Study On Damage Monitoring Mechanism Of CFRP Embedded In Fiber Bragg Grating

Carbon fiber reinforced composite materials have been widely used in many areas of military use and civil service because of their high strength and strong design ability.However,in the process of curing and using CFRP,there may be a variety of unvisible internal injuries,so as to monitor the health status of CFRP in real time,to ensure the safety and stability of the structure,the skin can be embedded in the optical fiber grating sensor,which makes up the intelligent composite material and makes real-time monitoring of the strain and temperature state of the material.But for composite materials,only the strain and temperature can not accurately determine the damage of the material inside the material,and the energy based damage criterion is the key to determining whether the internal damage of the composite material is damaged,and whether the crack after the injury will continue to expand.In this paper,the relationship between strain and energy release rate of composite materials is established,and the energy release rate of the material is established by the strain of the fiber optic grating sensor,and the effect of the energy release rate of the material within the material is obtained by the strain data of the fiber grating sensor,and the application of the fiber grating in the field of composite materials is more effective.To this end,this article mainly does the following:(1)Based on the mechanical properties of composite materials,the strain transfer rate of the CFRP in fiber optic grating was deduced,and the strain sensing mechanism of the composite material was mastered,and the corresponding model was used to verify the results of the derived results.(2)Using the double cantilever beam test,the unlocking fracture toughness of the type layer of the carbon fiber composite material of the fiber fiber grating sensor was studied.Through the experimental data,two different kinds of material fracture toughness were calculated,and the effect of the insertion of fiber grating on the fracture toughness of carbon fiber composite materials was analyzed.In this paper,the monitoring data of strain film and fiber optic grating are analyzed,and the advantages and disadvantages of the two kinds of sensors are summarized.(3)Through the study of the intermittent fracture toughness of the embedded and unimplanted fiber optic grating sensor,the method of the type fracture toughness of the two different conditions is obtained,and the effect of the fiber grating on the fracture toughness of the fiber fiber grating is analyzed,and the data obtained by the strain film and the fiber grating in the process of the test are studied.(4)In the infinite distance,the semi-infinite plate problem of the edge crack of the Y-axis direction is the case of the semi-infinite plate problem of the edge crack of a,and the relationship between the energy release rate g and the strain is established by the derivation of the damage and fracture mechanics.At the same time,in order to verify the derived formula,the finite element simulation software abaqusis was used to insert the internal cohesion model in the specimen to simulate the cracking process of the type of the type crack in the specimen,and verify the derivation results.