Modelling of Fracture Processes in the Ballistic Impact on Ceramic Armours (original) (raw)
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International Journal of Impact Engineering, 1992
In thas paper, the penetration of ceramic targets backed by thm metallic plates when impacted by cylindrical projectiles is studied. To achieve this, a two-dimensional axisymmetric numerical analysis of the normal impact problem is performed. The macroscopic material behavlour in the zone of finely pulverized ceramic ahead of the penetrator is modelled by means of a constitutive model taking into account internal friction and volumetric expansion. The amount of comminutlon at the computational cells is evaluated through a damage evolution equation, and the yield stress is assumed to be a function of the hydrostatic pressure, internal friction and amount of comminutlon. For the metallic materials involved, an elasto-plastic behaviour with a rupture condition was considered. Moreover, an erosion condition was included as a limit situation when the ruptured material limits its role m the penetration process to purely inertial effects. In this way, a detailed picture of the penetration process of the target by the impacting projectile was obtained. Then, the results of the numerical analysis were compared with the experimental observations of the projectde-target interaction, previously made by Reijer by usmg a flash X-ray technique. Under certain conditions, remarkable agreement between computations and experiments is encountered, thus suggesting the adequacy of the main assumptions made in the numerical approach to the physical situation.
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This article presents an analysis of the effectiveness of available numerical techniques in mapping the characteristic behavior of ballistic ceramics under projectile impact conditions. As part of the work, the ballistic tests were performed on the layered ceramic/steel composite armor and tested with the 7.62 × 39 mm, armor-piercing incendiary (API) BZ projectile. The experimental tests were then mapped using computer simulations. In numerical analyses, four different techniques were used to describe cubic ceramic tiles Al2O3 placed on the ARMOX 500T steel backing plate, i.e.,: the Finite Element Method without Erosion (FEM), Finite Element with erosion (FEM + Erosion), Smoothed Particles Hydrodynamics (SPH) and a hybrid method that converts finite elements to SPH particles after exceeding the defined failure criteria (FEM to SPH conversion). The effectiveness of the individual methods was compared in terms of quality (mapping of characteristic phenomena occurring during the penetr...
Numerical Simulation of Ballistic Impact on Ceramic Armor
Proceedings of the 4th …, 2006
A preliminary investigation of ballistic impact on ceramic armor was carried out by recourse to numerical simulation using finite element method. Following our earlier study [1] on the effect of stress wave propagation from dynamic loads, the current computational model was developed with built-in brittle failure criteria, aiming to correlate with experimental ballistic testing. It was found that the rate that the ceramic armor absorbed the bullet kinetic energy raised as the armor thickness increased.
Frattura ed Integrità Strutturale, 2020
Simulation and analysis of the projectile impact and penetration problem and its effects are among the practical topics that can be used to design bulletproof panel and military equipment, construction of impact and penetration resistant structures, design of projectiles with appropriate penetration strength and high performance noted. One of the most important parameters affecting penetration is the impact velocity of the projectile. The mechanism of penetration varies in different speed ranges. In this paper, Ansys Autodyn software is used for penetration simulation. The simulation carried out in this study is based on the accuracy and physical conditions of the problem and the compatibility of numerical simulation with the governing analytical relations indicates the validity and accuracy of the assumptions made in the simulation. In this study, we selected materials such as material behavior, grating, contact surfaces, and controls, as well as collision of the blunt projectile with angles of 0º,15º,30º,45º by of high velocity impact 1000 m/s with the same mass and diameter and shape of the projectile nose and properties. Ceramic materials are discussed. The result of the numerical simulation comparison shows relatively good agreement between them.
On the linkage of impact damage to modeling of ballistic performance
The assessment of terminal ballistic performance has historically been strongly biased toward the penetration resistance of the target architecture and its component materials. However, penetration modeling alone does not provide sufficient knowledge to create new and/or improved armor ceramics materials capable of mitigating and preventing penetration. It is apparent that physical impact damage occurs prior to, and strongly affects, the occurrence and progress of the penetration process and as such impact damage needs to be explicitly included in ballistic performance modeling. One aspect of this situation has been the difficulty in attaining a detailed volumetric characterization of actual sub-surface bulk impact damage. The x-ray computed tomography, XCT, diagnostic and 3D visualization techniques presently appear as the only effective nondestructive evaluation, NDE, modality for high resolution volumetric impact damage interrogation, spatial characterization, quantification, visualization, and 3D analysis. An overview of the current XCT impact damage diagnostic capabilities and results are discussed along with some remaining challenges and the need to incorporate 3D physical damage features into future computational models for predictive ballistic performance.
