Fatigue Crack Detection Method Simulation Analysis And Experimental Research Of Steel Structure Based On Thermal Imaging

Fatigue cracks in steel bridges are becoming a larger problem for the fatigue and aging steel bridges due to ever-increasing truck loads and deficient funding for civil infrastructure.Steel bridge fatigue cracking refers to bridge structure or structural member’s failure phenomenon at well below its ultimate strength of steel alternating stress without warning,it occurs suddenly with no plastic deformation,which belongs to cyclic loading brittle fracture under hard to take precautions and has great destructiveness.A new inspecting method is proposed to detect the fatigue crack of steel bridges based on the stress concentration feature.The relationship between stress and the temperature on the component is built theoretically,the fatigue crack can be located through calculating distortion stress on the base of detecting the temperature distortion on the component with infrared thermal imager.Taking a plate with hole as an example,the relationship between stress and temperature of hole edge spots was studied under cycle loads,the result shows that the temperature of left/right spots decrease and top/bottom spots increase when t=0.05 s,the temperature of left/right spots increase and top/bottom spots decrease when t=0.15 s,which is accordance with the theory results,and the mode test results verify the feasibility of this method.