Application of Highly Spatially Resolved Area Array Velocity Measurement in the Cracking Behavior of Materials

Understanding microscale dynamic behavior in heterogeneous materials (e.g., polycrystalline or semiconductor systems) under impact loading requires diagnostics capable of resolving ~100 μm features. This study introduces a 19-core fiber-optic array probe with 100 μm spatial resolution, integrated with DISAR velocimetry on a light gas gun platform, enabling two-dimensional continuous measurement of free-surface velocity. The system overcomes limitations of conventional single-point methods (e.g., VISAR’s millimeter-scale resolution and reflectivity constraints) by achieving nanosecond temporal resolution and sub-nanometer displacement sensitivity. Under ~8 GPa impact loading, the probe captures spatiotemporal velocity heterogeneity in polycrystalline materials, including localized pull-back signals and periodic oscillations caused by shock wave reflections at microstructural interfaces. These observations reveal dynamic processes such as damage initiation and evolution, directly linking velocity profiles to microscale material response. The results provide experimental evidence of how grain-scale defects influence shock propagation and energy dissipation, advancing predictive models for extreme-condition material performance. This high-resolution, multi-channel approach offers a paradigm shift in diagnosing heterogeneous material behavior under high-strain-rate loading.