A 4-node hybrid stress quadrilateral shell element with 3 rotational d.o.f.s per node is presented. The mid-surface displacement of the element is founded on Allman's rotation. The equal-rotation mode intrinsic to the rotation is suppressed by a stabilization vector. The assumed stress field and the
Hybrid stress tetrahedral elements with Allman's rotational D.O.F.s
β Scribed by K. Y. Sze; Y. S. Pan
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 145 KB
- Volume
- 48
- Category
- Article
- ISSN
- 0029-5981
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β¦ Synopsis
This paper presents two hybrid stress four-node tetrahedron solid elements which are equipped with the rotational d.o.f.s proposed by Allman. Inasmuch Allman's rotation is employed, the elements are plagued by zero-energy rotation modes which induce no strain. A modi"ed Hellinger}Reissner functional that treats the rotation and the skew symmetric stress as independent "elds is employed to formulate a stabilization scheme. Particular e!ort has been made to reduce the number of stress modes to minimum without sacri"cing the frame invariance and proper rank of the element. The computational cost of the element is reduced by adopting orthogonal constant and non-constant symmetric stress modes. Numerical benchmark tests indicate that accuracy of the element with the minimum number of stress modes is close to another multi-"eld element which, however, is not frame invariant and exhibits unsuppressed zero-energy deformation modes.
π SIMILAR VOLUMES
Two brick elements equipped with Allman's rotation are presented. Strain energy of both elements is sub-integrated by the second order quadrature which gives rise to the hourglass mechanisms. Inasmuch as Allman's rotation is employed, the elements are also plagued by the equal-rotation mechanisms. V