Unequal diameter twin-roll casting(UDTRC)can improve the formability,surface conditions,and production efficiency during the fabrication of clad strips.Using Fluent software,a numerical simulation is used to study the...Unequal diameter twin-roll casting(UDTRC)can improve the formability,surface conditions,and production efficiency during the fabrication of clad strips.Using Fluent software,a numerical simulation is used to study the asymmetric heat transfer characteristics of Cu/Al clad strips fabricated by UDTRC.The effects of roller velocity ratio,Cu strip thickness,and inclination angle on the kissing point position,as well as the entire temperature distribution are obtained.The heat transfer model is established,and the mechanism is discussed.The Cu strip and rollers are found to be the main causes of asymmetric heat transfer,indicating that the roller velocity ratio changes the liquid zone proportion in the molten pool.The Cu strip thickness determines the heat absorption capacity and the variations in thermal resistance between the molten Al and the big roller.The inclination angle of the small roller changes the cooling time of big roller to molten Al.Moreover,the microstructure of Al cladding under different roller velocity ratios is examined.The results show significant grain refinement caused by the shear strain along the thickness direction of Al cladding and the intense heat transfer at the moment of contact between the metal Al cladding and Cu strip.展开更多
A four-bar linkage mechanism with links fabricated from symmetric laminates was studied. The mass matrix of the beam dement was obtained in light of the mass distribution characteristics of composite materials. The st...A four-bar linkage mechanism with links fabricated from symmetric laminates was studied. The mass matrix of the beam dement was obtained in light of the mass distribution characteristics of composite materials. The stiffness matrix of the beam element was derived from the constitutive equations of each layer and the relationship between the strain distribution and the node displacement of the beam element. The specific damping capacity of the beam element was analyzed according to the strain distribution of the beam element and the strain energy dissipation caused by vibration in each direction of each layer; and the damping coefficients were obtained according to the principle that the total energy dissipation of the beam element was equal to the work done by the equivalent damping force during a cycle of vibration, from which the damping matrix of the dynamic equations was obtained. Using the finite element method, the dynamic analytic model of the mechanism was obtained. The dynamic responses and natural frequency of the mechanism were obtained by simulation, respectively, and those of the simulation obtained by the proposed model were analyzed and compared with the results obtained by the conventional model. The work provides theoretical basis to a certain extent for the further research on nonlinear vibration characteristics and optimum design of this kind of mechanism.展开更多
基金Project(51974278)supported by the National Natural Science Foundation of ChinaProject(E2018203446)supported by the Natural Science Foundation of Hebei Province Distinguished Young Fund Project,ChinaProject(2018YFA0707303)supported by the National Key Research and Development Project of China。
文摘Unequal diameter twin-roll casting(UDTRC)can improve the formability,surface conditions,and production efficiency during the fabrication of clad strips.Using Fluent software,a numerical simulation is used to study the asymmetric heat transfer characteristics of Cu/Al clad strips fabricated by UDTRC.The effects of roller velocity ratio,Cu strip thickness,and inclination angle on the kissing point position,as well as the entire temperature distribution are obtained.The heat transfer model is established,and the mechanism is discussed.The Cu strip and rollers are found to be the main causes of asymmetric heat transfer,indicating that the roller velocity ratio changes the liquid zone proportion in the molten pool.The Cu strip thickness determines the heat absorption capacity and the variations in thermal resistance between the molten Al and the big roller.The inclination angle of the small roller changes the cooling time of big roller to molten Al.Moreover,the microstructure of Al cladding under different roller velocity ratios is examined.The results show significant grain refinement caused by the shear strain along the thickness direction of Al cladding and the intense heat transfer at the moment of contact between the metal Al cladding and Cu strip.
基金Projects(50175031, 50565001) supported by the National Natural Science Foundation of China project (2003203) supported by the New Century Ten Hundred and Thousand Talent Project Special Foundation of Guangxi+1 种基金 project(0542005) supported by Guangxi Science Foundation project(205119) supported by the Key Project of Chinese Ministry of Education
文摘A four-bar linkage mechanism with links fabricated from symmetric laminates was studied. The mass matrix of the beam dement was obtained in light of the mass distribution characteristics of composite materials. The stiffness matrix of the beam element was derived from the constitutive equations of each layer and the relationship between the strain distribution and the node displacement of the beam element. The specific damping capacity of the beam element was analyzed according to the strain distribution of the beam element and the strain energy dissipation caused by vibration in each direction of each layer; and the damping coefficients were obtained according to the principle that the total energy dissipation of the beam element was equal to the work done by the equivalent damping force during a cycle of vibration, from which the damping matrix of the dynamic equations was obtained. Using the finite element method, the dynamic analytic model of the mechanism was obtained. The dynamic responses and natural frequency of the mechanism were obtained by simulation, respectively, and those of the simulation obtained by the proposed model were analyzed and compared with the results obtained by the conventional model. The work provides theoretical basis to a certain extent for the further research on nonlinear vibration characteristics and optimum design of this kind of mechanism.
