Research On Infrared Radiation Polarization Characteristics Of Metals During Fatigue

The main form of failure of metal parts commonly used in mechanical structures is fatigue failure.Metal materials will accumulate damage due to fatigue during use,and may break suddenly without warning,resulting in major accidents.At present,some existing fatigue monitoring methods cannot detect the metal fatigue damage state in real-time and without damaging the metal surface.Infrared thermal imaging technology is an effective way to solve this contradiction at present.But the information obtained by infrared thermal imaging technology is easily affected by the background environment,and there is only one characterization parameter using infrared thermal imaging technology.Therefore,it is particularly prone to misjudge when using infrared thermal imaging technology.In recent years,polarization detection technology has been rapidly developed and widely used in military camouflage detection,astronomical detection,atmospheric detection,and other fields.Compared with traditional optical images,polarized images can highlight the edge,texture and details of the target.Physically,infrared radiation also has polarization characteristics,so polarization detection technology is introduced into infrared thermal imaging technology to form infrared polarization detection technology.In the process of transmission,infrared polarization information is easily affected by physical and chemical properties of target material surface,transmission medium,wavelength and other factors,which are difficult to be estimated by previous methods.Therefore,it is necessary to analyze the main influencing factors of infrared polarization characteristics of target based on infrared radiation polarization components.During the fatigue process,the microstructure of metal surface will change,which will affect the infrared polarization characteristics of metal surface.Based on the above analysis,this paper mainly carries out the following three aspects of work:(1)The fatigue damage mechanism of metal and the principle of polarization thermography are studied.Due to the effect of extrusion,not only the surface temperature changes,but also the surface morphology evolves with the fatigue cycle.Based on the basic concept and representation method of polarized light,the imaging principle and analytical method of infrared polarization are deeply studied,and the imaging principle of three channel infrared polarization exothermic imaging used in this paper is given,so as to lay a theoretical foundation for the subsequent establishment of infrared polarization model.(2)Establishing a model of infrared polarization characteristics of metal rough surface.Based on the shortage of the existing polarization model,this paper consider different height of adjacent minivan yuan fluctuation caused by shield shadow effect difference,use Cauchy distribution characterization minivan yuan Angle distribution,with the help of a minivan yuan theory,Kirchhoff's law and the law of conservation of energy,build a rough metal surface based on masking function optimization model of infrared polarization,The effect of the model is verified by the infrared polarization data of metal at different emission angles.The results show that the modified model has higher accuracy than the existing model,and is more suitable for characterizing the infrared polarization characteristics of rough metal surfaces.(3)Combined with the infrared polarization model,the variation of the polarization characteristics of the infrared radiation on the metal surface during fatigue is analyzed.Fatigue experiments were carried out with Q235 and 45 steel as experimental objects.Polarization thermal images,infrared thermal images and morphology images of metal surface under different fatigue cycles were collected by infrared polarizing camera,thermal imager and profiler to explore the evolution of temperature,morphology and infrared polarization characteristics of metal surface during fatigue process.Results indicate that the strength of polarization and surface temperature change is consistent,at the same time,the change of the infrared polarization degree reflects the evolution of surface microstructure,shows that the infrared polarization degree of metal surface and the fatigue cycle times,there is a close relationship between the infrared polarization characteristics of the surface as the fatigue cycle time increasing changed some regularity.Through the research and analysis of the changes of the infrared polarization characteristics in the process of metal fatigue damage,it lays a theoretical foundation for the prediction of metal fatigue damage state by using the infrared polarization characteristics.Figure [32] table [1] reference [84]...