Experimental measurement of the mechanical impedance of a cantilever beam.

Abstract : In order to gain facility with mechanical impedance methods, and to determine the feasibility of using theoretical impedance functions in the design of machinery foundations, the mechanical impedance of a tip-driven cantilever beam of uniform cross section was determined. This experimental impedance function is compared with a theoretical impedance function. Correlation between the two impedance functions is good at the first resonant and the first antiresonant frequencies. Attachment of the means of driving the cantilever beam and measuring its resulting motion appears to modify the nature of the structure and its response to an exciting force. The accuracy of the experimental impedance function is limited by the accuracy of the phase angle determinations. A clamping jig for achieving experimentally the clamped end condition is described. The validity of the assumptions of linearity and negligible damping is established qualitatively.