Abstract: The ballistic trajectory of a projectile may deflect or it ricochets off a target when the projectile penetrates a hard target obliquely. Once the projectile ricochets off a hard target, it cannot perforate into the target, which cannot bring effective damage to the target. In order to ensure that the projectile penetrate the hard target effectively, the critical ricochet angles of projectile impacting the hard target need to be predicted，and the range of angles of that the projectile does not ricochet is given. Consequently, the ricochet of projectile penetrating a hard target obliquely is studied, and then an evaluation method of predicting the critical ricochet of projectile is proposed. The critical ricochet angles of projectiles penetrating the reinforced concretes with compressive strength of 30 MPa and 60 MPa are calculated using the proposed method, respectively, and the calculated results are compared with the experimental results. The results show that the evaluation method can be used to analyze and evaluate the ricochet of projectile precisely.

Key words: ordnance science and technology, warhead, evaluation method, oblique penetration, ballistic deflection, critical ricochet angle