A state-of-the-art review was delivered in the manuscript to analyze the current situations and the advantages/disadvantages of resilient deformation related issues to the unbound granular material(UGM),including test...A state-of-the-art review was delivered in the manuscript to analyze the current situations and the advantages/disadvantages of resilient deformation related issues to the unbound granular material(UGM),including testing methods,influencing factors and constitutive models,through which the bottlenecks in UGM resilient deformation characterizations were located and new theories and future research recommendations were proposed.Compared with other testing methods,the hollow cylinder test and true triaxial test are the only two to determine the anisotropic moduli of the UGM.Although significant advantages are observed in more advanced test apparatus such as true triaxial test,further improvements should be made,such as more advanced process identification control algorithm,to more conveniently control the nine independent hydraulic system and accurately measure UGM anisotropic properties.Confusions and conflicts in understanding the influencing factors to UGM resilient modulus were located,such as the stress history,the residual stress,the dry density,the gradation/fine content and the freeze-thaw cycle,based on which future research could be conducted.Through reviewing evolutions of the UGM constitutive models and comparing their representativeness and complexity comprehensively,major drawbacks were discovered and a new theory was proposed afterward to modify the UGM constitutive model,although further validations are still needed.展开更多
The fine-scale heterogeneity of granular material is characterized by its polydisperse microstructure with randomness and no periodicity. To predict the mechanical response of the material as the microstructure evolve...The fine-scale heterogeneity of granular material is characterized by its polydisperse microstructure with randomness and no periodicity. To predict the mechanical response of the material as the microstructure evolves, it is demonstrated to develop computational multiscale methods using discrete particle assembly-Cosserat continuum modeling in micro- and macro- scales,respectively. The computational homogenization method and the bridge scale method along the concurrent scale linking approach are briefly introduced. Based on the weak form of the Hu-Washizu variational principle, the mixed finite element procedure of gradient Cosserat continuum in the frame of the second-order homogenization scheme is developed. The meso-mechanically informed anisotropic damage of effective Cosserat continuum is characterized and identified and the microscopic mechanisms of macroscopic damage phenomenon are revealed. c 2013 The Chinese Society of Theoretical and Applied Mechanics. [doi： 10.1063/2.1301101]展开更多
ZnO/graphene oxide（ZnO/GO） composite material,in which ZnO nanoparticles were densely coated on the GO nanosheets,was successfully prepared by an improved two-step method and characterized by IR, XRD,TEM,and UV-vis ...ZnO/graphene oxide（ZnO/GO） composite material,in which ZnO nanoparticles were densely coated on the GO nanosheets,was successfully prepared by an improved two-step method and characterized by IR, XRD,TEM,and UV-vis techniques.The improved photocatalytic property of the ZnO/GO composite material,evaluated by the photocatalytic degradation of methyl orange（MO） under UV irradiation,is ascribed to the intimate contact between ZnO and GO,the enhanced adsorption of MO,the quick electron transfer from excited ZnO particles to GO sheets and the activation of MO molecules viaπ-πinteraction between MO and GO.展开更多
基金financed by Natural Science Foundation of Shaanxi Province,China (Grant Nos.2021JQ-280,2021JQ-293)Key Laboratory of Road and Traffic Engineering of the Ministry of Education,Tongji University (Grant No.K202102)+1 种基金National Natural Science Foundation of China (Grant No.51908057)Fundamental Research Funds for the Central Universities (Grant No.300102212211)。
文摘A state-of-the-art review was delivered in the manuscript to analyze the current situations and the advantages/disadvantages of resilient deformation related issues to the unbound granular material(UGM),including testing methods,influencing factors and constitutive models,through which the bottlenecks in UGM resilient deformation characterizations were located and new theories and future research recommendations were proposed.Compared with other testing methods,the hollow cylinder test and true triaxial test are the only two to determine the anisotropic moduli of the UGM.Although significant advantages are observed in more advanced test apparatus such as true triaxial test,further improvements should be made,such as more advanced process identification control algorithm,to more conveniently control the nine independent hydraulic system and accurately measure UGM anisotropic properties.Confusions and conflicts in understanding the influencing factors to UGM resilient modulus were located,such as the stress history,the residual stress,the dry density,the gradation/fine content and the freeze-thaw cycle,based on which future research could be conducted.Through reviewing evolutions of the UGM constitutive models and comparing their representativeness and complexity comprehensively,major drawbacks were discovered and a new theory was proposed afterward to modify the UGM constitutive model,although further validations are still needed.
基金supported by the National Natural Science Foundation of China(11072046,10672033,90715011 and 11102036)the National Basic Research and Development Program(973Program,2010CB731502)
文摘The fine-scale heterogeneity of granular material is characterized by its polydisperse microstructure with randomness and no periodicity. To predict the mechanical response of the material as the microstructure evolves, it is demonstrated to develop computational multiscale methods using discrete particle assembly-Cosserat continuum modeling in micro- and macro- scales,respectively. The computational homogenization method and the bridge scale method along the concurrent scale linking approach are briefly introduced. Based on the weak form of the Hu-Washizu variational principle, the mixed finite element procedure of gradient Cosserat continuum in the frame of the second-order homogenization scheme is developed. The meso-mechanically informed anisotropic damage of effective Cosserat continuum is characterized and identified and the microscopic mechanisms of macroscopic damage phenomenon are revealed. c 2013 The Chinese Society of Theoretical and Applied Mechanics. [doi： 10.1063/2.1301101]
基金supported by the Natural Science Foundation of China(No.21174114)the Ministry of Education Plan for Yangtze River Scholar and Innovation Team Development(No.IRT1177)+2 种基金Scientific and Technical Plan Project of Gansu Province(No. 1204GKCA006)the Natural Science Foundation of Gansu Province (No.1010RJZA024)Scientific and Technical Innovation Project of Northwest Normal University(No.nwnu-kjcxgc-03-63)
文摘ZnO/graphene oxide（ZnO/GO） composite material,in which ZnO nanoparticles were densely coated on the GO nanosheets,was successfully prepared by an improved two-step method and characterized by IR, XRD,TEM,and UV-vis techniques.The improved photocatalytic property of the ZnO/GO composite material,evaluated by the photocatalytic degradation of methyl orange（MO） under UV irradiation,is ascribed to the intimate contact between ZnO and GO,the enhanced adsorption of MO,the quick electron transfer from excited ZnO particles to GO sheets and the activation of MO molecules viaπ-πinteraction between MO and GO.
