A new geometric model of Multiaxial Warp-Knitted (MWK) performs, which is based on the experimental observations and analysis of basic stitch, is developed to relate the geometric parameters and process variables. The...A new geometric model of Multiaxial Warp-Knitted (MWK) performs, which is based on the experimental observations and analysis of basic stitch, is developed to relate the geometric parameters and process variables. The fiber volume fraction and fibre orientation of MWK reinforced composites are described in terms of structural and processing parameters in the model. And this model provides a basis for the prediction of mechanical behavior of the MWK reinforced composites.展开更多
Using a friction stir additive manufacturing(FSAM)process,the fabrication of a two-layer aluminum−copper pipe was studied experimentally and numerically.For this purpose,by presenting a 3D thermo-mechanical model in A...Using a friction stir additive manufacturing(FSAM)process,the fabrication of a two-layer aluminum−copper pipe was studied experimentally and numerically.For this purpose,by presenting a 3D thermo-mechanical model in ABAQUS software,the temperature and strain distributions during the process were studied.The simulation results show that,although the rotational-to-traverse speed ratio with a good approximation can predict the heat input during welding,it is not a precise measure to predict the occurrence of defects in the weld cross-section.There is a good agreement between the predicted and experimental thermal results,and the maximum relative error is 4.1%in estimating the maximum temperature during welding.Due to heat and severe plastic deformation in the stir zone,the aluminum−copper intermetallic compounds(CuAl_(2) and Cu_(9)Al_(4))are formed.The maximum hardness in the stir zone is 301.4 HV_(0.1) in sample welded with an overlap of−0.5 mm.The ultimate tensile strength and elongation of the two-layer pipe fabricated by friction stir additive manufacturing are(319.52±2.31)MPa and 19.47%,respectively.展开更多
We show that the isomorphism problem is solvable in the class of central extensions of word-hyperbolic groups,and that the isomorphism problem for biautomatic groups reduces to that for biautomatic groups with finite ...We show that the isomorphism problem is solvable in the class of central extensions of word-hyperbolic groups,and that the isomorphism problem for biautomatic groups reduces to that for biautomatic groups with finite centre.We describe an algorithm that,given an arbitrary finite presentation of an automatic group Γ,will construct explicit finite models for the skeleta of K(Γ,1) and hence compute the integral homology and cohomology of Γ.展开更多
文摘A new geometric model of Multiaxial Warp-Knitted (MWK) performs, which is based on the experimental observations and analysis of basic stitch, is developed to relate the geometric parameters and process variables. The fiber volume fraction and fibre orientation of MWK reinforced composites are described in terms of structural and processing parameters in the model. And this model provides a basis for the prediction of mechanical behavior of the MWK reinforced composites.
文摘Using a friction stir additive manufacturing(FSAM)process,the fabrication of a two-layer aluminum−copper pipe was studied experimentally and numerically.For this purpose,by presenting a 3D thermo-mechanical model in ABAQUS software,the temperature and strain distributions during the process were studied.The simulation results show that,although the rotational-to-traverse speed ratio with a good approximation can predict the heat input during welding,it is not a precise measure to predict the occurrence of defects in the weld cross-section.There is a good agreement between the predicted and experimental thermal results,and the maximum relative error is 4.1%in estimating the maximum temperature during welding.Due to heat and severe plastic deformation in the stir zone,the aluminum−copper intermetallic compounds(CuAl_(2) and Cu_(9)Al_(4))are formed.The maximum hardness in the stir zone is 301.4 HV_(0.1) in sample welded with an overlap of−0.5 mm.The ultimate tensile strength and elongation of the two-layer pipe fabricated by friction stir additive manufacturing are(319.52±2.31)MPa and 19.47%,respectively.
文摘We show that the isomorphism problem is solvable in the class of central extensions of word-hyperbolic groups,and that the isomorphism problem for biautomatic groups reduces to that for biautomatic groups with finite centre.We describe an algorithm that,given an arbitrary finite presentation of an automatic group Γ,will construct explicit finite models for the skeleta of K(Γ,1) and hence compute the integral homology and cohomology of Γ.
