The paper designs a novel material-level specimen and its dedicated fixture suitable for applying Combined high-and low-Cycle Fatigue(CCF)loads.Unlike full-scale or simulation specimens,the CCF specimen eliminates geo...The paper designs a novel material-level specimen and its dedicated fixture suitable for applying Combined high-and low-Cycle Fatigue(CCF)loads.Unlike full-scale or simulation specimens,the CCF specimen eliminates geometrically induced stress gradients in the test region.Experimental data on CCF life and strain responses of ZSGH4169 alloy are acquired under different CCF loads.The Maximum Strain within Each(MSE)CCF cycle is demonstrated to be independent of the Low-Cycle Fatigue(LCF)loads and High-Cycle Fatigue(HCF)stress amplitudes,but exhibits a correlation with the Cycle Ratio of HCF/LCF(Rf).The growth law of MSE changes from linear to logarithmic as Rfdecreases.Strain amplitudes in the dwell stage,observed unaffected by Rf,are quantified as a function of LCF nominal stresses and HCF stress amplitudes.However,under a defined CCF load,strain amplitudes in the dwell stage remain constant.Strain peaks in the dwell stage in a single CCF cycle decrease in a power function with increasing HCF cycles.展开更多
Covalent organic frameworks(COFs),as a class of crystalline porous polymers,featuring designable structures,tunable frameworks,well-defined channels,and tailorable functionalities,have emerged as promising organic ele...Covalent organic frameworks(COFs),as a class of crystalline porous polymers,featuring designable structures,tunable frameworks,well-defined channels,and tailorable functionalities,have emerged as promising organic electrode materials for rechargeable metal-ion batteries in recent years.Tremendous efforts have been devoted to improving the electrochemical performance of COFs.However,although significant achievements have been made,the electrochemical behaviors of developed COFs are far away from the desirable performance for practical batteries owing to intrinsic problems,such as poor electronic conductivity,the trade-off relationship between capacity and redox potential,and unfavorable micromorphology.In this review,the recent progress in the development of COFs for rechargeable metal-ion batteries is presented,including Li,Na,K,and Zn ion batteries.Various research strategies for improving the electrochemical performance of COFs are summarized in terms of the molecular-level design and the material-level modification.Finally,the major challenges and perspectives of COFs are also discussed in the aspect of large-scale production and electrochemical performance improvements.展开更多
基金co-supported by the National Natural Science Foundation of China(51805017)National Science and Technology Project(J2017-IV-0012-0049)+1 种基金National Science and Technology Project,China(J2019-IV-0007-0075)the Fundamental Research Funds for the Central Universities,China(JKF-20240036).
文摘The paper designs a novel material-level specimen and its dedicated fixture suitable for applying Combined high-and low-Cycle Fatigue(CCF)loads.Unlike full-scale or simulation specimens,the CCF specimen eliminates geometrically induced stress gradients in the test region.Experimental data on CCF life and strain responses of ZSGH4169 alloy are acquired under different CCF loads.The Maximum Strain within Each(MSE)CCF cycle is demonstrated to be independent of the Low-Cycle Fatigue(LCF)loads and High-Cycle Fatigue(HCF)stress amplitudes,but exhibits a correlation with the Cycle Ratio of HCF/LCF(Rf).The growth law of MSE changes from linear to logarithmic as Rfdecreases.Strain amplitudes in the dwell stage,observed unaffected by Rf,are quantified as a function of LCF nominal stresses and HCF stress amplitudes.However,under a defined CCF load,strain amplitudes in the dwell stage remain constant.Strain peaks in the dwell stage in a single CCF cycle decrease in a power function with increasing HCF cycles.
基金National Natural Science Foundation of China,Grant/Award Number:22209155。
文摘Covalent organic frameworks(COFs),as a class of crystalline porous polymers,featuring designable structures,tunable frameworks,well-defined channels,and tailorable functionalities,have emerged as promising organic electrode materials for rechargeable metal-ion batteries in recent years.Tremendous efforts have been devoted to improving the electrochemical performance of COFs.However,although significant achievements have been made,the electrochemical behaviors of developed COFs are far away from the desirable performance for practical batteries owing to intrinsic problems,such as poor electronic conductivity,the trade-off relationship between capacity and redox potential,and unfavorable micromorphology.In this review,the recent progress in the development of COFs for rechargeable metal-ion batteries is presented,including Li,Na,K,and Zn ion batteries.Various research strategies for improving the electrochemical performance of COFs are summarized in terms of the molecular-level design and the material-level modification.Finally,the major challenges and perspectives of COFs are also discussed in the aspect of large-scale production and electrochemical performance improvements.
