大型船舶轴系校中的非参数建模及安全状态评估方法研究

During the navigation of large ships, the propulsion shafting is affected by many dynamic factors, such as hull deformation, propeller hydrodynamics, bearing oil film, etc. The influence of these dynamic factors is largely ignored in the calculation of the former ship propulsion shafting. Yet recent studies have shown that the impact of these dynamic factors often results in the strong uncertainty of actual alignment state in the propulsion shafting of large ships, and it is difficult to establish accurate alignment calculation models and cannot obtain a uniform description of the model based on a single method. This leads to large errors between the existing calculation results and the actual ship test results and cannot accurately guide the design and installation of the propulsion shafting. Therefore, for this project the nonparametric modeling method is introduced into the alignment modeling of propulsion shafting, and the data uncertainty and model uncertainty is included in the alignment model. Based on the vibration response, the attractor theory is used to put forward the concept of the alignment attractor of the propulsion shafting, investigate the nonlinear dynamic behavior of the propulsion shafting, reveal the evolution mechanism of the uncertainty state in the propulsion shafting alignment, and establish the evaluation methods of the security state in the propulsion shafting alignment. Finally, the nonparametric modeling and security state evaluation are achieved in the propulsion shafting alignment of large scale ships. All these results have very important academic significance and engineering application value to guide the design and installation of propulsion shafting in the large scale ship, ensure the work reliability of the propulsion shafting and then improve the navigation performance of large scale ships.

大型船舶航行过程中，轴系会受到诸多动态因素的影响，如船体变形、螺旋桨水动力、轴承油膜等。在以往的船舶轴系校中计算中，大都忽略这些动态因素的影响。然而近年的研究表明，这些动态因素的影响往往造成大型船舶轴系的实际校中状态具有较强的不确定性，难以建立准确的校中计算模型，也无法基于单一方法得到模型的统一描述，导致校中计算结果与实船测试结果误差较大，很难准确指导轴系的设计与安装。为此，本项目拟引入非参数建模方法，将数据不确定性与模型不确定性包含在校中模型中；基于振动响应，引入吸引子理论提出轴系校中吸引子的概念，研究轴系的非线性动力学行为，揭示轴系校中不确定性状态的演化机制，建立轴系校中安全状态的评估方法，实现大型船舶轴系校中的非参数建模与安全状态评估。研究结果对指导大型船舶轴系的设计与安装、保证轴系工作的可靠性、进而提高船舶航行性能均具有十分重要的学术意义和工程应用价值。

在船舶航行过程中，船体变形、螺旋桨水动力及轴承油膜等动态因素的影响往往造成船舶推进轴系的实际校中状态具有较强的不确定性。因此，面对风、浪、流变化莫测的海洋环境下大型船舶推进轴系校中不确定性的描述是亟待重点研究的科学问题之一。本项目采用理论计算和试验相结合的方法，分析了动态因素对船舶推进轴系振动响应的影响，基于非参数方法和吸引子理论研究了船舶推进轴系的动力学建模与安全状态评估方法。理论研究包括：引入非参数方法建立了考虑数据不确定性和模型不确定性的船舶推进轴系的动力学建模，进行了振动响应数值计算，分析了不确定性下船舶推进轴系振动响应的变化规律。试验研究包括：基于船舶推进轴系校中模拟试验台和滑动轴承实验台开发了船舶推进轴系试验系统，进行了船舶推进轴系校中模拟试验；基于相空间重构和吸引子理论建立了振动信号的非线性特征提取方法，获得了船舶推进轴系吸引子，分析了不确定性下轴系校中状态的演化机制，掌握了吸引子与轴系校中状态的关系，证实了基于吸引子评估船舶推进轴系校中状态的有效性。