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Delay function-based frequency-domain response algorithm of marine floating structure

A delay function and floating structure technology, applied in complex mathematical operations and other directions, can solve problems such as the inability to obtain hydrodynamic coefficient solutions, and achieve the effect of good engineering application prospects, wide application scope, and avoidance of periodic assumptions.

Inactive Publication Date: 2018-02-16
OCEAN UNIV OF CHINA
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Problems solved by technology

At present, there is no algorithm to express the delay function in the Laplace domain to solve the motion response in the frequency domain, mainly because, on the one hand, in the traditional frequency domain motion response calculation method, the hydrodynamic parameters including additional mass and additional damping are generally obtained through the three-dimensional potential flow theory Obtained, its value changes with the wave frequency, and the solution of the hydrodynamic coefficient in the Laplace domain cannot be obtained; in addition, for the external load in the frequency domain, the traditional frequency domain method generally uses Fast Fourier Transform (FFT), but FFT requires Certain preconditions that the load is infinitely long or periodic

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  • Delay function-based frequency-domain response algorithm of marine floating structure
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  • Delay function-based frequency-domain response algorithm of marine floating structure

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[0059] In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

[0060] Doing Laplace transform on both sides of the Cummins motion equation, we can get:

[0061] the s 2 [M+A(∞)]X(s)+sK(s)X(s)+CX(s)=F exc (s)

[0062] In the formula, M is the mass matrix of the structure, A(∞) is the result of the additional mass matrix when the frequency tends to infinity, K(s) is the expression of the delay function in the Laplace domain, and C is the hydrostatic restoring force matrix of the structure ; X(s), F(s) are the Laplace transform results of the dynamic response X(t) and the original external load F(t), respectively. It can be seen from the background technology t...

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Abstract

The present invention relates to the technical field of dynamic response analysis of marine floating structures, in particular to a frequency-domain response algorithm for marine floating structures based on a delay function, comprising the following steps, S1. Decomposing the delay function in the Cummins equation of motion into a complex exponential, and solving The expression of the delay function in the Laplace domain; S2. Solve the expression of the transfer function in the Cummins motion equation in the Laplace domain; S3. Perform complex exponential decomposition of the external load in the Cummins motion equation, and solve the external load in the Laplace domain The expression of ; S4. Calculating the frequency domain motion response. The algorithm uses the complex exponential decomposition technique to express the delay function item in the time domain equation as a complex exponential form of extremum and residue, and then obtains the expression of the delay function in the Laplace domain, using the transfer function in the Laplace domain as a bridge, and The frequency domain motion response of the structure is obtained by solving the frequency domain load action; for the solution of the frequency domain load, this method uses the complex exponential decomposition technology instead of FFT, which overcomes the deficiency that the external load needs to be based on the assumption of periodic harmonics, making the periodic load a A special case of this method.

Description

technical field [0001] The invention relates to the technical field of dynamic response analysis of marine floating structures, in particular to a delay function-based frequency domain response algorithm for marine floating structures. Background technique [0002] Cummins proposed the famous Cummins equation in 1962, which is the time-domain motion equation of the floating structure. He assumed that the motion of the floating structure is a linear combination of a series of impulse responses, and then decomposed the velocity potential into instantaneous effects and memory effects and respectively solve. In 1964, Ogilvie transferred the Cummins equations of motion in the time domain to the frequency domain. Research on hydrodynamic analysis in the three-dimensional frequency domain mainly focuses on the Havelock source method and the Rankine source method. The basic idea is that the point sources (sinks) distributed on the wet surface of the floating body satisfy the Laplac...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F17/15G06F17/11G06F17/16
CPCG06F17/15G06F17/11G06F17/16
Inventor 刘福顺陈杰峰卢洪超刘程程金磊齐聪山崔高杰高树健来庆昊王睿敏刘丽
Owner OCEAN UNIV OF CHINA
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