Research On Nondestructive Testing Technology Of Infrared Thermography Composites Based On Multi-Mode Excitation

Carbon Fiber Reinforced Polymer(CFRP)is a new material with high strength and light weight.It is widely used in aviation industry and manufacturing.Defective problems such as debonding and delamination of composites are generated during manufacturing and service.In order to ensure the quality of the workpiece,Optical Thermography(OT)non-destructive testing technology is widely used in composite defect detection.The utility model has the advantages of large detection area,fast imaging speed and simple operation.Different excitation signals represent different excitation modes.In this paper,multi-mode optical thermography non-destructive testing technology is studied,including existing pulsed thermography(PT),Lock-In Thermography,as well as pulsecompression thermography excitation modes.In this paper,the research status of non-destructive testing of composite materials is studied.The theoretical basis of non-destructive testing technology for optical excitation infrared thermal imaging is analyzed.The composition of non-destructive testing system for optical thermography is discussed.The selection criteria of each component of the system are introduced,which provides a theoretical basis for the construction of the experimental platform.Multi-size and multi-type standard test pieces were prepared for experimental verification to ensure the reliability and robustness of the experimental results.In order to study the influence of different excitation modes on the experimental results,based on the optimal parameters,the flat test piece and the R area test piece were prepared for the comparison.Two common excitation mode methods are compared: pulsed thermography and lock-in thermography.The results show that both methods can detect defects,the pulse thermography excitation speed is faster,and the lock-in thermography heat contrast is higher.In order to improve the signal-to-noise ratio(SNR)and thermal contrast of the original data,a new excitation mode method is proposed: Pulse-Compression Thermography(PuCT),which is compared with pulse thermography.It can effectively reduce background noise and improve detection sensitivity.The main innovations of this paper are as follows:(1)Two new types of optical thermography detection platforms have been innovatively built to improve the uniformity and adaptability of the system,which can adapt to different detection environments.(2)A new excitation mode detection method was proposed innovatively: the refer pulse compression thermography non-destructive detection method of halogen lamp.The method uses a reference prior and fusion pulse compression excitation to break through the sensitivity and resolution of deep defect detection.(3)The multi-mode excitation optical thermography nondestructive testing technology is completed.The theoretical analysis and experimental comparison verify the advantages and disadvantages of the pulse excitation mode,the lock-in excitation mode,and the refer pulse compression excitation mode.The comparison results show that the refer pulse compression excitation mode detection effect is better than the pulse excitation mode.