A bell plate made of a flat sheet of metal may produce a sound like a bell. This work presents the design analysis of pentagonal shape of flat steel plate to produce harmonic sound. The parametric geometry model for the pentagonal plate is first defined to construct finite element model. By performing theoretical modal analysis (TMA), the plate's vibration modes, i.e. natural frequencies and corresponding mode shapes, can be obtained. From vibration modal characteristics of the pentagonal plate, the generated sound modes as well as sound frequencies can be postulated. The generated percussion sound response depends on the structural mode shapes for different striking locations. The optimization problem is then formulated to optimally design the plate dimensions such that the pentagonal plate can produce harmonic sound, i.e. the overtone frequency is twice as the fundamental frequency. The optimum design pentagonal plate is manufactured and performed experimental modal analysis (EMA). The plate's modal parameters obtained from TMA and EMA are compared to verify the design. The percussion sound test on the pentagonal plate is also carried out to show the effective design for harmonic sound. Finally, a set of pentagonal plates consisting of two octaves musical notes is analyzed and made to fabricate the percussion instrument. This work shows the design process for the pentagonal bell plate from design analysis to experimental verification.
