A post-acceleration system based on the accelerators at CSNS （China Spallation Neutron Source） is pro- posed to build a super-beam facility for neutrino physics. Two post-acceleration schemes, one using superconduct...A post-acceleration system based on the accelerators at CSNS （China Spallation Neutron Source） is pro- posed to build a super-beam facility for neutrino physics. Two post-acceleration schemes, one using superconducting dipole magnets in the main ring and the other using room temperature magnets, have been studied, both to achieve the final proton energy of 128 GeV and the beam power of 4 MW by taking 10% of the CSNS beam from the neutron source. The main design features and the comparison for the two schemes are presented. The CSNS super-beam facility will be very competitive in long-baseline neutrino physics studies, compared with other super-beam facilities proposed in the world.展开更多
Based on the nonlinear geometric theory of axially extensible beams and by using the shooting method, the thermal post-buckling responses of an elastic beams,with immovably simply supported ends and subjected to a tra...Based on the nonlinear geometric theory of axially extensible beams and by using the shooting method, the thermal post-buckling responses of an elastic beams,with immovably simply supported ends and subjected to a transversely non-uniformly distributed temperature rising, were investigated. Especially, the influences of the transverse temperature change on the thermal post-buckling deformations were examined and the corresponding characteristic curves were plotted. The numerical results show that the equilibrium paths of the beam are similar to what of an initially deformed beam because of the thermal bending moment produced in the beam by the transverse temperature change.展开更多
Based on the multi-rigid body discretization model, namely, finite segment model,a chain multi-rigid-body-hinge-spring system model of a beam was presented, then a nonlinear parametrically exacted vibration equation o...Based on the multi-rigid body discretization model, namely, finite segment model,a chain multi-rigid-body-hinge-spring system model of a beam was presented, then a nonlinear parametrically exacted vibration equation of multi-degrees of freedom system was established using the coordination transformation method, and its resonance fields were derived by the restriction parameter method, that is, the dynamical buckling analysis of the beam. Because the deformation of a beam is not restricted by the discrete model and dynamic equation, the post buckling analysis can be done in above math model. The numerical solutions of a few examples were obtained by direct integrated method, which shows that the mechanical and math model gotten is correct.展开更多
Traditional wooden joinery is the craft of connecting wood pieces for buildings or producing utensils by utilizing only the geometry of the components and material properties of the wood,without other materials such a...Traditional wooden joinery is the craft of connecting wood pieces for buildings or producing utensils by utilizing only the geometry of the components and material properties of the wood,without other materials such as glue or metal connectors.In its thousands of years of tradition,this construction technique has achieved high accomplishment in both East Asian and European architectural civilizations.Although sharing the same basic principles,joinery techniques vary between regions and cultures,rooted in the geographical environment,available wood species and their material properties,characteristics of craftsmanship,tools,and structural systems.Wood framing systems from China,Japan,and Western Europe are selected for comparison to assess the relationship between wood joinery and other aspects of building technology.The main conclusions include:in East Asia,the building tradition pays great attention to the design and execution of joinery(sunmao榫卯),making it responsible for multiple functions including architectural mechanics and the stability of the entire frame,which leads to a broader role meant by the term“joint”itself,while in Europe joinery is treated as the“node”or literally“joint”of the structure.Although in both East Asia and Europe wooden joinery serves as an aesthetic factor of the structure,its expression in East Asia is subtle,veiled,and restrained,while in Europe it is explicit and direct.The most important lesson we learn from the study of traditional joinery technology is that it should be seen in the context of the building process as a whole,taking into account geographical environment,material resources,craftsmanship,tools,construction methods,structural form,and the structural system.展开更多
Sheathed post-and-beam wooden structures are distinct from light-wood structures.They allow for using sheathing panels that are smaller(0.91 m×1.82 m)than standard-sized panels(1.22 m×2.44 m or 2.44 m×2...Sheathed post-and-beam wooden structures are distinct from light-wood structures.They allow for using sheathing panels that are smaller(0.91 m×1.82 m)than standard-sized panels(1.22 m×2.44 m or 2.44 m×2.44 m).Evidence indicates that nail spacing and panel thickness determine the lateral capacity of the wood frame shear walls.To verify the lateral shear performance of wood frame shear walls with smaller panels,we subjected 13 shear walls,measuring 0.91 m in width and 2.925 m in height,to a low-cycle cyclic loading test with three kinds of nail spacing and three panel thicknesses.A nonlinear numerical simulation analysis of the wall was conducted using ABAQUS finite element(FE)software,where a custom nonlinear spring element was used to simulate the sheathing-frame connection.The results indicate that the hysteretic performance of the walls was mainly determined by the hysteretic performance of the sheathing-frame connection.When same nail specifications were adopted,the stiffness and bearing capacity of the walls were inversely related to the nail spacing and directly related to the panel thickness.The shear wall remained in the elastic stage when the drift was 1/250 rad and ductility coefficients were all greater than 2.5,which satisfied the deformation requirements of residential structures.Based on the test and FE analysis results,the shear strength of the post-and-beam wooden structures with sheathed walls was determined.展开更多
This paper is focused on the post-buckling behavior of the fixed laminated composite beams with effects of axial compression force and the shear deformation.The analytical solutions are established for the original co...This paper is focused on the post-buckling behavior of the fixed laminated composite beams with effects of axial compression force and the shear deformation.The analytical solutions are established for the original control equations(that is not simplified)by applying the Maclaurin series expansion,Chebyshev polynomials,the harmonic balance method and the Newton’s method.The validity of the present method is verified via comparing the analytical approximate solutions with the numerical ones which are obtained by the shooting method.The present third analytical approximate solutions can give excellent agreement with the numerical solutions for a wide range of the deformation amplitudes.What’s more,the effect of shear deformation on the post-bucking configuration of the sandwich beam is also proposed.It can be found that the shear angle has a great influence on the post-buckling load of composite beams.Therefore,the model simplifying the shear formation term as small quantity is not accurate for the case of sandwich beam with soft core.展开更多
基金Supported by National Natural Science Foundation of China(11235012,10975150)
文摘A post-acceleration system based on the accelerators at CSNS （China Spallation Neutron Source） is pro- posed to build a super-beam facility for neutrino physics. Two post-acceleration schemes, one using superconducting dipole magnets in the main ring and the other using room temperature magnets, have been studied, both to achieve the final proton energy of 128 GeV and the beam power of 4 MW by taking 10% of the CSNS beam from the neutron source. The main design features and the comparison for the two schemes are presented. The CSNS super-beam facility will be very competitive in long-baseline neutrino physics studies, compared with other super-beam facilities proposed in the world.
