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使用ABAQUS中内嵌的声 - 固耦合法计算了圆板模型遭受水下冲击波载荷作用的响应,并将计算结果与实验值进行比较,数值结果与实验值吻合良好,验证了声 - 固耦合法模拟水下爆炸的准确性;对铝合金圆板和钢板进行了比较,考虑了结构质量,材料应变率和屈服极限,药量和爆距的影响;建立了1艘小型铝合金艇的有限元模型,使用同样的方法分析了铝合金艇遭受水下冲击波载荷的动力响应特性.得出了铝合金艇典型位置的加速度、速度和位移等响应量的时间历程曲线.此外,还得出了塑性变形区域和塑性变形曲线.这些计算结果对铝合金舰艇的抗冲击特性具有一定参考价值. 相似文献
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以水下非接触爆炸环境为研究背景,在论述隔冲原理及粘弹性材料力学特性的基础上,分析了粘弹性复合材料隔冲结构的各种非线性因素。根据物理样机的实际工况,建立了粘弹性复合材料隔冲结构的有限元模型,通过仿真计算,得到了瞬态激励条件下隔冲结构的动力衰减曲线。在此基础上完成了摄像机的抗冲击结构设计,并进行了实验室验证,满足了爆炸试验对摄像机的抗冲击要求。 相似文献
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带有复合结构的多层隔振系统振动传递及声辐射研究 总被引:13,自引:3,他引:10
本文将船体结构与安装在其上的设备和周围水介质合在一起建立了一个数学物理模型,即研究具有机器──上层隔振器──带有粘弹性材料(阻尼处理)的筏架结构──下层隔振器──基座艇体──外流场的艇体振动及声辐射。首先,从复合结构与流体相互作用问题的有关混合边值问题出发,针对声波辐射特点,推导了一种广义形式的Hamilton原理及有限元形式的运动方程。在此基础上,分别推导了带有粘弹性材料的筏架结构和艇体与声学介质耦合的动力学运动方程式。进一步在阻尼处理面积及位置、上下层隔振器刚体变化、基座面板厚度变化等四个方面对浮筏隔振系统声场特性的影响作了详细计算及分析研究,得到了一系列具有工程应用价值的结论。 相似文献
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针对喷水推进滑行艇的高速滑行原理,建立了其非线性的纵向运动数学模型。首先分析了滑行艇在高速滑行过程中的受力,详细地推导了艇体受到的重力、浮力和动升力,并根据喷水推进器的工作原理,推导了喷水推进力的表达式;然后建立了喷水推进滑行艇的非线性纵向运动数学模型;最后设计了基于该模型的滑行艇纵向运动预报软件,并进行了高速滑行的操纵性仿真试验,仿真结果与船模试验数据吻合较好,表明了该模型能够较准确的预报喷水推进滑行艇在静水中的纵向运动。 相似文献
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在船舶领域,以复合材料层合面板及泡沫芯材组成的夹芯复合材料板梁结构已大量应用在游艇及复合材料高速艇上.文章研究了受初始静载荷作用下夹芯复合材料曲梁的面板的局部自由振动问题,并给出一种相应的理论分析方法.文中通过将芯材简化为Winkler弹性地基,将面板简化为一复合材料曲梁,从而使所研究问题蜕化为有初始静载荷作用下弹性地基上任意曲梁的固有振动问题.在局部振动位移是基于初始静载平衡位置并与初始位移相比是小量的假定的基础上,根据能量原理推导出面板的运动方程.研究的结果表明,该面板的局部振动不只取决于面板的弯曲刚度和长度,以及芯材的弹性刚度,也在很大程度上取决于梁的曲率及面板所受到的初始轴向压力. 相似文献
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《舰船科学技术》2016,(19)
采用流固耦合(Fluid-Structure Interaction,FSI)的艇体波浪载荷和结构响应的数值分析方法,对顶浪、斜浪中复合材料双体艇结构的动态响应进行研究。分别建立了完整的复合材料艇体有限元模型以及流场模型,基于数值水池造波技术,通过计算获得了顶浪、斜浪中复合材料艇体结构的时域动态响应结果,选取高应力梯度区域,通过网格加密重构同时获得了复合材料的层间应力。选取具有代表性的前10大等效应力与内外面板最值主应力,在将FSI与传统基于经验公式的有限元法(Finite Element Method,FEM)的结果对比中发现,FSI中拱、中垂的计算结果更接近于FEM弯扭组合工况,而采用《钢制双体船直接计算指南》计算复合材料双体艇时,所用经验公式的顶浪航行波浪载荷计算值偏小。 相似文献
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采用流固耦合(Fluid-Structure Interaction,FSI)的艇体波浪载荷和结构响应的数值分析方法,对顶浪、斜浪中复合材料双体艇结构的动态响应进行研究。分别建立了完整的复合材料艇体有限元模型以及流场模型,基于数值水池造波技术,通过计算获得了顶浪、斜浪中复合材料艇体结构的时域动态响应结果,选取高应力梯度区域,通过网格加密重构同时获得了复合材料的层间应力。选取具有代表性的前10大等效应力与内外面板最值主应力,在将 FSI与传统基于经验公式的有限元法(Finite Element Method,FEM)的结果对比中发现,FSI中拱、中垂的计算结果更接近于 FEM弯扭组合工况,而采用《钢制双体船直接计算指南》计算复合材料双体艇时,所用经验公式的顶浪航行波浪载荷计算值偏小。 相似文献
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Ashish Verma H.S. Sudhira Sujaya Rathi Robin King Nibedita Dash 《Research in Transportation Economics》2013
Considering the present trends of urbanization and motorization in India, there is an urgent need for integration, revitalization and renewal of the smaller towns and cities to make urban areas in India more sustainable. Unless our regional space is reorganized to upgrade development of towns and cities and integrate them with each other and the larger cities, the urbanization process in India will become unsustainable. It is argued that High Speed Rail (HSR) can play a role in achieving this more balanced and sustainable development of towns and cities, opening up opportunities for growth across a wider, inter-connected, region, with the benefit of taking the pressure of the larger cities to absorb additional burgeoning populations. This paper will make the case that in the current Indian context, current patterns of mega-city growth are unsustainable, and that HSR can play an important role in providing opportunities for medium and smaller size cities through their interconnections. It begins by highlighting the role that railways have played in India and other countries, noting that merely economic analysis of their costs and benefits generally underestimated their contributions to development. It then provides an introduction to HSR and its potential impact in general, before applying this to the example of the State of Karnataka in South India. 相似文献
