Model test investigation on an innovative lifting system for deepwater riser installation

An S-lay crane barge,named CNOOC 201,has been built for pipe laying in deepwater oil/gas fields in the South China Sea.It is due to be commissioned by the end of the year 2010.A special lifting system is developed to meet the challenge that installing deepwater risers from an S-lay barge is difficult and has not been achieved.The purpose of this paper was to investigate the model test on such an innovative system,which has to be done before field application.By applying the similarity theory,the movement of the S-lay barge is simulated through a six degrees-of-freedom motion platform,and a truncated model riser is utilized for the model testing.The displacement and force boundary conditions at the truncated position of the riser are obtained from the catenary governing equation and become realized by a slideway cart and a loading system designed to control the configuration of the model riser,which presents a similar configuration to a real riser in deepwater.The test results are in very good agreement with theoretical calculations,showing that the active truncated test is applicable for controlling the configuration of the deepwater riser in model testing investigation.

Dynamic Analysis Method of Offshore Jack-up Platforms in Regular and Random Waves

A jack-up platform, with its particular structure, showed obvious dynamic characteristics under complex environmental loads in extreme conditions. In this paper, taking a simplified 3-D finite element dynamic model in extreme storm conditions as research object, a transient dynamic analysis method was proposed, which was under both regular and irregular wave loads. The steps of dynamic analysis under extreme conditions were illustrated with an applied case, and the dynamic amplification factor （DAF） was calculated for each response parameter of base shear, overturning moment and hull sway. Finally, the structural response results of dynamic and static were compared and analyzed. The results indicated that the static strength analysis of the Jack-up Platforms was not enough under the dynamic loads including wave and current, further dynamic response analysis considering both computational efficiency and accuracy was necessary.

Design of A Bionic Spudcan and Analysis of Penetration and Extraction Performances for Jack-up Platform

The mechanisms of soil structure interaction have drawn much attention in the past years in the installation and operation of jack-up platform. A bionic spudcan produced by biomimetic of egg and snail shell is proposed, and the performance of the penetration and extraction are analyzed by numerical method. The geometric contour of egg and snail shell is measured, and its mathematical model is established respectively. According to the structure of existing spudcan of jack-up platform, three kinds of typical biomimetic spudcan are designed. Furthermore, numerical analysis models of biomimetic spudcan are established respectively to study the soil structure interaction mechanism in the process of penetration and extraction, and contrastive analysis of resistance characteristics are carried out. To conclude, the results show that the biomimetic spudcan facilitates the platform installation, and it is also beneficial to the improvement of the bearing capacity of spudcan.

Soil-Structure Interaction Analysis of Jack-up Platforms Subjected to Monochrome and Irregular Waves

As jack-up platforms have recently been used in deeper and harsher waters, there has been an increasing demand to understand their behaviour more accurately to develop more sophisticated analysis techniques. One of the areas of significant development has been the modelling of spudean performance, where the load-displacement behaviour of the foundation is required to be included in any numerical model of the structure. In this study, beam on nonlinear winkler foundation （BNWF） modeling--which is based on using nonlinear springs and dampers instead of a continuum soil media--is employed for this purpose. A regular monochrome design wave and an irregular wave representing a design sea state are applied to the platform as lateral loading. By using the BNWF model and assuming a granular soil under spudcans, properties such as soil nonlinear behaviour near the structure, contact phenomena at the interface of soil and spudcan （such as uplifting and rocking）, and geometrical nonlinear behaviour of the structure are studied. Results of this study show that inelastic behaviour of the soil causes an increase in the lateral displacement at the hull elevation and permanent unequal settlement in soil below the spudcans, which are increased by decreasing the friction angle of the sandy soil. In fact, spudeans and the underlying soil cause a relative fixity at the platform support, which changes the dynamic response of the structure compared with the case where the structure is assumed to have a fixed support or pinned support. For simulating this behaviour without explicit modelling of soil-structure interaction （SSI）, moment- rotation curves at the end of platform legs, which are dependent on foundation dimensions and soil characteristics, are obtained. These curves can be used in a simplified model of the platform for considering the relative fixity at the soil- foundation interface.

