基于非线性有限元法的船舶冰区破冰数值模拟（英文）

应用非线性有限元法进行了破冰船冰区破冰数值模拟。通过比较数值模拟结果和试验结果,对冰体材料模型进行了验证;采用该冰体材料模型,对破冰船以不同航速在不同厚度的层冰中破冰航行时的动态响应进行了数值研究,给出了破冰过程中层冰的变形、冰力的大小以及冰的变形能和动能变化,分析了船速、冰层厚度对破冰阻力的影响。该研究结果对分析破冰船在层冰中破冰时的动态响应特性具有一定的参考价值。     

破冰船冲撞式破冰模拟及结构损伤分析

提出一种适用于船冰碰撞的海冰材料模型。基于该材料模型,通过非线性有限元模拟冰台撞击刚性墙,验证该模型的正确性,并成功将其运用于某PC3冰级破冰船冲撞式破冰过程数值模拟中。研究破冰船冲撞不同厚度层冰的动响应结果,总结船冰相互作用过程中碰撞力和能量的变化、船体结构损伤特性和破冰能力,研究成果可为破冰船结构设计提供参考。     

某型极地破冰船的艏部线型优化

极地破冰船首部线型的优化设计,既需要考虑在冰区作业时的破冰能力,又要兼顾其在敞水域中的航行性能.该文基于不同的冰阻力预报经验公式,对冰阻力和破冰船首部特征参数进行敏感性分析,提出破冰性能较佳的首部特征参数取值范围,并兼顾敞水域阻力性能进行首部线型优化.经过敞水域中的模型阻力试验验证和冰区中的阻力数值模拟验证,优化方案在敞水域中设计航速附近的阻力增加约2％,但在不同层冰厚度下、破冰航速时的冰阻力下降7％～12％.     

基于SPH方法的连续式破冰数值模拟

根据海冰的力学性质,采用光滑粒子流体动力学(SPH)方法建立海冰本构模型,模拟冰锥实验并与实验结果对比,对冰材料模型准确性进行验证.利用显式动力分析软件LS-DYNA模拟破冰船连续式破冰,得到了海冰的损伤变形和破冰阻力,同时研究了船舶航速和海冰厚度等参数对冰载荷的影响.分析研究表明:应用SPH方法建立的海冰模型能够真实的反映海冰的力学性能,对连续式破冰过程实现较为准确的模拟,为船冰碰撞的数值模拟提供了新思路.     

冰载荷的特性研究

应用六自由度数值模型对某破冰船的连续式破冰过程进行数值模拟,得到其冰载荷的时历,并将其与试验结果进行比较,验证该方法的正确性,同时分析冰载荷动态性变化的原因。通过计算得到破冰船在不同速度及冰厚条件下的冰载荷和运动响应,以及航速与船舶冰载荷之间的关系。     

破冰船冲破冰层的有限元数值仿真研究

基于＂冲撞式＂破冰法以及有限元仿真法的原理,利用MSC.Patran/Dytran软件进行冰载荷的数值模拟,研究模拟破冰船冲撞冰层的过程中的关键技术,分析确定适合于本文所用的研究方案,对整个破冰过程中冰层的变化过程进行分析,并通过对比不同的冲撞速度、撞击角度以及冰层厚度,研究这些参数的不同对破冰船破冰能力的影响。     

基于数值仿真与经验公式的船舶破冰阻力预报

首先选取并验证合适的冰材料模型,通过建立冰排与破冰船有限元模型,应用非线性显式动力学软件Ls-dyna对破冰船在不同冰厚、不同船速条件下的连续式破冰过程进行数值模拟,并将不同冰况下仿真结果和经验公式计算得到的冰力值做对比研究。最后对各个经验公式中的主要参数进行敏感性分析,得出各个参数对冰阻力计算的影响差异程度,对冰阻力估算和船体结构设计具有重要参考价值。     

