Tech Briefs

Gluing in Cyclic Symmetry

ADINA 8.5 has several enhancements to cyclic symmetry. One of these is the ability to use the powerful Mesh Gluing feature in cyclically symmetric static, dynamic and frequency analyses.

The example shown here is a simplified fan model where 32 blades are attached to the cylindrical base via mesh gluing. The key features of the analysis performed are:

  • Only one blade and the corresponding part of the base (which we call the fundamental cyclic part) have been meshed and modeled, see Fig. 1.

  • This fundamental cyclic part has been used cyclic-symmetrically to obtain the response of the complete fan.

  • Only the finite element equations corresponding to the fundamental cyclic part are solved to obtain the response of the complete fan.

  • The fundamental cyclic part itself has been meshed using 2 parts (the blade and the base), each meshed individually, see Fig. 2, and these parts have been glued together. Since each part is meshed separately, high quality mapped brick meshes could be used.

The fan is subjected to centrifugal forces, and a pressure load on one face of the blades. A nonlinear static analysis is performed, followed by a full cyclic frequency analysis. That way the effect of fan deformation on the natural frequencies and mode shapes of the fan is accounted for.

Fig. 1: Mesh Used in Problem

Fig. 2: Detail Showing Mesh Gluing

The movie above shows one of the mode shapes of the fan. Fig. 3 below shows the modal stresses.

Fig. 3: Stress Plot on Fan Blade

The ADINA cyclic symmetry analysis capabilities — with the mesh gluing also available — are clearly very useful in modeling many engineering problems.