Collision Analysis Between Spudcan and Seabed During the Process of Jack-up Platform Lowering Jack-up Legs

In the leg-lowering process,the offshore jack-up platform is in a floating state,and the spudcan may collide with the seabed due to the platform motion in waves,thereby threatening the safety and stability of the platform.This paper first analyzed the hydrodynamic response of a jack-up platform under different sea states.Then a finite-element model was established which considered the material and geometrical nonlinearity in the structure and the nonlinear interaction between soil and structure to investigate the collision response between the spudcan and seabed during lowering jack-up legs.The results show that the dynamic response of the platform decreases and gradually tends to be stable as the wave period increases.The motion response of the platform reach the largest value when the wave period is 8 s and the wave direction is 0°.The collision angle between the spudcan and seabed has a large influence on the collision response,while the velocity of leg-lowering has little influence on the collision response.The collision response is also significantly affected by soil conditions.For clay,the increase in undrained shear strength and Young’s modulus will increase the impact force.

Structure Analysis and Control Optimization on High Speed Lift Platform

Dynamic analysis of scissor hydraulic lift platform has been performed to invest/gate the key factors which determine size and shape of the platfolan. By using MATLAB, the position of hydraulic cylinder has been optimized to reduce jacking force of piston and the whole system. Thus structure deformation decreases which is beneficial to control accuracy. Additionally, a new proportion integration differentiation （PID） control mode based on BP neural network has been developed to improve the stability and accuracy for the pasitio^L control in this system. Compared with existing PID tuning meth~~ls and fuzzy self-adjusted PID controllers, the proposed back propagation （BP） based PID controller can achieve better performance for a wide range of complex processes and realize self-tuning of parameters. It was confirmed that the performance of the lift platform regarding the force variation and position accuracy was greatly enhanced by optimizing of the system both in structure and control. Considerable economic benefit can also be achieved thrangh the application of this intelligent PID system.

Solar Energy for a Traditional Coastal Fishing Platform

In order to introduce clean environment and sustainable energy to traditional coastal fishing community, the objective of this study is to encourage the Indonesian traditional coastal fishing community to use green and renewable energy in their fishing activities. Introducing solar power as the main source of energy for fish-attracting lights and boat propulsion can reduce the use of fossil fuels, and sustain clean and healthy environment. As the world’s largest archipelago, Indonesia accounts for a high percentage of traditional fishing communities spread out along its islands. This fishing communities use various traditional fishing boats, and platforms. The fishing platforms are usually made of bamboo and placed on top of supporting structures on the seabed. Diesel electric generators are used to obtain electricity needed for lighting to attract the fish at night, and as the source of power for lifting the fishing net. The structure and fuel used are neither environmentally friendly nor clean;thus, an innovation is introduced. Traditional fishing practices using a fishing platform were studied, including the common size of the platform and the power needed for the fishing light. Based on the gathered information, this study proposes a catamaran vessel with a special top structure designed for fish lifting outfitting, and equipped with photovoltaic solar cells as the energy source for the fishing lights and vessel propulsion. Through this innovative break through, the vessel can be moved to the shore and will not be a threat to ship navigation and the environment. Furthemore, powered by clean and sustainable energy, the vessel can be directed to the best fishing ground.

The Calculating Model of Structural Analysis for Jack-Up Rig Legs

The selection or establishment of structural calculating model is a matter of primary importance in structural analysis. By analysing the irrationality of the calculating models used by some research organizations at home and abroad in structural analyses for truss jack-up rig legs, this paper introduces a new calculation model which is more reasonable. This model can simulate better the load situation of a rig reflecting more precisely the effects of the leg loads caused by the spring support of gearboxes of the jacking system and the secondary bending moment raised by hull displacement under extreme conditions. The rig conversion was completed in 1989. In July 1991 the rig safely stood the frontal hitting of Typhoon with the wind speed of 52 m / s, which shows that the checking on the structure is correct.

Discussion on Key Points of Wind Load of Jack-up Unit

The anti-overturning ability and structure safety of jack-up unit in in-place condition are often affected by environment loads, especially wind load. According to the MODU rule, the projected area method is used for calculating the wind load. However, the calculated results are conservative and not good for structure optimization design. In this paper, a 400 ft jack-up is studied as an example. Based on the wind tunnel test and numerical simulation method, some key points of wind load calculation, such as shielding effect, lift effect and shape coefficient of component, are discussed. The study shows that the points mentioned above, which are ignored in the MODU rule calculation, result in the conservative result.

