Abstract: With the development of new weapon platforms, warheads with novel cross-sections (elliptical and variable elliptical cross-sections) have drawn wide attention due to high platform adaptability, lift-drag ratio, and stealth performance. This study investigates the oblique penetration mechanism and the attitude deflection of projectiles with variable elliptical cross-sections by examining projectiles with three types of cross-sections (circle，elliptic，and tapered elliptic) obliquely penetrating a double-layer thin steel plate through experiments. Based on the failure mode of the target plate and the mechanic characteristics of the projectile body, the penetration process is divided into four stages, namely press-in of the projectile nose, penetration of the nose, transition, and penetration of the projectile body. The mechanic characteristics of each projectile at each stage are also analyzed based on the law of energy conservation and virtual work principle. A theoretical model is constructed for the projectile's attitude deflection. The theoretical model is validated through comparing the experimental and simulation results. The model is used to study how the attitude deflection of projectiles with variable elliptical cross-sections is affected by different parameters, including impact velocity, initial oblique angle, centroid position, roll angle, and the long to short axis ratio of the elliptical cross-sections. The results show that as the impact velocity of the projectile increases, the attitude deflection angle decreases exponentially; the deflection increases as the initial oblique angle increases; the deflection increases as the centroid moves away from the projectile nose; the deflection angles vary when the projectile hits the target from different rolling angles; the deflection at γ_pt=0° is greater than that when γ_pt=90°; as the long to short axis ratio increases, the deflection increases when γ_pt=0°, yet it decreases when γ_pt=90°.

Key words: projectileswithvariableellipticalcross-sections, obliqueperforation, residualvelocity, attitudedeflection, longtoshortaxisratio