Determination of modal parameters from off-diagonal FRFs using the double-exponential windowing method

In a recently published paper (Sheng, 2012) [1], the double-exponential windowing method has been developed for the determination of modal parameters for lightly damped structures. This method, like many others, requires the driving-point frequency response function (FRF) to be measured. However, this requirement is sometimes practically hard to meet, especially when the structure is small, since it is difficult, if not impossible, to avoid interference between the force transducer and the laser beam as a response pick-up, thus limiting the usefulness of the method. To overcome this shortcoming, an alternative is therefore developed in this paper: a similar process but without requiring the measuring of any driving-point FRF.