Realizing the accurate characterization for the dynamic damage process is a great challenge. Here we carry out testing simultaneously for dynamic monitoring and acoustic emission （AE） statistical analysis towards fi...Realizing the accurate characterization for the dynamic damage process is a great challenge. Here we carry out testing simultaneously for dynamic monitoring and acoustic emission （AE） statistical analysis towards fiber composites under mode-Ⅱ delamination damage. The load curve, AE relative energy, amplitude distribution, and amplitude spectrum are obtained and the delamination damage mechanism of the composites is investigated by the microscopic observation of a fractured specimen. The results show that the micro-damage accumulation around the crack tip region has a great effect on the evolutionary process of delamination. AE characteristics and amplitude spectrum represent the damage and the physical mechanism originating from the hierarchical microstructure. Our finding provides a novel aud feasible strategy to simultaneously evaluate the dynamic response and micro-damage mechanism for fiber composites.展开更多
Modern wearable electronics are thirsty for flexible, lightweight energy storage and supply devices. Flexible fiber-shaped supercapacitors, possess good flexibility, high power density, fast charging capability and lo...Modern wearable electronics are thirsty for flexible, lightweight energy storage and supply devices. Flexible fiber-shaped supercapacitors, possess good flexibility, high power density, fast charging capability and long cycle life, becoming a promising option for wearable devices. The past decade has witnessed the emergence of graphene fiber based supercapacitors（GFSCs） as one of the most active vicinity in fiber-supercapactiors, for their excellent properties including high surface area, chemical stability, excellent electrical conductivity, lightweight and mechanical properties. In this perspective, we introduced the basic energy storage mechanisms of GFSCs, followed by the analysis in improving their overall performances, recent advances, and a conclusive discussion on the challenges and opportunities.展开更多
Development of simple methods for preparation of polymeric electrode materials with nanofibrous network structure is a perspective way toward cheap supercapacitors with high specific capacitance and energy density. In...Development of simple methods for preparation of polymeric electrode materials with nanofibrous network structure is a perspective way toward cheap supercapacitors with high specific capacitance and energy density. In this work one-pot synthesis of electroactive ternary composite based on polypyrrole, polyacrylamide and chitin nanofibers with beneficial morphology was elaborated. Ternary system demonstrates better electrochemical performance in comparison with both polypyrrole–polyacrylamide and polypyrrole–chitin binary composites. Possible mechanism of synergistic effect of simultaneous influence of polyacrylamide and chitin nanofibers on the formation of composite＇s structure is discussed.The highest attained specific capacitance of electroactive polypyrrole in ternary composite reached 249 F/g at 0.5 A/g and 150 F/g at 32 A/g. Symmetrical supercapacitor was assembled using the elaborated electrode material. High specific capacitance 89 F/g and good cycling stability with capacitance retention of 90% after 3000 cycles at 2 A/g were measured.展开更多
Chinese top planner-State Development and Reform Commission,has decided to organize and coordinate an implementation of a special project for high tech industrialization of fiber-reinforced compound materials in 2008 ...Chinese top planner-State Development and Reform Commission,has decided to organize and coordinate an implementation of a special project for high tech industrialization of fiber-reinforced compound materials in 2008 up to 2009.The decision has recently been issued in its national circular(doc. 3177,Yr.2007)to call for local enterprises to apply for this special project support.展开更多
In order to explore the bonding failure mechanism of high modulus carbon fiber composite materials,the tensile experiment and finite element numerical simulation for single-lap and bevel-lap joints of unidirectional l...In order to explore the bonding failure mechanism of high modulus carbon fiber composite materials,the tensile experiment and finite element numerical simulation for single-lap and bevel-lap joints of unidirectional laminates are carried out,and the stress distributions,the failure modes,and the damage contours are analyzed. The analysis shows that the main reason for the failure of the single-lap joint is that the stress concentration of the ply adjacent to the adhesive layer is serious owing to the modulus difference,and the stress cannot be effectively transmitted along the thickness direction of the laminate. When the tensile stress of the ply exceeds its ultimate strength in the loading process,the surface fiber will fail. Compared with the single-lap joint,the bevel-lap joint optimizes the stress transfer path along the thickness direction,allows each layer of the laminate to share the load,avoids the stress concentration of the surface layer,and improves the bearing capacity of the bevel-lap joint. The improved bearing capacity of the bevellap joint is twice as much as that of the single-lap joint. The research in this paper provides a new idea for the subsequent study of mechanical properties of adhesively bonded composite materials.展开更多
There have been many interesting studies on high-entropy alloys（HEAs）, also known as multi-component（MC） alloys（MCAs）, in recent years. MC metallic-glasses（MGs） have shown the potential to express the advantag...There have been many interesting studies on high-entropy alloys（HEAs）, also known as multi-component（MC） alloys（MCAs）, in recent years. MC metallic-glasses（MGs） have shown the potential to express the advantages of MCAs and MGs in tandem. Amorphous phase formation rules are a crucial issue in the HEA and MCA field. For equal or near-equal atomic ratio alloys, mixed-entropy among the elements has a significant effect on the phase formation. This paper focuses on HEA amorphous phase formation rules. In the first two sections, the recent progress in amorphous phase formation in HEAs and MCAs is reviewed, including the effective factors and correlative parameters related to amorphous phase formation. In the third section, novel MCMGs including high-entropy（HE） bulk-metallic-glass（HE-BMG） and MCMG films developed in recent decades are summarized, and the giant-magnetic-impedance（GMI） effect of MC amorphous fibers is discussed.展开更多
基金Supported by the Natural Science Foundation of Hebei Province under Grant No E2012201084the National University Students’ Innovative Training Program under Grant No 201410075004
文摘Realizing the accurate characterization for the dynamic damage process is a great challenge. Here we carry out testing simultaneously for dynamic monitoring and acoustic emission （AE） statistical analysis towards fiber composites under mode-Ⅱ delamination damage. The load curve, AE relative energy, amplitude distribution, and amplitude spectrum are obtained and the delamination damage mechanism of the composites is investigated by the microscopic observation of a fractured specimen. The results show that the micro-damage accumulation around the crack tip region has a great effect on the evolutionary process of delamination. AE characteristics and amplitude spectrum represent the damage and the physical mechanism originating from the hierarchical microstructure. Our finding provides a novel aud feasible strategy to simultaneously evaluate the dynamic response and micro-damage mechanism for fiber composites.
