Proposes a simplified finite element model for steel-concrete composite beams. The effects of slip can be taken into account by creating a special matrix of shear connector stiffness and using the iteration method. Me...Proposes a simplified finite element model for steel-concrete composite beams. The effects of slip can be taken into account by creating a special matrix of shear connector stiffness and using the iteration method. Meanwhile, the effect of material non-linearity of steel and concrete on rigidity and strength of composite beams is considered. With the age-adjusted effective modulus method, the analysis for the whole process of shrinkage and creep under long-term load can be performed. The ultimate load, deflection, stress and slip of continuous composite beams under short-term and long-term load are computed using the proposed finite element model. The numerical results are compared with the experimental results and existing values based on other numerical methods, and are found to be in good agreement.展开更多
The transient response of an unlimited cylindrical cavity buried in the infinite elastic soil subjected to an anti-plane impact load along the cavern axis direction was studied.Using Laplace transform combining with c...The transient response of an unlimited cylindrical cavity buried in the infinite elastic soil subjected to an anti-plane impact load along the cavern axis direction was studied.Using Laplace transform combining with contour integral of the Laplace inverse transform specifically,the general analytical expressions of the soil displacement and stress are obtained in the time domain,respectively.And the numerical solutions of the problem computed by analytical expressions are presented.In the time domain,the dynamic responses of the infinite elastic soil are analyzed,and the calculation results are compared with those from numerical inversion proposed by Durbin and the static results.One observes good agreement between analytical and numerical inversion results,lending the further support to the method presented.Finally,some valuable shear wave propagation laws are gained: the displacement of the soil remains zero before the wave arrival,and after the shear wave arrival,the stress and the displacement at this point increase abruptly,then reduce and tend to the static value gradually at last.The wave attenuates along the radial,therefore the farther the wave is from the source,the smaller the stress and the displacement are,and the stress and the displacement are just functions of the radial distance from the axis.展开更多
An approach for the contact analysis and load distribution of double-envelop hourglass worm gearing is presented, which is based on a 3-D elastic contact finite element method (FEM) model that accommodates the influen...An approach for the contact analysis and load distribution of double-envelop hourglass worm gearing is presented, which is based on a 3-D elastic contact finite element method (FEM) model that accommodates the influence of errors and load. As compared with existing tooth contact analysis model that assumes rigidity for the contacting surfaces, the proposed model provides a more realistic analysis on the contact patterns, the distribution of contact load and transmission errors. It is also capable of exploring the influence of different errors on meshing performances, the contact deformation, the shift of the contact zone and load share among the meshing tooth-pairs under different load.展开更多
A rectangular finite element for laminated plate with bonded and/or embedded piezoelectric sensors and actuators is developed based on the variational principle and the first order shear deformation theory. The elemen...A rectangular finite element for laminated plate with bonded and/or embedded piezoelectric sensors and actuators is developed based on the variational principle and the first order shear deformation theory. The element has four-node, 20-degrees-of-freedom with one potential degree of freedom for each piezoelectric layer to represent the piezoelectric behavior. The higher order derivation of deflection is obtained by using the normal rotation expressions to take the effects of transverse shear deformation into considerations. The finite element can accurately simulate the deformation of both thin and moderately thick plates. A Fortran program is written and a number of benchmark tests are exercised to verify its effectiveness. Results are compared well with the existing data. The unbalanced composite with piezoelectric layers is then analyzed by using the model. Results show that the changes of the ratio between the thickness of positive angle layers and the negative angle layers have an effect on the deformation of the structure under the same electric loading.展开更多
The discrete element method is used to simulate specimens under three different loading conditions（conventional triaxial compression,plane strain,and direct shear）with different initial conditions to explore the und...The discrete element method is used to simulate specimens under three different loading conditions（conventional triaxial compression,plane strain,and direct shear）with different initial conditions to explore the underlying mechanics of the specimen deformation from a microscale perspective.Deformations of specimens with different initial void ratios at different confining stresses under different loading conditions are studied.Results show that the discrete element models successfully capture the specimen deformation and the strain localization.Particle behaviors including particle rotation and displacement and the mesoscale void ratio distributions are used to explain the strain localization and specimen deformation.It is found that the loading condition is one of the most important factors controlling the specimen deformation mode.Microscale behavior of the granular soil is the driving mechanics of the macroscale deformation of the granular assembly.展开更多
文摘Proposes a simplified finite element model for steel-concrete composite beams. The effects of slip can be taken into account by creating a special matrix of shear connector stiffness and using the iteration method. Meanwhile, the effect of material non-linearity of steel and concrete on rigidity and strength of composite beams is considered. With the age-adjusted effective modulus method, the analysis for the whole process of shrinkage and creep under long-term load can be performed. The ultimate load, deflection, stress and slip of continuous composite beams under short-term and long-term load are computed using the proposed finite element model. The numerical results are compared with the experimental results and existing values based on other numerical methods, and are found to be in good agreement.
