Papers by Keyword: Projectile

Abstract: This paper, with the simplified concrete damage plasticity (SCDP) model, studying the penetration depth of steel projectile in the concrete block by Abaqus software. Comparing the results calculated by Abaqus software with the Modified NDRC formula to check the reliability of the computational model and material model. From there, studying the effect of concrete strength on penetration depth in concrete B20, B30, B40, B50.

Abstract: The paper presents a comparative analysis of the dynamic loading of a polymethyl methacrylate (PMMA) target by a polyethylene (PE) projectile exposed to laser radiation with similar initial energy characteristics of the projectile and the laser pulse. The similarities and differences in the mechanisms of the target's response and its destruction to high-speed mechanical and laser action are shown. A higher efficiency of laser irradiation in the destruction of PMMA was found, and the conditions for the transition of the fracture mechanism from brittle to elastic-plastic were shown.

Abstract: Impact conditions involve velocities below the sonic speed, which is normally of the order few hundreds up to few thousands m/s. The implications of impact depend on projectile and target materials, impact velocity, incident angle and the mass and shape of the projectile impacting head. The superimposition of progressing and reflected waves can lead to local stress levels that exceed the material’s strength, thus causing cracks and / or fracture at significant velocities. At low impact velocities, plastic deformation normally prevails. With increasing velocities the projectile will leave a hole in the target. With decreasing target thickness, the effects range from perforation, via internal cracks, and finally to plug formation. In this paper, the damages caused by impact which include: perforation, plugs formation and their fracture, metallurgical changes e.g. shear bands, twinning, recrystallization and phase transformation and fractures both in the projectile and the target plate are presented and discussed.

Abstract: The present study deals with ballistic performance of corundum and silicon carbide ceramics against 7.62 mm calibre projectile. In particular, ceramic samples of dimension 100 x 100 mm with various thickness in the range of 6.94 – 6.96 mm and 7.77 - 7.79 mm were glued to Al plate with thickness of 8 mm and tested against 7.62 mm calibre projectiles, namely 30.06 M2 AP, 7.62 mm x 51 AP (WC) and 7.62 mm x 54 R B32. The conducted tests have provided the V₅₀ value for tested materials composed of 8 mm Al plate and ceramic.Furthermore, applying linear approximation the value V₅₀ for normalized ceramic areal density of 26 kg/m² was calculated. From the given V₅₀ values, the energy of projectile absorbed in ceramic and in Al plate was also calculated. Finally, the results showed that corundum ceramic exhibited significantly lower ballistic efficiency probably due to lower thickness (26 kg/m² corresponds to thickness of 6.61 mm) in comparison with SSiC ceramic (26 kg/m² corresponds to thickness of 8.33 mm). The highest efficiency showed 7.62 mm x 51 AP (WC) with a hard core against both ceramics. An unexplained point remains similar V₅₀ value for 30.06 M2 AP and 7.62 mm x 54 R B32 projectile for corundum ceramic and significantly different for SSiC ceramic.Graphical abstract

Abstract: High temperature generated by target impact causes projectile austenite phase transformation. At high temperature, the austenite strength decreases rapidly and undergoes phase transformation erosion because of target impact. On this basis, a projectile material model which took phase transformation erosion into consideration was established and then the model was verified. Model simulation showed that after phase transformation erosion the projectile was subjective to tensile and compression instability. Dual-arc head design would significantly reduce projectile penetration resistance and decrease phase transformation influence on projectile stability.

Abstract: It was found from the experiment that the high temperature caused by target impact led to projectile austenite phase transformation. Based on this finding, a phase transformation model was established and verified by experiments, which proved the model had a relatively high calculation precision. Then, the model was used for numerical simulation. The result showed that the phase transformation zone was at the projectile head surface and the area increased as the impact velocity increased. The critical impact velocity which would cause phase transformation and affect projectile performance was around 700m/s.

Abstract: On the basis of dual-spin projectile multi-body characteristics, the angular motion model is established in the quasi-body coordinates. Through linearization, the system dynamic stability factor and gyroscopic stability factor are obtained by differential equations characteristic roots. There is also informative to compare the dual-spin projectile gyroscopic stability factor to the conventional rigid projectile results. The comparison can be viewed where the influence of the spin rates ration γ_f/γ_a and the ratio of inertia moments C_f/C_a on the ratio S_g/S^y_g of the gyroscopic stability factors. Through the numerical example, the dual-spin projectile has a similar stability to that of a conventional rigid projectile, and the curves of the relationship between the ratio S_g/S^y_g of the gyroscopic stability factors with the ratio of spin rates γ_f/γ_a and the ratio of inertia moments C_f/C_a are got by simulation.

Abstract: Explicit finite element code was applied to simulate the steel fiber reinforced concrete (SFRC) and reactive powder concrete (RPC) target penetrated by kinetic energy projectile. Crater formation, spall of concrete target in penetration process was simulated very well. The numerical results of penetration depths are in good agreement with recent experimental results obtained from ballistic gun with 57mm caliber. The factors effecting on anti-penetration property of SFRC and RPC are analyzed. The results show that: the compressive strength and toughness of the target body have greater impact on anti-penetration performance in the range of projectile velocity 300m/s-600m/s. Anti-penetration capability of RPC concrete is stronger than that of ordinary steel fiber at the higher speeds.

Abstract: To the question of the breakup of the space target impacted by projectile, an engineering model is developed. The space target characteristic is analyzed, and the target equivalent model is established based on the thin plate. The average size model for the impact fragment of thin plate is established depending on strain rate, fragments are discrete according to Poisson statistic and fragment distribution model is figured out. The length and velocity degraded model is set up against projectile with the shape of cylindrical rod. The simulation case is analyzed and the result indicates that the related models are effective, flexible and have important reference value.

Abstract: For making sure the dry bay ignition and fire, it’s necessary to calculate the number and the sizes of the droplets and determine the mass flow rate of the fuel induced by high-speed impact and penetration of a rigid projectile into fuel tank. An analytical model is founded and the method for calculating the initial leaking velocity of the fuel is determined. It gives the equation for calculating the drop size distributions of fuel and the Sauter mean diameter (SMD) of droplets, through the Maximum Entropy Theory and the conservation for mass. Using the Harmon’s equation for SMD,the fuel droplets SMD can be calculated. Results shows that the initial leaking velocity of the fuel is about linearly increasing with the velocity of the projectile, the SMD of fuel droplets increases with the hole size of the fuel tank which induced by the penetration of the projectile and linearly decreases with the velocity of the projectile. The results can be used for the ignition and fire analysis of the dry bay adjacent to fuel tanks.