文摘Based on the nonlinear geometric theory of axially extensible beams and by using the shooting method, the thermal post-buckling responses of an elastic beams,with immovably simply supported ends and subjected to a transversely non-uniformly distributed temperature rising, were investigated. Especially, the influences of the transverse temperature change on the thermal post-buckling deformations were examined and the corresponding characteristic curves were plotted. The numerical results show that the equilibrium paths of the beam are similar to what of an initially deformed beam because of the thermal bending moment produced in the beam by the transverse temperature change.
文摘Based on the multi-rigid body discretization model, namely, finite segment model,a chain multi-rigid-body-hinge-spring system model of a beam was presented, then a nonlinear parametrically exacted vibration equation of multi-degrees of freedom system was established using the coordination transformation method, and its resonance fields were derived by the restriction parameter method, that is, the dynamical buckling analysis of the beam. Because the deformation of a beam is not restricted by the discrete model and dynamic equation, the post buckling analysis can be done in above math model. The numerical solutions of a few examples were obtained by direct integrated method, which shows that the mechanical and math model gotten is correct.
基金Project supported by the National Natural Science Foundation of China(Grant No.52008194)。
文摘Traditional wooden joinery is the craft of connecting wood pieces for buildings or producing utensils by utilizing only the geometry of the components and material properties of the wood,without other materials such as glue or metal connectors.In its thousands of years of tradition,this construction technique has achieved high accomplishment in both East Asian and European architectural civilizations.Although sharing the same basic principles,joinery techniques vary between regions and cultures,rooted in the geographical environment,available wood species and their material properties,characteristics of craftsmanship,tools,and structural systems.Wood framing systems from China,Japan,and Western Europe are selected for comparison to assess the relationship between wood joinery and other aspects of building technology.The main conclusions include:in East Asia,the building tradition pays great attention to the design and execution of joinery(sunmao榫卯),making it responsible for multiple functions including architectural mechanics and the stability of the entire frame,which leads to a broader role meant by the term“joint”itself,while in Europe joinery is treated as the“node”or literally“joint”of the structure.Although in both East Asia and Europe wooden joinery serves as an aesthetic factor of the structure,its expression in East Asia is subtle,veiled,and restrained,while in Europe it is explicit and direct.The most important lesson we learn from the study of traditional joinery technology is that it should be seen in the context of the building process as a whole,taking into account geographical environment,material resources,craftsmanship,tools,construction methods,structural form,and the structural system.
基金supporting this study with a research grant(No.2019YFD1101001).
文摘Sheathed post-and-beam wooden structures are distinct from light-wood structures.They allow for using sheathing panels that are smaller(0.91 m×1.82 m)than standard-sized panels(1.22 m×2.44 m or 2.44 m×2.44 m).Evidence indicates that nail spacing and panel thickness determine the lateral capacity of the wood frame shear walls.To verify the lateral shear performance of wood frame shear walls with smaller panels,we subjected 13 shear walls,measuring 0.91 m in width and 2.925 m in height,to a low-cycle cyclic loading test with three kinds of nail spacing and three panel thicknesses.A nonlinear numerical simulation analysis of the wall was conducted using ABAQUS finite element(FE)software,where a custom nonlinear spring element was used to simulate the sheathing-frame connection.The results indicate that the hysteretic performance of the walls was mainly determined by the hysteretic performance of the sheathing-frame connection.When same nail specifications were adopted,the stiffness and bearing capacity of the walls were inversely related to the nail spacing and directly related to the panel thickness.The shear wall remained in the elastic stage when the drift was 1/250 rad and ductility coefficients were all greater than 2.5,which satisfied the deformation requirements of residential structures.Based on the test and FE analysis results,the shear strength of the post-and-beam wooden structures with sheathed walls was determined.
基金supported by the National Natural Science Foundation of China(Grant No.41972323 and 51991364)Science and Technology Project of the 13th Five-Year Plan of Jilin Provincial Department of Education(Grant No.JJKH20190126KJ)the Science and Technology Developing Plan Project of Jilin Province(Grant No.20160520021JH).
文摘This paper is focused on the post-buckling behavior of the fixed laminated composite beams with effects of axial compression force and the shear deformation.The analytical solutions are established for the original control equations(that is not simplified)by applying the Maclaurin series expansion,Chebyshev polynomials,the harmonic balance method and the Newton’s method.The validity of the present method is verified via comparing the analytical approximate solutions with the numerical ones which are obtained by the shooting method.The present third analytical approximate solutions can give excellent agreement with the numerical solutions for a wide range of the deformation amplitudes.What’s more,the effect of shear deformation on the post-bucking configuration of the sandwich beam is also proposed.It can be found that the shear angle has a great influence on the post-buckling load of composite beams.Therefore,the model simplifying the shear formation term as small quantity is not accurate for the case of sandwich beam with soft core.
