DETERMINATION OF BOUNDARY CONDITIONS ON AFRICAN XYLOPHONE BEAMS USING MODAL ANALYSIS

摘要

A xylophone is a wooden percussion instrument widely used traditionally in Africa. In this paper, we model xylophone beams as Euler beams in, free lateral vibration with free ends. The response of such beams to a sudden impact at their midpoint is investigated analytically and experimentally to determine the boundary conditions that are applicable. We compare the first nonzero mode shape and the associated frequency predicted analytically to those measured. Three xylophones are used. They had a total number of thirty-eight beams which were all tested. The material properties as well as the boundary conditions were assumed constant for all beams and the relationship between fundamental frequency and geometry was studied. Theoretical frequencies were found to be consistently lower than measured ones by thirteen percent.