Bending resistance test and buckling failure prediction model of pipelines with wrinkled dents
Dent is one of the typical defects in oil and gas pipelines,and it poses a threat to pipeline integrity.To this end,this paper studies the buckling behavior and ultimate bending resistance of pipelines with wrinkled dents under the action of bending moment load.Firstly,a four-point bending test of full-scale pipeline with wrinkled dents is conducted in the laboratory,and the critical buckling load and strain response law of the pipeline in the process of buckling failure are tested.Then,a nonlinear finite element(FE)numerical model of buckling failure of pipeline with wrinkled dents subjected to bending moment load is developed,and its reliability is verified by comparing with the experimental data.Based on this,parameter sensitivity analysis is carried out.Finally,based on the results of a large number of FE numerical simulation cases,a novel model of predicting the ultimate bending moment of pipeline with wrinkled dents is developed.The following results are obtained.First,the existence of wrinkled dents can weaken the bending resistance of the pipeline,especially the deeper wrinkled dents.Second,in the process of pipeline buckling,a considerable compressive strain is generated at the center of the dent bottom,which is much higher than the strain value at the corresponding position of the intact pipeline.The strain at the ends of both sides of dent axis direction gradually changes from the compressive strain at the initial stage of bending to the tensile strain after buckling failure.Third,with the increase of the dent depth,the bending resistance of the pipeline decreases rapidly.The smaller the pipeline diameter-thickness ratio,the stronger the bending resistance of the pipeline with wrinkled dents.The increase of the internal pressure can improve the bending performance of the pipeline to a certain extent,so as to avoid the occurrence of buckling.The bending resistance of the pipeline with wrinkled dents increases with the increase of yield strength and tensile strength,but the enhancement is limited.In conclusion,the maximum prediction error of the buckling failure prediction model is 10.87%,and the average error is only 3.59%.In engineering,therefore,it can be used to evaluate the ultimate bending resistance of pipelines with wrinkled dents of below 15%D depth.What's more,the established model can quantitatively evaluate the critical bending moment of pipelines with wrinkled dents,and can be used in the evaluation and early warning of the buckling stability failure of such pipeliness.
万方数据
维普