文摘The transient response of an unlimited cylindrical cavity buried in the infinite elastic soil subjected to an anti-plane impact load along the cavern axis direction was studied.Using Laplace transform combining with contour integral of the Laplace inverse transform specifically,the general analytical expressions of the soil displacement and stress are obtained in the time domain,respectively.And the numerical solutions of the problem computed by analytical expressions are presented.In the time domain,the dynamic responses of the infinite elastic soil are analyzed,and the calculation results are compared with those from numerical inversion proposed by Durbin and the static results.One observes good agreement between analytical and numerical inversion results,lending the further support to the method presented.Finally,some valuable shear wave propagation laws are gained: the displacement of the soil remains zero before the wave arrival,and after the shear wave arrival,the stress and the displacement at this point increase abruptly,then reduce and tend to the static value gradually at last.The wave attenuates along the radial,therefore the farther the wave is from the source,the smaller the stress and the displacement are,and the stress and the displacement are just functions of the radial distance from the axis.
基金the Doctorate Degree Program Foundation of the Ministry of Education (No. 2000061120)
文摘An approach for the contact analysis and load distribution of double-envelop hourglass worm gearing is presented, which is based on a 3-D elastic contact finite element method (FEM) model that accommodates the influence of errors and load. As compared with existing tooth contact analysis model that assumes rigidity for the contacting surfaces, the proposed model provides a more realistic analysis on the contact patterns, the distribution of contact load and transmission errors. It is also capable of exploring the influence of different errors on meshing performances, the contact deformation, the shift of the contact zone and load share among the meshing tooth-pairs under different load.
文摘A rectangular finite element for laminated plate with bonded and/or embedded piezoelectric sensors and actuators is developed based on the variational principle and the first order shear deformation theory. The element has four-node, 20-degrees-of-freedom with one potential degree of freedom for each piezoelectric layer to represent the piezoelectric behavior. The higher order derivation of deflection is obtained by using the normal rotation expressions to take the effects of transverse shear deformation into considerations. The finite element can accurately simulate the deformation of both thin and moderately thick plates. A Fortran program is written and a number of benchmark tests are exercised to verify its effectiveness. Results are compared well with the existing data. The unbalanced composite with piezoelectric layers is then analyzed by using the model. Results show that the changes of the ratio between the thickness of positive angle layers and the negative angle layers have an effect on the deformation of the structure under the same electric loading.
基金The National Natural Science Foundation of China(No.51079030)
文摘The discrete element method is used to simulate specimens under three different loading conditions（conventional triaxial compression,plane strain,and direct shear）with different initial conditions to explore the underlying mechanics of the specimen deformation from a microscale perspective.Deformations of specimens with different initial void ratios at different confining stresses under different loading conditions are studied.Results show that the discrete element models successfully capture the specimen deformation and the strain localization.Particle behaviors including particle rotation and displacement and the mesoscale void ratio distributions are used to explain the strain localization and specimen deformation.It is found that the loading condition is one of the most important factors controlling the specimen deformation mode.Microscale behavior of the granular soil is the driving mechanics of the macroscale deformation of the granular assembly.
