Research On Pipeline Damage Identification Method Based On Analysis Of Strain Modal And Dynamic Characteristics

As one of the important transportation tools,pipelines have special advantages in transporting fluid media and are widely used in petrochemical,heating and water supply fields.During the service process,the pipeline will be damaged due to the corrosion of the internal medium and the influence of the external working environment.Pipeline damage will cause pipeline deformation,rupture,leakage and other problems,which will bring safety issues that cannot be ignored to industrial production and residents' lives.Therefore,it is necessary to conduct research on pipeline damage identification methods.Aiming at the difficulty of damage identification of complex pipelines with compound damage,this paper has carried out research on pipeline damage identification based on the method of dynamic characteristics analysis.The main research contents are as follows:1.Based on the research of pipeline statics analysis theory and vibration modal analysis theory,based on the characteristics of engineering pipelines,a proportional similar pipeline model is constructed,and a numerical model of the pipeline is established using finite element software.2.Research on the statics characteristics of the pipeline.The finite element software was used to analyze the stress and strain changes before and after the pipeline damage,and the stress and strain test system platform was built to analyze the actual situation of the pipeline,and the numerical simulation results were compared with the actual measurement results.Experimental studies have shown that when a simple pipeline is damaged,stress concentration occurs at the damage location,and the strain changes before and after the pipeline damage are more obvious,which can be used to judge the damage of the pipeline.When the research object is a complex pipeline,the stress and strain changes before and after the pipeline damage are not large,and the damage situation of the pipeline cannot be judged.Therefore,the damage identification method based on the static characteristics of the pipeline is effective for the damage of simple pipelines,but the ability to identify the damage of complex pipelines is limited.3.In order to study the damage of pipelines with relatively complex structures,a pipeline damage identification method that takes the square change ratio of natural frequency as a key parameter is proposed.The modal analysis of the pipeline is carried out by using the finite element software to obtain the natural frequency of the pipeline,and the square change ratio of the natural frequency of each order of the pipeline is calculated,which is used to identify the damage of the pipeline.Finally,it is verified by the method based on the pipeline test modal.Studies have shown that the damage identification method based on the squared change ratio of the natural frequency of the pipeline has a good identification effect,but this method is suitable for the single damage mode of the complex pipeline,and has limitations on the compound damage mode of the complex pipeline,and further research is needed.4.Aiming at the compound damage mode of complex pipelines,a damage identification method based on strain mode difference is studied.The strain mode theory of pipeline is introduced,the strain mode of pipeline is simulated numerically by using finite element software,and the strain mode difference of pipeline is calculated,through which the damage identification of pipeline is carried out.In order to verify the feasibility of this method,a strain modal experiment was carried out on the pipeline.Research has shown that,for complex pipeline damage modes,the pipeline damage identification method based on poor strain modal has a good identification effect.This paper studies the pipeline damage identification method,enriches the theoretical methods and treatment means of pipeline damage diagnosis,and has good engineering guiding significance for the health monitoring of inservice pipelines in petrochemical industry.