1981 年 37 巻 10 号 p. 494-503
A conical shell has been utilized as a sound radiator of direct radiator type loudspeakers and its vibration has a main role in their frequency characteristics. It is important to understand the vibratory behabiour and to find the natural frequencies of conical shells. They are the primary information which designer requires. The aim of the present work is to provide these fundamental knowledge or a perspective of axisymmetric vibrational modes and the associated eigenvalues of conical shells through the numerical calculation based on the finite difference approach. Modal shapes for the shells with fixed-free ends are presented for some apical angles. The effect of the apical angle, the meridional length and the thickness of the conical shells on their eigenvalues, coupling of the bending vibrations to the extensional and the driving-point admittance at their inner edge are discussed.