Experimental Study On The Bonding Quality Of CFRP Plate-steel Based On The Nonlinear Ultrasonic Technology

Reinforcement of Steel Structure by carbon fiber reinforced polymer(CFRP)has been widely used in engineering practice as a new type of reinforcement and repair technology.The CFRP plate-steel bonding structure often faces the combined effects of overload,fatigue and environmental influences during service.The durability of the bonding interface has been tested,the bonding performance will be degraded,and the bonding strength will be reduced.At the same time,in the construction process of CFRP reinforcement and repair of steel structure,the bonding surface is prone to defects such as pores,slag inclusions,pore,and delaminations.The development of these defects will seriously affect the quality of bonding interface,to bring serious structural safety risks.Therefore,It is necessary to study the bonding quality inspection of CFRP plate-steel bonding structure.The nonlinear ultrasonic experimental system is used to effectively detect the bonding quality of the CFRP plate-steel bonding structure.Set up the nonlinear ultrasonic experimental system to perform nonlinear ultrasonic testing of CFRP plate-steel bonding structure with bonding layer defects.Analyze the correlation between ultrasonic nonlinear characteristic parameters and bonding defects.Establish the relationship between nonlinear ultrasonic coefficient and intensity.Evaluate the performance of the CFRP plate-steel bonding structure.The main work of this paper is summarized as follows.1.In order to achieve the inspection of the bonding quality of the CFRP board-steel bonding structure.The nonlinear ultrasonic experimental system suitable for bonding quality inspection of CFRP plate-steel bonding structure was built.And the non-linear influence brought by the system is excluded.2.Specimens with different ratios of adhesives and specimens with different bonding defect areas are designed.Nonlinear ultrasonic testing was performed on the above-mentioned defective specimens.The parameter changes caused by defects are analyzed from both time domain and frequency domain.Then establish the relationship between nonlinear ultrasonic coefficient and defect parameters.3.Completed the tensile shear test of CFRP plate-steel bonding structure and analyzed the racture morphology of different specimens through the above test.In the next place the shear strength of the CFRP plate-steel interface of each specimen was measured.The variation rules of defect parameters and shear strength are studied.4.Establish the relationship between the nonlinear ultrasonic coefficient and the shear strength.The influence of defects on the nonlinear ultrasonic coefficient is analyzed.Obtain the nonlinear ultrasonic evaluation standard of CFRP plate-steel bonding quality.