Abstract: |
Soft bullet proof vests can effectively intercept conventional handgun bullets and low velocity fragments and are the main protective equipment for police and other law enforcement officers. To study the dynamic mechanical response of a UHMWPE soft bullet proof vest under gunshot impact, this paper conducts a test on a 9 mm pistol bullet penetration soft bullet proof vest by using three dimensional digital image correlation (3D DIC). The test obtains data on the deformation, velocity and strain fields of the soft bullet proof vest back face signature (BFS). The results show that the BFS height of the soft bullet proof vest increases sharply within 1 000 μs after bullet impact, reaching 34.2 mm. Then, the growth slows down and reaches the maximum BFS height of 60.2 mm at about 3 000 μs. The shape of BFS changes from the initial quadrilateral cone into the final “pyramid shape”. The BFS velocity increases rapidly within 200 μs after the impact, reaching a maximum value of about 126.3 m/s, and then decreases slowly and tends to 0. The strain field of von mises behind the soft bullet proof vest is divided into 4 L shaped areas, and the maximum strain occurs at the inflection point of the L shaped area. The maximum strain at 400 μs is 0.27. Finally, an improved Gauss function is used to fit the surface of the BFS profile at different moments, which provides an effective technical means to estimate the BFS shape at any moment quickly. |