The various factors influencing the settlement of composite foundation have been more completely studied through numerical simulation. The influence on the settlement of composite foundation of the geometry and mechan...The various factors influencing the settlement of composite foundation have been more completely studied through numerical simulation. The influence on the settlement of composite foundation of the geometry and mechanical properties of the pile, soil, cushion, and the interface between pile and soil have been investigated through computer simulation, in which the contact elements with zero thickness are used. Some valuable conclusions for the settlement of composite foundation have been obtained: (1) The method using the contact element of zero thickness is successful when used in the simulation of the settlement of composite foundation; (2) Among the factors influencing the settlement of composite foundation, the compression modulus of the soil is the largest, and the cohesion of the soil is the second largest; (3) The effects on settlement of the internal friction angle of the soil, the elastic modulus, the radius, and the length of the pile, and the elestic modulus of the cushion are also more obvious.展开更多
[目的]研究T_(1)倾斜角(T_(1)-slope,T_(1)S)对Zero-P术后椎间活动度及椎间盘应力的影响。[方法]选择2例C_(5/6)椎间盘突出患者为研究对象。术前进行C_(1)-T_(2)椎体螺旋CT薄层扫描,在Mimics 14.0、Geomagic Studio 10.0、Cero 3.0分别...[目的]研究T_(1)倾斜角(T_(1)-slope,T_(1)S)对Zero-P术后椎间活动度及椎间盘应力的影响。[方法]选择2例C_(5/6)椎间盘突出患者为研究对象。术前进行C_(1)-T_(2)椎体螺旋CT薄层扫描,在Mimics 14.0、Geomagic Studio 10.0、Cero 3.0分别建立T_(1)S≤18°及T_(1)S>18°的颈椎C_(5/6)节段Zero-P固定及正常对照颈椎的有限元模型,测量椎间活动度及椎间盘应力。[结果]T_(1)S≤18°组与T_(1)S>18°组各节段的活动度均显著大于对照组(P<0.05)。屈伸载荷下,T_(1)S≤18°组活动度显著>T_(1)S>18°组(P<0.05)。而单侧弯和单侧旋转载荷下,T_(1)S≤18°组与T_(1)S>18°组中各节段的活动度比较差异均无统计学意义(P>0.05)。在前屈、后伸、侧弯及旋转载荷作用下,Zero-P模型邻近节段椎间盘的应力均显著大于对照模型组(P<0.05)。而前屈、后伸载荷下,T_(1)S≤18°组中C_(4/5)、C_(5/6)融合器、C_(6/7)应力均显著>T_(1)S>18°组(P<0.05)。侧弯及旋转载荷下,两模型之间应力差异无统计学意义(P>0.05)。[结论]T_(1)S减小可能是导致颈椎前路单节段Zero-P融合术后邻近节段椎间盘活动度及椎间融合器应力增加的主要因素。展开更多
Combined multi-body dynamics with structural dynamics, a new discrete element with flexible connector, which is applicable for 3-D beam structures, is developed in this paper. Both the generalized elastic coefficient ...Combined multi-body dynamics with structural dynamics, a new discrete element with flexible connector, which is applicable for 3-D beam structures, is developed in this paper. Both the generalized elastic coefficient matrix of the flexible connector and the mass matrix of discrete element may be off-diagonal in a general case. The zero-length rigid element is introduced to simulate the node at which multiple elements are jointed together. It may also be effective when the axes of adjacent elements are not in the same line. The examples for eigenvalue calculation show that the model is successful. It can be extended to the geometric nonlinear response analysis.展开更多
A new kind of material cast polyurethane elastomers (CPUE) is introduced to take the place of rubber on load bearing wheel for the first time. Based on load bearing wheel dimensions, material properties and operatin...A new kind of material cast polyurethane elastomers (CPUE) is introduced to take the place of rubber on load bearing wheel for the first time. Based on load bearing wheel dimensions, material properties and operating conditions, the structure of wheel flange is optimized by zero order finite element method. A detailed three dimensional finite element model of flange of load bearing wheel is developed and utilized to optimize structure of wheel flange. Its service life, which is affected by flange structure parameter, is analyzed by comparing the optimization results with those of prototype of wheel. The results of optimization are presented and the stress field of load bearing wheel in optimal dimension obtained by using finite element analysis method is demonstrated. The finite element analysis and optimization results show that the CPUE load bearing wheel is feasible and suitable for the tracked vehicle and has a guiding value in practice of the weighting design of the whole tracked vehicle.展开更多
