Numerical and experimental investigations of dynamic deformation and failure on impact of rectangular plates

It is important to have reliable failure criterion when solving reliability and safety problems of the modern structures, especially in extreme conditions. In a number of areas, such as aircraft industry, nuclear power industry, the strength requirements to products under high local dynamic loadings are to comply with regulatory documents. In such local impacts, based on numerical calculations, it is possible to select the model experiments in which a history of deformation in the most stressed point is very close to the real structure. This paper considers dynamic deformations and failure of a rectangular aluminum plate of constant thickness impacted by a titanium plate in the range of V 0 = 160.8…195.0 m/s. A numerical solution of the elastic-plastic problem is conducted by the finite element method with an explicit scheme of integration in time. The true stress-strain curves of the materials in strain rate ranges of = 10-3…104 с-1 are used, the friction between elements is modelled with friction coefficient f = 0.1…0.2. By investigating convergence of the numerical solutions, we defined the needed size of finite element Δ=1mm. By relying on the numerical results, agreed with experimental depth of shear of the target, the limit level of the effective plastic strain was obtained ε р1 = 2.5δ (δ is material elongation) in three axial compression condition. Destruction of the plate from the opposite side is realized close to two axial tension conditions reaching the limit level of effective plastic strain of ε р2 = 1.17δ. Within the experimental-computational approach it is discovered that for through penetration it is necessary to reach the limit levels of effective plastic strain both from the impact side of the plate and from the opposite side of the plate.