Rapid alternating stress is formed in structure subjected to harsh thermal-acoustic loads,which will affect fatigue performance and reduce fatigue life seriously.First,fatigue experiment of superalloy thin-walled stru...Rapid alternating stress is formed in structure subjected to harsh thermal-acoustic loads,which will affect fatigue performance and reduce fatigue life seriously.First,fatigue experiment of superalloy thin-walled structure was carried out to obtain fatigue damage location and failure time of the experiment specimen,and S-iN curves of superalloy thin-walled structure at 723 K were fitted.Then,dynamic response simulation of superalloy thin-walled structure under the same load as experiment was implemented,and fatigue life was estimated based on the fatigue life prediction model which mainly included:improved rain-flow counting method,Morrow average stress model and Miner linear cumulative damage theory.Further,comparisons between simulation solutions and experimental results achieved a consistency,which verified the validity of the Fatigue Life Prediction Model(FLPM).Moreover,taking a rectangle plate as the analysis object,the distributions of Fain-low circulation blocks and damage levels of the structure were discussed respectively.Finally,current research indicates that in pre-buckling the structure is in softened area and fatigue life decreases with the increase of temperature;in post-buckling the structure is in hardened area and fatigue life increases with the increase of temperature within a certain range.展开更多
For large deflection strongly nonlinear response problem of thin-walled structure to thermal-acoustic load, thermal-acoustic excitation test and corresponding simulation analysis for clamped metallic thin-walled plate...For large deflection strongly nonlinear response problem of thin-walled structure to thermal-acoustic load, thermal-acoustic excitation test and corresponding simulation analysis for clamped metallic thin-walled plate have been implemented. Comparing calculated values with experimental values shows the consistency and verifies the effectiveness of calculation method and model for thin-walled plate subjected to thermal-acoustic load. Then this paper further completes dynamic response calculation for the cross reinforcement plate under different thermalacoustic load combinations. Based on the obtained time-domain displacement response, analyses about structure vibration forms are mainly focused on three typical motions of post-buckled plate,indicating that the relative strength between thermal load and acoustic load determines jump forms of plate. The Probability spectrum Density Functions（PDF） of displacement response were drawn and analyzed by employing statistical analysis method, and it clearly shows that the PDF of postbuckled plate exhibits bimodal phenomena. Then the Power Spectral Density（PSD） functions were used to analyze variations of response frequencies and corresponding peaks with the increase of temperatures, as well as how softening and hardening areas of the plate are determined. In the last section, this paper discusses the change laws of tensile stress and compressive stress in pre/post buckling areas, and gives the reasons for N glyph trend of the stress Root Mean Square（RMS）.展开更多
基金co-supported by Aviation Basic Science Fund Project of China(No.20151554002)Natural Sciences Key Project of Chengdu Aeronautic Polytechnic in China(No.061754)Natural Sciences General Project of Sichuan Province Education Department in China(No.18ZB0057).
文摘Rapid alternating stress is formed in structure subjected to harsh thermal-acoustic loads,which will affect fatigue performance and reduce fatigue life seriously.First,fatigue experiment of superalloy thin-walled structure was carried out to obtain fatigue damage location and failure time of the experiment specimen,and S-iN curves of superalloy thin-walled structure at 723 K were fitted.Then,dynamic response simulation of superalloy thin-walled structure under the same load as experiment was implemented,and fatigue life was estimated based on the fatigue life prediction model which mainly included:improved rain-flow counting method,Morrow average stress model and Miner linear cumulative damage theory.Further,comparisons between simulation solutions and experimental results achieved a consistency,which verified the validity of the Fatigue Life Prediction Model(FLPM).Moreover,taking a rectangle plate as the analysis object,the distributions of Fain-low circulation blocks and damage levels of the structure were discussed respectively.Finally,current research indicates that in pre-buckling the structure is in softened area and fatigue life decreases with the increase of temperature;in post-buckling the structure is in hardened area and fatigue life increases with the increase of temperature within a certain range.
基金supported by Aviation Basic Science Fund Project of China (No. 20151554002)
文摘For large deflection strongly nonlinear response problem of thin-walled structure to thermal-acoustic load, thermal-acoustic excitation test and corresponding simulation analysis for clamped metallic thin-walled plate have been implemented. Comparing calculated values with experimental values shows the consistency and verifies the effectiveness of calculation method and model for thin-walled plate subjected to thermal-acoustic load. Then this paper further completes dynamic response calculation for the cross reinforcement plate under different thermalacoustic load combinations. Based on the obtained time-domain displacement response, analyses about structure vibration forms are mainly focused on three typical motions of post-buckled plate,indicating that the relative strength between thermal load and acoustic load determines jump forms of plate. The Probability spectrum Density Functions（PDF） of displacement response were drawn and analyzed by employing statistical analysis method, and it clearly shows that the PDF of postbuckled plate exhibits bimodal phenomena. Then the Power Spectral Density（PSD） functions were used to analyze variations of response frequencies and corresponding peaks with the increase of temperatures, as well as how softening and hardening areas of the plate are determined. In the last section, this paper discusses the change laws of tensile stress and compressive stress in pre/post buckling areas, and gives the reasons for N glyph trend of the stress Root Mean Square（RMS）.
