Abstract
In a gas turbine engine, it is often impossible to have rotating components running free of resonance at all operating conditions. As such, blades may be subject to episodes of intense vibration, resulting in fatigue damage at the connection between blade and disk. This paper presents a novel finite element approach allowing to evaluate in the time domain the behavior at the disk fir-tree or dovetail contacts caused by a high response on a resonance. The method can be applied to simple bending or torsion modes as well as to higher modes with complex shapes.
The application of a one-time velocity perturbation is an efficient way to initiate an oscillating motion at the frequency of interest. The behavior of the 3D-contact is then studied in the time domain, allowing non-linear behaviors to develop. The basic principle of this approach is described in this work.
In the design of turbomachinery blade attachments, this approach can be used to study in the time domain the fretting effect of load, coefficient of friction and sliding distance at different frequency regimes. In conjunction with fretting criteria such as Ruiz and Smith-Watson-Topper, fretting fatigue life can then be predicted.
