Elastic-plastic Deformation Based On Infrared Technology - Experiment And Finite Element Study Break

With the fast developing of national air industry,the statue of high-strength materials becoming more and more important.However,the strength of the material increased the ability of to resistance crack propagation is weak,so low stress brittle fracture phenomenon is very serious. So research the elastic-plastic deformation and fracture behavior of metal material have great significance to ensure the security of equipment.In view of the elastic-plastic deformation and fracture process where the strain energy is released in the form of heat, and on account of macroscopic perspective to evaluate elastic-plastic deformation and fracture behavior of crack tip.This paper respectively research the process by experiment and numerical simulation methods,. By observing the elastic-plastic deformation and temperature distribution at the tip of crack,we can make qualitative and quantitative analysis in fracture process, and get the following results:(1) In order to improve the accuracy of infrared image and measured temperature,the relation between surface roughness and emissivity of SUS304steel in plastic deformation under uniaxial tension was studied by using infrared imager,CCD camera and laser surface shape measuring microscope,based on the measurement principle of infrafed imaging and the principle of infrafed radiation. The temperature distribution in plastic deformation was measured by using thermocouple and thermal infrared imager.Results show that the emissivity is increased proportionably with surface roughness,resulting in the plastic deformation zone by the thermal infrared imager is larger than practical deformation area.The effective emissivity may be improved through setting the surface roughness of the material in advance, thereby better infrared image and higher temperature measurement precision can be obtained.(2) In this study, the elasto-viso/plastic deformation, COD and surface temperature around crack tip of pure titanium plate were measured under uniaxial tension used CCD camera, thermocouples and infrared camera. Furthermore FEM elasto-viso/plastic analysis coupled with unsteady heat conduction was performed in elasto-viso/plastic deformation and fracture process. It was shown that the heat distribution of surface around crack tip which titanium and SUS304plate with different strain rates by FEM analysis with unsteady heat conduction good agree with the thermal image measured by infrared camera.