Research On Failure Mechanism Of Composite Repair Corroded Pipe Based On Durability

In order to study the failure mechanism of the composite material to repair the corrosion pipeline more deeply,the debonding condition and ultimate bearing capacity of the composite material to repair the corrosion pipeline under different load types are obtained,and the composite material repair pipeline under the joint action of temperature field and chemical field is obtained.The failure mechanism and durability law solve some restrictive problems in the popularization of composite materials.This paper attempts to study the stress distribution of the bonding layer by theoretical method,and obtain the initial debonding of the bonding layer by comparing the strength limit of the bonding agent.Through the experimental method to study the durability of composite repair pipelines under different temperature fields and different seawater immersion time,the theoretical and experimental phenomena were compared by finite element method.(1)In this paper,based on the structural characteristics of composite materials to repair corrosion pipelines,a theoretical model of bonded composite reinforced multi-layer pipelines was established,and the distribution function of various stresses along the axial direction of the complete multi-layer pipeline bonding layer was derived.The factor predicts the maximum stress of the corrosion layer of the corrosion pipe.At the same time,the stress distribution of the finite element extraction is compared and verified,and the stress distribution of the corrosion layer of the corrosion pipeline is further verified by finite element method.(2)Through the debonding criterion of the bonding material,the initial debonding load of the bonding layer is estimated by theoretical method,and the bonding layer failure condition is obtained by the Cohesive element.According to the ultimate bond load durability law of the bonding layer,the durability law of the initial debonding load is obtained.(3)A new finite element model was established.By defining the ductile damage of metal materials to simulate the fracture phenomenon of metal materials,the Cohesive bonding unit was introduced to represent the bonding layer,and the failure phenomenon of the bonding layer of the composite material layer and the corrosion pipeline was simulated.Define the failure state of composite progressive damage simulation composites.Tensile fracture failure simulations of four models of unrepaired corrosion pipelines,complete pipelines,composite repair corrosion pipelines and composite reinforcement pipelines were carried out by finite element method,and the experimental results were verified.(4)Study the durability law of pipelines in different temperature fields through experimental methods.In the experiment,the durability of composite tensile specimens,binder resin casting specimens,intact pipelines and composite materials to repair corrosion pipelines were studied.The experimental temperature set in the wet test chamber was room temperature 20 °C,50 °C and 80 °C,respectively.After immersing in brine for different time(0h,250 h,500h,750 h,1000h),the tensile test was carried out by universal tensile testing machine.The ultimate load of various specimens decreases with temperature and soaking time.