The effect of arc-ultrasound on microstructures and mechanical properties of SiCp/6061A1 MMCs joints produced by arc-ultrasound plasma arc ＂in-situ＂ alloy-welding with different excitation frequencies was investigat...The effect of arc-ultrasound on microstructures and mechanical properties of SiCp/6061A1 MMCs joints produced by arc-ultrasound plasma arc ＂in-situ＂ alloy-welding with different excitation frequencies was investigated, in which argon-nitrogen mixture was used as plasma gas, Ti wire as filler and the arc-ultrasound was produced by modulating the plasma arc with high frequency. The results show that arc-ultrasound could refine the new reinforced composites such as TiC, TiN significantly, and improve their distribution greatly. And new phase A13Ti becomes finer and less. The test results of mechanical properties indicate that the maximum tensile strength of welded joints is gained when the excitation frequency is 50 kHz, and the maximum is 225 MPa, raising by about 7% comoared with conventional nlasma arc welding （PAW） （20q MPa）.展开更多
An explicit topology optimization method for the stiffener layout of composite stiffened panels is proposed based on moving morphable components(MMCs).The skin and stiffeners are considered as panels with different be...An explicit topology optimization method for the stiffener layout of composite stiffened panels is proposed based on moving morphable components(MMCs).The skin and stiffeners are considered as panels with different bending stiffnesses,with the use of equivalent stiffness method.Then the location and geometric properties of composite stiffeners are determined by several MMCs to perform topology optimization,which can greatly simplify the finite element model.With the objective of maximizing structural stiffness,several typical cases with various loading and boundary conditions are selected as numerical examples to demonstrate the proposed method.The numerical examples illustrate that the proposed method can provide clear stiffener layout and explicit geometry information,which is not limited within the framework of parameter and size optimization.The mechanical properties of composite stiffened panels can be fully enhanced.展开更多
Fiber-reinforced composite materials have excellent specific stiffness,specific strength,and other properties,and have been increasingly widely used in the field of advanced structures.However,the design space dimensi...Fiber-reinforced composite materials have excellent specific stiffness,specific strength,and other properties,and have been increasingly widely used in the field of advanced structures.However,the design space dimensions of fiber-reinforced composite materials will expand explosively,bringing challenges to the efficient analysis and optimal design of structures.In this paper,the authors propose an explicit topology optimization method based on the moving morphable components for designing the fiber-reinforced material.We constrain the intersection area between components to guarantee the independence of each component and avoid the situation that one component is cut by other components.Adding the fiber orientation angle as a design variable,the method can optimize the structural layout and the fiber orientation angle concurrently under the given number of fiber layers and layer thickness.We use two classical examples to verify the feasibility and accuracy of the proposed method.The optimized results are in good agreement with the designs obtained by the 99-line code.The authors also popularize the proposed method to engineering structure.The results manifest that the proposed method has great value in engineering application.展开更多
Taking three kinds of metal-matrix composites (MMCS) (laminated composites, fibers reinforced MMCs, and particle-reinforced MMCs)as examples, the recent develop ments in modeling the damping behaviors of MMCs are ext...Taking three kinds of metal-matrix composites (MMCS) (laminated composites, fibers reinforced MMCs, and particle-reinforced MMCs)as examples, the recent develop ments in modeling the damping behaviors of MMCs are extensively reviewed. The damping mechanisms of different kinds of composites are quite different, and therefore, the analytical of numerical methods for different kinds of MMCs are also quite different. This will he shown in this extensive review. Furthermore, the directions of future developments in modeling the damping behavior of MMCs are also presented.展开更多
Corrections to:Acta Mechanica Solida Sinica https://doi.org/10.1007/s10338-021-00305-0 During production of the article unfortunately several typesetting mistakes have been introduced.In Eq.(17).
Advances in controllable growth of ultra thin two-dimensional molecular crystals(2DMCs)or even monolayer molecular crystals(MMCs)propelled their application in high-performance,high-sensitivity,lowcontact-resistance o...Advances in controllable growth of ultra thin two-dimensional molecular crystals(2DMCs)or even monolayer molecular crystals(MMCs)propelled their application in high-performance,high-sensitivity,lowcontact-resistance optoelectronic devices.However,the rational molecular design strategies for materials prone to grow into ultrathin 2DMC or MMC have rarely been addressed.Here,systematically tailoring theπ-conjugation and alkyl chain types of asymmetric anthracene derivatives,2DMCs and even MMCs were obtained under the synergetic regulation of inter-and intralayer interactions.High-quality MMCs were obtained for SAP-C6 by traditional physical vapor transport technique(PVT),and corresponding organic field-effect transistors(OFETs)exhibited high mobility of 3.22 cm^(2)V^(-1)s^(-1).In addition,band-like charge transport with low activation energy was achieved by SAP-C6 MMC-OFETs.Furthermore,the SAPC6 MMC-based device exhibits excellent thermal stability,retaining~70%of its initial performance at 140℃in air,which is the first report on the thermal stability of MMC devices.This research highlights the potential of alkyl-substituted asymmetric molecules as a design strategy to achieve ultrathin 2DMC or MMC growth,and improve the mobility and thermal stability in OFETs.展开更多
基金Project (09003)supported by the Open Research Fund of State Key Laboratory of Advanced Welding Production Technology, Harbin Institute of Technology, ChinaProject (JSAWT-07-04 ) supported by Provincial Key Research Fund of Advanced Welding Technology, Jiangsu University of Science and Technology, China
文摘The effect of arc-ultrasound on microstructures and mechanical properties of SiCp/6061A1 MMCs joints produced by arc-ultrasound plasma arc ＂in-situ＂ alloy-welding with different excitation frequencies was investigated, in which argon-nitrogen mixture was used as plasma gas, Ti wire as filler and the arc-ultrasound was produced by modulating the plasma arc with high frequency. The results show that arc-ultrasound could refine the new reinforced composites such as TiC, TiN significantly, and improve their distribution greatly. And new phase A13Ti becomes finer and less. The test results of mechanical properties indicate that the maximum tensile strength of welded joints is gained when the excitation frequency is 50 kHz, and the maximum is 225 MPa, raising by about 7% comoared with conventional nlasma arc welding （PAW） （20q MPa）.
