基于超声逆散射模型的损伤定量成像研究

Research on quantitative imaging of damage based on ultrasonic inverse scattering model

针对传统的全聚焦算法(TFM)无法实现对损伤的定量评估问题,建立了以损伤表面反射率为成像指标的超声逆散射模型,实现TFM方法对损伤的定量成像。通过分析入射超声波场与损伤之间的相互作用,推导出包含损伤响应散射振幅的频域超声散射模型,进而逆转该散射模型,反演得到损伤表面的反射率与入射和接收超声信号之间的定量关系,从而实现损伤的定量评估。为验证模型的有效性,比较分析了该TFM方法与传统的时域、频域TFM方法对模拟裂纹和圆孔损伤的成像。结果表明,基于超声逆散射模型的TFM成像方法,不仅能够对损伤进行精准定位,而且能够定量表征损伤的大小,尤其是对裂缝状损伤长度的判别。

Aiming at the problem that the traditional Total Focusing Method(TFM)can not quantitatively evaluate the damage,an ultrasonic inverse scattering model based on the reflectivity of the damage surface is established,and the quantitative imaging of the damage by TFM method is realized.By analyzing the interaction between the incident ultrasonic field and the damage,a frequency-domain ultrasonic scattering model including the scattering amplitude of the damage is developed,and then the scattering model is reversed.The quantitative relationship between the reflectivity of the damage surface and the incident and received ultrasonic signals is inverted,so as to realize the quantitative evaluation of the damage.In order to demonstrate the validity of the model,the TFM method proposed in this paper is compared with the traditional time-domain and frequency-domain TFM methods in imaging simulated crack and circular hole.The results show that the TFM imaging method based on the ultrasonic inverse scattering model can not only accurately locate the damage,but also quantitatively characterize the size of the damage,especially the length of the crack.