Research On Testing Elastic-Plasitc Fatigue-Thermal Deformation Around The Hole

The research on the material mechanics behavior such as the process of fatigue damnification, forming and expanding of crack etc of heat-resisting alloy GH4169 ,which occupies a central place in the aviation industry for its predominant heat-resisting performance, upstanding corrosion-heat-resistant performance, antioxidant performance, anti-fatigue performance and some other excellent general performances including well fracture toughness, is important for the prediction of the fatigue life and the control of the reliability of key components of aero-engine.The research work indicated that the fatigue-cycle time of materials had relationship with plastic deformation yielding where the strain is centralized at the end of the crack. So it is of great importance in theory and application to test and study the damnification of materials that testing the elastic-plastic deformation around the bore where the strain is centralized for the purpose of preventing the cracks in the aero-engine components from forming and expanding.The research of dissertation bases on the task"the research on mechanism of fatigue damnification on isotropic heat-resisting alloy component",which is the second subject of a major foundation of national security research projects"Basic research of aero-engine structural integrity and reliability". The relationship between fatigue-cycle time and fatigue-thermal deformation at the notch root of the tensile plate specimen made from heat-resisting alloy GH4169 was tested and studied in the work. Digital speckle correlation method is applied for testing fatigue deformation during the experiments, considering all the testing experiments were going to be carried out at MTS machine, digital speckle correlation method is a rather perfect destaging experimental testing method. All the fatigue deformation was tested by digital speckle correlation method in the work.The main work in the dissertation contains three aspects:1,For GH4169 tensile plate specimen with single hole, digital speckle correlation method is applied for testing the relationship between elastic-plastic deformation around the hole and the fatigue-cycle time under the room temperature.2,For GH4169 tensile plate specimen with single hole, digital speckle correlation method is applied for testing the relationship between elastic-plastic deformation around the hole and the fatigue-cycle time under 450 .3,For GH4169 tensile plate specimen with single hole, digital speckle correlation method is applied for testing the relationship between nominal hysteresis loop and the fatigue-cycle time under 450 .A large number of fatigue deformations in the area where the strain was centralized of all the GH4169 was tested successfully in the work. So was the relationship between the fatigue deformation with the fatigue-cycle time. The experimental results in dissertation were significant for researching the fatigue life of GH4169 alloy material, exploring the method in which the fatigue life of GH4169 is forecast.It was rarely reported that there were the same research method and results with the work in dissertation.