Papers by Keyword: Penetration

Abstract: As a promising transport in the future, electric vehicles plays an important role in people's lives and energy conservation. In recent years, the rapid development of electric vehicles, inevitably causes the overload problems to the original grid. This paper presents a transformer load models with the consideration of electric vehicle charging load. We analyze the transformer overload problem by the results obtained by simulation of the model.

Abstract: Concrete is a brittle material which cracks under the tension and pulverized when the compressive stress exceeds the ultimate compressive strength. Confined concrete performs better than that of concrete without confinement in resisting penetration. Based on the Griffith strength theory, a quasi-static cylindrical cavity expansion model for the penetration of steel-tube-confined concrete targets is proposed. Numerical results show that ratio of tube wall thickness to tube radius significantly effects cavity expansion stress, which is in proportion to the former ratio. The results are in good agreement with the cavity expansion process.

Abstract: Cavity expansion modeling is an important method for penetration analysis. Based on the Mohr-Coulomb criterion, a quasi-static cylindrical cavity expansion model for the penetration of confined concrete targets was proposed in this paper. Formulas of cavity expansion stresses calculation were obtained and the lateral confinement effects of steel tubes on the cavity expansion stresses were also investigated. Numerical results about the relationships between the ratio of tube wall thickness to tube radius and cavity expansion stresses were discussed.

Abstract: Objective: To study the influence of disc cutter spacing on rock fragmentation efficiency and optimize cutter layout and improve the efficiency of disc cutter. Method: ANSYS, a finite element software was used to simulate double disc cutter cutting process. Result: Find a good corresponding relationship between penetration and cutter spacing. At the process of sandstone, if disc cutter spacing as 54 ~ 55 mm, rock crushing as the largest and rock fragmentation efficiency is the highest; with the penetration of 10 mm. If disc cutter spacing as 66~68.5mm, rock crushing as the largest and rock fragmentation efficiency is the highest with the penetration of 15 mm. Changing the cutter spacing and penetration, rock stress and broken degree will also change. Conclusion: Double disc cutters change within the range of best cutter spacing, cutter spacing is proportional to the rock crushing. If the cutter distance is greater than the best cutter spacing, the ledge will be appeared. For one type of rocks, the penetration would have some effects on the optimal cutter spacing. If the penetration increases, the optimal cutter spacing increases gradually, at the time of other construction parameters unchanged.

Abstract: In this work, the shaped charge jet formation depends on different parameters which can has effect on jet behavior such as jet velocity, breakup and penetration. Jet radius or liner thickness, shell thickness, liner material density, α angle and stand-off distance are evaluated in purpose to investigate their effect on performance of shaped charge jet velocity and jet breakup phenomena, also we investigate the effect of stand-off distance on shaped charge jet penetration into steel target. We also studied the performance of some protective shields materials in order to assure more protection for vehicle structure against shaped charge jet penetration. For that, different materials were used as armors such as: kevlar epoxy, polyethylene, glass epoxy, steel-1006 and Al₂O₃ ceramic. These protective shields were evaluated in order to show their performance against shaped charge penetration into target. To do so, adopted explicit dynamic analyzing program Autodyn basing on finite element were used to simulate shaped charge jet formation and penetration. Autodyn-2D simulationshighlight the efficiency of our work comparing with the experiments done in literature and Birkhoff’s theory. In other terms, increasing in shell thickness, alpha angle and liner densityenhance jet breakup time, protective shields layered armor of steel-1006, steel 1006 with polyethylene and steel-1006 with Al₂O₃ceramic give more protection for structure against shaped charge jet penetration comparing with others armors.

Abstract: Laser aided activating TIG welding was called LA-TIG. At first, the surface of weld was melted by the mini power laser protected by oxygen, and then the conventional TIG was used to cover the weld, which achieved the target of the weld with deeper penetration and narrower width. In this article, the weld bead morphology, arc images, microstructures and mechanical properties of laser aided activating TIG welding joint were analyzed. The results shows that the penetration increased significantly, excellent weld appearance and finger shape penetration were gained by laser aided activating TIG welding. It was found that the arc images of the LA-TIG was only the enlarged form compared with which observed in the conventional TIG and the arc constriction was also observed. LA-TIG weld exhibits better mechanical properties than the conventional TIG welding. Thus laser aided activating TIG welding was developed as a novel active welding method.

Abstract: In the given work, the investigations have been directed to the creation of porous composite materials with MgO and B₄C ceramic filler. The laboratory technology of obtaining rods from the given materials has been developed. The experimental part of this work was carried out on ballistic set-ups with shaft-reactive and electrochemical technologies of throwing with the use of high-energy plastisol fuels with nanosize metallic fillers. Mathematical modeling of the behavior of materials under conditions of high-speed interaction was carried out in the framework of a porous elastoplastic medium according to different destruction mechanisms.

Abstract: Penetration of adhesive into the wood cell and lumens is an important factor that may enhance the durability of the adhesive bonds. In this study, the diffusion of adhesive polyvinyl acetate (PVAc) into the cell wall of various types of wood was evaluated making use of micro-CT. Compression shear block tests were also applied to examine the mechanical performance of the bond. In adhesive assemblies examined, cell walls at the immediate surface which were damaged during machine planning were full of adhesives. As the penetration of PVAc increased, the variation in the observed bind strengths was not substantial. Bonded with the same type of glue, black spruce appeared to have lower shear strength than Douglas fir and lodgepole pine. Moreover, gravity seemed to play a role in the glue penetration. During clamping and adhesive curing, the substrate on the lower of the shear block specimen had a deeper glue penetration. There are some correlations between glue penetration and glue line thickness measured using micro-CT.

Abstract: The purpose of this study is development of gun-bullet protection board. In this experiment, the air gun’s performance and the effective bullet supporting sabot’s shape were evaluated. The launched gun-bullet velocity was measured by high speed video method.

Abstract: Adding polymer emulsion to concrete can increase the bonding strength at the interface of steel fiber and matrix and the property of matrix is improved. Tensile strength, bending strength, deformation and toughness of the concrete are also increased. Anti-penetration performance of steel fiber reinforced concrete (SFRC), polymer-modified concrete (PMC) and steel fiber reinforced polymer-modified concrete (SFRPMC) are studied in this paper. Experiment was conducted by launching steel projectiles into concrete targets, and damage distributions of concrete after penetration are obtained. The results showed the anti-penetration performance of steel fiber concrete by adding polymer can be increased obviously.