A new experimental modal analysis method based on double-exponential windowing and application to lightly damped bladed wheels

In this paper, a new method is presented for experimental modal analysis for lightly damped structures such as bladed wheels. Like most of existing methods, the one proposed here is also based on frequency response functions (FRFs). An FRF can be calculated to be the ratio of the Fourier transforms of a response and a force. For a pair of force–response time-histories generated by a force hammer impacting on a lightly damped structure, an exponential window is required to apply on both the force- and response-time histories when performing the Fourier transforms. This results in an approximate of the true FRF. Using a different decaying rate in the exponential window, a second approximated FRF is produced. These two approximated FRFs, instead of one as in existing experimental modal analysis methods, are then combined to abstract modal information and recover the true FRF.