Advanced propulsion systems experience critical challenges under extreme service conditions,including aerodynamic loads and thermal loads.Especially,flutter stability is a key bottleneck restricting the design and saf...Advanced propulsion systems experience critical challenges under extreme service conditions,including aerodynamic loads and thermal loads.Especially,flutter stability is a key bottleneck restricting the design and safe op⁃eration of hot structures in advanced propulsion systems employing ceramic matrix composites(CMCs).Compared to traditional nickel-based alloys,CMCs offer superior high-temperature resistance and specific strength,making them ideal for next-generation engine hot structures.The inherent anisotropy,heterogeneity,and complex nonlinear behav⁃ior of CMCs,coupled with extreme operating environments,result in strong multi-physics interactions,including aero-thermo-structural,thermo-mechanical,and damage-aeroelastic coupling.These complexities significantly com⁃plicate vibration stability and flutter analysis.The recent research progresses on these problems are systematically ex⁃amined,focusing on multi-field coupling mechanisms,material constitutive and damage evolution models,multi-scale modeling methods,coupled solution strategies,and the influence of key parameters on flutter characteristics.The current challenges are highlighted,including the complexity of high-temperature nonlinear modeling,the effi⁃ciency of multi-field coupling calculations,and the multi-scale modeling of complex weaving structures.Finally,an outlook on future development directions is presented to provide theoretical support for the design and safety assess⁃ment of hot structures of advanced CMCs.展开更多
The development of modern engineering components and equipment features large size,intricate shape and long service life,which places greater demands on valid methods for fatigue performance analysis.Achieving a smoot...The development of modern engineering components and equipment features large size,intricate shape and long service life,which places greater demands on valid methods for fatigue performance analysis.Achieving a smooth transformation between small-scale laboratory specimens’fatigue properties and full-scale engineering components’fatigue strength has been a long-term challenge.In this work,two dominant factors impeding the smooth transformation—notch and size effect were experimentally studied,in which fatigue tests on Al 7075-T6511(a very high-strength aviation alloy)notched specimens of different scales were carried out.Fractography analyses identified the evidence of the size effect on notch fatigue damage evolution.Accordingly,the Energy Field Intensity(EFI)initially developed for multiaxial notch fatigue analysis was improved by utilizing the volume ratio of the Effective Damage Zones(EDZs)for size effect correction.In particular,it was extended to a probabilistic model considering the inherent variability of the fatigue phenomenon.The experimental data of Al 7075-T6511 notched specimens and the model-predicted results were compared,indicating the high potential of the proposed approach in fatigue evaluation under combined notch and size effects.展开更多
基金supported by the Na⁃tional Science and Technology Major Project(No.Y2019-Ⅰ⁃0018-0017)the National Natural Science Foundation of China(No.U24A2051)+2 种基金the Natural Science Foundation of Jiangsu Province(No.BK20232037)the Foundation of Key Laboratory of Aero-engine Thermal Environment and Structure,Ministry of Industry and Information Technology(No.CEPE2024002)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KY⁃CX24_0605)。
文摘Advanced propulsion systems experience critical challenges under extreme service conditions,including aerodynamic loads and thermal loads.Especially,flutter stability is a key bottleneck restricting the design and safe op⁃eration of hot structures in advanced propulsion systems employing ceramic matrix composites(CMCs).Compared to traditional nickel-based alloys,CMCs offer superior high-temperature resistance and specific strength,making them ideal for next-generation engine hot structures.The inherent anisotropy,heterogeneity,and complex nonlinear behav⁃ior of CMCs,coupled with extreme operating environments,result in strong multi-physics interactions,including aero-thermo-structural,thermo-mechanical,and damage-aeroelastic coupling.These complexities significantly com⁃plicate vibration stability and flutter analysis.The recent research progresses on these problems are systematically ex⁃amined,focusing on multi-field coupling mechanisms,material constitutive and damage evolution models,multi-scale modeling methods,coupled solution strategies,and the influence of key parameters on flutter characteristics.The current challenges are highlighted,including the complexity of high-temperature nonlinear modeling,the effi⁃ciency of multi-field coupling calculations,and the multi-scale modeling of complex weaving structures.Finally,an outlook on future development directions is presented to provide theoretical support for the design and safety assess⁃ment of hot structures of advanced CMCs.
基金support from the Key Program of the National Natural Science Foundation of China(No.12232004)the Training Program of the Sichuan Province Science and the Technology Innovation Seedling Project(No.MZGC20230012)are acknowledged.
文摘The development of modern engineering components and equipment features large size,intricate shape and long service life,which places greater demands on valid methods for fatigue performance analysis.Achieving a smooth transformation between small-scale laboratory specimens’fatigue properties and full-scale engineering components’fatigue strength has been a long-term challenge.In this work,two dominant factors impeding the smooth transformation—notch and size effect were experimentally studied,in which fatigue tests on Al 7075-T6511(a very high-strength aviation alloy)notched specimens of different scales were carried out.Fractography analyses identified the evidence of the size effect on notch fatigue damage evolution.Accordingly,the Energy Field Intensity(EFI)initially developed for multiaxial notch fatigue analysis was improved by utilizing the volume ratio of the Effective Damage Zones(EDZs)for size effect correction.In particular,it was extended to a probabilistic model considering the inherent variability of the fatigue phenomenon.The experimental data of Al 7075-T6511 notched specimens and the model-predicted results were compared,indicating the high potential of the proposed approach in fatigue evaluation under combined notch and size effects.
