Constructing The Transducer Design Of The Ultrasound Focused Sound Field

Ultrasound technology is very important in daily life,medical diagnosis,industrial testing,military and other fields.In this paper,the acoustic matching layer of ultrasonic transducer was firstly studied theoretically.By changing the mass fraction of the doped tungsten powder,the acoustic characteristic variation trend of the matched layer samples with different tungsten powder mass fraction was explored,and then the matched layer sample library with different characteristic impedance values was obtained.Then select acoustic matching layer of the sample material,and satisfying the matched condition from the aspects of production technology and the acoustic field characteristics,design of several different shape matching layer concave spherical surface focused ultrasound transducer,the sound field simulation study of several kinds of transducer,analysis of shape matching layer for the influence law of concave spherical surface focused ultrasound transducer acoustic performance,be able to raise the utilization ratio of sound energy,as well as a way of making process on the accessibility of the concave spherical surface focused ultrasound transducer matching layer design scheme.Finally,in order to obtain a focused sound field with higher intensity,a practical spherical coronal array focused ultrasonic transducer was designed and prepared under the condition of both the production cost and the focusing effect of the sound field,and the sound field was scanned to analyze the characteristics of the sound field.Theoretical research and experimental results in this paper show that:(1)The density of the matched layer increases with the increase of the mass fraction of the doped tungsten powder and has a decisive effect on the variation of the characteristic impedance of the sample.With the increase of the mass fraction of the doped tungsten powder,the sound velocity of the matched layer also decreased in a small range,but it had little effect on the characteristic impedance of the sample.The acoustic impedance of the matched layer increased with the increase of the mass fraction of tungsten powder,and the relationship was basically proportional.The acoustic impedance parameters of the prepared matched layer samples ranged from 3.0 MRayl to 10.0 MRayl,and the samples with tungsten powder mass fraction between 60%and 70%could meet the ideal matching condition of the monolayer matching layer.(2)Compared with the unmatched layer,the transmission efficiency of the concave spherical focused ultrasonic transducer with the appropriate matched layer is higher,which can effectively reduce the loss of sound energy in the transmission process.It was also found that when it has a 2.03 matching layer,it can not achieve a more ideal matching effect;However,when the 3.38 matching layer is available,the concave spherical focused ultrasonic transducer achieves the maximum sound energy transfer efficiency,and the focus position achieves the maximum sound pressure and sound strength,which is the easiest and fastest way to make the transducer.(3)A spherical coronal array focused ultrasonic transducer is designed and fabricated.The transducer consists of two single-array probes in the inner ring and 16 single-array probes in the outer ring.A sound field scanning system was established to scan its sound field,and a relatively ideal focused sound field was obtained.The acoustic focal area showed a jujube nucleus with a size of about 2 × 2 × 9 mm3.