Experimental Research On Fatigue Damage Failure Of Aeronautical Materials

Currently, fatigue is a major cause of aeronautical component failure. To have a more precise prediction of fatigue failure of materials, existing theory and research method develop constantly in both micro and macro aspects. Therefore, the experimental study of fatigue damage failure of aeronautical materials is summarized; existing micro-mechanisms and mechanical models of fatigue crack are analyzed; the relevant life prediction models and methods are described. Main work is as below: An experimental program is developed to simplify the flight maneuver and gust load spectrum, under which the equivalent flight cycles of Aluminum alloy 2024 are calculated. Thus, simplified load spectrums are validated to accelerate high cycle fatigue experiment. By experimentally studying low cycle fatigue behavior of stainless Steel 45# under different strain amplitudes, variation of mechanical behavior is analyzed, including stress-strain cyclic response and Young Modulus. Life prediction models are optimized after the test data is analyzed, and thus life prediction modes are validated and assessed accordingly. In micro scale, each damage failure area is shown to compare the different figure and to discover the crack initiation point and the crack propagation trend. Variation of hardness in both radical and axial directions near fatigue break area is measured to study the difference between fatigue characteristic areas after cyclic loading.