Study On Mechanism Of Anti-fragment Penetration Of Polyurea Coated Composite Structure

The vitality of surface ships is mainly composed of three parts: concealment,damage resistance and self-repair.For surface vessels,the improvement of concealment cannot be greatly improved,and self-repair will only work after the damage of the ship.Therefore,improving the damage resistance of hull structures by using lightweight protective materials is an important way to enhance the vitality of surface ships,and is the focus of research at home and abroad.In this thesis,the polyurea-coated composite structure(glass fiber front,aramid fiber in the back)as the object,compared before and after the coated and uncoated composite fiber board's anti-elastic energy,analysis of polyurea coating composite structure resistance Fragment penetration mechanism.First,a 3.3-g square-shaped fragment loading test was carried out on a non-coated target plate,an elastic-coated target plate,and a back-elastic coated target plate using a 12.7 mm sliding rifle,and three ballistic ballistic limit methods were respectively used to obtain three.The ballistic limit of the target.Numerical simulation was conducted to verify the credibility of the simulation results.Combined with the results of the tests,the anti-penetration mechanism of the composite structure was analyzed: 1)The non-coated target uses the high hardness and high strength of the glass fiber to resist the elastomer.The impact of the pit,followed by aramid fiber is to use its own stretching and delamination to play energy.2)The target is coated on the elastic surface because the polyurea layer penetrates the high-speed projectile and absorbs energy with its glass transition at a high strain rate.It does not affect the subsequent glass fiber and aramid fiber.Energy consumption,so it can achieve the effect of improving the target's anti-elasticity.3)The energy dissipation effect of the glass fiber layer in the early stage of the back-elastic coated target plate is not changed,and the elasticity of the polyurea coating inhibits the stretching and delamination of the aramid fiber itself in the later period,thereby making the target plate The overall resistance to elasticity weakened.Based on the above studies,numerical simulations were conducted to analyze the thickness effect of the target coated polyurea coating and its anti-penetration effect on different missiles.The conclusions were reached: 1)As the contact area between the projectile and the projectile becomes smaller and smaller,the anti-elastic properties of the target become weaker and weaker regardless of whether or not the polyurea coating is applied.The anti-penetration ability of the coated target plate shows linear enhancement as the thickness of the polyurea coating increases.