Finite Element Analysis Of 1-3 Piezocomposites Are Used For Medical Ultrasonic Transducers

Piezoelectric materials play a crucial role in medical diagnoses. They are the heart of the transducer, converting the electrical driving pulse into an acoustics beam that is projected into the soft tissues of the human body, and then detecting the weak echos reflected by organ boundaries and internal structures. The piezoelectric materials must meet following demands: interfacing with the drive/receive electronics, performing the electromechanical energy conversion, projecting the strong acoustic pulse into tissue, and gathering the weak echos. In each of these roles, the piezoelectric materials allow the device engineer to tailor the material properties: adjusting the electrical impedance to that of the electronic chain, enhancing the electromechanical coupling, moving the acoustic impedance close to that of tissue, and shaping the transducer to focus the beam. Specially, in designing piezocomposites, a single material design does not optimize all material properties simultaneously. The material engineer has a challenging task in designing a piezocomposite for each particular device.Piezocomposites which consist of piezoelectric ceramic and large molecules polymer, are well suited for ultrasonic transducers in medical imaging application due to their advantages over conventional piezoelectric materials, such as low acoustics impendence, low transverse electromechanical coupling coefficient and high electromechanical coupling coefficient. Due to these advantages, piezocomposites have become increasingly attractive for various applications. The piezocomposites are classified as ten types by combinations of piezoelectric ceramic and polymer. Among these ten types, 1-3 piezocomposite is that one dimension connective ceramic pillars place in the three connective dimension polymers. The dice and fill technique is the most widespread fabrication method for materials used in medical ultrasonic applications due to easy batch production.Because 1-3 piezocomposites is composed of two phases, it's properties depend on not only the properties of these two components but also their geometry structure. So the material design is far more complicate than unitary ceramic design.The key factors that influence the properties of 1-3 piezocomposites are theceramic volume fraction, properties and geometry dimension of ceramic, properties of polymer, processing technology and polarization technology of piezocomposites. Studying how these factors influence the properties of 1-3 piezocomposites are of great significant in fabricating high sensitivity piezocomposites transducers. Generally, there are three methods to analysis the properties of 1-3 piezocomposites: analytic computation > finite element method and experiment. Analytic computation is based on a lot of hypotheses, so the results from which are very different from the actual results. Experiment study can produce more accurate results. However, it is impossible to study every case experimentally, which is both expensive and time consuming.Finite element method has become a proven and reliable numerical simulation method and had been widely applied to engineering structures design and mechanics analysis as a tool, so it would be signality to apply finite element method topiezocomposites analysis.The main content is following as:At first, materials and piezocomposites used for medical ultrasonic transducers are briefly reviewed. The fabrication and study method of 1-3 piezocomposites are summarized.Give a brief introduction of the finite element method and the finite element method software ANSYS applications in piezocomposites analysis. And presents some commonly process and attentions in applying the finite element method software ANSYS to piezocomposites analysis. Some factors that influence of the properties of 1-3 piezocomposites are studied utilizing ANSYS.A new program used in ANSYS was developed. We can set the factor influcing the properties of 1-3 piezocomposites as parameters. When this program is performed, the parameters are needed. You can easily change these parameters' value, in order to study every case. So, it made the design of 1-3 piezocomposites very convenient. Furthermore, it is very significant to develop new 1-3 piezocomposites.Piezoelectric characters of 1-3 piezocomposites were measured using impedance analyzer and d33 meter. The results obtained through finite element analysis, analytic computation and experiment are compared and it is found that the finite element method is utilizable and produces more precise results than analytic computation.