DocumentCode :
1426764
Title :
Ultrasound transducer modeling-general theory and applications to ultrasound reciprocal systems
Author :
Willatzen, M.
Author_Institution :
Mads Clausen Inst. for Product Innovation, Univ. of Southern Denmark, Sonderborg, Denmark
Volume :
48
Issue :
1
fYear :
2001
Firstpage :
100
Lastpage :
112
Abstract :
A tutorial presentation on the theory of reciprocal ultrasound systems is given, and a complete set of modeling equations for one-dimensional multi-layer ultrasound transducers is derived from first principles. The model includes dielectric losses and mechanical losses in the transducer material layers as well as sound absorption in the transmission medium. First, the so-called constitutive relations of a piezoelectric body are derived based on general thermodynamic considerations, assuming that transducer operation takes place under almost isentropic conditions. Second, full attention is given to transducers oscillating in the thickness mode, discarding all other vibration modes. Dynamic transducer equations are determined using Newton´s Second Law, Poisson´s equation, and the definition of strain applied to a piezoelectric transducer with one or more non-piezoelectric layers on the front surface (multilayer transducer). Boundary conditions include continuity of normal velocity and stress across material interfaces as well as a subsidiary electrical condition over the piezoceramic electrodes. Sound transmission is assumed to take place in a water bath such that the Rayleigh equation can be used to obtain the incoming pressure at the receiver aperture from the acceleration of the opposing transmitter. This allows, e.g., a detailed treatment of receiver signal variations as the receiver moves from the near-field zone to the far-field zone of the transmitter. In the remaining part of the paper, receiver voltage and current signals are obtained by solving the full set of dynamic equations numerically. Special attention is given to transducers consisting of a) a pure piezoceramic layer only, b) a piezoceramic layer and a quarter-wavelength matching layer of polyphenylensulphide (PPS), c) a piezoceramic layer and a half-wavelength matching layer of stainless steel, and d) a piezoceramic layer and a half-wavelength matching layer of stainless steel tuned to resonance b- a parallel inductance. Results are also given for receiver incoming pressure and receiver voltage signals when sound reception takes place in the near-field and far-field zones of the transmitter.
Keywords :
Poisson equation; dielectric losses; piezoceramics; piezoelectric transducers; ultrasonic transducers; Newton´s Second Law; Poisson´s equation; Rayleigh equation; constitutive relations; dielectric losses; dynamic transducer equations; far-field zone; isentropic conditions; mechanical losses; multilayer transducer; near-field zone; one-dimensional multi-layer ultrasound transducers; parallel inductance; piezoceramic electrodes; piezoceramic layer; piezoelectric transducer; polyphenylensulphide; quarter-wavelength matching layer; receiver incoming pressure; receiver signal variations; receiver voltage signals; sound absorption; subsidiary electrical condition; thermodynamic considerations; thickness mode; transducer modeling; ultrasound reciprocal systems; water bath; Acoustic transducers; Dielectric losses; Piezoelectric materials; Piezoelectric transducers; Poisson equations; Propagation losses; Transmitters; Ultrasonic imaging; Ultrasonic transducers; Voltage;
fLanguage :
English
Journal_Title :
Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on
Publisher :
ieee
ISSN :
0885-3010
Type :
jour
DOI :
10.1109/58.895916
Filename :
895916
Link To Document :
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