组合杂交有限元方法对等参双线性Q4-平板元的粗网格精度改进

Coarse-Mesh-Accuracy Improvement of Bilinear Q_4-Plane Element by the Combined Hybrid Finite Element Method

组合杂交有限元法具有增强低阶位移格式粗网格精度的内在机制· 能量误差为零的组合杂交格式可获得改进的粗网络精度,而其中组合参数起着极其重要的作用· 采用最简便的四边形位移\应力模式作为对协调双线性Q4＿平板元的改进:协调等参双线性位移插值和纯粹常应力模式· 通过调整组合参数,得到了组合杂交元的优化型· 数值试验表明这种参数＿调整型显著改进了协调Q4＿元,达到粗网格高精度· 由于应力参数可在单元水平消去。

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.