Abstract
In turbomachines, dry friction devices (under platform dampers, shrouds, and tie-wire) are usually introduced to reduce resonant responses of bladed disks. Dry friction between rubbing elements induces a highly nonlinear dynamic behaviour which flattens the frequency response functions. It is clear that such behaviour requires an optimisation process to find the optimum parameters that lead to the minimum forced response amplitudes. However, different interpretations still remain concerning the explanation of the physical origin of this type of flattening. The most common one is based on dissipated energy. In this case, heat resulting from the relative frictional motion between contacting surfaces is supposed to bring sufficient dissipation to flatten response functions. On the other hand, a different approach considers that a decrease in vibrational amplitudes is explained by changes in boundary conditions induced by a stick/slip behaviour. In this study, a single degree-of-freedom system is used and analysed both in time and in frequency domains (Harmonic Balance Method) in order to show the contribution of respectively energy dissipation and change of contact state on peak levels.
Highlights
Devices involving dry friction [1,2] are often used to decrease maximal amplitudes of structures during resonance
A common characteristic between all friction devices relies on the induced flattening of frequency response function (FRF) peaks obtained when specific normal loads are applied at the contact
A classical Multi Harmonic Balance Method (MHBM) operating in the frequency domain [17–19] compared to a reference transient solution obtained in the time domain is used to determine the influence of dissipated energy and changes in boundary conditions associated to contact states
Summary
Devices involving dry friction [1,2] are often used to decrease maximal amplitudes of structures during resonance. A common characteristic between all friction devices relies on the induced flattening of frequency response function (FRF) peaks obtained when specific normal loads are applied at the contact. When normal load is very high in comparison with the excitation force, the dynamic behaviour is almost linear and FRF exhibits high level resonance peaks. When normal load is much lower than the excitation force, the dynamic behaviour is linear again and the FRF may exhibit high amplitude peaks [11,12]. As presented for example in [13], suppose a direct relationship between peak flattening and the energy dissipated by dry friction. Peak flattening may be explained as a consequence of changes in boundary conditions during stick/slip states. A classical Multi Harmonic Balance Method (MHBM) operating in the frequency domain [17–19] compared to a reference transient solution obtained in the time domain is used to determine the influence of dissipated energy and changes in boundary conditions associated to contact states
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
