Reliability analysis of carbon fiber rod-reinforced umbilical cable under tension using an improved sampling method

The umbilical cable is a vital component of subsea production systems that provide power,chemical agents,control signals et al.,and its requirement for reliability is exceedingly high.However,as the umbilical cable is a composite structure comprising multiple functional units,the reliability analysis of such cables involves numerous parameters that can impact calculation efficiency.In this paper,the reliability analysis of a new kind of umbilical cable with carbon fiber rod under tension is analyzed.The global dynamic analytical model is first established to determine the maximum tension load,then the local analytical model of umbilical cable including each unit are constructed by finite element method(FEM).Based on the mechanical analytical model,the reliability of umbilical cable under tension load is studied using response surface method(RSM)and Monte Carlo method.During the calculation process,a new tangent plane sampling method to calculate the response surface function(RSF)is proposed in this paper,which could make sampling points faster come close to the RSF curve,and it is proved that the calculation efficiency increases about 33%comparing with traditional method.

Assessment of the Mechanical Properties of Carbon-Fiber Heating Cables in Snow and Ice Melting Applications

The use of carbon-fiber heating cables(CFHC)to achieve effective melting of snow and ice deposited on roads is a method used worldwide.In this study,tensile and compressive tests have been conducted to analyze the mechan-ical properties of the CFHC and assess whether the maximum tensile and compressive strengths can meet the pavement design specifications.In order to study the aging produced by multiple cycles of heating and cooling,in particular,the CFHC was repeatedly heated in a cold chamber with an ambient temperature ranging between-20℃ and+40℃.Moreover,to evaluate how the strength of the pavement is affected by its presence,the CFHC was embedded at different depths and concrete blocks with different curing ages were subjected to relevant com-pression and splitting tensile tests.Numerical simulations based on the ANSYS software have also been performed and compared with the outcomes of the static loading tests.The results show that the CFHC embedded in the concrete does not affect the compressive splitting tensile strengths of the pavement.Overall,the CFHC meets the conditions required for continued use in road ice melting applications.

Optical Fiber Grating Sensor for Force Measurement of Anchor Cable

The development of the sensor suitable for measuring large load stress to the anchor cable becomes an important task in bridge construction and maintenance. Therefore, a new type of optical fiber sensor was developed in the laboratory - optical fiber grating sensor for force measurement of anchor cable （OFBFMAC）. No similar report about this kind of sensor has been found up to now in China and other countries. This sensor is proved to be an effective way of monitoring in processes of anchor cable installation, cable cutting, cable force regulation, etc, with the accurate and repeatable measuring results. Its successful application in the tie bar cable force safety monitoring for Wuhan Qingchuan bridge is a new exploration of optical fiber grating sensing technology in bridge tie bar monitoring system.

A new monitoring method of cable tension of cable-stayed bridge—fiber Bragg grating method

A new on-line monitoring method based on fiber Bragg grating(FBG) for cable tension of cable-stayed bridge was introduced. The major structure of sensing head using in the test of cable tension is elastic annular. The FBG is attached inflexibility to the exterior surface of annulus and form straight-through sensing head. Sensing head is installed between the anchor device and stow-board of funiculus holes of the cable-stayed bridge. Accompany with the change of the outside pressure, the Bragg center reflective wavelength of optical fiber grating changed correspondingly. According to this characteristic, through demodulating the Δλ, the value of the cable tension can be determined. The experiment results and the theory indicate that the test system has simple structure, good stability and linear,wide response capacity, and has no special request for tester, The measurement method for the test of cable tension is practical and effective.

Reattachment of the Osteotomized Greater Trochanter in Hip Surgery Using an Ultrahigh Molecular Weight Polyethylene Fiber Cable: A Multi-Institutional Study

The purpose of this multicenter study was to evaluate the clinical performance of an ultrahigh molecular weight polyethylene (UHMWPE) fiber cable for re-attachment of the osteotomized greater trochanter in hip surgery. Included in the study were 85 hips that had undergone surgery with greater trochanter osteotomy, including 50 hip arthroplasty procedures and 35 hip osteotomies. The osteotomized greater trochanter was reattached using one or more UHMWPE fiber cables. The bone union and displacement of the greater trochanter were assessed in radiographs for up to 12 months after surgery. Non-union of the osteotomy site occurred in 4.7% of the cases. In approximately 90% of the cases, displacement was less than 2 mm at up to 12 months after surgery. The UHMWPE fiber cable was a good biomaterial for reattaching the osteotomized greater trochanter and may also be an option for osteosynthesis procedures.