基金The financial supports from the National Key Research and Development Plan(2016YFB0201601)the Foundation for Innovative Research Groups of the National Natural Science Foundation(11821202)+3 种基金the National Natural Science Foundation(11872138,11702048,11732004 and 11772076)Program for Changjiang Scholars,Innovative Research Team in University(PCSIRT)Young Elite Scientists Sponsorship Program by CAST(2018QNRC001)Liaoning Natural Science Foundation Guidance Plan(20170520293)111 Project(B14013)are gratefully acknowledged.
文摘An explicit topology optimization method for the stiffener layout of composite stiffened panels is proposed based on moving morphable components(MMCs).The skin and stiffeners are considered as panels with different bending stiffnesses,with the use of equivalent stiffness method.Then the location and geometric properties of composite stiffeners are determined by several MMCs to perform topology optimization,which can greatly simplify the finite element model.With the objective of maximizing structural stiffness,several typical cases with various loading and boundary conditions are selected as numerical examples to demonstrate the proposed method.The numerical examples illustrate that the proposed method can provide clear stiffener layout and explicit geometry information,which is not limited within the framework of parameter and size optimization.The mechanical properties of composite stiffened panels can be fully enhanced.
基金supports from the National Key Research and Development Plan(2020YFB1709401)the National Natural Science Foundation of China(11872138,11702048),Dalian Young TechStar Project(2019RQ045,2019RQ069)and the Scientific Research Fund Project of Education Department of Liaoning Province(JDL2020021).
文摘Fiber-reinforced composite materials have excellent specific stiffness,specific strength,and other properties,and have been increasingly widely used in the field of advanced structures.However,the design space dimensions of fiber-reinforced composite materials will expand explosively,bringing challenges to the efficient analysis and optimal design of structures.In this paper,the authors propose an explicit topology optimization method based on the moving morphable components for designing the fiber-reinforced material.We constrain the intersection area between components to guarantee the independence of each component and avoid the situation that one component is cut by other components.Adding the fiber orientation angle as a design variable,the method can optimize the structural layout and the fiber orientation angle concurrently under the given number of fiber layers and layer thickness.We use two classical examples to verify the feasibility and accuracy of the proposed method.The optimized results are in good agreement with the designs obtained by the 99-line code.The authors also popularize the proposed method to engineering structure.The results manifest that the proposed method has great value in engineering application.
文摘Taking three kinds of metal-matrix composites (MMCS) (laminated composites, fibers reinforced MMCs, and particle-reinforced MMCs)as examples, the recent develop ments in modeling the damping behaviors of MMCs are extensively reviewed. The damping mechanisms of different kinds of composites are quite different, and therefore, the analytical of numerical methods for different kinds of MMCs are also quite different. This will he shown in this extensive review. Furthermore, the directions of future developments in modeling the damping behavior of MMCs are also presented.
文摘Corrections to:Acta Mechanica Solida Sinica https://doi.org/10.1007/s10338-021-00305-0 During production of the article unfortunately several typesetting mistakes have been introduced.In Eq.(17).
基金supported by the Ministry of Science and Technology of China through the National Key R&D Plan(Nos.2022YFA1205900,2022YFB3603801)Chinese Academy of Sciences(Hundred Talents Plan,Youth Innovation Promotion Association),the Strategic Priority Research Program of Sciences(No.XDB0520201)+1 种基金Young Scientists in Basic Research(No.YSBR-053)National Natural Science Foundation of China(Nos.T2225028,22475219,22075295,U22A6002,U21A20497)。
文摘Advances in controllable growth of ultra thin two-dimensional molecular crystals(2DMCs)or even monolayer molecular crystals(MMCs)propelled their application in high-performance,high-sensitivity,lowcontact-resistance optoelectronic devices.However,the rational molecular design strategies for materials prone to grow into ultrathin 2DMC or MMC have rarely been addressed.Here,systematically tailoring theπ-conjugation and alkyl chain types of asymmetric anthracene derivatives,2DMCs and even MMCs were obtained under the synergetic regulation of inter-and intralayer interactions.High-quality MMCs were obtained for SAP-C6 by traditional physical vapor transport technique(PVT),and corresponding organic field-effect transistors(OFETs)exhibited high mobility of 3.22 cm^(2)V^(-1)s^(-1).In addition,band-like charge transport with low activation energy was achieved by SAP-C6 MMC-OFETs.Furthermore,the SAPC6 MMC-based device exhibits excellent thermal stability,retaining~70%of its initial performance at 140℃in air,which is the first report on the thermal stability of MMC devices.This research highlights the potential of alkyl-substituted asymmetric molecules as a design strategy to achieve ultrathin 2DMC or MMC growth,and improve the mobility and thermal stability in OFETs.
