离岸浮力腿存储和再气化平台结构健康监测的试验研究（英文）

Offshore platforms are of high strategic importance, whose preventive maintenance is on top priority. Buoyant Leg Storage and Regasification Platforms(BLSRP) are special of its kind as they handle LNG storage and processing, which are highly hazardous. Implementation of structural health monitoring(SHM) to offshore platforms ensures safe operability and structural integrity.Prospective damages on the offshore platforms under rare events can be readily identified by deploying dense array of sensors. A novel scheme of deploying wireless sensor network is experimentally investigated on an offshore BLSRP, including postulated failure modes that arise from tether failure. Response of the scaled model under wave loads is acquired by both wired and wireless sensors to validate the proposed scheme. Proposed wireless sensor network is used to trigger alert monitoring to communicate the unwarranted response of the deck and buoyant legs under the postulated failure modes. SHM triggers the alert mechanisms on exceedance of the measured data with that of the preset threshold values; alert mechanisms used in the present study include email alert and message pop-up to the validated user accounts. Presented study is a prima facie of SHM application to offshore platforms, successfully demonstrated in lab scale.     

离岸深水构筑物的自动监测新方法

目前水运工程建设距离陆地越来越远,水深也越来越大。离岸深水构筑物的监测受网络信号覆盖范围、恶劣天气、施工等干扰,一直无法很好地实现既实时又方便的数据采集。文中介绍了一种新的自动监测方法,该方法包括监测传感器、自动采集系统、水下无线传输系统和数据处理系统。工程实践证明,该方法能实时、可靠地得到离岸深水构筑物的监测数据,可供类似工程借鉴。     

Feasibility of modal expansion for virtual sensing in offshore wind jacket substructures

The present paper investigates the feasibility of modal expansion-based virtual sensing in the context of offshore wind jacket substructures. For this specific application, issues have been reported when expanding wind-driven brace vibrations and wave-driven vibrations in the splash-zone based on a sensor network placed solely above the sea level. These limitations are addressed in this paper by extending the sensor network with sub-sea vibration sensors and a wave radar sensor, which allow for capturing local brace vibration modes and the wave-driven vibration response. The brace expansion is thus improved by including the local brace vibration modes in the expansion basis, while the representation of wave-driven vibrations is improved by including load-dependent Ritz vectors computed based on input from the wave radar sensor. The merit of the proposed extension is explored using a numerical model of an offshore wind turbine supported by a jacket substructure in a simulation setting with different operational and environmental conditions. It is documented that the extended setup provides an improvement in the expansion-based estimation of both wind- and wave-driven vibrations. The former improvement is particularly relevant for operational cases, while the latter is relevant for idling cases. Despite the documented improvements, a systematic reduction in the expansion quality is observed for higher wind speeds in operational cases for both the basic and the extended setup. It is contended that this phenomenon is due to the operational variability of the controller, which violates the fundamental assumption of the structural system being linear and time-invariant.     

Strength reliability analysis of stiffened cylindrical shells considering failure correlation

The stiffened cylindrical shell is commonly used for thepressure hull of submersibles and the legs of offshore platforms.There are various failure modes because of uncertainty with thestructural size and material properties, uncertainty of the calculationmodel and machining errors. Correlations among failure modesmust be considered with the structural reliability of stiffenedcylindrical shells. However, the traditional method cannot considerthe correlations effectively. The aim of this study is to present amethod of reliability analysis for stiffened cylindrical shells whichconsiders the correlations among failure modes. Firstly, the jointfailure probability calculation formula of two related failure modesis derived through use of the 2D joint probability density function.Secondly, the full probability formula of the tandem structuralsystem is given with consideration to the correlations among failuremodes. At last, the accuracy of the system reliability calculation isverified through use of the Monte Carlo simulation. Result of theanalysis shows the failure probability of stiffened cylindrical shellscan be gained through adding the failure probability of each mode.     

