Damage evolution in ceramics during the dwell/penetration transition under oblique impact loading

In practice, armor faces oblique strikes from long-rod projectiles (LRPs), not conventional attacks. To improve protection and reduce weight, the armor is inclined, increasing its effective thickness against LRPs. Impact obliquity critically influences ceramic armor damage, particularly in interface defeat and dwell/penetration transitions during LRP strike. A theoretical model for damage evolution in ceramics under oblique impact is established on the basis of the free stream line theory, contact mechanics and crack propagation models. After the model validation, the influence of various impact factors on the asymmetry failure during interface defeat and dwell/penetration is examined. The model accurately predicts ceramic failure asymmetry governed by stress fields. The dwell time is primarily determined by the cone cracks propagation. The transition velocity remains relatively stable at obliquity angles below 45°, but exhibits a linear increase as the angle rises from 45° to 75°. Projectiles with low yield strength exhibit extended dwell/penetration transitions, while fracture toughness governs cone crack propagation throughout both interface defeat and transition phases. This study provides valuable insights and guidance for the application of interface defeat and dwell in armor design, t thereby significantly improving the ballistic performance of ceramic armor against high-velocity projectile threats.