4

4.1 HEXAHEDRON NO.1 WITH 8 NODES

The hexahedron element calculates deflections and stresses in space. It is a transformed element, therefore it can have a wedging form or another oblique-angled form. The transformation is isoparametric. The integration is carried out numerically in all three axises according to Gauss- Legendre. Thus, the integration order can be selected in Z88I1.TXT in the material information lines. The order 2 is mostly sufficient. Hexahedron No.1 is also well usable as a thick plate element, if the plate's thickness is not too small against the other dimensions. The element causes high computing load and needs a lot of memory, because the element stiffness matrix has the order 24*24.

Hexahedrons No.1 can be generated by the net generator Z88N from super elements Hexahedrons No.10, but Hexahedron No.1 cannot be used as a super element.

Input:

CAD (see chapter 2.7.2):

Upper plane: 1 - 2 - 3 - 4 - 1, quit LINE function
Lower plane: 5 - 6 -7 - 8 - 5, quit LINE function
1 - 5, quit LINE function
2 - 6, quit LINE function
3 - 7, quit LINE function
4 - 8, quit LINE function

Z88I1.TXT

> KFLAG for cartesian (0) or cylindrical coordinates (1)

> 3 degrees of freedom for each node

> Element type is 1

> 8 nodes per element

> Cross-section parameter QPARA is 0 or any other value, has no influence

> Integration order INTORD for each mat info line. 2 is usually good.

Z88I3.TXT

> Integration order INTORD for stress calculation:

Can be different from INTORD in Z88I1.TXT.

0 = Calculation of stresses in the corner nodes

1,2,3,4 = Calculation of stresses in the Gauss points

> any KFLAG, has no influence

> Reduced stress flag ISFLAG:

0 = no calculation of reduced stresses

1 = von Mises stresses in the Gauss points ( INTORD not 0 !)

Results:

Displacements in X, Y and Z

Stresses: SIGXX, SIGYY, SIGZZ, TAUXY, TAUYZ, TAUZX, respectively for corner nodes or Gauss points. Optional von Mises stresses.

Nodal forces in X, Y and Z for each element and each node.