A distributed measurement method for in-situ soil moisture content by using carbon-fiber heated cable

Moisture content is a fundamental physical index that quantifies soil property and is closely associatedwith the hydrological, ecological and engineering behaviors of soil. To measure in-situ soil moisturecontents, a distributed measurement system for in-situ soil moisture content （SM-DTS） is introduced.The system is based on carbon-fiber heated cable （CFHC） technology that has been developed to enhancethe measuring accuracy of in-situ soil moisture content. Using CFHC technique, a temperature characteristicvalue （Tt） can be defined from temperatureetime curves. A relationship among Tt, soil thermalimpedance coefficient and soil moisture content is then established in laboratory. The feasibility of theSM-DTS technology to provide distributed measurements of in-situ soil moisture content is verifiedthrough field tests. The research reported herein indicates that the proposed SM-DTS is capable ofmeasuring in-situ soil moisture content over long distances and large areas.

Parameters of static response of carbon fiber reinforced polymer(CFRP) suspension cables

The feasibility of longer spans relies on the successful implementation of new high-strength light weight materials such as carbon fiber reinforced polymer(CFRP). First, a dimensionless equilibrium equation and the corresponding compatibility equation are established to develop the cable force equation and cable displacement governing equation for suspension cables, respectively. Subsequently, the inextensible cable case is introduced. The formula of the Irvine parameter is considered and its physical interpretation as well as its relationship with the chord gravity stiffness is presented. The influences on the increment of cable force and displacement by λ2 and load ratio p′ are analyzed, respectively. Based on these assumptions and the analytical formulations, a 2000 m span suspension cable is utilized as an example to verify the proposed formulation and the responses of the relative increment of cable force and cable displacement under symmetrical and asymmetrical loads are studied and presented. In each case, the deflections resulting from elastic elongation or solely due to geometrical displacement are analyzed for the lower elastic modulus CFRP. Finally, in comparison with steel cables, the influences on the cable force equation and the governing displacement equation by span and rise span ratio are analyzed. Moreover, the influences on the static performance of suspension bridge by span and sag ratios are also analyzed. The substantive characteristics of the static performance of super span CFRP suspension bridges are clarified and the superiority and the characteristics of CFRP cable structure are demonstrated analytically.

STUDY ON MINE FIRE-RESISTANT OPTICAL FIBER CABLE KL5004

This paper introduces a new-developed mine fire-resistant optical fiber cable (OFC)KL5004,its structural characteristics, main feature, the theory about fire resistance and its application in high output and efficiency mine.

Performance evaluation of two types of heated cables for distributedtemperature sensing-based measurement of soil moisture content

Distributed temperature sensing(DTS)using heated cables has been recently developed for distributed monitoring of in-situ soil moisture content.In this method,the thermal and electrical properties of heated cables have a significant influence on the measurement accuracy of soil moisture content.In this paper,the performances of two heated cables,i.e.the carbon-fiber heated cable(CFHC)and the metalnet heated cable(MNHC),are studied in the laboratory.Their structures,uniformity in the axial direction,measurement accuracy and suitability are evaluated.The test results indicate that the MNHC has a better uniformity in the axial direction than CFHC.Both CFHC and MNHC have high measurement accuracy.The CFHC is more suitable for short-distance measurement(500 m),while the MNHC can be used for longdistance measurement(>500 m).

Aerodynamic stability of cable-supported bridges using CFRP cables

To gain understanding of the applicability of carbon fiber reinforced polymer (CFRP) cable in cable-supported bridges, based on the Runyang Bridge and Jinsha Bridge, a suspension bridge using CFRP cables and a cable-stayed bridge using CFRP stay cables are designed, in which the cable’s cross-sectional area is determined by the principle of equivalent axial stiffness. Numerical investigations on the aerodynamic stability of the two bridges are conducted by 3D nonlinear aerodynamic stability analysis. The results showed that as CFRP cables are used in cable-supported bridges, for suspension bridge, its aerodynamic stability is superior to that of the case using steel cables due to the great increase of the torsional frequency; for cable-stayed bridge, its aerodynamic stability is basically the same as that of the case using steel stay cables. Therefore as far as the wind stability is considered, the use of CFRP cables in cable-supported bridges is feasible, and the cable’s cross-sectional area should be deter-mined by the principle of equivalent axial stiffness.

