Measurement of Strain Field Evolution in Real Time around Shockloaded Dynamically Collapsing Holes with X-ray Digital Image Correlation

Shock-loaded dynamic collapse of pores in solids has been a problem of interest because of its relevance to a variety of applications. Our previous experiment at the ESRF revealed the motion of the pore boundary in stunning detail, but was unable to track the kinematics in the material around the pore. In this work we propose to measure real-time evolution of strain field around shock-loaded collapsing holes on the mid-plane of the specimen with X-ray digital image correlation (XDIC). It involves introducing a micro speckle pattern on the specimen mid-plane around a through-hole and imaging its evolution during shock loading. The strain field is extracted through digital image correlation (DIC) of the micro speckle pattern. These experiments build on preliminary data we have collected at Advanced Photon Source (ID 35) recently. We plan to conduct experiments over a wide range of impact velocities that span the strength dominated regime to the hydrodynamic regime.

固体中孔隙受冲击加载后的动态坍塌问题一直是学界关注的热点，因其在诸多工程应用中具有重要价值。我们此前在欧洲同步辐射装置（European Synchrotron Radiation Facility, ESRF）开展的实验，以精细至极的细节揭示了孔隙边界的运动过程，但未能追踪孔隙周围材料的运动学行为。本研究拟采用X射线数字图像相关法（X-ray digital image correlation, XDIC），测量试样中平面处受冲击加载的坍塌孔洞周围应变场的实时演化过程。该实验方案将在试样中平面的通孔周围制备微散斑图案，并对冲击加载过程中散斑图案的演化进行成像观测。通过微散斑图案的数字图像相关法（digital image correlation, DIC）即可提取得到应变场。本项实验基于我们近期在先进光子源（Advanced Photon Source，光束线ID 35）采集的预实验数据开展。我们计划在涵盖强度主导区至流体动力学主导区的宽泛冲击速度范围内开展系列实验。