The miniaturization of the low frequency, high-power transducer has becoming the hot spot in the transducers research. With the variety type of sonar’s working frequency went below, the increasing demand for low-frequency performance of the underwater acoustic counter device. The conventional low-frequency transducer can’t meet the demand for underwater acoustic counter device as their limited spatial arrangement. The flexural disc transducer with adjustable width can be arranged axially is very suitable for low-frequency device with limited size. In this paper, we have introduced the configuration of the flexural disc assembled system (FDAS) and the concept of interaction radiation also been discussed. The prototype of the FDAS has been shown and some testing data also been published. Introduction The FDAS is comprised of numbers of flexural disc transducers (benders) arranged axially. By exploiting the interaction between the closely-packed underwater sound projector, we can reduce the resonance frequency and expand the bandwidth without dimension increasing. This type of transducer is very suitable for daggling acoustic device. Bender description The foreign have developed a novel flexural disc transducer based on the triple and double plates. The two plates is built by putting piezoelectric ceramics and metal disc bonded together, then putting the two plates connected together through the thin ring. The ceramics are positioned on the outside of the metal discs. The thin ring is positioned in the middle of the two plates. The air filled gap is also made between the double plates. The basic working concept for this type of transducer is that bending vibration of the metal driven by the radical contraction of the piezoelectric ceramics which project the acoustic wave. The air-filled gap plays a role of unmatching the impedance and improving the projection efficiency. Fig.1 cross-sectional views of flexural disc transducer Theory discussion According to the superposition principle of linear acoustic, The acoutic pressure at any point should be equal to the sum of the acoutic pressure of each radiation field from the different acoustic source. In this paper, the simple analysis has been given. Supposing one FDAS is assembled by numbers of elements, and each elements are labeled as 1,2,3...n. Bender is equivalent to the piston International Industrial Informatics and Computer Engineering Conference (IIICEC 2015) © 2015. The authors Published by Atlantis Press 1691 motion wherein each points have the same velocity, the average velocity of u, so the total force F1 on the projection plane of the 1 element is given in Eq.1: F1=f11+f12+f13+ +f1n=f11+∑ (ff1ss) ss=2 =Z1×u� R1 (1) f11—represent the force of the element 1’s radiation field acoustic pressure on its own plane f12—represent the force of the element 2’s radiation field acoustic pressure on its own plane f1n—represent the force of the element n’s radiation field acoustic pressure on its own plane According to the definition of radiation impedance, the total radiation impedance of the element 1 is: Z1=Z11+∑ (ZZss1) ss=2 =Z11+Zr (2) Z11=R11+X11,X11=(jωm11j ωC11 ). (3) In Eq.3, C11 represent the capacitive reactance. m11 represent self-quality reactance of the element one and R11 represent self-radiation impedance of the element one. Zr=∑ (ZZss1) ss=2 =∑ (RRss1+XXss1) ss=2 is the sum of mutual radiation impedance by the other elements toward the element one. Because the closely-packed configuration of the FDAS and maximum separation distance between the bender is far smaller than the wavelength of the acoustic wave, so the value of equation is always positive. The single bender in the FDAS can be analogy to the equivalent circuit shown in Fig.2: Fig.2 euivalent circuit for the FDAS The resonant frequency of the element one can be derived in Eq.4: ωres=� 1 (m11+mr1)C11 (4) The resonant frequency of the other elements can also be derived by the same method: ωn=� 1 (mnn+mrn)Cnn (5) It can be reffered from Eq.5 that little spacing between the nearest benders and the value of mrn is positive leading to the resonant frequency of a single bender is higher than the FDAS assembled by numvers of small benders. Manufacture We built the prototype of the FDAS shown in Fig.3 to verify the testing value with the theory. FDAS is comprised of eight benders arranged axially with uniform spacing, the distance between the closest center of the benders is given by 30mm. The size of the FDAS is 200mm and the weight of the FDAS is lower than 12kg in order to reduce the cavitate phenomenon.