Method for detecting long-distance linear organization abnormal vibration based on distributed optical fibre sensor

Abstract

The invention is characterized in that: Brillouin distribution type optical fiber sensor is arranged on linear structure, and the strain signal of optical fiber is detected, and then the strain signal is calibrated so as to obtain linear structural strain curve, moreover by adopting mode identification method based on time sequence analysis method, data processing is made, so as to extract abnormal data in the linear structure strain time sequence and judge the state of linear structure. EMD method is adopted to extract potential simulation component in linear structure span random strain response, random decrement method RDT is applied to extract self-vibration frequency of each stage from the linear structure span random strain response, according to the self-vibration frequency experimental formula given by related standard, the span length of linear structure is calculated. The invention adopts the multi-shaft fatigue strain life model (Shangdeguang model) based on rain flow count method to predict fatigue life of linear structure.

Description

technical field [0001] The invention relates to the field of optical fiber sensing and detection, in particular to a method for detecting abnormal vibration of a long-distance linear structure based on a distributed optical fiber sensor, which is used to analyze and judge the abnormality of strain and frequency of the monitored linear structure, and provide the remaining life of the structure. Background technique [0002] Linear structure is one of the more common structural forms in industrial production, such as: submarine pipelines, oil / gas / water pipelines, cables, etc. In order to solve the problem of safe production of linear structures, some advanced countries in the world began to develop linear structure testing equipment as early as the 1960s. At present, the more common linear structure detection methods are mainly divided into two types: in-pipe monitors and out-pipe monitors of submarine pipelines. [0003] 1) In-tube detection technology. Including: smart pig...

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Problems solved by technology

Although the in-pipe detection technology of submarine pipelines is relatively mature, the in-pipe detection is mainly aimed at corrosion and radial deformation of submarine pipelines, and the erosion of subsea water flow causes partial subsea pipelines to hang in the air; vortex-induced vibrations cause buckling deformation, cracking and damage of subsea pipelines; The liquefaction of the seabed soil under the action of the earthquake causes the subsea pipeline to sink and other submarine pipeline damages, but it is difficult to diagnose

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