Defence Technology, 2015
Determination of ballistic performance of an armor solution is a complicated task and evolved significantly with the application of finite element methods (FEM) in this research field. The traditional armor design studies performed with FEM requires sophisticated procedures and intensive computational effort, therefore simpler and accurate numerical approaches are always worthwhile to decrease armor development time. This study aims to apply a hybrid method using FEM simulation and artificial neural network (ANN) analysis to approximate ballistic limit thickness for armor steels. To achieve this objective, a predictive model based on the artificial neural networks is developed to determine ballistic resistance of high hardness armor steels against 7.62mm armor piercing ammunition. In this methodology, the FEM simulations are used to create training cases for Multilayer Perceptron (MLP) three layer networks. In order to validate FE simulation methodology, ballistic shot tests on 20 mm thickness target were performed according to standard Stanag 4569. Afterwards, the successfully trained ANN(s) is used to predict the ballistic limit thickness of 500 HB high hardness steel armor. Results show that even with limited number of data, FEM-ANN approach can be used to predict ballistic penetration depth with adequate accuracy. 1. Introduction The ballistic penetration modeling has become of prime importance in development of armor solutions and continues to be a challenging research field for engineers. Due to its complexity, in investigation of ballistic penetration problems, three modeling approaches are quite popular. These are experimentally derived empirical formulation, analytical model derivation and numerical simulation. Numerous empirical formulations were derived with the tests conducted in laboratory environment and used in solution of ballistic problems [1]. In contrary to straight forward methodology of deriving empiric formulation, their limited applicability to various cases is a bottleneck for widespread usage. Analytical models are quite useful due to their direct applicability on various problems but derivation always requires simplified assumptions in governing equations which results in deviation from realistic outcomes [2,3]. It is inherent that, empirical and analytic approaches cannot capture the complex nature of impact phenomenon, thus numerical simulation has become a necessary tool for the study of ballistic penetration. Numerical methods and subsequent computing technologies have been developed to the level where mentioned complex penetration behavior can be truly estimated. A review of the impact simulation literature shows that the researches under this topic have been focused on the implementing explicit hydro-codes [4-8]. Although FE analysis is a powerful tool, due to the difficulty of development procedure and high computational cost, easy to apply approaches are always valuable for armor development studies. Especially, a computational tool which is based on
Numerical Simulations of Level 3A Ballistic Impact on Ceramic/Steel Armor
Proceedings of the …, 2006
This article concerns with the ABAQUS simulation of 9-mm-bullet impacts with initial velocities between 419 -431 m/s on ceramic/steel armor plates, which complies with the level 3A of the National Institute of Justice (NIJ) standard. In most studies, the impactators are very hard compared to the armor. In reality, the bullets are quite soft and frequently disintegrate upon impacts, making them particularly difficult to model. This preliminary study aims to confirm that the relative strength of the bullet and armor is a major aspect in the ballistic simulations. Without trying to accurately capture the bullet rupture, pragmatic numerical models may be obtained by using hard bullets and armor plates with heightened strengths. That is, the bullet is elastic while the strength of ceramic armor, whose function is to shatter the bullet, is raised by increasing the tensile strength. It can be argued that rough simulations of impacts may be obtained and numerical results of 4 simulations, in which the tensile strength of ceramics are heightened, qualitatively agree with the experimental observations.
Ballistic Impact Simulation of Ceramic/Metal Armor Structures
Uluslararası Muhendislik Arastirma ve Gelistirme Dergisi, 2017
The study presents a comparative numerical investigation on ballistic performance of ceramic/metal armor structures. 2D axisymmetric numerical model was developed for ballistic impact simulations using LS-DYNA ® finite element software. The armor structures included combinations of boron carbide (B4C), Al6061-T6 and 4340 steel constituents. The interfaces in the armor structure were modelled with an epoxy resin adhesive. In order to define proper material behavior, Johnson-Holmquist-Ceramics material model for B4C and Plastic-Kinematic material model for Al6061-T6, 4340 steel and epoxy resin was used. The armor structures were subjected to 7.62 mm ogive-nosed steel projectile impact. In the first section, the influence of back plate material on the ballistic performance of the armor structure for bi-layers ceramic/metal configuration (ceramic front face and metal back plate) was investigated for Al6061-T6 and 4340 steel materials under same thickness and areal density. In the second section, the effect of removing half thickness of the metal constituent from the back plate and placing on the front face was investigated for both Al6061-T6 and 4340 steel materials. Finally, the influence of adhesive thickness on the ballistic performance of the armor structure was investigated. Perforation response of the armor structures were examined in terms of residual velocity of the projectile and damage mechanisms of the armor structure.
Finite element simulation of ceramic/composite armor under ballistic impact
Composites Part B: Engineering, 2011
In this paper, based on LS-Dyna code, a new finite element (FE) simulation of the ballistic perforation of the ceramic/composite targets, which impacted by cylindrical tungsten projectiles, has been presented. Research on this method has been conducted by a few research groups in recent years. The ceramic material, which is the front plate, has been made of Alumina 99.5% and composite backup plate composed of Twaron fibers. The 2-dimensional (2D), axi-symmetric, dynamic-explicit, Lagrangian model has been considered in this simulation. The Johnson-Cook, Johnson-Holmquist and Composite-Damage materials behaviors have been used for projectile, ceramic and composite materials respectively. The brittle fracture and fragmentation of ceramic conoid, the failure criteria based on fracture of fibers or matrixes of composite materials and erosion or flattening of projectile during perforation have been considered. The residual velocity and perforation time has been obtained and compared with the available analytical models. The results show that when the ceramic is impacted by a projectile, a fragmented ceramic conoid breaks from ceramic tile and the semi-angle of ceramic conoid with increasing initial velocity decreases. Furthermore, the dishing of composite layers at high impact velocities and the delamination of layers near the ballistic limit velocity decrease.
Numerical study of penetration in ceramic targets with a multiple-plane model
1998
The penetration mechanics in different material/structure systems has been investigated by numerical simulations with the finite element code EPIC95. A multi-plane microcracking model was implemented Go simulate ceramic fragmentation and comminution. Two kinds of confined structures, depth-of-penetration (DOP) and interface-defeat (ID) configurations, were examined in the simulations. The results revealed that the penetration process is found to be less dependent on the ceramic material than usually assumed by most investigators. By contrast, tile penetration process is highly dependent on the multi-layered configuration and the target structural design (geometry, and boundary conditions). From a sinmlation standpoint, we found that the selection of the erosion parameter plays an important role in predicting the deformation history and interaction of the penetrator with the target. These findings show that meaningful light weight armor design can only be accomplished through a combined experimental/numerical study in which relevant ballistic materials and structures are simultaneously investigated.