Dynamical modeling and non-planar coupled behavior of inclined CFRP cables under simultaneous internal and external resonances

A dynamic model for an inclined carbon ?ber reinforced polymer(CFRP)cable is established, and the linear and nonlinear dynamic behaviors are investigated in detail. The partial differential equations for both the in-plane and out-of-plane dynamics of the inclined CFRP cable are obtained by Hamilton's principle. The linear eigenvalues are explored theoretically. Then, the ordinary differential equations for analyzing the dynamic behaviors are obtained by the Galerkin integral and dimensionless treatments.The steady-state solutions of the nonlinear equations are obtained by the multiple scale method(MSM) and the Newton-Raphson method. The frequency-and force-response curves are used to investigate the dynamic behaviors of the inclined CFRP cable under simultaneous internal(between the lowest in-plane and out-of-plane modes) and external resonances, i.e., the primary resonances induced by the excitations of the in-plane mode,the out-of-plane mode, and both the in-plane mode and the out-of-plane mode, respectively. The effects of the key parameters, e.g., Young's modulus, the excitation amplitude,and the frequency on the dynamic behaviors, are discussed in detail. Some interesting phenomena and results are observed and concluded.

Evaluation of cable tension sensors of FAST reflector from the perspective of EMI

The active reflector of FAST （ five-hundred-meter aperture spherical radio telescope） is suppor- ted by a ring beam and a cable-net structure, in which nodes are actively controlled to form series of real-time paraboloids. To ensure the security and stability of the supporting structure, tension must be monitored for some typical cables. Considering the stringent requirements in accuracy and long- term stability, magnetic flux sensor, vibrating wire strain gauge and fiber bragg grating strain gauge are screened for the cable tension monitoring of the supporting cable-net. Specifically, receivers of radio telescopes have strict restriction on electro magnetic interference （EMI） or radio frequency in- terference （RFI）. These three types of sensors are evaluated from the view of EMIfRFI. Firstly, these fundamentals are theoretically analyzed. Secondly, typical sensor signals are collected in the time and analyzed in the frequency domain, which shows the characteristic in the frequency domain. Finally, typical sensors are tested in an anechoic chamber to get the EMI levels. Theoretical analysis shows that Fiber Bragg Grating strain gauge itself will not lead to EMI/RFI. According to GJB151 A, frequency domain analysis and test results show that for the vibrating wire strain gauge and magnetic flux sensor themselves, testable EMIfRF1 levels are typically below the background noise of the ane- choic chamber. FAST finally choses these three sensors as the monitoring sensors of its cable ten- sion. The proposed study is also a reference to the monitoring equipment selection of other radio tele- scopes and large structures.

预应力锚索用腐蚀传感器的设计

预应力锚索的腐蚀程度与结构安全密切相关,但一直缺乏有效的监测手段。考虑到腐蚀的发生与周围环境pH变化密切相关,选用HEMA-AA水凝胶作为敏感材料并结合光纤光栅的传输优势设计传感器,识别灌浆部分受拉开裂时腐蚀介质侵入引起的pH值变化,在锚索面临腐蚀威胁时做出预警。测试结果表明:传感器的测量范围为pH值4~11,灵敏度为25 pm/pH,相关系数0.997;对比裸光纤发现将水凝胶的涂覆并没有带来光纤光栅温度特性的明显变化,灵敏度为9.5 pm/℃;试验模拟传感器在环境中持续进行监测的性能较为稳定。若考虑应用环境干湿循环的限制,则需提高水凝胶和光纤光栅结合度。通过在锚索内设置腐蚀传感器,可以达到腐蚀监测的目的。

光纤光栅索力传感器的酸碱耐久性

拉索作为斜拉桥的主要受力构件常处于复杂、恶劣的工作环境,传统的索力监测手段存在一定的局限性。将光纤光栅传感器内嵌封装进金属承压块上的凹槽,研制一种光纤光栅索力传感器,并对两种环氧树脂胶黏剂封装的光纤光栅索力传感器在酸碱腐蚀环境下的耐久性能进行研究,然后依托逆幂律模型与老化动力学理论,推导出传感器寿命预测方程。试验结果表明:该传感器的线性度和稳定性良好,传感器在腐蚀溶液中失效的主要原因是封装部位界相区胶黏剂受腐蚀剥落。A类传感器的耐酸碱性强于B类传感器,A类传感器在弱酸弱碱环境中的使用寿命均超过35年,大于斜拉桥拉索平均20年的换索年限,可以实现拉索全生命周期的监测。