果园采摘升降平台设计

为解决果园机械化采摘过程中费时费力、可达性差等问题,设计了一款高度和行距可调的果园采摘平台,以适应不同果园地形的采摘作业。整机采用履带式底盘,并搭载可调式升降平台,选用ZGL-E100×1200型液压缸为其提供升降动力,并通过输送装置完成水果的运输和收集。采用SolidWorks软件完成整机及零部件的结构设计和三维建模,联合ANSYS Workbench软件对部分零部件进行仿真模拟。有限元分析结果表明,垂直输送轴与水平输送轴强度、升降平台机架均符合设计要求,通过模态分析得出升降平台在作业过程中稳定性较好。

考虑SSI效应的升降作业平台惯容减振优化设计

升降作业平台在野外工地、河滩等环境中高空作业时,其支腿底盘的明置基础与软土地基会发生动力相互作用,从而改变作业平台系统的动力特性。提出了考虑土与结构相互作用效应下的含3种不同惯容减振系统(SIS,SPIS-1,SPIS-2)的升降作业平台动力学模型,推导了作业平台在简谐激励下的振幅放大因子以及在随机激励下的响应均方值的解析表达式。利用遗传算法分别求解了位于中硬土、中软土以及软弱土3种地基表面的作业平台在H_(∞)和H_(2)优化准则下,惯容减振系统的最优设计刚度比和阻尼比。对最优状态下的各减振系统进行减振效果分析,结果表明:SPIS-2减振系统效果最佳,不仅最大程度地抑制了升降作业平台的共振效应,而且更有效地拓宽频带范围;SSI效应可以降低简谐激励下作业平台的位移振幅放大因子和随机激励下作业平台绝对位移的均方值;SSI效应对简谐激励和随机激励下惯容减振系统的最优设计参数影响很小,因此针对3种惯容减振系统位于不同地基表面下的最优设计参数拟合出经验公式,为升降作业平台的研发和减振设计奠定了理论基础。

液压调平举升平台虚拟拆装系统研究

在维修和培训过程中,机电产品的虚拟拆装系统可以降低对硬件设备的依赖,能够减少设备的损耗。通过研究液压调平举升平台的VR(Virtual Reality)拆装系统,分析其结构组成和工作原理,基于Unity3D开发环境,编写交互脚本,以HTC Vive Pro2.0作为交互设备,完成了三维模型的构建与处理、虚拟场景的设计、碰撞检测、拆装序列规划、交互功能的设计、用户界面的设计以及拆装功能的设计,开发出沉浸式人机交互的虚拟拆装系统,实现场景漫游、结构认知、拆装引导和虚拟拆装训练等功能。实验结果表明:所开发的虚拟拆装系统沉浸性良好,交互方便,虚拟拆装训练效率高。

海洋平台潜海水电机绝缘失效解决方法探讨

针对目前国产电动海水提升泵电机绝缘失效率高、质量不够稳定的问题,结合实际案例,通过温度场仿真分析等方法,得出潜海水电机绝缘失效的主要原因包括绕组线选型缺陷、内部散热不足、密封性能差和缺少温度监控。针对上诉原因,逐条提出可行的改进方法,提高电动潜海水泵的产品质量。

果园作业平台关键技术研究进展

果园机械化是提升生产效率、增加果农经济收入的重要手段。总结国内外果园作业平台关键技术研究进展,分析作业平台最新的研究成果,对比不同类型底盘结构之间的性能差异,概括常见作业平台升降机构、自动调平机构的类型与特点以及安全与稳定性方面的研究进展,探讨无人驾驶技术在作业平台中的应用情况并阐述常见路径规划技术路线。指出果园机械化发展存在配套设施不完善以至平台扩展性差、智能化程度低等问题,并提出果园作业平台应向着适应性强、底盘专用化、整机高度智能化、调平精度高等发展建议。