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This study investigates the effects of high-speed rail (HSR) services on Chinese airlines. Our analysis suggests that the HSR service will be competitive in terms of network connectivity, total travel time and cost efficiency. On the other hand, growth of the Chinese airline industry has been unbalanced in terms of traffic distribution, airline network development, airport capacity and share of international traffic. While the long term prospects of Chinese airlines are bright, the carriers must develop effective hub-and-spoke networks and increase their competitiveness in international markets in order to achieve sustainable growth in the coming years. For the Chinese government, continued investment at hub airports and support to low-cost carriers are also necessary. 相似文献
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Peter Nielsen Liping Jiang Niels Gorm Malý Rytter Gang Chen 《Maritime Policy and Management》2014,41(7):667-682
This paper evaluates the influence of forecast horizon and observation fit on the robustness and performance of a specific freight rate forecast model used in the liner shipping industry. In the first stage of the research, a forecast model used to predict container freight rate development is presented by exploring the relationship between individual company’s rates and aggregated market rates, and thus assists in dealing with uncertainty and market volatility for a given business situation. In the second stage, a design of experiment approach is applied to highlight the influence of the forecast horizon and observation fit and their interactions on the forecast model’s performance. The results underline the complicated nature of creating a suitable forecast model by balancing business needs, a desire to fit a good model and achieve high accuracy. There is strong empirical evidence from this study; that a robust model is preferable, that overfitting is a true danger, and that a balance must be achieved between forecast horizon and the number of observations used to fit the model. In addition, methodological guidance has also been provided on how to test, design, and choose the superior model for business needs. 相似文献
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船舶动力设备因故障监测信号样本少、变化缓慢且数据特征呈非线性,使得设备故障模式的准确识别和状态预测比较难。鉴于此,文章研究了基于隐马尔科夫模型的故障模式识别方法,利用该模型将微弱变化的信号特征转换为变化较大的对数似然概率对故障模式实现有效识别。在此基础上进一步提出基于HMM-SVR的设备状态预测模型,将遗传算法用于支持向量回归模型参数寻优,并结合隐马尔科夫模型,实现对设备状态的预测。对船用柴油机进行仿真,结果表明上述模型具有较高的识别率,能准确预测船舶动力设备的当前状态。 相似文献
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散货船和油船协调后的共同结构规范(HSR)将于2011年生效。为促进规范的发展,使之符合IMO目标型船舶标准(GBS)的要求,从整体舱段有限元分析、详细应力评估和疲劳强度评估的热点应力分析3个方面阐述了散货船共同结构规范的不足之处,并提出了相应的建议。 相似文献
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Subsea pipelines buried in the seabed may undergo large lateral displacement under environmental, operational, and accidental loads at different interaction rates and hence different drainage conditions. The undrained shear strength is commonly used in practice to assess the pipe-soil interaction assuming a sufficiently high displacement rate. This approach neglects consolidation effects and the rate-dependent response of the soil and may significantly underestimates the lateral resistance for a pipeline moving slowly relative to the ground. In this study, a coupled large deformation finite element (LDFE) framework is developed via a remeshing and interpolation technique with small strain (RITSS). A Modified Cam-Clay (MCC) model with efficient numerical integration is used. The proposed coupled LDFE framework is verified against selected physical model tests. Effects of the interaction rate and hence drainage condition on the p-y curve, excess pore pressure generation and dissipation, and failure mechanisms are discussed. An empirical relationship between the ultimate resistance and the normalized velocity of the pipe (denoting the drainage condition) is proposed, which may be applied for the integrity and safety analysis of buried pipes in landslide or fault-crossing regions. 相似文献
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选择性催化还原技术对氮氧化物脱除具有显著效果,是当前最广泛使用的脱硝处理技术。本文从介观角度出发,采用CFD方法建立了船用SCR脱硝系统的物理模型,分析了SCR脱硝系统的反应机理,并通过用户自定义函数将PI控制算法融合进介观系统模型中,摒弃传统控制模型中的均匀分布假设,实现了介观尺度上的非均匀喷氨控制。仿真测试结果表明:船用SCR脱硝系统的气体分布呈现严重非均匀性;融合介观尺度上PI控制算法后,不仅可改善系统的非均匀性,还可提高系统的整体脱硝率、降低系统的氨逃逸量。本研究为宏观控制与介观机理建模的融合提供了新的研究思路。 相似文献
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