桥梁缆索智能监测多参量光纤传感器及其封装保护技术

本文介绍了一种可直接植入缆索结构内部,实现缆索温度、湿度和应变多参量同步监测的新型光纤传感器。采用飞秒光纤光栅无损刻写技术制作缆索监测传感光纤,大幅提升了传感器耐久性。研发了基于聚酰亚胺套管的增敏型湿度传感器,大幅提升传感器测量灵敏度。提出了基于螺旋铠装+不锈钢套管的双层光纤传感器封装保护方案。研究了传感光纤从缆索锚头区域引出工艺,并开展了缆索试验研究,验证了本文研发的缆索监测多参量光纤传感器在实际缆索样品应用中的效果。

基于光纤传感技术的工程监测应用研究

光纤传感技术作为当前热门技术之一,在工程监测领域有着许多重要应用。通过探讨光纤传感技术在工程形变监测中的应用案例,展示了其在工程监测领域的重要性。光纤传感技术利用光纤作为传感元件,可以实现对形变的连续、实时监测,并提供高精度的监测数据。通过布设应变光缆和温度补偿光缆,在合璧津高速公路K134段高架桥上进行了监测实验。结果表明,光纤传感技术能够准确评估结构的变形情况,并通过温度补偿算法消除了温度变化对数据的影响。通过几何方法计算沉降位移,可以实现对沉降位移的估算。

同轴电缆用超疏水二氧化硅@石英纤维复合材料的性能研究

具有低介电常数的SiO_(2)复合材料在低介电和隔热保温材料领域有着广阔的应用前景,但SiO_(2)复合材料在实际应用中存在吸水性强、保存条件苛刻等问题。使用疏水改性剂(六甲基二硅氮烷(HMDS)、硬脂酸、十二烷基硫酸钠)对SiO_(2)@石英纤维复合材料进行改性,研究疏水改性剂类型及质量分数对复合材料疏水性能和介电性能的影响。结果表明,3%的HMDS改性复合材料的疏水改性效果最好(接触角为151.6°),保存240d后接触角最低为132.6°,200℃煅烧后复合材料的介电常数低至1.87。将疏水改性SiO_(2)@石英纤维复合材料制成同轴通信电缆,所得电缆的电压驻波比为1.48,衰减值为1.56dB,特性阻抗为48Ω。疏水改性复合材料具有优异的电缆性能,在通信电缆等领域展示出潜在的应用价值。

动态缆上弯段曲率分布特征研究

动态缆的疲劳寿命设计与分析过程中需要获得疲劳热点位置的准确响应,而动态缆曲率的理论预测模型与数值模型基于大量假设且结果缺乏验证,因此需要对动态缆上弯段曲率分布情况开展实验研究。该文提出基于分布式光纤测量技术的曲率测量方法,建立含空隙的动态缆-防弯器系统在疲劳荷载作用下的有限元模型,并设计动态缆-防弯器系统原型拉弯试验,采用所提出的测量方法进行动态缆曲率分布测量。结果表明动态缆缆体处最大曲率较防弯器处最大曲率偏大9.9%,且增大拉力值与摆动角度将增大动态缆最大曲率并使最大曲率发生位置前移。该文提出的基于分布式光纤测量技术的动态缆曲率测量方法可为动态缆的原型试验和疲劳设计提供数据支持。

分布式复合缆光纤产出剖面测井工艺在海上油气田的应用

复合光纤测井技术是一种高精度、高可靠性、高分辨率的测井技术,在油气勘探和开发领域得到广泛应用。在现场实施过程中,复合光纤测井技术可以实时监测油气井储层温度、压力、应变等参数,及时发现异常情况,并采取相应措施,保障油气生产的稳定性和安全性。文章详细介绍了复合光纤测井技术的原理、方法和实现方式,与常规技术进行对比,分析了该技术在现场应用中的优点和局限性,并提出了未来研究的方向和建议。

多层光纤线包结构稳定性高效计算模型与分析

光纤线包的结构稳定性显著影响光纤系统的服役状态,为解决以有限单元法为代表的数值分析方法,因光纤线包缠绕层数多、非线性强等因素导致的计算时间长、效率低等问题,根据光纤层间仅受压的特点建立光纤线包结构稳定性的高效计算模型,分析光纤的缠绕制度和线径的均匀程度对光纤线包结构稳定性的影响规律,给出线包失稳的线径均匀性临界值。研究结果表明:相比于有限元仿真,该模型在不损失计算精度的前提下计算效率可提升约100倍;等残余张力缠绕制度更有利于线包的结构稳定性;当线径的偏差值超过标准线径的±3%时,光纤位移急剧增大,严重影响光纤线包的结构稳定性;此研究对于多层光纤线包绕制工艺的实时分析和控制具有重要的意义。