Nonlinear Stochastic Extreme MDOF Motions Analysis for Design of Ships and Floating Offshore Platforms

船舶和海上浮动平台设计的非线性随机极端 MDOF 运动分析

• 批准号: 9908241
• 负责人: Jeffrey Falzarano
• 金额: $ 10万
• 依托单位: University of New Orleans
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-09-15 至 2002-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9908241&HistoricalAwards=false
• 关键词: Nonlinear; Stochastic; Extreme; MDOF; Motions

PI's Name, Institution Dr. Jeffrey M. Falzarano, University of New Orleans Proposal Number (# 9908241)Proposal Title Nonlinear Stochastic Extreme Multiple-Degrees of Freedom Motions Analysis for Design of Ships and Floating Offshore PlatformsProject Abstract This research project deals with the development of a dynamics based methodology to analyze very large amplitude ship/floating platform extreme motions in a realistic seaway. This technique focuses on determining the stable invariant manifolds which form the basin boundaries between the bounded (safe/non-capsize) and unbounded (unsafe/capsize) behavior of a given vessel in a realistic wave environment. The key to this methodology is a new dynamical perturbation technique which is currently being developed. This technique determines the time-varying solutions lying in the stable manifolds for general single degree of freedom ship/floating platform equations of motion which may include pseudo-random wave excitation. Another aspect of this project is the development of various decoupling which utilize nonlinear normal modes. These decoupling schemes yield the single degree of freedom equations of motion. Finally this approach will utilize the results of physical model tests or numerical time domain simulations in order to determine nonlinear and time-varying coefficients in the Integro-differential equations of motion. The general frequency dependent/time-varying nonlinear coefficients are determined using a technique which being developed under a related project. The proposed project builds upon the results of current, and previous deterministic investigations of vessel roll motion and platform tilt to consider realistic random environmental excitation, coupled dynamics and accurate physical modeling. This proposal will apply and refine recently developed techniques to analyze the global nonlinear dynamics of randomly forced systems, with nonlinear normal modes and reverse MI/SO nonlinear system identification. Random excitation, coupling and accurate physical modeling are areas which have not received adequate attention in previous transient global nonlinear dynamics studies. In this project, a number of techniques which are currently being developed, refined, extended and applied in order to improve the analysis methodology and evaluate the importance of various exact modeling and the possibility of simplified modeling schemes.

项目名称：船舶和海上浮式平台设计的非线性随机极端多自由度运动分析项目摘要：本研究项目涉及基于动力学的方法的发展，以分析现实航道中非常大幅度的船舶/浮式平台极端运动。该技术的重点是确定在现实波浪环境中给定船舶的有界（安全/非倾覆）和无界（不安全/倾覆）行为之间形成盆地边界的稳定不变流形。该方法的关键是目前正在开发的一种新的动态摄动技术。该方法确定了一般单自由度船舶/浮动平台运动方程稳定流形中的时变解，其中可能包含伪随机波激励。该项目的另一个方面是利用非线性正态模态的各种解耦的发展。这些解耦方案产生了单自由度运动方程。最后，该方法将利用物理模型试验或数值时域模拟的结果来确定运动积分微分方程中的非线性和时变系数。一般的频率相关/时变非线性系数是使用相关项目下正在开发的技术确定的。拟议的项目建立在当前和以前对船舶侧倾运动和平台倾斜的确定性研究结果的基础上，考虑了现实的随机环境激励、耦合动力学和精确的物理建模。本提案将应用和完善最近开发的技术来分析随机强迫系统的全局非线性动力学，具有非线性正态模态和反向MI/SO非线性系统识别。在以往的瞬态全局非线性动力学研究中，随机激励、耦合和精确的物理建模是没有得到足够重视的领域。在本项目中，目前正在开发、改进、扩展和应用的一些技术，以改进分析方法并评估各种精确建模的重要性和简化建模方案的可能性。