Dear Hamid,

The followings links and attached file may be helpful,

1-International Journal of Solids and Structures

Volume 44, Issue 20, 1 October 2007, Pages 6701–6723

 On the ballistic resistance of double-layered steel plates: An experimental and numerical investigation

S. Deya, T. Børvika, b, , ,X. Tengc,T. Wierzbickic,O.S. Hopperstada

A review article:

Abstract

Civil and military ballistic protection systems often consist of thin, high-strength steel plates. Such plates may either be monolithic or layered with or without spacing. The idea of using layered plates instead of a monolithic one in order to increase the ballistic perforation resistance is not new, and the effect of using targets made up of several thinner plates has been investigated in the literature for a long time. However, results by various authors are contradicting and detailed experimental and numerical work is still required.

In the present study, the ballistic perforation resistance of double-layered steel plates impacted by blunt and ogival projectiles was investigated both experimentally and numerically. In the tests, 12 mm thick (monolithic or layered) targets of Weldox 700 E were impacted using a gas-gun at sub-ordnance velocity, and the ballistic limit velocity of the different target combinations was obtained. In general, good agreement was obtained between the numerical simulations and the experimental results. It was found that in the case of blunt projectiles a large gain in the ballistic limit is offered by double-layered systems. These advantages seem to disappear when ogival projectiles are used. However, the main conclusion from both the experimental and numerical studies is that the overall protection level, i.e. the minimum ballistic limit velocity obtained independently of projectile nose shape, seems to increase significantly by double-layering the target.

http://www.sciencedirect.com/science/article/pii/S0020768307001242

2-Experimental and numerical analysis of normal and oblique ballistic impacts on thin carbon/epoxy woven laminates

J. Lo´pez-Puente *, R. Zaera, C. Navarro

Carlos III University of Madrid, Department of Continuum Mechanics and Structural Analysis, Avda. de la Universidad 30, 28911 Legane´s,

Madrid, Spain

Abstract

A finite element numerical model for carbon/epoxy woven laminates has been used to predict residual velocity and damaged area

when subjected to high impact velocities. Experiments using a gas gun were conducted to investigate the impact process and to validate

the model, measuring the two variables previously indicated. A morphology analysis was also made to investigate the different breakage

mechanisms that appear during the penetration process. The influence of the impact velocity and obliquity has been studied using the

numerical tool, in a wide range of impact velocities and considering two impact angles, 0° and 45°.

http://orff.uc3m.es/bitstream/handle/10016/7316/experimental_zaera_ca_2008_ps.pdf?sequence=3

3-Numerical simulation of ballistic impact on composite laminates

M.A.G. Silvaa , C. Cismasiu- a,*, C.G. Chioreanb

International Journal of Impact Engineering 31 (2005) 289–306

Abstract

The paper reports experimental and numerical simulation of ballistic impact problems on thin composite laminated plates reinforced with Kevlar 29. Ballistic impact was imparted with simulated fragments designed in accordance with STANAG-2920 on plates of different thickness. Numerical modelling was

developed and used to obtain an estimate for the limit perforation velocity ðV50Þ and simulate failure modes and damage. Computations were carried out using a commercial code based on finite differences and values obtained are compared with the experimental data to evaluate the performance of the simulation. Good

correlation between computational simulation and experimental results was achieved, both in terms of deformation and damage of the laminates. Future work is advanced to include the interposition of an outer ceramic layer as well as examining the influence of dry-wet and temperature cycles on the mechanical

strength of the plates and their temporal evolution under accelerated ageing.

r 2004 Elsevier Ltd. All rights reserved.

http://www2.dec.fct.unl.pt/projectos/SMA/FCT/Sil05.pdf

4-Experimental and Numerical Simulation Based Assessment of Kevlar Composite Specimens under Ballistic Impact

Abstract

Experimental and numerical based investigations are carried out to study the behaviour of Kevlar composite panel subjected to ballistic impact. Immersion type ultrasonic C-scan is performed on impacted Kevlar composite panel and extent of damages are identified through C-scan imaging of A-scan data. The methodology, based on segmentation of ultrasonic data into different clusters, is implemented for automated generation of the C-scan image of the scanned domain. The core damage area for ballistically impacted composite panel is evaluated from the respective C-scan image. Numerical simulation is also performed to study the impact event on Kevlar/Epoxy panel of different thicknesses struck normally by projectiles (7.62AP shot) with different impact velocities using ABAQUS/Explicit. A suitable failure criteria is adopted to predict the initiation and subsequent propagation of damage. Results in the form of residual velocity and perforated area show similar trends with those found from experiment.

https://www.researchgate.net/publication/264840609_Experimental_and_Numerical_Simulation_Based_Assessment_of_Kevlar_Composite_Specimens_under_Ballistic_Impact

Hoping this will be helpful,

Rafik

Article Experimental and Numerical Simulation Based Assessment of Ke...

thanks rafik

whats mean V50?!!