连续破冰模式下极地破冰船艏部冰载荷计算方法研究

极地破冰船在破冰过程中的冰载荷预报是破冰船设计过程中亟待解决的问题。论文根据能量守恒原理提出了连续破冰模式下冰载荷的分析方法;运用非线性有限元软件模拟破冰船的连续破冰过程,获得不同冰厚和不同船速下的船艏碰撞力时历曲线。通过理论计算及数值仿真结果的对比分析,证实作者提出的连续式冰载荷理论计算公式和数值仿真方法的可行性。计算方法及计算结果对于破冰船结构设计具有重要的参考价值。     

船-冰碰撞下冰材料有限元数值方法研究进展

浮冰碰撞下极地船舶结构响应研究是当今的热点话题.由于冰体是一种包含着固体冰、卤水、气体以及杂质等较为复杂的天然复合材料,其力学性质受盐分、杂质等成分含量,以及温度、应变率和形成年份等因素影响较大,开发准确有效的冰体材料本构模型以及有限元数值模拟方法是船-冰相互作用研究的关键难点问题.本文总结了几种常见的冰体有限元数值材料模型,如各向同性弹性失效材料模型、弹塑性材料模型、损伤材料模型以及可压碎泡沫型材料模型等;此外,选取了三种模型实验工况,开展了与实验场景相对应的不同冰材料模型下有限元数值模拟,对比分析了各自冰材料模型的特点以及应用局限;最后,总结了用于船-冰碰撞数值模拟的冰材料模型准确性和可行性评估方法,以便给今后所开发的冰材料数值模型提供验证手段.     

不同船艏类型破冰模式差异的数值预报分析

船艏形状是决定破冰船破冰性能的关键要素之一.为了探究不同船艏型线特征对破冰船破冰性能的影响,本文采用常规型近场动力学方法建立了平整冰层的无网格数值模型,提出了一种基于几何数学概念用于解决冰粒子与船体碰撞问题的接触检测算法,最后应用消息传递接口(MPI)并行技术搭建了破冰船破冰过程的数值预报方法,并在FORTRAN语言环境下编写了相关计算程序.基于该仿真程序,分别预报了传统型破冰船艏形状和非传统型破冰船艏形状连续冲破平整冰层的过程,并对传统型破冰船艏的计算结果与试验结果进行了比较,验证了本文所搭建的模型的准确性.对比了两种不同船艏破冰船的破冰模式和破冰载荷特征,分析了两种破冰船艏形状各自的优缺点.本文进行的研究对于破冰船的设计具有一定的工程参考价值.     

Numerical Simulation of Turret Moored Ship Performance in Variable Ice Drift Based on Heading Control

The frequent change in ice drift direction poses a significant challenge for turret moored ship in ice. Variability in ice drift is mainly caused by the winds and currents. To solve this problem, a new method with numerical simulation based on heading control is applied to reduce the risk of operation of The Arctic Tandem Offloading Terminal(ATOT),which includes an offloading icebreaker(OIB) moored to a submerged turret and a shuttle tanker moored at the stern of the OIB in this paper. An icebreaking tanker, MT Uikku, was modeled in a simulation program. Then the level ice load on the tanker was calculated with different ice thicknesses and drift speeds, after which a heading controller assisted with mooring system is used to simulate the horizontal motion of the tanker under the ice action.     

