sea, traditional fixed jacket platforms are no longer suitable, which leads to the application of many floating platforms. However, considering the severe environment in deep waters, floating platforms may be destroyed easily, causing significant loss of life and property. Therefore, it is vital to carry out the analysis of dynamic response at the design stage to improve the service performance of floating platforms.
The time domain method can be used to obtain the dynamic response of floating platforms by solving the differential equations of motion in time domain by using a numerical approach. When the time domain method is adopted, all the matrices of the differential equation of motion are required to be known. Oglivie (1964) found that the retardation function can be obtained by the cosine transform when the hydrodynamic parameters are known.
The first order potential theory method can be used to analyze the dynamic response of floating structures depending on assumption of Gaussian process in frequency domain(Newman, 1997; Faltinsen, 1990; Faltinsen, 2005). The well-established theory for Gaussian process is used to obtain the response statistics. The method based on the linear theory suggests that the step of the wave is small, and the response due to the wave excitation is proportional to the wave amplitude (Faltinsen, 2005).
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