THEORY OF EXCITATION METHODS AND ESTIMATION OF FREQUENCY-RESPONSE FUNCTIONS IN COMPLEX MODAL TESTING OF ROTATING MACHINERY

Abstract Various excitation methods are proposed for the effective use of complex modal testing for rotating machinery. The proposed excitation methods are developed, based on the input/output relationships for complex signals, for the direct or indirect assessment of frequency response and coherence functions between complex inputs and outputs. From the views of practicality, required testing efforts and estimation errors, the advantages and disadvantages of each method are investigated, when the measurement noises and the errors involved with realisation of excitation forces are present. Numerical simulations are also performed to demonstrate the testing procedures and results using the proposed methods.