VIBRATION CHARACTERISTICS OF SELF-MONITORING BENDER ELEMENTS WITH VARIOUS DIMENSIONS AND GEOMETRIES

Abstract

For the purpose of improving measurement accuracy of bender element test, the vibration characteristics of several bender element and self-monitoring bender elements with different dimensions and geometries were evaluated at multiple points by a laser displacement sensor. The elements exhibited damped vibration following multi-degree-of-freedom system with several natural frequencies. As a result of experimental modal analysis, an unexpected eigen mode consisting of transverse bending motion, which is beyond the assumption was observed in all the elements. Considering modelization of the element vibration using modal approximation, responses of the elements were reconstructed based on frequency responses which were approximated by superposition of the eigen modes, and compared with the observed responses. The responses reconstructed using the two main eigen modes well reproduced the observed ones, and resulted in mean error through the whole element surface of approximately 10% in the respective elements.