Internal Crack Detection Of Brake Pad Based On Pulsed Thermography

Brake pads are important parts of the brake system of the vehicles.The existed detection methods of the brake pads mainly depend on the manual judgment.In order to avoid the subjectivity of manual detection,to realize the detection automatically and get more crack information,in this paper,a detection method based on pulse thermal imaging is proposed,which is applied to the detection of internal defects of automobile brake pads.The main work is divided into the following parts:(1)Establish three-dimensional simulation model,analysis the internal errors caused by brake pads.To simplify the modeling,the brakes are simplified to the two layers model.The simulation shows that the defects in the brake pads can be detected by comparing the temperature distribution of the brake pads.And the basic rules of the different shape and position of the crack on the test results are obtained.(2)Analyze the impact of interference factors during the test.This paper mainly analyzes the two disturbances of heating and observation.The degree of reproducibility of the heating error is about 95%,and the influence of the temperature on the observation surface is less affected by the influence of the heating abnormality on the abnormalities of the observed data.Based on the analysis of the influence of the observation factors,the non-uniformity correction method of the thermal imager is easy to be affected by the inhomogeneity of the blackbody,and the non-uniformity of the thermal imager based on the uniform motion is proposed.And evaluate the influence of the temperature error of the imager before and after the imager on the detection results.(3)Carry out experimental verification,build experimental devices,including an independent developed high-power pulse induction heater,a data acquisition and analysis software.The experimental results show that the pulse thermal imaging method can detect most of the internal defects,but it can not detect the smaller internal defects.For the small defects located at the edge of the brake pads,this paper makes use of the side observation method as a compensation for the lack of the front observation.