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

派的名字，机构，杰弗里·M·法尔扎拉诺博士，新奥尔良大学提案编号(#9908241)提案标题船舶和浮动离岸平台设计的非线性随机极端多自由度运动分析项目摘要这项研究项目致力于开发一种基于动力学的方法来分析现实海浪中极大幅度的船舶/浮动平台极端运动。这项技术的重点是确定稳定的不变流形，这些流形形成了给定船舶在现实波浪环境中有界(安全/不倾覆)和无界(不安全/倾覆)行为之间的盆地边界。这一方法的关键是目前正在开发的一种新的动力学微扰技术。该方法确定了一般单自由度船舶/浮式平台运动方程的稳定流形上的时变解，其中可能包含伪随机波浪激励。该项目的另一个方面是开发利用非线性简正模的各种解耦方法。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-微分方程组中的非线性和时变系数。一般的频率相关/时变非线性系数是利用相关项目正在开发的技术来确定的。建议的项目建立在当前和以前关于船舶横摇运动和平台倾斜的确定性调查结果的基础上，以考虑现实的随机环境激励、耦合动力学和精确的物理模型。这一建议将应用和改进最近发展的技术来分析随机强迫系统的全局非线性动力学，包括非线性正态模式和逆MI/SO非线性系统辨识。在以往的暂态全局非线性动力学研究中，随机激励、耦合和精确的物理模型是没有得到足够重视的领域。在这个项目中，目前正在开发、改进、推广和应用一些技术，以改进分析方法，评估各种精确建模的重要性和简化建模方案的可能性。

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.