Research On Non-invasive Detection Method Of Pipeline Pressure Based On Fiber Bragg Grating

With the extensive use of pressure pipelines in various fields,the safe operation of complex pipeline systems has become increasingly important.Therefore,pipeline pressure detection technology has also received more and more attention in various industrial and engineering fields.However,due to many limitation,traditional pipeline pressure detection methods are unable to meet the application requirements.In term of non-intrusive detection of pipeline pressure,fiber grating has advantages such as light weight,small size,low loss,anti-electromagnetic interference,long-distance transmission,ability to realize distributed array networking and embed various smart materials flexibly,and gradually it become an efficient and reliable detection method.In this paper,the pressure pipeline is taken as the research object,and the design and experiment which were based on non-intrusive sensors of fiber grating were carried out,It mainly includes the following three contents:This paper deeply analyzes the types of stress and strain in the pipeline and its production principle,focusing on the influence of various factors such as pipe material,pipe inner diameter,pipe wall thickness,and pipe internal pressure on the pipe wall strain law.With the help of AutoCAD,ProE and AnsysWorbench software,the pipeline pressure non-intrusive sensors were designed,modeled and simulated.A pipeline pressure detection mechanism with a 10 mm width,4mm thickness,and a two-leaf hoop structure with ears and a 4mm thick,double-beam-shaped rhombus structure with a width of 4mm on the side of the base body was proposed.On the basis of further understanding of the sensing principle of fiber grating,the mathematic model of pipeline pressure testing mechanism was deduced based on the content of materials and elastic mechanics.The characteristics of pipeline fluid-solid coupling are analyzed emphatically,Taking a stainless steel pipe with 120 mm inner diameter and 2mm wall thickness as the research object,a simulation model of fluid,pipeline and detection mechanism was established,the simulation method of computational fluid mechanics and material mechanics was used,and the distribution of flow field and pressure field in the pipe when the pipe is under pressure and the strain characteristics of the pipe wall caused by fluid pressure were known well and the rationality of design of pipeline pressure sensor has been verified.Various diamond detection mechanism models with different materials and sizes was processed,pipeline stress test experiment been done many times based on strain gage and fiber grating.It is proved that the long diagonal is about 2.5 times shorter than the short diagonal and the material is a diamond structure of 7075 aluminum alloy has the best measurement effect on the strain of the pipe wall.The strain transfer efficiency of fiber grating is much higher than that of strain gauge.