Numerical study on the dynamic response of a truncated ship-hull structure under asymmetrical slamming

Dynamic response of ship-hull structure under slamming has tracked widespread attention in the marine structural design. However, our understanding on the dynamic characteristics largely relies on the symmetrical slamming cases. This paper presented a preliminary numerical investigation on the dynamic response of a truncated ship-hull structure under asymmetrical slamming based on the uncoupled CFD-FE method. Asymmetrical slamming loads were predicted through combining the seakeeping analysis and CFD method. In there, three kinds of motions (vertical, horizontal and roll motions) of 2D ship sections were obtained through the seakeeping analysis and then the slamming pressure was predicted through simulating the water entry with various motions based on CFD method. The dynamic response was analyzed through finite element method. Numerical predictions including ship motions, slamming loads and dynamic analysis were validated against published experimental data and numerical calculations. The characteristics of asymmetrical slamming loads were analyzed showing obvious asymmetry in space, and the dynamic characteristic of the ship bow structure was further clarified through discussing the deformation and stress distribution. These results are useful for readers for better understanding the dynamic characteristics of the bow structure under slamming.     

Simplified buckling-and-contact-based expansion method for assessment of crashworthiness of double-hulled ship structure

Ship-to-ship collision events can have severe consequences such as loss of life and environmental degradation. For this reason, modern ship designs are required to incorporate a double-hulled structure to prevent inner-hull damage from such events. Using the experimental or numerical method to analyze the crashworthiness of double-hulled ship structures entails much effort, for which reason neither method is easy to adopt at the early design stage. In this paper, an existing simplified method called Ito's method is improved by a new buckling-and-contact-based expansion method. This method can be applied to double-hulled-structure or outer-hull-local-rupture failure mode. The perpendicular bow-to-side collision scenario is assumed for a conservative estimation of damage to a double-hulled structure. The method was verified in the present study by numerical ship collision simulations of several cases. The results for the buckling-and-contact-based expansion method and numerical simulation were similar for a blunt shape of striking body but different for a sharp shape.     

激光焊接技术在轨道交通车辆中的应用

为解决轨道交通车辆不锈钢车体电阻点焊的外观质量差、密封性差、效率低等缺点,对部分熔透激光焊接工艺在不锈钢车体焊接中的应用开展了研究。研究包括:部分熔透激光叠焊原理、参数优化试验、显微组织分析、疲劳性能分析,以及激光焊接不锈钢车辆侧墙的结构改进。研究结果表明,不锈钢车体焊接中采用部分熔透激光叠焊工艺,可以获得高质量的表面状态及疲劳强度,车体结构强度高于EN12663标准中的要求。     

地铁隧道二次衬砌钢筋网防裂性能研究

为了定量分析防裂钢筋网提高隧道衬砌结构抗裂性能的机理和幅度,以地铁双线隧道二次衬砌结构为研究对象,采用荷载结构法和杆系有限元数值模拟方案,定量分析二次衬砌结构不设置与设置钢筋网这2种情况下的开裂临界荷载。其中素混凝土结构以达到极限拉应变为临界状态,衬砌结构增设钢筋网后以达到GB 50157-2013《地铁设计规范》允许的最大裂缝宽度0.2mm为临界状态。分析结果表明,配置防裂钢筋网后,Ⅲ级和Ⅳ级围岩衬砌结构抗裂性能可分别提高22.4%和19.3%,Ⅴ级围岩衬砌结构抗裂性能提高15.2%;Ⅲ级和Ⅳ级围岩二次衬砌结构的破坏形式由脆性破坏变为延性破坏,从而提高了其安全性能。     

线性绞车电控系统开发与应用

基于广州打捞局120 000 kN抬浮力打捞工程船配套4 500 kN线性绞车的技术要求,提出线性绞车电控系统设计方案。从线性绞车在打捞工程船中的作业工况、电控系统的通讯架构、线性绞车单台控制及远程联动的自动控制、人机界面操作等方面进行研究,介绍线性绞车电控系统的设计思路,为线性绞车在打捞沉船工作中的正确运用提供了理论支撑和技术保障。     

张紧器的结构参数对顶张式立管动力响应的影响研究

本文针对带液压气动式张紧器的顶张式立管,综合考虑浮式平台-张紧器-立管之间的运动关系、液压气柱的张力-冲程非线性关系、立管的真实截面布置以及采油树的作用,建立更加符合工程实际的三维有限元分析模型,并通过与实验结果对比验证了该模型的正确性。基于该有限元模型,研究了张紧器的结构参数对顶张式立管动力响应的影响。结果表明:活塞和活塞杆的直径以及高压气体的初始压强对立管的动力响应影响最大;低压气体的初始压强以及液压气柱和立管之间的夹角对立管的动力响应也有重要影响;在相同的环境条件下,高压气体和低压气体的初始体积对立管的动力响应的影响较小。     

轨道安全监测中传感器优化配置研究

为了研究轨道结构安全监测中传感器的合理配置方法,确保城市轨道交通安全运营,通过建立桥上交叉渡线道岔模型和钢轨应变传递误差最小的目标函数,提出传感器测点选择依据和监测方案评价标准,保证监测方案的经济性、合理性。结论表明:模型数据曲线可以指导监测系统的测点位置选择;随着传感器测点数量增加,监测误差逐渐减小,但在误差比率的"拐点"后增加单位个数传感器带来的收益降低;通过建立误差最小准则的目标函数,结合误差指标可以评价和优化传感器布设方案;钢轨位移、附加力等指标的监测方案也可以通过本文方法确定。     

基于DES方法的螺旋桨尾涡演化数值研究

采用分离涡模拟(DES)方法对多工况下螺旋桨的尾流场特性及尾涡结构进行数值研究,应用滑移网格技术完成螺旋桨敞水试验模拟,采用Spalart-Allmaras湍流模型封闭N-S方程组。数值计算结果显示:采用DES方法得到的水动力特性结果与模型试验结果吻合度高,DES方法能够较好地捕捉到螺旋桨尾流场中复杂的尾涡结构,螺旋桨不同桨叶产生的梢涡之间的自诱导和相互诱导作用引起尾涡结构形态变化,4叶桨梢涡结构之间会产生2次融合重组,毂涡振荡与梢涡演化之间存在相互干扰作用,不同进速系数下尾涡演化规律基本一致。     

沉箱开孔对平均越浪量的影响

针对开孔沉箱对平均越浪量影响的问题,以国内某港区通用码头工程为基础,对比分析了直立式沉箱和开孔沉箱平均越浪量的多种经验公式计算方法,并和断面物理模型试验结果进行比较。公式计算结果显示,开孔沉箱与不开孔沉箱平均越浪量之比为25%~50%;断面物理模型试验结果显示,沉箱开孔与不开孔时越浪量之比为30%~82%。研究表明开孔沉箱能够有效降低海岸结构物的平均越浪量;国内学者提出的开孔沉箱越浪量计算方法所得结果更加接近物理模型试验结果。     

海上装配式混凝土石油平台设计

以渤海湾某油田为例,针对海油陆采一体化技术所需平台的功能要求,基于我国水运工程规范体系及现状技术水平,提出一种适用于油田开采的新型装配式混凝土平台结构方案,并对平台的结构设计理念、规范适应性研究、设计方案、施工船机配置、平台弃置等进行研究,可为类似海上大型平台结构提供借鉴。