偶极声波换能器振动特性计算

Calculation of vibration characteristics of acoustic dipole transducer

利用ANSYS有限元软件计算了声波测井中使用的偶极子换能器在不同机械边界条件下的振动模态和频率响应。计算结果显示,偶极子换能器在一定的频率范围内有多个振动模态,不同的机械边界条件不仅影响振动模态的个数而且还影响同一振动模态的谐振频率;从频率响应曲线上还可以看出此结构的偶极子换能器在做弯曲振动时的频带较窄,这对在不同地层井眼中进行的偶极子声波测井非常不利。通过多个不同主频的偶极子换能器组合工作可以从根本上拓宽偶极声波换能器的频带宽度。

The vibration modes and frequency response of a dipole source are calculated by ANSYS FEM software. The results show that there are many vibration modes in a certain frequency range; the different fixed boundary can excite different numbers of vibration modes; even the same vibration mode has the different leading frequency; the frequency band of the bending-vibrating mode is narrow. The computing results for frequency response are in agreement with the laboratory findings. By using of multi-dipole transducers the frequency band may be widened.