Analysis of structural crashworthiness of double-hull ships in collision and grounding

A conceptual design framework for collision and grounding analysis is proposed to evaluate the crashworthiness of double-hull structures. This work attempts to simplify the input parameters needed for the analysis, which can be considered as a step towards a design-oriented procedure against collision and grounding. Four typical collision and grounding scenarios are considered: (1) side structure struck by a bulbous bow, (2) side structure struck by a straight bow, (3) bottom raking, (4) bottom stranding. The analyses of these scenarios are based on statistical data of striking ship dimensions, velocities, collision angles and locations, as well as seabed shapes and sizes, grounding depth and location. The evaluation of the damage extent considers the 50- and 90-percentile values from the statistics of collision and grounding accidents. The external dynamics and internal mechanics are combined to analyse systematically the ship structural damage and energy absorption under accidental loadings.     

大型船舶钨极氩弧重熔工艺应用

疲劳破坏是船体结构的主要破坏形式之一。改进结构节点的设计和施工工艺,可保证船体结构中受交变载荷作用的构件有足够的疲劳寿命。钨极氩弧(Tungsten Inert Gas, TIG)重熔是改善结构节点焊后疲劳强度的有效方法。与目前船上常用的几种改善疲劳强度的方法进行分析对比,对TIG重熔工艺的重要性进行充分论证,获得实施TIG重熔工艺的技术标准和操作要点。TIG重熔工艺不仅改善结构节点疲劳强度,而且为建造具有较长疲劳寿命的大型船舶找到一个行之有效的方法,可产生良好的经济和社会效益。     

A multiscale material-structure-hydroelasticity coupled analytical model for floating sandwich structures with hierarchical cores

A novel material-structure-hydroelasticity coupling analytical model is proposed for marine structures, which is utilized for the calculation and optimization of a very large floating sandwich structure (VLFSS) with a hierarchical ultrahigh-performance concrete (UHPC) core in this study. For the coupling material and structure analysis, three-dimensional representative volume element and self-consistent methods are developed to reveal the physical relations between the UHPC core's macroscale mechanical properties (e.g., modulus and density) and mesoscale hierarchical characteristics (e.g., aggregate and porosity) and to obtain the corresponding parameterized formulas. For the coupling material-structure-hydroelasticity analysis, a sixth-order dynamical equation for the potential flow model of the VLFSS, in which the hierarchical core's parameters are introduced through the material-structure coupling formulas, is developed. The hydroelasticity equations containing multiscale parameters are solved, and the mechanical responses are calculated. Using this coupled multiscale method, the shear force in the representative VLFSS is optimized for a smaller amplitude, which relies on the interactivity of the hierarchical structural parameters and wave conditions. These results demonstrate the potential of the multiscale coupling methodology to achieve the physically significant optimization of a floating composite structure in ocean engineering.     

Experimental study on seismic vibration control of an offshore wind turbine with TMD considering soil liquefaction effect

Wind energy is clean and sustainable. Taiwan is establishing offshore wind farms using wind turbines in the Taiwan Strait. However, these are located in an earthquake-prone area with sandy seabed conditions. To ensure their safety and reliability, the turbines’ support structure must be protected against wind, waves, and seismic loads. Tuned mass dampers (TMDs) are commonly employed to reduce structural vibrations. A TMD is more simply incorporated into turbine structures than are other energy dissipation devices. In this study, a 1:25-scale test model with a TMD was constructed and subjected to shaking table tests to experimentally simulate the dynamic behavior of a typical 5-MW wind turbine with a jacket-type support structure and pile foundation. The scaled-down wind turbine model has a nacelle without rotating blades; therefore, the aerodynamic and rotational effects due to the rotating blades were ignored in this study. A large laminar shear box filled with saturated sandy ground was used to simulate the typical seabed conditions of Taiwanese offshore wind farms. The TMD system was designed to be tuned the first-mode frequency of the test model. Two ground accelerations, selected by considering wind farm site condition and near-fault characteristics, were used for excitation in the test. The responses of the test model with and without the TMD system were compared, and the influence of soil liquefaction on the effectiveness of TMD vibration control was addressed.     

复杂载荷作用下船体板格屈曲强度计算公式研究

分析复杂载荷作用下船体板格结构屈曲强度的影响因素,基于ANSYS软件APDL模块参数化建模,对这些因素进行相关性分析,排除无关参数,保留有关参数,得到屈曲强度的定性表达式。然后变更有关参数,得到不同的有限元模型,通过计算得到不同模型下的屈曲强度,分析大量数据,最终得到屈曲强度的定量表达式。该公式可以在工程上用于复杂载荷作用下船体板格结构的屈曲评估,具有重要的实用价值。     

某型汽轮机超速脱扣试验浅析

某型汽轮机的超速保护装置采用脱扣结构,文章针对该汽轮机的超速脱扣结构进行分析,总结此种超速脱扣装置的装配要求和试验方法,以利于该型汽轮机的生产。     

水力式升船机单井塔柱内对拉钢索优化布置

单井型塔柱结构极大改善了水力式升船机竖井水位同步性问题,但随着提升高度增大,竖井内水深越大,侧壁位移、弯矩过大等问题更加突出.以150米级单井塔柱为例,提出了竖井内布置对拉钢索的设想和简化布置方案.基于钢索拉力权重分配系数的优化方法,取得了钢索等应力的密度分布最优解,并离散转化为等效的等荷载布置方案,可在实际工程中应用...     

大型集装箱船整船有限元分析计算技术研究

本文在研究大型集装箱船整船分析的基础上,总结研究和发展了二种集装箱船整船有限元分析时调整节点力和惯性平衡的处理方法.对于正确地进行大型集装箱船整船结构强度直接计算具有指导作用和实用价值.同时本文提出了对集装箱船整船结构强度分析的分工况计算和应力合成技术,可应用于集装箱船的整船结构有限元计算分析.     

钢箱筒基础结构应用优势及前景

钢箱筒基础结构是由桶形基础发展而来,桶形基础取代桩基作为海上采油平台基础在国内外获得成功应用。结合钢箱筒结构取代抛石基床作为码头和防波堤基础首次在工程中成功应用的实践,论述了钢箱筒结构特点和作用机理。钢箱筒结构具有加工制作快捷、浮运稳定、就位下沉简便、下沉上浮方便可兼作施工平台、后期沉降稳定等特点,拥有节约成本、缩短工期、保证质量等优势。钢箱筒结构在水运工程中尤其是渤海湾淤泥质海岸作为码头和防波堤结构基础拥有很好的应用前景。     

45#钢大厚度结构的焊接工艺

对中碳钢大厚度结构的焊接工艺流程的每个步骤都做了详尽的技术说明,通过对结构以及母材的可焊性分析,制定合理的焊接工艺措施,取得了满意的效果,可为类似的焊接作业提供借鉴。