The Research Of Axisymmetric Solid Elements With Hybrid Stress Finite Element Methods

A 4-node axisymmetric solid element is derived by combined hybrid methods in this paper at first. The combined hybrid finite element method is of an intrinsic mechanism of enhancing coarse-mesh-accuracy of lower order displacement schemes. It is comfirmed that the combined hybrid scheme without energy error leads to enhancement of accuracy at coarse meshes, and that the combination parameter α( 0< α<1) plays an important role in the enhancement. In this paper, compatible isoparametric bilinear displacement approximations and the constant stress mode are employed. By adjusting the combined parameter α, the optimized version of the combined hybrid element was obtained. Numerical experiments indicate that the element is of good accuracy. Due to elimination of stress parameters at the elemental level, this combined hybrid version is of the same computational cost at that of 4-node compatible isoparametric bilinear displacements element. This method allows use of the simplest stress mode, i.e. the piecewise constant stress mode, as avoids the difficulty of stress design. A new four-node axisymmetric elements are derived based on the Hellinger-Reissner variational principle. After the energy compatibility condition is applied to the linear stress with Wilson's bubble, a hybrid scheme using eight parameter stress fields ss AXH 8βis achieved. This paper applies the element to the axisymmetric solid problem and obtains . The element LQ₆ALQ₆ AXH 8βand ALQ₆ are equivalence element. In this paper, equivalence between AXH 8βand and convergence analysis are provided. The resulting elements exhibit good performance at thick-walled cylinder of infinite length under internal pressure, distortions of the element geometry and centrally loaded ss circular plate. In particular, circular plate indicate that the new elements lead to best accuracy in displacements and stresses. ALQ6An axisymmetric solid element CHAW (α) with combined hybrid method is derived by Wilson's bubble. At last, some incompatibility displacement elements are presentation. Numerical experiments indicate that the element is of good accuracy.