Partial penetration of annular grooved projectiles impacting ductile metal targets

Changing and optimizing the projectile nose shape is an important way to achieve specific ballistic performance.One special ballistic performance is the embedding effect,which can achieve a delayed high-explosive reaction on the target surface.This embedding effect includes a rebound phase that is significantly different from the traditional penetration process.To better study embedment behavior,this study proposed a novel nose shape called an annular grooved projectile and defined its interaction process with the ductile metal plate as partial penetration.Specifically,we conducted a series of lowvelocity-ballistic tests in which these steel projectiles were used to strike 16-mm-thick target plates made with 2024-O aluminum alloy.We observed the dynamic evolution characteristics of this aluminum alloy near the impact craters and analyzed these characteristics by corresponding cross-sectional views and numerical simulations.The results indicated that the penetration resistance had a brief decrease that was influenced by its groove structure,but then it increased significantlydthat is,the fluctuation of penetration resistance was affected by the irregular nose shape.Moreover,we visualized the distribution of the material in the groove and its inflow process through the rheology lines in microscopic tests and the highlighted mesh lines in simulations.The combination of these phenomena revealed the embedment mechanism of the annular grooved projectile and optimized the design of the groove shape to achieve a more firm embedment performance.The embedment was achieved primarily by the target material filled in the groove structure.Therefore,preventing the shear failure that occurred on the filling material was key to achieving this embedding effect.

Mathematical model and simulation of partial penetrated weld pool

The qualitative analysis on the behavior of partial penetrated weld pool transferring from pulsed peak current to base current in pulsed TIG welding is carried out in this paper. Based on the analysis results, the mathematical models for 3D liquid surface shape of partial penetrated weld pool in pulsed TIG welding are created including surface potential energy model, gravitational energy model and volumetric potential energy. The numerical simulation with these models and the experiments on low carbon steel are carried out using the software Surface Evolver. The simulation results and model are then amended with experimental results. Two important characteristic quantities, the liquid metal coverage ratio and the stripping width of liquid metal, are put forward in this paper, which paves a way for further weld pool full penetration control.

Quantitative Analysis of Groundwater Flow near a Partially Penetrating River under Riverside Pumping

According to practical geological and hydrogeological conditions of riverside water-supply well fields in northwestern China, an ideal hydrogeological model has been generalized and a three-dimensional mathematical model has been set up. A finite difference method was applied to simulating groundwater flow near a partially penetrating river under riverside pumping, and to analyzing the effects of river width, partial penetration and permeability of riverbed sediments on groundwater recharges. Results show that riverside pumping may cause groundwater to flow beneath the partially penetrating river, and that river width, penetration and riverbed permeability obviously influence flows from the partially penetrating river and constant-head boundaries. However, the pumping output is mainly from the partially penetrating river.

Analytical solution based on stream-aquifer interactions in partially penetrating streams

An analytical solution of drawdown caused by pumping was developed for an aquifer partially penetrated by two streams. The proposed analytical solution modifies Hunt＇s analytical solution and considers the effects of stream width and the interaction of two streams on drawdown. Advantages of the solution include its simple structure, consisting of the Theis well function and parameters of aquifer and streambed semipervious material. The calculated results show that the proposed analytical solution agrees with a previously developed acceptable solution and the errors between the two solutions are equal to zero without consideration of the effect of stream width. Also, deviations between the two analytical solutions increase with stream width. Four cases were studied to examine the effect of two streams on drawdown, assuming that some parameters were changeable, and other parameters were constant, such as the stream width, the distance between the stream and the pumping well, the stream recharge rate, and the leakage coefficient of streambed semipervious material.