Influence of projectile shape on dynamic behavior of steel sheet subjected to impact and perforation

Authors thank Ministry of Science and Higher Education of Poland for financial support under Grants: R00 0097 12. Authors thank also M. Tavian technician in electronics from ENIM for his contribution on the development of the residual velocity measurement sensors.The paper describes a work focused on the process of perforation of steel sheet.Experimental,analytical and numerical investigations have been carried out to analyze in details the perforation process.Based on these approaches,the ballistic properties of the material and the failure modes depending on the projectile nose shape(conical,blunt or hemispherical) have been studied.Different failure modes have been observed,including petaling, plug ejection and circumference necking.The special study about the number of petals has been done for different nose angles using conical shape projectiles.The complete energy balance is also reported and the absorbed energy by the steel sheet has been obtained by measuring initial and residual projectile velocities.A wide range of impact velocities from 35to180m/s has been covered during the tests.All the projectiles are 13mm in diameter and the plates are1mm thick.Moreover,the mass ratio(projectile mass/steel sheet mass) and the ratio between the span of the steel sheet and the diameter of the projectile are constant, equal to 0.38 and 3.85, respectively

Dynamic behavior of aluminum alloy AW 5005 undergoing interfacial friction and specimen configuration in split hopkinson pressure bar system at high strain rates and temperatures

This article belongs to the Special Issue Behavior, Damage and Fracture of Aluminum Alloy: Experiments and Modeling.In this paper, experimental and numerical results of an aluminum alloy’s mechanical behavior are discussed. Over a wide range of strain rates (10−4 s−1 ≤ έ ≤ 103 s−1) the influence of the loading impact, velocity and temperature on the dynamic response of the material was analyzed. The interface friction effect on the material’s dynamic response is examined using a split Hopkinson pressure bar (SHPB) in a high temperature experiment using finite element analysis (FEA). The effect of different friction conditions between the specimen and the transmitted/incident bars in the SHPB system was examined using cylinder bulk specimens and cylinder plates defined with four-layer configurations. The results of these tests alongside the presented numerical simulations allow a better understanding of the phenomenon and reduces (minimizes) errors during compression tests at high and low strain rates with temperatures ranging from 21 to 300 °C

Ballistic behavior of steel sheet subjected to impact and perforation

The paper is reporting some comparisons between experimental and numerical results in terms of failure mode, failure time and ballistic properties of mild steel sheet. Several projectile shapes have been considered to take into account the stress triaxiality effect on the failure mode during impact, penetration and perforation. The initial and residual velocities as well as the failure time have been measured during the tests to estimate more physical quantities. It has to be noticed that the failure time was defined using a High Speed Camera (HSC). Thanks to it, the impact forces (average and maximum level), were analyzed using numerical simulations together with an analytical description coupled to experimental observations. The key point of the model is the consideration of a shape function to define the pulse loading during perforation

BONE STRENGTH (ossis tibiae) OF NATIVE PIGS ZŁOTNICKA SPOTTED BREED AND CROSSBREDS OF POLISH LARGE WHITE AND PoLISH LANDRACE PIGS

The purpose of this study was to compare the bone strength traits in two groups of pigs different in terms of genetic value, fast growth capability and meat deposition in the body. The study covered 33 fatteners of the Złotnicka Spotted breed (ZŁP) and 20 crossbreds F1 (Polish Large White x Polish Landrace). Tibial bones were obtained following slaughter and evaluated in terms of properties and geometry, as well as bending and compressive strength. Mineral composition of the bone tissue was also established, i.e.: ash, Ca, P, Na, K, Zn and Mg. The significance of differences between the traits demonstrated by pigs in both groups subject to the study was estimated, with calculated overall correlations between the primary bone properties. The results confirmed significant differences in terms of geometry of the bones in both animal groups. In the ZŁP breed pigs, compared to the F1 crossbred group (PLW x PL), the outside and inside diameters of the tibial shaft were smaller (P ≤ 0.01), yet the average thickness of the wall of the bone was slightly larger. The bending force required to fracture the bone turned out to be lower in Złotnicka Spotted pigs, the opposite of the results obtained with regard to the compressive strength. Furthermore, calcium content, calcium-phosphorus ratio (Ca : P) and sodium content were highly statistically or significantly larger in the bone tissue of the Złotnicka Spotted pigs. Consequently, the final results show that the bone strength demonstrated by modern pig breeds subject to intensive selection focused on high growth rate and increased meat deposition is in no way lower than the same trait recognized in the Złotnicka Spotted breed kept in preservative breeding conditions

