摘要
本文运用Thompson等提出的“安全池破损（safebasinerosion）”理论研究不规则波浪作用下的船舶倾覆问题。安全池表征在外载荷的作用下，船舶经历足够长时间后不发生倾覆的初始条件范围。随着外载荷强度的变化，安全池的特性，包括安全池的面积和形状，将逐渐变化。但最重要的是，当外载荷强度超过某一阈值后，安全地会发生急剧的变化：其边界将具有分形的特点，安全池的而积也将急剧减小。这就是所谓的“安全池破损”现象。Thompson等发展了船舶在规则波作用下的安全池破损理论，其工作的意义在于，由于新发现的“安全池破损”现象，我们将不得不重新认识船舶倾覆的机理。由于“安全地破损”现象，当外载荷的强度超过某阈值时，船舶实际上已经处于危险区。通常，这些阈值往往远小于根据常规方法所确定的倾覆条件。本文运用安全池破损理论研究了由两个正弦波组成的波群和随机波作用下的船舶横摇。从中我们会看到规则波和不规则波作用下的安全池特性。我们希望本文的工作对船舶倾覆判据的确定能有所帮助。
In this paper we examine ship capsize under irregular wave excitation by means of the socalled 'safe basin' of this ship according to Thompson's proposal. With the changing of external excilation, the properties of safebasin would change gradually too. And finally, when the parameters of external excitation, such as amplitude and angUlar velocity of external wave, excess a certain threshold, some dramatic change would haPPen, the boundary of safe basin would be fractal and its area would decrease rapidly too.This is so-called' safe basin erosion' phenomenon. Thompson developed theory of ship's safe basin erosion under regular wave excitation, the sighficance of his work means our former understanding of mechanism Of ship capsize must be recon sidered completely. Because of safe basin erosinon phenomenon, a ship must be considered as unsafe when the parameters of external excitation excess the thresholds, which are usually a small fraction of safe conditions according to traditional understanding. In this paper, we will use the theory of safe basin to examine ship's rolling under waves composed of two sinusoidal wave and irregular wave.Significant difference between safe basin under regUlar and irmgular excitahon would be demonstrated. We hope our research would be helpful for deciding the criterion of ship's capsize which is left for further research.
出处
《船舶力学》
EI
1999年第5期7-14,共8页
Journal of Ship Mechanics
