Development And Industrial Application Of Strain Fiber Bragg Grating Sensors

Fiber Bragg Grating(FBG),as a new type of detection component,uses optical signals as the measurement source,is not subject to electromagnetic interference,has high sensitivity,has unique advantages that piezoelectric sensors do not have,and is widely used.However,in practical applications,because the fiber grating is a brittle material,especially when it is used under complex working conditions or even harsh conditions,phenomena such as deactivation,signal chirp,and breakage often occur.Therefore,bare fiber gratings require proper packaging and protection before they can be put into practical use.In recent years,the development of fiber composite materials has been extremely rapid,and it has been applied to a large extent in the military field,which has greatly promoted the development of the entire composite material field and also pointed out the direction for the future development of composite materials.Today,fiber composite materials Slowly infiltrating the civilian field has brought fundamental changes to the national economy and people's livelihood.From carbon fiber fitness equipment to today's carbon fiber clothing,it has continuously changed human perception.Compared with metal materials,carbon fiber composite materials have excellent specific strength and specific modulus,and are widely used in the field of lightweight.The development of new energy vehicles is changing with each passing day,and the use of fiber composite materials in the aerospace field is also increasing significantly The proportion can be used to reduce the weight;in addition,the order of the fiber composite material layer can be designed by itself,and the advantages of designable size and thickness make the fiber composite material have great application prospects in the field of multifunctional materials.However,the fiber composite material belongs to a multiphase mixture system,and most of the physical performance parameters have anisotropic characteristics.Due to the mismatch of the thermal expansion coefficients of the fiber and the resin matrix,the heat released by curing is not easy to be derived,and residual stress will inevitably occur inside the product.In the course of commissioning,there are problems that the damage is not visible and the mechanism is unclear.Therefore,the carbon fiber composite material and the fiber gating sensor are organically combined,that is,the excellent mechanical properties of the fiber composite material are used as the carrier to encapsulate and protect the FBG sensor,improve the survival rate and test accuracy of the sensor,or use the FBG sensor to sense temperature and strain It is of great theoretical significance and practical application value to monitor the state change of composite structural parts during the preparation and service process.First of all,taking the packaging technology of FBG sensors as the main research content,according to different packaging processes and layering sequences,three groups of different types of substrate-type fiber grating sensors were prepared.Among them,1#fiber grating sensor is prepared by unidirectional carbon fiber prepreg;2#fiber grating sensor is packaged by orthogonal layering;both are prepared by hot molding;3#fiber grating sensor is vacuum assisted The infusion process is used to prepare and shape,with glass fiber prepreg and glass fiber electronic cloth as the main materials,wherein the glass fiber prepreg substrate is prepared by secondary curing.Subsequently,the strain calibration experiment was carried out on the above three groups of fiber grating sensors.The results showed that:Among the two groups of fiber grating sensors prepared by the molding method,the strain sensing characteristics of the 1#sensor are much better than those of the 2#sensor,which has better The strain transfer performance of the 3#fiber grating sensor prepared by the vacuum-assisted infusion process has the best strain sensing characteristics and the smallest strain transfer loss,but the performance between the layers is slightly worse and it is easy to debond and delaminate.Then,on the basis of satisfying the packaging criteria,this paper embeds the bare fiber grating sensor between the layers of carbon fiber laminates,and completes the implantation of the FBG sensor through the hot molding process;after that,the carbon fiber laminates with the FBG sensor implanted The static load experiment is carried out.The results show that:during the static load experiment,the strain sensitive area of the fiber grating sensor is not a standard circle,but an ellipse;and the distance between the center wavelength offset of the sensor and the load point,the size of the load and the The change of the angle of the load point has a great relationship,and the strain response of the FBG sensor decreases with the distance of the load point,the load increases,and the angle of the load point increases.Finally,the FBG sensor is applied to engineering practice.First,the bare fiber grating sensor is embedded in the wind power blade mold to monitor the temperature and strain evolution during the production of the blade root tile mold,and the profile in the wind power blade mold A certain number of fiber Bragg grating sensors are pasted on the surface,which is used in conjunction with the conventional wireless laser tracker to jointly monitor the changes of the wind turbine blade mold surface;subsequently,a method to improve the survival rate of the fiber grating sensor embedded in the wind turbine blade mold is proposed Technical solutions to provide technical support for intelligent wind power blade molds.