Front End Coating Interface Bonding Performance Evaluation Method For The Projectile Impact Study

The substrate coated by film is widely used but the methods to evaluate the combination performance have deficiencies. Here a novel method of impact by the front-end-coated projectile to evaluate adhesion between substrate and film was proposed. The analysis and researches were carried on the dynamic measurement method.First of all, the propagation law of one dimensional elastic stress wave was analyzed and based on the impact process between the front-end-coated projectile and the substrate coated by film, physical geometry model with reasonable assumptions was established. Then, stress wave theory was used to derive calculation formula of film’s free surface stress and interfacial normal stress. Taking the specimen of steel substrate with nickel film for examples, the influence of the thin coating’s acoustic impedance on interfacial stress between the substrate and film was calculated and analyzed. The self-made cylinder nylon projectile, whose coating is same with the substrate, was accelerated to strike the specimen via the ballistic gun. Verify the launch velocity of the projectile to prove this method can generate enough force to make the film splitting from the substrate. The situations of different shapes of projectile’s head, penetration angle, the thickness of front-end coating were numerically simulated by ANSYS/LS-DYNA. Dependences of different ceramic films were also considered. Compared with the theoretical calculation results, the corresponding reasonable analysis was made. Finally, the design of the sensitive measurement system with high frequency was put forward. With PVDF piezoelectric sensor on the film, waveform curve was measured by the oscilloscope. Based on the relationship between film’s surface stress stress and the interfacial stress, the resuilt indirectly came out.