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A mathematical model is developed, which describes the behavior of reinforced concrete under highvelocity impact and explosion conditions within the framework of mechanics of continuous media. The problem of a model projectile penetrating into a layered target consisting of two concrete slabs separated by a sand layer and blasting of an explosive charge encased in the embedded projectile is solved in the three-dimensional formulation by the finite-element method. The effect of reinforcement on penetration and failure of reinforced-concrete slabs is studied by means of mathematical simulations.In designing protective structures of underground installations, it is necessary to estimate their resistance to high-rate dynamic loads. This problem can effectively be solved by mathematical simulation of deformation and failure of these structures subjected to an impact or explosion.The problem of the impact interaction between cylindrical metal impactors and concrete targets was solved in [1,2]. To study concrete failure, a phenomenological approach was applied, where the strength criteria are expressed in terms of invariant relations between the critical values of macrocharacteristics of the process: stresses and strains. A comparison of mathematical simulations with the results of a special experiment showed that this approach to the failure problem, used to solve static problems, can also be used to analyze concrete failure under dynamic loads.A mathematical model was developed in [3,4] to analyze the behavior of sandy soil under shock-wave loading. The processes of penetration of cylindrical and star-shaped impactors into a sandy half-space were studied by the method of computer modeling. The effect of the impactor shape on the penetration depth was revealed [4]. The problem of cylindrical impactors penetrating into structures composed of sandy soil and concrete was solved in a three-dimensional formulation [3].Much attention has been given to mathematical simulation of collisions of solid bodies with various monolithic and layered targets made of metal, ceramics, and composite materials (see, e.g., [5][6][7][8]). However, calculating the penetration of solids into reinforced-concrete slabs is still an open question. Results of experimental and theoretical studies on the impact interaction of cylindrical bodies with ogival head parts with concrete and reinforced-concrete slabs within the impact-velocity range of 100-650 m/sec and the impact-angle range of 0-40 • (the angle is counted from the normal to the target surface) can be found in [9]. In the experiments performed, the impactor diameter was smaller than the characteristic size of the reinforcing grid cell. The experimental studies show that reinforcement of a concrete target improves its bearing capacity by preventing the global failure but has little influence on the character of local failure. It follows from the experimental and theoretical results that concrete reinforcement affects the penetration of solids into typical reinforced-concrete targets only sl...

Abstract. This paper presents the study of the evolution in situ of distribution of local deformations in near-surface layers in pads made of carbon lamellas under strain deformation. The specimens were produced from two face-to-face docked steel pads 120×40×4 mm and two carbon lamellas FibARM Lamel 120×40×1,2 mm joint using the adhesion 'FibARM Resin Laminate+". The strain tests were performed using the "INSTRON 3386" test bed with a maximum tension of 100 кN (10,19 тs). Optical measurement system VIC-3D was used to identify the evolution of deformations distribution in the near-surface layers. The VIC-3D system allowed obtaining the images that reflect the evolution of distribution of relative deformations iso-fields under different loads. In situ experimental research was conducted focused on strain deformations in specimens made of a layered composite: metal/adhesive/carbon lamella. A crack in the specimen was modeled, which allowed determining that with a growth of the overall deformation there develops an evolution of special structural elements from chaotic (along the whole lamella area) to localized ones with higher deformation values in the crack region. It was established that at higher levels of overall deformation in the crack region on the carbon lamella surface, the maximum deformation region with one extremum is divided by a narrow line of low deformation into two parts along the joint of steel plates. A limit deformation is identified.

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A method of computer simulation is used to investigate the processes of compact cylindrical projectile penetration into steel specimens separated by air gaps during successive group impacts, impact interaction of long steel bars with an explosive screened by a system of spatially separated multilayered screens, and fracture of ferroconcrete columns under repeated longitudinal and transverse impact loading.