Dynamic behaviors of high-strength steel plates under close-in blast loads: Insights from single-camera stereo-digital image correlation and numerical analysis

Understanding the dynamic response of high-strength steel plates under blast loading is important for blast-resistant structural design. In this study, a single-camera stereo digital image correlation (DIC) system was developed and utilized to investigate the dynamic responses of Q460 steel plates at different stand-off distances. After validating the DIC results by using the three-dimensional scanning results, the displacement distribution of the steel plates during blast processes and the residual displacement were accordingly analyzed. Based on the blast tests, a series of explicit nonlinear numerical models were then established to investigate the dynamic behaviors of steel plates under a wider range of stand-off distances. The interaction processes between the shock wave and plates were numerically investigated, and the effect of stand-off distances on the full-field deformation distribution and evolution of steel plates were studied as well. The results show that the single-camera stereo-DIC method can directly capture millisecond-level full-field deformation behavior of steel plates subjected to blast loading. As the stand-off distance increases from 50 mm to 300 mm, the damage mode gradually transitions from localized tearing (Mode IIc) to rebound-dominated deformation (Mode I), accompanied by a corresponding decrease in peak displacement. Numerical simulations validate these observations and further demonstrate that this transition is governed by the competition between shock-wave-induced shearing and inertial bending. Consequently, a quantitative classification framework is established using a dimensionless Rebound Index, which divides the Mode I response into three distinct regimes, i.e., localized plasticity (Mode I-A), transitional elastic-plastic coupling (Mode I-B), and predominantly elastic rebound (Mode I-C). These findings provide a basis for optimizing structural design and safety assessment of high-strength steel components in blast environments.