中高频段下的粘弹性材料声学参数测量

为了实现粘弹性材料在高频段上的声学参数测量,提出一种自由场测量方法,通过测量目标的水下散射声场指向性,计算目标散射场声压的前几阶勒让德系数,建立以目标的材料声学参数为变量的数学模型,并运用遗传算法进行参数反演.仿真结果表明以铝球的杨氏模量(E)为例,不存在声场误差的情况下反演精度可达0.0014%,铝球散射场的实验数据也提供了较高的参数反演精度.将此方法应用于中高频段上某种成分的粘弹性材料参数测量,成功地获取了其在此频段上的声学参数.提高目标散射场的测量精度有利于目标材料反演精度的提高.此方法避免了对声压相位的测量,减少了影响精度的因素.

Acoustic parameters measurement of viscoelastic material in median and high frequency

In order to realize the acoustic parameters measurement of viscoelastic material in median and high frequency,a measurenent method in free field is presented.The directivity pattern of underwater scattering field of target is measured and the Legendre coefficients of the scattering field pressure are computed.The mathematical model is built with respect to the acoustic parameters and the parameters are inversed by Genetic Algorithm.The computer simulation shows that the inversion precision for example Young's modulus E is close to 0.0014% without measurement error of scattering field.The experiment data of scattering field also can inverse parameters of material with high precision.This method is applied to inverse the acoustic parameters of some kind of viscoelastic material and the value of parameters are achieved successfully in median and high frequency.The measurement precision of scattering field is improved in favor of the inversion precision of acoustic parameters.This method avoids the measurement of the phase,so it reduces the error factor.