Nonlinear Cyclic Symmetry Analysis
Nonlinear cyclic symmetry analysis is a new feature in ADINA 8.1 that can be used for static, dynamic and frequency analyses. In static and dynamic analyses, the loads applied to each cyclic part must be identical (when rotated around the cyclic axis). In this case, called periodic symmetry, most nonlinear features available in ADINA can be present (including contact, plasticity, deformation dependent centrifugal loads). Nonlinear cyclic frequency analysis can also be performed after a periodically symmetric static or dynamic analysis. In this case, the frequencies and mode shapes of the deformed structure can be obtained at a fraction of the computational time and storage space used without this option.
The animations above and below show a simplified aeroengine disk with 30 blades connected to the disk using dovetail attachments. A large deformation periodic static analysis is first performed where the centrifugal force leads to contact between the blades and the disk (above animation). The frequencies and mode shapes of the whole disk-blades assembly are then obtained using frequency analysis with cyclic symmetry. This frequency analysis accounts for the deformed geometry, the initial stresses, the contact constraints and the spin softening resulting from centrifugal loading. The first and the fourth modes are shown in the animation below.