导管架式海洋平台自适应预测逆控制研究

文章提出了一种新的基于动态刚度阵法的导管架式海洋平台模糊神经网络自适应预测逆控制模型。该模型是通过安放在海洋平台桩腿上的压力传感器实时采集海洋平台所受波浪力,然后应用动态刚度阵法快速而准确地计算出平台顶部的响应,再将此响应作为模糊神经网络预测逆控制器的输入信号,预测出下一时刻平台顶部的控制力来对海洋平台振动响应进行控制;同时,通过反馈的自适应预测逆控制器来减小扰动和前馈控制的误差。为了验证该模型的抗干扰能力,文中还对有随机风载荷扰动情况下的导管架式海洋平台主动控制进行了研究。最后的数值算例结果表明,文中所提出的导管架式海洋平台主动控制模型具有较强的抗干扰能力,能很好地解决控制系统中存在的时滞问题,可有效地控制导管架式海洋平台的振动响应。     

铺管船托管架结构动态监测系统的研究应用

近年来结构健康监测技术不断发展,现已成熟应用于桥梁、隧道、船舶以及海洋平台等结构物的健康监测中,但面向铺管船托管架结构健康监测技术的应用研究仍处于空白状态。在此研究背景下,本文以某铺管船为例,研究开发了一套适用于铺管船托管架的结构作业动态监测及预警系统,实现了对托管架结构健康实时和科学的监测。为保证监测系统的安全性,进行了防护密封方案研究,并通过模型试验验证了方案的可靠性。最后通过海上测试采集监测数据,对实测数据进行分析,确保托管架的安全性。     

自升式钻井平台的抗冰性能评价

自升式钻井平台属于典型的柔性结构。由于冰与柔性抗冰结构相互作用的复杂性,长期以来尚未形成基于动冰力响应分析的结构设计。结构抗冰设计中大都是从极端荷载出发,只考虑最大静冰力或最大倾覆力矩是否能推倒平台。基于对渤海辽东湾柔性抗冰平台的多年监测,发现强烈的冰激振动引起平台管节点疲劳失效、上部设施的非正常运行、作业人员不舒适等问题的风险性要远大于极端静冰荷载下结构的整体安全问题。文中基于多年现场冰与结构作用观测及冰荷载的研究成果,提出了柔性抗冰结构设计中应考虑的主要失效模式及评价方法。最后,以渤海某典型自升式钻井平台为例,对其抗冰性能进行评价。该文的研究可为寒区自升式平台的抗冰概念设计提供合理依据。     

Detecting damage to offshore platform structures using the time-domain data

A new method that uses time-domain response data under random loading is proposed for detecting damage to the structural elements of offshore platforms. In our study, a time series model with a fitting order was first constructed using the time-domain of noise data. A sensitivity matrix consisting of the first differential of the autoregressive coefficients of the time series models with respect to the stiffness of structural elements was then obtained based on time-domain response data. Locations and severity of damage may then be estimated by solving the damage vector whose components express the degrees of damage to the structural elements. A unique aspect of this detection method is that it requires acceleration history data from only one or a few sensors. This makes it feasible for a limited array of sensors to obtain sufficient data. The efficiency and reliability of the proposed method was demonstrated by applying it to a simplified offshore platform with damage to one element. Numerical simulations show that the use of a few sensors＇ acceleration history data, when compared with recorded levels of noise, is capable of detecting damage efficiently. An increase in the number of sensors helps improve the diagnosis success rate.     

基于结构动力学特性的高桩码头横向排架传感器优化布置方法

为了对高桩码头结构健康监测系统中的传感器布置提供理论指导,提出了一种基于结构动力学特性的传感器优化布置方法。在对高桩码头代表性结构单元横向排架进行结构动力学分析的基础上,运用模态应变能法选择高桩码头横向排架传感器初始测点;建立初始模态矩阵,然后利用模态置信度法和序列法对模态矩阵进行迭代、优化,确定传感器测点布置。建立了单个横向排架的数值仿真模型,利用传感器优化布置方法得到横向排架7根桩基的传感器测点布置结果,并对测点布置进行评估。模态向量间的夹角趋于正交,传感器布置方案有效,证明该传感器优化布置方法适用于高桩码头的传感器优化布置。     

