Research On Fatigue Life Prediction Of Materials Based On Infrared Thermography And Energy Dissipation Method

Fatigue property is a very important mechanical property index of materials and also the basis of structural reliability design and evaluation.In order to describe the fatigue process,various methods and theories have been proposed,among which thermal imaging method,as a non-destructive testing method,has important application value in science and engineering.So this paper on the basis of summarizing predecessors' work,aiming at the shortcomings of the fatigue test is expensive,time-consuming,from two aspects of theory and experiment,to put forward a kind of efficient to accurately obtain the specimen material fatigue life theory prediction model and test method.The main tasks include:(1)The energy dissipation in each stage of the fatigue process is analyzed by combining the temperature change curve.In view of the existing problems in the current research,a theoretical method based on infrared thermal imaging technology and energy dissipation method to predict the high cycle fatigue life of materials is proposed.This method predicted the fatigue life of specimens by calculating the rate of temperature evolution in the initial stage of fatigue test.(2)At the same time,a parameter which can represent the fracture resistance of the material during the fatigue process is derived,and its physical meaning can be simplified as:the maximum temperature rise of the material after high-cycle fatigue fracture under ideal adiabatic conditions.(3)Introduce that test equipment and material as well as the t relate process.The method model was verified by fatigue test,and it was found that under the condition of high cycle fatigue,the surface temperature of the specimen increased with the increase of stress amplitude,and the surface temperature rise rate of the specimen increased with the increase of loading frequency.The fatigue life of the specimen is only related to the mechanical energy dissipated in each cycle,but not necessarily related to the test loading frequency.Finally,the prediction model is compared with the experimental data obtained under other loads,and it is found that the fatigue life prediction model is in agreement with the experimental data,which verifies the correctness of the prediction model.(4)The stress-temperature coupling model of the specimens under adiabatic conditions was established,and the cloud map of temperature field and stress field during the fatigue loading process was obtained by solving.It could be seen that the temperature was higher and the stress value was larger.The distribution trend of the two was consistent,indicating the feasibility of monitoring fatigue by thermal external thermal imager.The reliability of the simulation results is verified by comparing the temperature cloud map with the infrared thermal image.