The Study Of Three-dimensional Stress And Strain Based On FBG Sensors

Fiber Bragg grating(FBG)sensor is widely used in health monitoring of structures due to it has many irreplaceable advantages.The author of this paper applied FBG sensors to health monitoring of Shenyang Culture and Art Center concert hall.The concert hall is large-span space structure and the stress in it is complicated,so it is a representative special architecture.In nearly two years,strains and temperature of the key positions of the concert hall were monitored in each construction stage.We could master the stress state of the structure and judge whether it was necessary to change the original design or adjust the construction technology through analyzing the monitoring data.In order to further verify the degree of safety and comfort of the structure in normal use stage,constant monitoring of the concert hall was conducted during a test performance with audience.The monitoring results are accorded with the expectation.Health monitoring of Shenyang Culture and Art Center concert hall proves the feasibility and superiority of FBG sensors in monitoring complicated special architecture and provides experience for similar engineering in the future.In order to make up for the defect that traditional FBG strain sensor can only measure the axial stress and strain while it can't detect the stress state in three-dimensional space,the author has developed three-dimensional FBG sensor.The three-dimensional FBG sensor is composed of six FBG strain sensors,one FBG temperature sensor,one metal frame,and some auxiliary components by a certain way.Through processing the data which were measured by the seven sensors,magnitudes and directions of three-dimensional principal stresses,strains and maximum shearing stress,strain can be obtained.This paper introduces a numerical example of solving three-dimensional stresses and strains to describe the measurement principle and calculation method in detail.A three-dimensional FBG sensor is manufactured to verify the feasibility of its structure and it provides the prototype for massively manufacturing in practical engineering.The sensor can be not only used in monitoring of concrete members but also can be utilized in detecting three-dimensional stresses and strains in the interiors of many other materials.Considering the utility of three-dimensional FBG sensor,the author programmed computational process of three-dimensional stresses and strains based on LabVIEW2013 and developed three-dimensional stresses,strains calculation and display system based on FBG sensors.The system is verified to have high computational rate and accuracy through testing it.Establishment of the system is an important step for the application of the three-dimensional FBG sensor.