论文标题
在未知背景下超声成像的差分演化指标的实验验证
Experimental validation of differential evolution indicators for ultrasonic imaging in unknown backgrounds
论文作者
论文摘要
在实验室环境中检查了最近引入的用于成像机械演化的差分演化指标，重点是弹性标本中前进损伤区的时空跟踪。为此，在三点弯曲（3pb）构型中，木炭花岗岩的棱柱形平板在某些时间步骤中定期在样品中定期生成$t_κ$，$κ= \ circe，1，2，...，...，4 $ 4 $。通过3D扫描激光多普勒振动仪，探测波与传播损伤的相互作用会导致在板边界上测得的瞬态速度响应。因此，仔细处理获得的感官数据，以检索每个$t_κ$的散射位移字段$ v^κ$的相关光谱。在部署连续成对的多频数据$（v^κ，v^{κ+1}）$时，计算差异指标，以暴露样品中3pb诱导的损害的进度。通过原位观察验证，每个指标映射成功地重建了（a）新生儿骨折的支撑，以及（b）在过程区域中不连续性的基因座，在指定的时间段$ [t_κ\，\，\，\，\，\，t_ {κ+1}] $中经历了界面进化的过程。此外，可以表明，进化指标有助于更好地理解损伤机制，例如，通过对诱导裂纹及其合并的零散性质的启示。为了完整性，研究了通过减少和部分孔径数据的数据反演，包括单方面重建。
The differential evolution indicators, recently introduced for imaging mechanical evolution in highly scattering solids, is examined in a laboratory setting with the focus on spatiotemporal tracking of an advancing damage zone in an elastic specimen. To this end, a prismatic slab of charcoal granite is quasi-statically fractured in the three-point-bending (3PB) configuration, while ultrasonic shear waves are periodically generated in the sample at certain time steps $t_κ$, $κ= \circ, 1, 2, ..., 4$. The interaction of probing waves with the propagating damage give rise to transient velocity responses measured on the plate's boundary by a 3D scanning laser Doppler vibrometer. Thus obtained sensory data are then carefully processed to retrieve the associated spectra of scattered displacement fields $v^κ$ at every $t_κ$. On deploying consecutive pairs of multi-frequency data $(v^κ, v^{κ+1})$, the differential indicators are computed exposing the progress of 3PB-induced damage in the specimen. Verified with in-situ observations, each indicator map successfully reconstructs (a) the support of newborn fractures, and (b) the loci of discontinuities in the process zone that undergo interfacial evolution in the designated timeframe $[t_κ\,\,\, t_{κ+1}]$. Further, it is shown that the evolution indicators help better understand the damage mechanism e.g., by shining light on the fragmented nature of induced cracks and their coalescence. For completeness, data inversion via reduced and partial-aperture data is investigated, including the one-sided reconstruction.
