Study On Defect Detection Of Carbon Fiber Sheet Reinforced Concrete By Active Infrared Thermography

Driven by market demand,the concrete industry is in a stage of rapid development,and its total volume has ranked first in the building materials industry.Due to its excellent physical and mechanical properties,carbon fiber sheet is commonly used in civil engineering to repair and reinforce concrete.The health and the safety issues of the structures have gradually become an unignorable problem.The debonding area and natural hole defects lying between the carbon fiber reinforced sheet and the concretes will greatly reduce the strength,reliability,service life of the concretestructure,and even the stability of the entire building.Therefore,it is important to develop reliable methods forconcrete interface defects detection failure analysis and damage monitoring of carbon fiber reinforced concrete.In this paper,an infrared thermography detection method based on optical excitation of carbon fiber sheet to reinforce concrete defects is developed.The specific method is to use optical excitation to generate heat flow in the carbon fiber sheet reinforced concrete,and use the infrared thermal imager to quickly measure and image the surface,and then use the related algorithm to comprehensively process the thermal image sequence.Detection of concrete defects reinforced by carbon fiber sheet.A digital optical excitation infrared thermography detection system is established.The system is mainly composed of computer,infrared thermal imager,double halogen lamp,halogen lamp power supply,and tested samples.The problem of edge blurring for natural cavity image defect detection in conventional thermography is solved.An improved natural void defect identification method is proposed by using the histogram threshold image instead of the original binary image.In the pulsed and phase-locked excitation modes,a large number of carbon fiber sheet reinforced concrete is obtained by using the detection system experimental platform.Thermal imaging,time-domain temperature analysis of the thermographic image was obtained,and the timetemperature curve and temperature profile of the defect location of the carbon fiber sheet reinforced concrete were obtained.The original method was processed by Fourier transform,independent component analysis and principal component analysis.The thermography sequence is obtained,and the enhanced display of the thermal image is obtained.The visual inspection of a 25cm×25cm debonding defect of a carbon fiber sheet reinforced concrete is realized,and the edge detection is performed by using an improved recognition algorithm for the natural hole defect,and the four-layer carbon fiber sheet reinforcement is realized.Natural hole defects of 6mm in diameter and 3mm in depth can be visual inspection.