Angle-of-Attack, Induced Attitude Evolution in a Coupled Crater, and Plugging Penetration of Thin Concrete Targets

To address the limitations of existing models that typically treat crater formation and shear plugging as independent processes and only consider angle of attack effects during the initial crater phase, this study proposes a dynamic shear _plugging model for projectile penetration into thin concrete targets. The model is built upon the improved three-stage penetration theory and cavity expansion principles, and introduces a coupled cratering, plugging mechanism that captures the simultaneous interaction between these stages. A differential surface force approach is employed to describe the asymmetric stress distribution on the projectile nose under non-zero angle of attack conditions, while free surface effects are incorporated to refine local stress predictions. A series of validation experiments was performed with 30 mm rigid projectiles penetrating 27 MPa concrete slabs under different impact velocities and initial angles of attack. The results show that the proposed model achieves prediction errors of less than 20% for both residual velocity and exit attitude angle, significantly outperforming classical models such as those of Duan and Liu, which tend to underestimate post-impact deflection by treating cratering and plugging separately. Based on this validated framework, parametric studies were conducted to examine the effects of the initial inclination, impact velocity, and target thickness on the evolution of projectile attitude and angle of attack. The findings demonstrate that the dynamic shear plugging mechanism exerts a critical regulatory influence on projectile deflection during thin target penetration. This work, therefore, not only resolves the directional reversal issue inherent in earlier theories but also provides theoretical support for the engineering design of concrete protective structures subjected to angular impact conditions.