A Test Rig for Frictionally Damped Bladed Segments

The paper describes the development of an instrumented test rig suitable to carry out vibration testing of the bladed segments of a turbine (belonging to a stator low pressure stage) in which the friction occurring at the contact of neighboring segments is used in service to damp the vibrations. The system is able to assign the desired preload to the segment and to measure the forces exerted in the contact and the relative displacements due to slipping. The main results that can be obtained concern the type of motion that takes place (stick/slip) and the effect of the interlocking on it, the friction coefficients, the contact tangential stiffness, and, more generally, the frequency response.