The effect of friction damping on the dynamic response of vibrating structures: an insight into model validation

Dry friction is widely used in turbomachinery in the form of under platform dampers to limit resonant vibration and avoid high-cycle fatigue failures of the blades. Most test rigs that are used to investigate the behavior of dampers aim to evaluate their performance by reduction in blade vibration amplitude. This approach is insufficient to understand local nonlinearities of the contact and influence of blade dynamics on UPDs behavior. A newly developed test rig provides the user with an unprecedented set of information: it measures contact forces and relative displacements between dampers and blade together with the overall blade response. This controlled environment, together with a state-of-the-art numerical model of the test rig, is used to provide an insight into the subject of model validation. The presented experimental and numerical study of the damper is used to highlight the relevance of an accurate representation of the constraints induced by friction contacts and to discuss the adequacy of state-of-the-art contact models