基于光纤布拉格光栅的船闸人字门健康状态远程监测系统

为解决船闸人字门长期工作过程中形成的结构损伤及积累损伤，提出了一种基于光纤布拉格光栅（fiber bragg grating，简称FBG）的船闸人字门健康状态远程实时监测技术方案。依据船闸人字门实际受力状况及特殊水域环境工作状态，布设FBG传感器网络对船闸状态进行远程监控，经信号解调、数据处理与分析、损伤识别与安全评定系统综合评定船闸人字门的整体健康状态，解决了定期停航进行人工检修方式存在的影响航道运输、无法实时监测及预警等弊端。对提高安全通航效率、保障设备设施运行安全具有重要意义。     

Towards a holistic digital twin solution for real-time monitoring of aquaculture net cage systems

Digital twins and relevant concepts are being applied in a wide variety of ways, and they are of most use when an actual real-world physical system or process (a physical twin) is changing over time and when measurement data correlated with this change can be captured. In this work, a digital twin model was implemented for real-time monitoring of aquaculture net cage systems, which is notoriously challenging because of several difficult-to-measure properties, such as forces on and deformation of the flexible netting structures, waves and flow field alterations around the cage and complex stiffness behaviour of the mooring elements made by fibre ropes. These properties were set to be adaptable according to the resultant outputs, such as cage responses and mooring loads that were continuously compared with the measurement data obtained from remote monitoring sensors. In this way, real-time sensor data were assimilated into the numerical simulation model for representing the actual net cage system. No dedicated sensors were used for fish monitoring, but the fish behavioural responses to current, wave and cage deformation were modelled according to relevant field observational data. A wireless sensor network has also been tested for the digital twin implementation, which was found to be suitable for practical uses in fish farms.     

冰区海上风电基础的抗冰性能分析

海上风电基础属于典型的柔性结构。由于冰与柔性抗冰结构相互作用的复杂性,长期以来尚未形成基于动冰力响应分析的结构设计。结构抗冰设计中大都是从极端荷载出发,只考虑最大静冰力或最大倾覆力矩。基于对渤海辽东湾柔性抗冰结构的多年监测,发现强烈的冰激振动引起柔性结构的风险性要远大于极端静冰荷载下结构的整体安全问题。为了明确冰区风电基础结构的抗冰性能及抗冰设计的合理性,文章结合基于多年现场冰与结构作用观测及冰荷载的研究成果,明确该类柔性结构与海冰作用形式及其动力特性;提出了柔性抗冰结构设计中应考虑的主要失效模式及评价方法。最后,以渤海某典型风电基础为例,对其抗冰性能进行评价。该文的研究可为寒区风电基础的抗冰设计及安全保障提供合理依据。     

抗冰海洋平台的全寿命优化设计I-理论与模型

文章基于投资—效益准则,建立了抗冰平台全寿命总费用最小的优化设计模型;考虑了多种类型的性能要求(结构、设备、人员),并建立了相关判据;提出了包括结构的初始费用、维修费用和期望损失费用的冰区海洋平台全寿命总费用评估模型;提出了平台结构主要功能的确定及描述方法、相应的功能失效损失值估计模型。     

Potential of a repair system for grouted connections in offshore structures: Development and experimental verification

Grouted connections are intensively used in offshore rigs, platforms as well as jacket and monopile offshore wind turbine structures. Being located in remote offshore conditions, these connections can experience considerable adverse loading during their lifetimes. Degradation was reported inside similar connections, which were installed in the last three decades. Grouting in the offshore sites may often be proven difficult, which eventually leads to reduced load-bearing capacity of connections in the long run. Thus, repair and rehabilitation of such connections should be planned ahead to minimize operational delays and costs. In this study, scaled grouted connections were manufactured using a novel mould, whose integrity were monitored using digital image correlation (DIC). The connections were loaded under static load to visualize the main failure pattern using distributed fibre optic sensors and acoustic emission (AE) analysis. Grouted connections were then repaired using a cementitious injectable grout. The effectiveness of the grout injection was monitored using dye penetration technique. Finally, specimens are reloaded to identify the potential of such repair for grouted connections.     