CMM-2011 -Computer Methods in Mechanics Using of Smoothed Particle Hydrodynamics (SPH) method for concrete application

Abstract The paper deals with the Smoothed Particle Hydrodynamics (SPH) method used for the analyses of quasi-static and dynamic problems of concrete structures. The influence of the loading velocity, the particle density, the smoothing length and renormalization are discussed

Modeling and Design of SHPB to Characterize Brittle Materials under Compression for High Strain Rates

This paper presents an analytical prediction coupled with numerical simulations of a split Hopkinson pressure bar (SHPB) that could be used during further experiments to measure the dynamic compression strength of concrete. The current study combines experimental, modeling and numerical results, permitting an inverse method by which to validate measurements. An analytical prediction is conducted to determine the waves propagation present in SHPB using a one-dimensional theory and assuming a strain rate dependence of the material strength. This method can be used by designers of new SPHB experimental setups to predict compressive strength or strain rates reached during tests, or to check the consistencies of predicted results. Numerical simulation results obtained using LS-DYNA finite element software are also presented in this paper, and are used to compare the predictions with the analytical results. This work focuses on an SPHB setup that can accurately identify the strain rate sensitivities of concrete or brittle materials

Experimental and Numerical Analysis of the Concrete Maturation Process with Additive of Phase Change Materials

The article presents selected types of phase change materials (PCM) and their properties in terms of applications in various fields of science such as construction and concrete technology. The aim of the article is to present a comparative analysis between the results of the laboratory tests and numerical simulations. The analysis contains two types of PCM (powder and in liquid), which were dosed in a hybrid system to the concrete mix. The purpose of using PCM is to allow the technological barrier to be exceeded in hot and dry climate conditions, enabling the construction of non-cracking concrete structures. The paper presents a parametric analysis of the influence of various modeling elements on the obtained results. The procedure of generating and absorbing heat caused by the applied PCM was also implemented using user subroutine into finite element code (Abaqus/Standard). The numerically obtained results are consistent with the experimental results. The presented results demonstrate that the use of PCM improves the conditions of concrete maturation by reducing the average temperature of the mixture in its entire volume

Experimental study of brass properties through perforation tests using a thermal chamber for elevated temperatures

International audienceExperimental analysis on standard brass alloy has been carried out using a high pressure gas gun. Perforation tests have been performed for a variety of impact velocities from 40 to 120 m/s in order to study the material behaviour and to define failure modes.The main aim of the study has been to provide results using an innovative thermal chamber that allows to heat specimens before impact. The range of available temperatures is from the room temperature up to 260 ˚C.The experimental study has allowed to discuss the ballistic properties of the structure. The ballistic resistance of sheet plates is strongly dependent on the material behaviour under dynamic loading and changes with temperature. The ballistic properties are also intensely related to interaction between the projectile and thin brass target. The results in terms of the ballistic curve VR (residual velocity) versus V0 (initial velocity) have shown the temperature effect on the residual kinetic energy and thus on the energy absorbed by the plate, revealing a thermal softening of the brass. The ballistic limit corresponding to the maximum impact velocity without complete perforation has decreased by 5-7% for the highest temperature considered.A changing failure pattern is observed. The number of petals varies as a function of impact velocity and temperature. It can be concluded based on experimental observations that thermal softening is a key point on the process of perforation.Preliminary temperature records have been provided using a thermal imaging camera