To solve the problem of difficultly getting response data of an interface between substructures with the traditional inverse substructure method, based on the existing constant cross-section FR probe technique, reconciling the contradiction that a too thin constant cross-section FR probe was unable to fix sensors and exert excitation and a too thick one was unable to enter deeply a system's
... [Show full abstract] coupling interface, a variable cross-section FR probe technique was proposed. Firstly, based on the general dynamic equation of longitudinal vibration rods, the solution to the variable cross-section rods' longitudinal vibration equation was derived through the substitution of variable cross-section function. Then, the formulas for variable cross-section FR probe technique were obtained through theoretical derivation. These formulas were optimized to remove effects of the probe's mass on the measured results. Finally, the proposed technique was verified with the finite element method. It was shown that the variable cross-section FR probe technique can be used to indirectly get immeasurable data of interface responses. © 2017, Editorial Office of Journal of Vibration and Shock. All right reserved.