基于k-检测的无线传感器网络探测能力分析

对进入监控区域的运动目标进行探测跟踪是无线传感器网络的重要功能之一,论文以BOOL模型传感器节点为基础,分析了基于k-检测的无线传感器网络中,目标从无线传感器网络边界进入内部一定距离被发现的概率,以及目标的运动速度与网络探测概率之间的关系.通过仿真表明,传感器节点的布设密度、传感器的感知半径与探测概率以及目标的最大速度之间存在着一定的关系,这为根据实际需要进行传感器节点布设和传感器参数设计提供了参考.     

船舱内异常压力警戒监控平台的设计与实现

传统方法一般基于物联网技术对船舱内的异常压力警戎监控,且主要通过增加数据分析模块来缩短监控时间,却忽略了监控领域对监控性能的影响,存在监控不准确、效率低及性能差的问题。提出一种船舱异常压力警戒监控的无线网络平台。对硬件部分的警戒模块、接口模块、电源模块、控制模块、传输模块、采集模块进行分析,通过采集模块对船舱异常压力警戒监控数据进行采集,利用传输模块将所得数据进行传输,借助接口模块对各模块进行接口设置,电源模块提供电源,警戒模块主要是对船舱内异常压力进行警戒,并设计无线网络平台软件部分。实验结果证明,所设计的监控无线网络平台其监控所需时间更短、准确度更高,具有更好的性能。     

腐蚀和裂纹损伤下海洋平台极限强度试验研究

根据墨西哥湾某一典型固定式海洋平台为原型,按照刚度相似性和几何相似性,分别设计并制作了完好模型、腐蚀模型、裂纹模型,并对三个试验模型开展极限强度试验研究,试验结果表明腐蚀、裂纹损伤严重影响试验模型极限承载力,且试验模型失效模式各不相同.同时,采用非线性有限元方法,分别对三个试验模型进行计算,将计算结果与试验结果对比分析,验证了该方法在固定式海洋平台极限强度计算方面的有效性.     

Detection of nonlinearity effects in structural integrity monitoring methods for offshore jacket-type structures based on principal component analysis

The detection of changes in the dynamic behavior of structures is an important issue in structural safety assessment. The development of detection methods assumes greater significance in the case of offshore platforms because the inherent problems are compounded by the harsh environment. Here, we describe an instrumented physical model for the structural health monitoring of an offshore jacket-type structure and the results of tests in several different damage scenarios. In a comparative investigation of two different methods, we discuss the difficulties of implementing damage detection techniques for complex structures, such as offshore platforms. The combined algorithm of a fuzzy logic system and a model updating method are briefly discussed, and a method based on stochastic autoregressive moving average with exogenous input is adopted for the structure. The consideration of uncertainties and the effects of nonlinearity were major objectives. So, the methods were also investigated based on the test scenarios consisting of the physical model with a geometric nonlinearity. The principal component analysis method was utilized for the detection of nonlinearity in the recorded data. The results show that the developed methods are suitable for damage classification, but the quality of the acquired signals must be considered an important factor influencing successful classification. The development of these methods may be extremely useful, as such technologies could be applied for offshore platforms in service, enabling damage detection with fewer false alarms.     

基于嵌入式的海洋运输环境数据采集与动态监控节点设计

为保障海上船舶运输数据的有效采集和监控,需要对海上船舶运输数据环境监控系统进行设计。采用当前算法进行监控时,存在监测范围小、成本高、功耗高、实时性低等问题。为此,提出一种低功耗适用于海洋运输环境的物联网动态监控的节点设计方案。该方案先定义基于物联网的海上船舶运输环境数据监控系统模型,将此系统模型分为无线传感网络、汇聚节点和监控中心,在此基础上对传感器节点、汇聚节点以及监控中心的硬件均进行设计,并给出基于ZigBee技术的无线传感器组网过程,设计出基于物联网的海上船舶运输环境数据监控系统。实验结果表明,该方法能够对海洋环境信息进行数据采集和动态监控,具有低成本、功耗低和丢包率低等方面的优点,具有可行性。     

基于ZigBee无线网络的海岛环境监测系统研究

ZigBee是一种基于IEEE802.15.4协议的新兴无线网络技术。文章简要介绍了ZigBee技术的发展概况,对基于ZigBee无线网络的海岛环境监测网络系统的工作原理进行了分析。最后进行了传感器数据收发试验,结果验证了系统的可行性。