基于重载荷大跨度桁架机器人的电力物资智能搬运系统研究

随着国家电网“具有中国特色国际领先的能源互联网企业”战略目标的提出,电力物资仓储逐步向数字化、智能化方向迈进。针对重型电力物资仓储的核心环节——智能搬运,提出一套桁架机器人配合AGV及顶升平台的智能搬运解决方案。分析在重载荷、大跨度、外形各异等复杂工况条件下,如何实现高安全性、高精度、高效率的搬运;分析桁架机器人与AGV及顶升平台之间的协同工作,以及如何在重载荷下实现双顶升平台的高精度同步控制;提出采取RFID技术实现智能搬运过程的自动数据采集。

设施农业履带电动作业平台设计与试验

针对设施多元生态立体种植模式对机械化的作业需求,结合该新型种植模式的农艺参数,研制履带式电动作业平台。阐述整机结构与工作原理,对履带动力底盘、液压升降平台等关键部件进行结构设计与动力参数计算,并开发驱动控制系统。对电动作业平台进行行驶速度、续航能力和最小通过圆试验。试验结果表明:电动作业平台达到额定载重200 kg的设计要求;慢速挡平均行驶速度为0.40 m/s,快速挡平均行驶速度为0.98 m/s;100 kg负载下作业续航时间可达4.69 h,锂电池供电稳定;最小通过圆直径为1.54 m,可实现设施多元生态立体种植机械化物资搬运和辅助登高作业。

音圈电机直驱气浮升降平台的设计及其性能测试

在半导体的精密加工与精密测量中,针对一些光路限制、加工设备固定的情况下,设计了一种音圈电机直驱的气浮升降平台,承载起工件进行精密定位。平台的驱动元件采用两个高精度、高频率、无摩擦的音圈电机进行驱动,平衡元件采用了低摩擦气浮气缸进行平衡运动部件的重力,导向元件采用了多孔式节流的环绕式气体静压导轨进行导向,同时反馈元件采用高精度光栅尺作为实时反馈装置。对气体静压导轨进行了气体理论分析,用Ansys仿真软件进行导轨承载力和刚度的仿真,并结合实验进行验证仿真分析。考虑到两个音圈电机驱动时的机械耦合作用,采用了主令并行交叉耦合控制算法,来对升降平台进行精密控制。最后对升降平台的定位精度、俯仰误差、偏摆误差、直线度进行了性能测试,证明了该升降平台具备了精密加工与精密测量的能力。

高速重载大行程运动升降平台设计及实现

[目的]为满足恶劣海况下舰船的大幅运动模拟需求,开展高速、重载、大行程运动升降平台的研发工作。[方法]针对运动平台的重载、高速及变参数特点,基于Adams仿真平台对采用重量平衡、4钢缆同步伺服驱动的高速升降平台进行动力学仿真分析,提出一种基于模糊PID控制的多电机同步驱动控制系统,并基于控制特性相似原理研制了1∶14的缩比高速升降平台。[结果]通过平台的响应特性试验,验证了控制系统具有同步性强、控制精度高的优点,运动平台可以良好地模拟恶劣海况下舰船的升沉运动。[结论]所设计的重量平衡、4钢缆同步伺服驱动的高速升降平台可填补舰船大幅升沉运动模拟领域的空白,并对类似运动模拟器的研发具有参考意义。

钢结构雨棚及行人天桥综合吊装技术及施工质量控制

温州北站是由既有甬台温铁路永嘉站改建而成,站台雨棚和行人天桥钢结构的施工受既有线的影响,施工和管理难度大。结合该站钢结构雨棚与行人天桥的施工实践,文中探讨了既有铁路大跨度钢结构桁架的综合吊装技术及施工质量控制要点,验算了站台雨棚和天桥吊装工况。通过该施工技术,成功解决了钢结构施工与既有运营线相互影响的问题。

防坠性工具式卸料平台在高层建筑中的应用研究

以济南中央商务区4–14地块项目1号主楼施工为研究对象,提出一种防坠性工具式卸料平台,分析其工艺原理,并给出相应的设计和施工方法,研究其工程应用效果。研究结果表明,防坠性工具式卸料平台可以有效地解决超高层建筑卸料平台的搭设问题,平台安装一次到位,通过动力装置沿预设轨道,与附着式升降脚手架随层爬升,无需进行拆装,在保证了施工进度的同时兼顾安全性,大幅提高了施工效率,减少了操作时间,较传统卸料平台可节约成本22700元,节约工期约60d,达到了降本增效的目的。