Analysis And Research On Cross-sectional Tensile Properties Of The Composite Cable

Jacket platform plays an important role in offshore oil and gas.Many jacket platforms,especially in South China Sea and the Bohai Sea,have been working for many years and close to the service life,so how to prolong the service life is an important challenge.The tension anode system has become the choice of many cathodic protection for over-age service platforms with its reliable structure design uniform protection,relatively low construction difficulty and cost.Two vertically tensioned anode string are developed by DLUT and CNOOC,based on the need of the platform in South China Sea.The vertically tensioned anode string mainly includes DC power Supply,multiplex controller,composite cable,impressed current anode electrode,gravity base and other supporting equipment.The composite cable is one of the key components of the tensile anode system.It has met the requirements of the factory testing such as fatigue test,water tightness test,high pressure test and insulation resistance test.At the same time,it was a special kind of the cable,which has the abilities of the tensile capacity and the electrical properties.There are more correlation tests to verify its performance but less theoretical study for the composite cable.Therefore,the research object of this paper is the theoretical study of the composite cable.The aim of this paper is to provide a theoretical basis for the optimization of the composite cable,through the study of the tensile strength of the composite cable section.Firstly,this paper introduces the research background and significance of the paper.According to the structure of the composite cable structure and the mechanical characteristics,this paper focuses on the wire rope of the composite cable.Then the current research status and shortcomings of the wire rope are introduced,and the research content and the structure arrangement are put forward.Then,this paper develops the further perfected the theory of the strand and study the relationships of axially applied loads and displacements of a simple rope,which contains simple straight stand and multilayered strands.The results from the current model have been compared to the theory developed by Costello.Afterwards,a theoretical approach to formulate the axial behavior of complex rope has been developed.This is a modification of the frictionless strand theory.The modified method is used in the analysis a 6X24 wire rope with fibrous core and 6X19 IWRC wire rope.The stiffness matrix is obtained finally.Finally,the theory of the complex wire rope is applied to analyze the inner wire rope of the composite cable.First,the deformation relationships between steel wire,strands and wire rope is discussed,so as to provide a theoretical basis for the monitoring of composite cable tension.Then the equivalent axial stiffness of the wire rope under axial load is further obtained.The axial stiffness of the wire rope is obtained,according to the relevant parameters provided by the manufacturer and is compared with the experimental value of the abstract.