基金supported by the National Natural Science Foundation of China(Nos.21325417 and 51533008)National Key R&D Program of China(No.2016YFA0200200)+1 种基金Fundamental Research Funds for the Central Universities(No.2017XZZX008-06)the China Postdoctoral Science Foundation(No.2017M621927)
文摘Modern wearable electronics are thirsty for flexible, lightweight energy storage and supply devices. Flexible fiber-shaped supercapacitors, possess good flexibility, high power density, fast charging capability and long cycle life, becoming a promising option for wearable devices. The past decade has witnessed the emergence of graphene fiber based supercapacitors（GFSCs） as one of the most active vicinity in fiber-supercapactiors, for their excellent properties including high surface area, chemical stability, excellent electrical conductivity, lightweight and mechanical properties. In this perspective, we introduced the basic energy storage mechanisms of GFSCs, followed by the analysis in improving their overall performances, recent advances, and a conclusive discussion on the challenges and opportunities.
基金supported by Russian Foundation(grant 16-13-10164)financial support of Russian Ministry of Education within State Contract 14.W03.31.0014(megagrant)
文摘Development of simple methods for preparation of polymeric electrode materials with nanofibrous network structure is a perspective way toward cheap supercapacitors with high specific capacitance and energy density. In this work one-pot synthesis of electroactive ternary composite based on polypyrrole, polyacrylamide and chitin nanofibers with beneficial morphology was elaborated. Ternary system demonstrates better electrochemical performance in comparison with both polypyrrole–polyacrylamide and polypyrrole–chitin binary composites. Possible mechanism of synergistic effect of simultaneous influence of polyacrylamide and chitin nanofibers on the formation of composite＇s structure is discussed.The highest attained specific capacitance of electroactive polypyrrole in ternary composite reached 249 F/g at 0.5 A/g and 150 F/g at 32 A/g. Symmetrical supercapacitor was assembled using the elaborated electrode material. High specific capacitance 89 F/g and good cycling stability with capacitance retention of 90% after 3000 cycles at 2 A/g were measured.
文摘Chinese top planner-State Development and Reform Commission,has decided to organize and coordinate an implementation of a special project for high tech industrialization of fiber-reinforced compound materials in 2008 up to 2009.The decision has recently been issued in its national circular(doc. 3177,Yr.2007)to call for local enterprises to apply for this special project support.
文摘In order to explore the bonding failure mechanism of high modulus carbon fiber composite materials,the tensile experiment and finite element numerical simulation for single-lap and bevel-lap joints of unidirectional laminates are carried out,and the stress distributions,the failure modes,and the damage contours are analyzed. The analysis shows that the main reason for the failure of the single-lap joint is that the stress concentration of the ply adjacent to the adhesive layer is serious owing to the modulus difference,and the stress cannot be effectively transmitted along the thickness direction of the laminate. When the tensile stress of the ply exceeds its ultimate strength in the loading process,the surface fiber will fail. Compared with the single-lap joint,the bevel-lap joint optimizes the stress transfer path along the thickness direction,allows each layer of the laminate to share the load,avoids the stress concentration of the surface layer,and improves the bearing capacity of the bevel-lap joint. The improved bearing capacity of the bevellap joint is twice as much as that of the single-lap joint. The research in this paper provides a new idea for the subsequent study of mechanical properties of adhesively bonded composite materials.
基金supported by the National Natural Science Foundation of China(Grant No.51471025)
文摘There have been many interesting studies on high-entropy alloys（HEAs）, also known as multi-component（MC） alloys（MCAs）, in recent years. MC metallic-glasses（MGs） have shown the potential to express the advantages of MCAs and MGs in tandem. Amorphous phase formation rules are a crucial issue in the HEA and MCA field. For equal or near-equal atomic ratio alloys, mixed-entropy among the elements has a significant effect on the phase formation. This paper focuses on HEA amorphous phase formation rules. In the first two sections, the recent progress in amorphous phase formation in HEAs and MCAs is reviewed, including the effective factors and correlative parameters related to amorphous phase formation. In the third section, novel MCMGs including high-entropy（HE） bulk-metallic-glass（HE-BMG） and MCMG films developed in recent decades are summarized, and the giant-magnetic-impedance（GMI） effect of MC amorphous fibers is discussed.