考虑流场影响下破冰船艏部结构响应研究

通常考虑船-冰碰撞附连水的水动力效应有附加质量法和流固耦合法。本文建立了破冰船破冰场景,基于流固耦合法进行了数值仿真计算,分析了水域流场对船体的冲击压力变化、流场的速度分布变化以及流场的动能变化。同时与附加质量法的计算结果进行了比较,对比分析了船艏的碰撞力大小、损伤变形以及局部冰载荷等差异,揭示了流场对船-冰碰撞的影响规律,对于破冰船结构设计具有重要的参考价值。     

Numerical study of ice-induced loads on ship hulls

A numerical model is introduced in this paper to investigate both global and local ice loads on ship hulls. This model is partly based on empirical data, by which the observed phenomena of continuous icebreaking can be well reproduced. In the simulation of a full-scale icebreaking trial, the interdependence between the ice load and the ship’s motion is considered, and the three degree-of-freedom rigid body equations of surge, sway and yaw are solved by numerical integration. The variations in the level ice thickness and in the strength properties of ice can also be taken into account. The simulated ice loads on ship hulls are discussed through two case studies, in which the ship’s performance, the statistics of ice-induced frame loads, and the spatial distribution of ice loads around the hull are analyzed and compared with field measurements. As far as we know the present paper is the first to integrate all the features above. It is hoped that further studies on this numerical model can supplement the field and laboratory measurements in establishing a design basis for the ice-going ships especially for ships navigating in the first-year ice.     

Dilated-polyhedron-based DEM analysis of the ice resistance on ship hulls in escort operations in level ice

The ice resistance on ships in escort operations in level ice are investigated using the discrete element method (DEM). A dilated polyhedron—generated by the Minkowski sum of a sphere and a polyhedron—is employed in the DEM; this dilated polyhedron-based DEM (DPDEM) is adopted to simulate the ship–ice interaction, wherein the contact force and bond-failure criterion are considered for the collision and fracture of sea ice, respectively. A three-point bending test was simulated with DPDEM, and a field test was conducted in the Bohai Sea to validate the DEM results. Further, a parametric analysis of flexural strength was conducted to identify the parameters involved in the bond-failure criterion. The ice resistance on icebreakers and cargo ships in level ice are simulated using DPDEM. The simulated ice resistances are compared with the Lindqvist and Riska formulas and the model test, which proves the validity of the DEM simulation. The interaction between ships and level ice is simulated parametrically to investigate the ice resistance on cargo ships with and without the icebreaker escort. Influencing factors such as ship speed, ice thickness, and ship breadth were examined to investigate the ice resistance on the escorted cargo ship. Analysis and change rules of the ice resistance on cargos affected by those factors were given.     

破冰船冲撞式破冰结构强度数值仿真方法研究

本文基于瞬态动力学分析法对破冰船冲撞式破冰过程进行有限元数值仿真研究.针对该方法中的船冰撞击分析、海冰浮力模拟等一些关键问题进行研究,根据上述方法对某破冰船冲撞式破冰过程进行数值模拟,并对应力计算结果进行校核.总之,本文建立的一套评价破冰船冲撞式破冰过程船体应力方法,对于中国老龄破冰船的强度评估具有重要意义.     

Numerical Study of the Ice Breaking Resistance of the Icebreaker in the Yellow River Through Smoothed-Particle Hydrodynamics

A ship–ice–water interaction model is established using smoothed-particle hydrodynamics (SPH) to predict the ice breaking resistance of the icebreaker in the Ye...     

Ice impact response and energy dissipation characteristics of PVC foam core sandwich plates: Experimental and numerical study

In this paper, the dynamic responses and energy dissipation characteristics of polyvinyl chloride (PVC) foam core sandwich plates under ice impact are investigated. The ice impact tests of PVC foam core sandwich plates were conducted by employing the horizontal impact experimental apparatus. The finite element simulations were conducted to analyze the dynamic response of PVC foam core sandwich plates based on soil and concrete material model for ice impactor. It was demonstrated that numerical results were in good agreement with experimental results. The deformation modes of the top facesheets were coupling of local indentation with global bending deformation, while the deformation modes of bottom facesheets were overall bending deformation. The permanent deformation of face sheets show that the impact resistance of sandwich plate is better than that of equivalent weight hull plate (EWHP). In addition, based on the actual navigation environment of ship, the effect of impact angle and ice floe shape on dynamic response and energy dissipation are analyzed.