The combined hybrid finite element method is of an intrinsic mechanism of enhancing coarse-mesh-accuracy of lower order displacement schemes. It was confirmed that the combined hybrid scheme without energy error leads...The combined hybrid finite element method is of an intrinsic mechanism of enhancing coarse-mesh-accuracy of lower order displacement schemes. It was confirmed that the combined hybrid scheme without energy error leads to enhancement of accuracy at coarse meshes, and that the combination parameter plays an important role in the enhancement. As an improvement of conforming bilinear Q(4)-plane element, the combined hybrid method adopted the most convenient quadrilateral displacements-stress mode, i.e.,the mode of compatible isoparametric bilinear displacements and pure constant stresses. By adjusting the combined parameter, the optimized version of the combined hybrid element was obtained and numerical tests indicated that this parameter-adjusted version behaves much better than Q(4)-element and is of high accuracy at coarse meshes. Due to elimination of stress parameters at the elemental level, this combined hybrid version is of the same computational cost as that of Q(4)-element.展开更多
In this paper a new quadrilateral plate element concerning the effect of transverse shear strain has been presented. It is derived from the hybrid finite element model based on the principles of virtual work. The outs...In this paper a new quadrilateral plate element concerning the effect of transverse shear strain has been presented. It is derived from the hybrid finite element model based on the principles of virtual work. The outstanding advantage of this element is to use more rational trial functions of the displacements. For this reason, every variety of plate deformation can be simulated really whilc the least degrees of freedom is employed.A wide range of numerical tests was conducted and the results illustrate that this element has a very wide application scope to the thickness of plates and satisfactory accuracy can be obtained by coarse mesh for all kinds of examples.展开更多
The new methods to determine the zero-energy deformation modes in the hybrid elements and the zero-energy stress modes in their assumed stress fields are presented by the natural deformation modes of the elements. And...The new methods to determine the zero-energy deformation modes in the hybrid elements and the zero-energy stress modes in their assumed stress fields are presented by the natural deformation modes of the elements. And the formula of the additional element deformation rigidity due to additional mode into the assumed stress field is derived. Based on, it is concluded in theory that the zero-energy stress mode cannot suppress the zero-energy deformation modes but increase the extra rigidity to the nonzero-energy deformation modes of the element instead. So they should not be employed to assume the stress field. In addition, the parasitic stress modes will produce the spurious parasitic energy and result the element behaving over rigidity. Thus, they should not be used into the assumed stress field even though they can suppress the zero-energy deformation modes of the element. The numerical examples show the performance of the elements including the zero-energy stress modes or the parasitic stress modes.展开更多
文摘The various factors influencing the settlement of composite foundation have been more completely studied through numerical simulation. The influence on the settlement of composite foundation of the geometry and mechanical properties of the pile, soil, cushion, and the interface between pile and soil have been investigated through computer simulation, in which the contact elements with zero thickness are used. Some valuable conclusions for the settlement of composite foundation have been obtained: (1) The method using the contact element of zero thickness is successful when used in the simulation of the settlement of composite foundation; (2) Among the factors influencing the settlement of composite foundation, the compression modulus of the soil is the largest, and the cohesion of the soil is the second largest; (3) The effects on settlement of the internal friction angle of the soil, the elastic modulus, the radius, and the length of the pile, and the elestic modulus of the cushion are also more obvious.
