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具有一定宽度和厚度的无穷长压电条置于均匀各向同性半空间上 ,压电条在电激励下产生机械振动从而在整个空间产生声场 .将压电条取为 6mm晶系 ,其对称主轴沿长度方向 .针对这种压电换能器结构 ,深入研究了SH波的激发和辐射特性 .首先将压电条中的声场展开为傅里叶级数 ,而将压电条下的无界半空间中的声场展开为傅里叶积分 ,然后根据边界条件得到了整个空间中声场的求解方案 ,通过数值模拟计算了声场的分布特性 ,并和传统方法进行了定量的对比和分析 .最后采用最陡下降法 (鞍点法 )研究并得到了压电条声辐射场的远场近似表达式 ,分析了声场的指向性规律 .结果表明只有当频率f和压电条宽度a的乘积fa <1kHz·m时 ,传统方法得到的结果是可靠的 ,当频率升高时 ,压电条内应力和位移呈振荡式分布 ,频率愈高振荡愈激烈 ,且与传统方法的差异愈大 .本文对声学微系统与声传感器件的研究具有重要意义 .
Infinitely long piezoelectric strips with a certain width and thickness are placed in a homogeneous isotropic half-space, and the piezoelectric strips generate mechanical vibration under the electric excitation to generate sound field in the whole space. The piezoelectric strip is taken as a 6mm crystal system whose symmetry For the piezoelectric transducer structure, the excitation and the radiation characteristics of SH wave are studied in depth.First, the acoustic field in the piezoelectric strip is expanded into Fourier series, and the piezoelectric strip is unbounded The sound field in half-space is expanded to Fourier integral, and then the solution of the sound field in the whole space is obtained according to the boundary conditions. The distribution of the sound field is calculated by numerical simulation and compared with the traditional method. Finally, The steepest descent method (saddle point method) is used to study and obtain the far-field approximate expression of the acoustic radiation field of the piezoelectric strip. The directivity of the acoustic field is analyzed. The results show that only when the product of the frequency f and the piezoelectric strip width a is less than 1 kHz · M, the results obtained by the traditional method are reliable. When the frequency increases, the stress and displacement in the piezoelectric strip are distributed in an oscillatory manner. The higher the frequency, the more intense the oscillation, and the greater the difference with the traditional method. Research on acoustic microsystems and acoustic sensors is of great significance.