Prediction of slamming pressure considering fluid-structure interaction. Part II: Derivation of empirical formulations

This is Part II in a series of papers. Part I [1] investigated the slamming responses of flexible flat stiffened steel and aluminum plates using the nonlinear explicit finite element code LS-Dyna with the Multi-Material Arbitrary Lagrangian-Eulerian (MMALE) solver. Subsequently, a simplified finite element FSI model of water hitting structures that is realistically close to the slamming phenomenon occurring on the bottom part of offshore structures was proposed. The proposed FSI methodology presented in Part I was verified by comparison with the relevant test data. It was evident that the use of the proposed numerical method presented in Part I was very effective for a benchmarking investigation of slamming load considering the hydroelastic effect. However, the method required much effort in terms of computation time and power analysis resources. The present study, Part II, aimed, as an alternative to the FSI analysis approach, to develop empirical formulae for prediction of slamming loads acting on deformable flat stiffened plates used in marine applications. This paper begins by describing the limitations of the existing approaches based on theoretical, experimental and even numerical studies conducted in the past for estimation of slamming loads. Next, it presents, based on the simulation methodology developed in Part I, rigorous parametric studies that had been performed on actual scantlings of marine-seagoing structures. The effects of structural geometry and water impact velocity on slamming pressure are then investigated in detail. Subsequently, the parametric results are analyzed and utilized to derive empirical formulations for the prediction of slamming loads acting on flat stiffened plates of marine structures. The accuracy and reliability of the proposed formulations are established by comparison with the results of the test and other existing formulations. The proposed formulations are expected to be used for the purposes of the design without any time-consuming FSI analysis of advanced and optimal structures that are robust to slamming.     

石油产品管道运输定量研究

成品油管道运输计划和调度是具有多约束的复杂问题,包括炼油厂的生产进度、市场需求、相邻油品的规格等都需考虑。另外,炼油厂和分销中心现有库存量和库存能力以及管道中的输油量等也要详细分析。文中对该领域的定量研究文献进行了梳理、综述,对未来研究趋势做了分析展望,以便研究人员作进一步研究。     

陕西省轨道交通自动售检票系统地方标准建设的思考

陕西省轨道交通自动售检票系统地方标准的建设依托于西安市轨道交通建设的实际,其技术来源于西安城市轨道交通线网规划及自动售检票系统设计,服务于西安城市轨道交通自动售检票系统的建设,结合陕西省轨道交通的规划建设情况,对省内轨道交通自动售检票系统的建设有重要指导意义.阐述该标准的提出、建设的程序和方法、技术难点及执行过程应注意...     

城市轨道交通高架线规划体系构建

根据高架线特征分析,提出高架线规划体系构建的总体框架思路,从高架线的需求条件规划、控制规划、减振降噪规划、景观规划、车站形式规划、桥梁形式规划等方面阐述高架线规划体系的主要内容,并对高架线规划的实施保障提出具体建议,为早日建立我国的城市轨道交通高架线规划体系提供技术参考。     

Numerical Simulation of Coupled Thermo-mechanical Behavior of a Cylinder Billet during Hot-forging Process

IntroductionInhotforging,variationanddistributiol1oftemperatureplayveryimportantroIeinviewofthermalstressesorthermalstrainaswe1lasthemateria1properties.MechanicaldefOrmationcangenerateheatbyfrictionalslidingand/ordissipatiOI1ofplasticwork.Theboundaryconditionfortemperatureismodifiedbythechangeinmaterialshape.Dietemperatureusuallyislowerthanworkpiecetemperatureandthisfactresultsindiechilling.Itsignificantlyaffectsthetemperatureoftheworkpiecea11d,consequently,alterstheflowstress.Whenthedieisr…     

A simplified analytical method for estimating the crushing resistance of an inclined ship side

This paper provides a new contribution to the simplified analytical treatment of collisions between two ships. It is directly connected to the well-known super-elements method, which is a simplified procedure allowing for a quick estimation of the damages caused to both the striking and struck vessels during such events. In this article, a new analytical formulation is presented for estimating the impact resistance provided by inclined ship side panels. Two different scenarios are treated. We first deal with the case of an impact between the oblique plate and the stem of the striking ship, and then we consider the situation where the inclined panel is impacted by the bulb. For these two scenarios, an analytical formulation relating the force and the penetration is provided and these developments are validated by comparing them to the results of finite elements simulations. Finally, the new inclined plate super-element is integrated in a simplified model of a frigate collided by another ship, and the resistance given by the super-elements method is then compared to the one obtained by a numerical simulation of this collision.     

我国方舱设备的发展回顾

简要回顾了我国电子设备方舱的起源与发展,介绍了方舱标准的制订与应用。     

钢-轻骨料混凝土简支组合梁承载及变形能力研究

为了确定轻骨料混凝土组合梁的性能,以对称集中荷载为加载方式,同时考虑栓钉间距、钢梁尺寸等影响组合梁承载及变形能力的因素,研究了钢-轻骨料混凝土组合梁结构的承载及变形能力。根据剪切滑移的挠曲线方程,提出组合梁在集中荷载作用下跨中挠度的简化计算公式,并选用ANSYS软件进行了有限元对比模拟分析,计算结果吻合良好。算例表明,轻骨料混凝土组合梁相比于相同尺寸的普通混凝土组合梁,应力值偏小5%左右,跨中挠度偏大10%左右,钢-轻骨料混凝土组合梁承载力及变形能力可满足实际应用,同时验证了计算公式应用的可行性。     

《城市客运术语第1部分：通用术语》国家标准研究及制定

城市客运作为一项民生工程和城市功能的重要组成部分,为促进城市发展和经济快速增长提供了良好的支撑。虽然,国家已经组织并出台了相关的指导意见,但支撑行业发展的标准规范尚不能满足行业发展的需要。特别是城市客运专业领域范围内的基础性、通用性国家标准,如术语、分类、基础性技术导则等,没有统一的标准。通过对本标准的研究,并按照国家标准的制修订程序,起草完成了本国家标准的文本和编制说明,进入报批阶段。该标准由七个部分组成,适用于城市客运专业领域,涉及到城市公共汽电车、城市轨道交通、出租汽车、水上旅游、城市客运轮渡以及缆车索道等不同客运方式领域的通用性、基础性名词术语。该标准的实施将有助于促进我国城市客运行业学术交流,促进城市客运可持续发展,提升行业管理水平。     

桥面环氧覆层路用性能及加铺技术研究

以抗拉强度、伸长率、弹性模量为指标,研究不同种类固化剂对弹性环氧胶黏剂性能的影响,并选取3组固化剂复配的环氧体系进行综合性能测试,对环氧胶黏剂配方进行优化;同时,以洛杉矶磨耗值、磨光值为指标,对骨料进行选择,并从环氧胶黏剂固化产物性能、骨料级配及性能、环氧覆层路用性能方面,对桥面环氧覆层性能进行综合测试。最后,结合工程实际,针对环氧覆层铺装制定相应的施工工艺。研究表明,不同固化剂组合在性能方面会有区别,将自制的改性胺类与韧性酚醛胺复合后,其固化性能较好;同时,作为环氧覆层铺装集料,金刚砂、玄武岩、花岗岩碎石较为适合,而河砂的耐磨性能差。研究可为桥面环氧覆层应用提供一定参考。