This example shows further results of a helmet impact analysis (courtesy of MET S.p.A., Italy). This time the head and helmet both have an initial speed of 5 m/s and side-impact a rigid anvil. This is one of several impact tests that MET uses to evaluate their new helmet designs. The results of another analysis compared with laboratory test results were presented some time ago.
The objective of the analysis is to ensure that the helmet provides adequate protection for the head. ADINA is used to check that the deceleration of the head does not exceed 250g, and that the stresses in the helmet do not exceed the capacity of the material. More information can be found in a previous News.
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.
