In the pseudo dynamic (PsD) test method, the equations of motion are solved using a time stepping numerical integration technique with the inertia and damping being numerically modelled whilst restoring force is physically measured over an extended timescale.
Highly non-linear fluid stiffness and damping are observed, the damping being sensitively related to oil viscosity and unbalance.
A semi-active damper utilising dry friction is employed, with balance logic, a class of sequential damping, being used to minimise the force transmitted.
In this work, the source of aerodynamic damping being the result of the relative velocity between the structure and wind flow will be revised.
The analysis is carried out in the frequency domain, the properties of the damper being characterised by a complex stiffness, and the viscoelastic damping being represented by an exponential model.
To increase the range between the critical speed and the instability threshold the designer usually applies to the stator a suitable amount of non-rotating damping, being always stabilizing.
