In this paper, an electrical equivalent circuit of a loaded thick Lang
evin flexural transducer is proposed. As there are two vibration compo
nents at the mechanical output terminal of a thick flexural transducer
, that is, lateral and rotational components. A load, corresponding to
each vibration component, applied to the transducer must also be cons
idered separately. When it is assumed that the load is fluid and that
the mechanical output port is the end surface of the flexural transduc
er, the rotary motion of the end surface only contributes to sound rad
iation into fluid. An analytical solution of Timoshenko's beam theory
given by Miklowitz and the piezoelectric equation are applied to calcu
late the free vibration mode and the electrical equivalent components
of transducer. Using this derived equivalent circuit, the behavior of
the loaded flexural transducer is experimentally studied to prove the
validity of the proposed circuit.