Numerical and experimental investigations on underplatform damper mechanics

So called under-platform dampers are widely used as a source of friction damping to mitigate resonance in gas turbine blades and avoid service failures. Due to the high computational cost of performing dynamic analysis of structures constrained through frictional contacts, ad hoc numerical codes have been developed in the frequency domain. Whatever the numerical model, it requires knowledge of contact-friction parameters, which are established either through single contact frictional measurements, or by tuning the damper parameters though comparison of the experimental response of damped blade against its computed response or, else, by fine tuning the damper parameters by comparing the measured v. the calculated hysteresis cycle. The last one is these authors’ choice. Equipment and method are described accordingly.