“…There are also other experimental methods for natural frequency estimation, an example is Estimation of Turbine Blade Natural Frequencies from Casing Pressure and Vibration Measurements where the authors described experimental frequency identification by using the casing pressure [ 15 ]. There can be found a large number of different methods for natural frequency estimation that are meant for various purposes [ [16] , [17] , [18] ]. There are many methods that are used for natural frequency estimation, however, each of them requires a huge amount of time in terms of the testing set up, etc.…”