Damage Monitoring For Repair Struction Of Composites Based On The Carbon Nanosensor

Glass fiber（GFRP）composite materials are widely used in industries such as aerospace,military important parts and components,and automobile manufacturing due to their excellent performance.When the damage in the structure exceeds the threshold defect,the repair technology is often used to strengthen the structure to ensure the safety of the structure.The repaired structure will also produce various structural damages during the service process,which will affect the safety and stability of the overall structure.Therefore,it is particularly important for the detection of repaired structures.This paper takes the glass fiber composite repair structure of wind blades as the research object.It is proposed to use a combination of carbon nano sensor health monitoring technology and ultrasonic detection technology to detect and evaluate the damage in the composite repair structure.Researched the preparation method of carbon nanosensor.The whole process of GFRP loading damage process was monitored through the health monitoring technology based on carbon nanosensor.At the same time,the contact ultrasonic method was used to detect and analyze the defects of the composite material specimen after loading.This paper analyzes the progress of carbon nanosensor health monitoring technology and composite material non-destructive testing technology at home and abroad in detail.The sensing mechanism of carbon nanosensor in composite materials is introduced.Explain the detailed production process of carbon nano sensor and prepare the corresponding sensor.Introduce the embedded position of composite material sensor and the integrated molding process steps.Successfully produced glass fiber composite material testing specimens with abundant sensors.Four composite repair specimens were tested on the mechanical properties of four schemes: quasi-static tensile,graded loading,unloading,tensile-tension fatigue,and tensile-compression fatigue.At the same time,the process was monitored by carbon nano-sensor in real time.Through the analysis of the experimental results,the real-time monitoring of repairing damage based on the carbon nano sensor composite material is completed.Using this technology,the small structural damage changes when the internal defects of the material are initiated under the action of external force can be accurately monitored.It has high monitoring sensitivity.And real-time monitoring and early warning of the damage evolution process.Ultrasonic testing technology is used to test the specimens after loading.The principle of composite ultrasonic reflection method and transmission method detection are explained in detail.The influence of defects on the echo signal is analyzed.The COMSOL finite element simulation software is used for modeling.The ultrasonic propagation behavior inside the composite material is visualized.The influence of large and small layered defects on the detection signal.Actually inspect the specimens that produce defects in the fatigue test health monitoring and use the ultrasonic C-scan technology to verify the results.Using time-frequency analysis and fast Fourier transform to analyze the signal.The results show that the ultrasonic non-destructive testing technology can accurately detect different depths,different sizes of layered defects and fiber breaks in the specimen.The large-sized layered signal has a higher Fourier transform amplitude,while the small-sized layered signal has a higher Fourier transform.The transformation amplitude is low,and the time-frequency analysis can quickly and accurately identify the arrival time and amplitude of the defect signal.The results obtained by the contact method and the C-scan are basically the same.Ultrasonic detection technology can quickly and conveniently locate and qualitatively characterize damage in composite materials.In this paper,sensor health monitoring technology and ultrasonic nondestructive testing technology are combined to detect GFRP.The research results lay a good foundation for the practical application of carbon nano sensor composite health monitoring technology.