文摘[目的]研究T_(1)倾斜角(T_(1)-slope,T_(1)S)对Zero-P术后椎间活动度及椎间盘应力的影响。[方法]选择2例C_(5/6)椎间盘突出患者为研究对象。术前进行C_(1)-T_(2)椎体螺旋CT薄层扫描,在Mimics 14.0、Geomagic Studio 10.0、Cero 3.0分别建立T_(1)S≤18°及T_(1)S>18°的颈椎C_(5/6)节段Zero-P固定及正常对照颈椎的有限元模型,测量椎间活动度及椎间盘应力。[结果]T_(1)S≤18°组与T_(1)S>18°组各节段的活动度均显著大于对照组(P<0.05)。屈伸载荷下,T_(1)S≤18°组活动度显著>T_(1)S>18°组(P<0.05)。而单侧弯和单侧旋转载荷下,T_(1)S≤18°组与T_(1)S>18°组中各节段的活动度比较差异均无统计学意义(P>0.05)。在前屈、后伸、侧弯及旋转载荷作用下,Zero-P模型邻近节段椎间盘的应力均显著大于对照模型组(P<0.05)。而前屈、后伸载荷下,T_(1)S≤18°组中C_(4/5)、C_(5/6)融合器、C_(6/7)应力均显著>T_(1)S>18°组(P<0.05)。侧弯及旋转载荷下,两模型之间应力差异无统计学意义(P>0.05)。[结论]T_(1)S减小可能是导致颈椎前路单节段Zero-P融合术后邻近节段椎间盘活动度及椎间融合器应力增加的主要因素。
基金The project was financially supported by the National Natural Science Foundation of China
文摘Combined multi-body dynamics with structural dynamics, a new discrete element with flexible connector, which is applicable for 3-D beam structures, is developed in this paper. Both the generalized elastic coefficient matrix of the flexible connector and the mass matrix of discrete element may be off-diagonal in a general case. The zero-length rigid element is introduced to simulate the node at which multiple elements are jointed together. It may also be effective when the axes of adjacent elements are not in the same line. The examples for eigenvalue calculation show that the model is successful. It can be extended to the geometric nonlinear response analysis.
文摘A new kind of material cast polyurethane elastomers (CPUE) is introduced to take the place of rubber on load bearing wheel for the first time. Based on load bearing wheel dimensions, material properties and operating conditions, the structure of wheel flange is optimized by zero order finite element method. A detailed three dimensional finite element model of flange of load bearing wheel is developed and utilized to optimize structure of wheel flange. Its service life, which is affected by flange structure parameter, is analyzed by comparing the optimization results with those of prototype of wheel. The results of optimization are presented and the stress field of load bearing wheel in optimal dimension obtained by using finite element analysis method is demonstrated. The finite element analysis and optimization results show that the CPUE load bearing wheel is feasible and suitable for the tracked vehicle and has a guiding value in practice of the weighting design of the whole tracked vehicle.
文摘The combined hybrid finite element method is of an intrinsic mechanism of enhancing coarse-mesh-accuracy of lower order displacement schemes. It was confirmed that the combined hybrid scheme without energy error leads to enhancement of accuracy at coarse meshes, and that the combination parameter plays an important role in the enhancement. As an improvement of conforming bilinear Q(4)-plane element, the combined hybrid method adopted the most convenient quadrilateral displacements-stress mode, i.e.,the mode of compatible isoparametric bilinear displacements and pure constant stresses. By adjusting the combined parameter, the optimized version of the combined hybrid element was obtained and numerical tests indicated that this parameter-adjusted version behaves much better than Q(4)-element and is of high accuracy at coarse meshes. Due to elimination of stress parameters at the elemental level, this combined hybrid version is of the same computational cost as that of Q(4)-element.
文摘In this paper a new quadrilateral plate element concerning the effect of transverse shear strain has been presented. It is derived from the hybrid finite element model based on the principles of virtual work. The outstanding advantage of this element is to use more rational trial functions of the displacements. For this reason, every variety of plate deformation can be simulated really whilc the least degrees of freedom is employed.A wide range of numerical tests was conducted and the results illustrate that this element has a very wide application scope to the thickness of plates and satisfactory accuracy can be obtained by coarse mesh for all kinds of examples.
文摘The new methods to determine the zero-energy deformation modes in the hybrid elements and the zero-energy stress modes in their assumed stress fields are presented by the natural deformation modes of the elements. And the formula of the additional element deformation rigidity due to additional mode into the assumed stress field is derived. Based on, it is concluded in theory that the zero-energy stress mode cannot suppress the zero-energy deformation modes but increase the extra rigidity to the nonzero-energy deformation modes of the element instead. So they should not be employed to assume the stress field. In addition, the parasitic stress modes will produce the spurious parasitic energy and result the element behaving over rigidity. Thus, they should not be used into the assumed stress field even though they can suppress the zero-energy deformation modes of the element. The numerical examples show the performance of the elements including the zero-energy stress modes or the parasitic stress modes.
