A finite element program developed elastic-plastic crack propagation simulation using Fortran language. At each propagation step, the adaptive mesh is automatically refined based on a posteriori h-type refinement usin...A finite element program developed elastic-plastic crack propagation simulation using Fortran language. At each propagation step, the adaptive mesh is automatically refined based on a posteriori h-type refinement using norm stress error estimator. A rosette of quarter-point elements is then constructed around the crack tip to facilitate the prediction of crack growth based on the maximum normal stress criterion and to calculate stress intensity factors under plane stress and plane strain conditions. Crack was modelled to propagate through the inter-element in the mesh. Some examples are presented to show the results of the implementation.展开更多
We review recent advances in the finite element method (FEM) simulations of interactions between waves and structures. Our focus is on the potential theory with the fully nonlinear or second-order boundary condition. ...We review recent advances in the finite element method (FEM) simulations of interactions between waves and structures. Our focus is on the potential theory with the fully nonlinear or second-order boundary condition. The present paper has six sections. A review of previous work on interactions between waves and ocean structures is presented in Section one. Section two gives the mathematical formulation. In Section three, the finite element discretization, mesh generation and the finite element linear system solution methods are described. Section four presents numerical methods including time marching schemes, computation of velocity, remeshing and smoothing techniques and numerical radiation conditions. The application of the FEM to the wave-structure interactions are presented in Section five followed by the concluding remarks in Section six.展开更多
Mesh-based image warping techniques typically represent image deformation using linear functions on triangular meshes or bilinear functions on rectangular meshes.This enables simple and efficient implementation,but in...Mesh-based image warping techniques typically represent image deformation using linear functions on triangular meshes or bilinear functions on rectangular meshes.This enables simple and efficient implementation,but in turn,restricts the representation capability of the deformation,often leading to unsatisfactory warping results.We present a novel,flexible polygonal finite element(poly-FEM)method for content-aware image warping.Image deformation is represented by high-order poly-FEMs on a content-aware polygonal mesh with a cell distribution adapted to saliency information in the source image.This allows highly adaptive meshes and smoother warping with fewer degrees of freedom,thus significantly extending the flexibility and capability of the warping representation.Benefiting from the continuous formulation of image deformation,our polyFEM warping method is able to compute the optimal image deformation by minimizing existing or even newly designed warping energies consisting of penalty terms for specific transformations.We demonstrate the versatility of the proposed poly-FEM warping method in representing different deformations and its superiority by comparing it to other existing state-ofthe-art methods.展开更多
提出了一种适用于电机优化设计的参数化网格剖分方法。该方法将所有剖分节点坐标表示为一组几何参数的线性函数,当电机的几何尺寸变化时不需要网格重新剖分,能显著减少有限元(finite element method,FEM)预处理时间,并通过自适应网格剖...提出了一种适用于电机优化设计的参数化网格剖分方法。该方法将所有剖分节点坐标表示为一组几何参数的线性函数,当电机的几何尺寸变化时不需要网格重新剖分,能显著减少有限元(finite element method,FEM)预处理时间,并通过自适应网格剖分方法和交换对角线技术提高网格单元质量。对电机的参数化网格剖分模型进行FEM计算,利用表面响应法对FEM计算的结果进行处理,构建电机的优化模型,再利用粒子群优化算法寻求优化模型的最优解,得到电机的最优结构参数。将该方法应用于电机优化设计的两个实例,验证了其有效性。展开更多
文摘A finite element program developed elastic-plastic crack propagation simulation using Fortran language. At each propagation step, the adaptive mesh is automatically refined based on a posteriori h-type refinement using norm stress error estimator. A rosette of quarter-point elements is then constructed around the crack tip to facilitate the prediction of crack growth based on the maximum normal stress criterion and to calculate stress intensity factors under plane stress and plane strain conditions. Crack was modelled to propagate through the inter-element in the mesh. Some examples are presented to show the results of the implementation.
文摘We review recent advances in the finite element method (FEM) simulations of interactions between waves and structures. Our focus is on the potential theory with the fully nonlinear or second-order boundary condition. The present paper has six sections. A review of previous work on interactions between waves and ocean structures is presented in Section one. Section two gives the mathematical formulation. In Section three, the finite element discretization, mesh generation and the finite element linear system solution methods are described. Section four presents numerical methods including time marching schemes, computation of velocity, remeshing and smoothing techniques and numerical radiation conditions. The application of the FEM to the wave-structure interactions are presented in Section five followed by the concluding remarks in Section six.
基金The research of Juan Cao was supported by the National Natural Science Foundation of China(Nos.61872308,61972327,and 62272402)the Xiamen Youth Innovation Funds(No.3502Z20206029)Yongjie Jessica Zhang was supported in part by NSF CMMI-1953323 and a Honda grant.
文摘Mesh-based image warping techniques typically represent image deformation using linear functions on triangular meshes or bilinear functions on rectangular meshes.This enables simple and efficient implementation,but in turn,restricts the representation capability of the deformation,often leading to unsatisfactory warping results.We present a novel,flexible polygonal finite element(poly-FEM)method for content-aware image warping.Image deformation is represented by high-order poly-FEMs on a content-aware polygonal mesh with a cell distribution adapted to saliency information in the source image.This allows highly adaptive meshes and smoother warping with fewer degrees of freedom,thus significantly extending the flexibility and capability of the warping representation.Benefiting from the continuous formulation of image deformation,our polyFEM warping method is able to compute the optimal image deformation by minimizing existing or even newly designed warping energies consisting of penalty terms for specific transformations.We demonstrate the versatility of the proposed poly-FEM warping method in representing different deformations and its superiority by comparing it to other existing state-ofthe-art methods.
文摘提出了一种适用于电机优化设计的参数化网格剖分方法。该方法将所有剖分节点坐标表示为一组几何参数的线性函数,当电机的几何尺寸变化时不需要网格重新剖分,能显著减少有限元(finite element method,FEM)预处理时间,并通过自适应网格剖分方法和交换对角线技术提高网格单元质量。对电机的参数化网格剖分模型进行FEM计算,利用表面响应法对FEM计算的结果进行处理,构建电机的优化模型,再利用粒子群优化算法寻求优化模型的最优解,得到电机的最优结构参数。将该方法应用于电机优化设计的两个实例,验证了其有效性。