Dear Hamid,

V50 or V50 value:

Ballistic Limit: For a given bullet type, the velocity at which the bullet is expected to perforate the armor 50 % of the time. The ballistic limit is typically denoted as the V50 or V50 value.

http://nist.gov/oles/upload/ballistic.pdf

Hoping this will be helpful,

Rafik

The ballistic limit or limit velocity is the velocity required for a particular projectile to reliably (at least 50% of the time) penetrate a particular piece of material. In other words, a given projectile will generally not pierce a given target when the projectile velocity is lower than the ballistic limit.

what is mean the "plate perforated" mean?

any type at any size perforation or a spacial pattern?

see this equations 

Dear Hamid,

Please read the following:

Penetration: Any impact where the projectile passes into the armor is a penetration. A penetration may either be a stop or a perforation. The result is considered a stop or partial penetration if (1) the entire projectile is captured or deflected by the armor, and (2) no fragments of either the projectile or the armor become embedded in the backing material. If any part of the projectile passes through the armor, the result is considered a perforation or a complete penetration. Although the terms partial penetration and complete penetration are no longer used in this standard, they may still be used by test laboratories for compatibility with military standards.

Perforation: Any impact that creates a hole passing through the armor. This may be

evidenced by any of the following: (1) the presence of the projectile, a projectile fragment, or an armor fragment in the clay backing material; (2) a hole that passes through the armor and/or backing material; or (3) any portion of the bullet being visible from the body side of the armor panel. The term perforation is synonymous with the term complete penetration.

Plate Inserts: Hard armor plates or semi-rigid plates that are intended to be inserted into pockets of flexible vests and jackets to provide increased protection, particularly to provide protection against rifle threats.

Hoping this will be helpful,

Rafik

The ballistic limit or limit velocity is the velocity required for a particular projectile to reliably (at least 50% of the time) penetrate a particular piece of material. In other words, a given projectile will generally not pierce a given target when the projectile velocity is lower than the ballistic limit. The term ballistic limit is used specifically in the context of armor; limit velocity is used in other contexts.

thanks all about your Ans.

let me know about different between impact of projectile vs fragment  response on  steel plate.are these response same? what is the method of model the fragment for impact simulation?

Dear Hamid,

The two terms Impact of projectile and fragment penetration into steel mean the same.

The following publication illustrates a modeling fragment simulating projectile penetration into steel plates:

Modeling Fragment Simulating Projectile Penetration into Steel Plates Using Finite Elements and Meshfree Particles

James O’Daniel, Kent Danielson, and Nicholas Boone

Shock and Vibration

Volume 18 (2011), Issue 3, Pages 425-436

http://dx.doi.org/10.3233/SAV-2010-0523

Abstract

Simulating fragment penetration into steel involves complicated modeling of severe behavior of the materials through multiple phases of response. Penetration of a fragment-like projectile was simulated using finite element (FE) and meshfree particle formulations. Extreme deformation and failure of the material during the penetration event were modeled with several approaches to evaluate each as to how well it represents the actual physics of the material and structural response. A steel Fragment Simulating Projectile (FSP) – designed to simulate a fragment of metal from a weapon casing – was simulated for normal impact into a flat square plate. A range of impact velocities was used to examine levels of exit velocity ranging from relatively small to one on the same level as the impact velocity. The numerical code EPIC, used for all the simulations presented herein, contains the element and particle formulations, as well as the explicit methodology and constitutive models needed to perform these simulations. These simulations were compared against experimental data, evaluating the damage caused to the projectile and the target plates, as well as comparing the residual velocity when the projectile perforated the target.

http://www.hindawi.com/journals/sv/2011/520187/abs/

Hoping this will be helpful,

Rafik