The Experts below are selected from a list of 2607 Experts worldwide ranked by ideXlab platform
Mica Grujicic - One of the best experts on this subject based on the ideXlab platform.
-
the role of adhesive in the Ballistic structural performance of ceramic polymer matrix composite hybrid armor
Materials & Design, 2012Co-Authors: Mica Grujicic, B Pandurangan, B DentremontAbstract:Abstract Transient non-linear dynamics computational finite-element analyses are employed to investigate the role of the adhesive used in ceramic strike-face/composite back-face hybrid armor. The role of the adhesive is investigated under: (a) high loading-rate conditions accompanying impact of an armor-piercing projectile onto the armor structure; and (b) low loading rate conditions associated with the ingress of the loads which are generated at the road/tire contact interfaces and transmitted into the armor structure through the vehicle frame. The high loading-rate conditions were analyzed since they reveal the role of the adhesive under Ballistic impact scenarios which controls the overall penetration resistance of the armor. On the other hand, the low loading-rate conditions were analyzed since they may reveal the potential structural damage that armor may experience due to sustained in-service loads. Since structural thermoset-polymer-based adhesives suffer from inadequate ductility, only the case of flexible (elastomer-based) adhesives was considered. The following two specific aspects of the adhesive mechanical response are given special attention: (a) strain rate sensitivity and (b) the degree of volumetric compressibility. The results obtained show that while significant improvements in the Ballistic Protection performance and durability of hybrid armor can be attained by proper modifications in the adhesive layer mechanical properties, there is no single combination of these properties which simultaneously optimizes all the performance requirements.
-
A Computational Investigation of the Multi-Hit Ballistic-Protection Performance of Laminated Transparent-armor Systems
Journal of Materials Engineering and Performance, 2012Co-Authors: Mica Grujicic, B Pandurangan, N. CoutrisAbstract:Multi-hit Ballistic-Protection performance of a prototypical laminated glass/polycarbonate transparent armor is investigated using a series of transient nonlinear dynamics analyses of armor impact with a sequence of four M2AP full metal jacket (FMJ) armor-piercing bullets. All calculations were carried out using ABAQUS/Explicit commercial finite element program (ABAQUS Version 6.7, User Documentation, Dessault Systems, 2007), and the computational results obtained were compared to their experimental counterparts obtained by Dolan (Ballistic Transparent-armor Testing Using a Multi-hit Rifle Pattern, Bachelors, Thesis, Kettering University, December 2007). The comparison revealed that (a) The proposed computational procedure can reasonably well account for the observed multi-hit Ballistic-Protection performance of the laminated transparent armor; (b) The role of prior bullet hits in reducing armor’s Ballistic-Protection performance is clearly revealed; (c) The role of polycarbonate lamina in preventing glass fragments from entering the vehicle interior is clearly demonstrated; and (d) Experimentally observed inability of the transparent armor to defeat 0.50-caliber Fragment Simulating Projectiles (FSPs) is confirmed.
-
design and material selection guidelines and strategies for transparent armor systems
Materials & Design, 2012Co-Authors: Mica Grujicic, W C Bell, B PanduranganAbstract:Abstract As evidenced by the recent experience of the US Armed Forces involved in the missions in Iraq and Afghanistan, armoring military-vehicle windshields and side windows is a very challenging task. Apart from providing the required single-hit and multi-hit Ballistic Protection to the vehicle occupants, the armor must also possess and retain optical transparency and be compatible with on-board imaging and communications equipment. In addition, standard low cost and light-weight requirements are also critical in the design and engineering of transparent armor systems. At the present time, the design and fabrication of transparent armor systems is done almost exclusively using empirical, trial-and-error and legacy approaches. Consequently, new transparent armor system development lead times are long, the costs are quite high and many shortcomings of the systems become apparent only after they have been fielded. To help better understand and overcome this situation, a brief overview and discussion of the basic transparent armor architectures, functional layers and transparent materials is provided and a set of design and material selection guidelines is proposed.
-
Ballistic Protection performance of carbon nanotube doped poly vinyl ester epoxy matrix composite armor reinforced with e glass fiber mats
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2008Co-Authors: Mica Grujicic, W C Bell, Lonny L Thompson, K L Koudela, B A CheesemanAbstract:Abstract In the present work, a material model development approach and transient non-linear dynamics simulations of the projectile/armor interactions are employed to explore the role of multi-walled carbon-nanotube (MWCNT) reinforcements in improving the Ballistic-Protection performance of poly-vinyl-ester-epoxy matrix (PVEE)/E-glass fiber matrix reinforced laminate armor. Two different architectures of the composite-laminate armor are considered: (a) a hybrid armor consisting of a 100 μm-thick high MWCNT-content PVEE-matrix MWCNT-reinforced lamina sandwiched between two PVEE-matrix/E-glass mat reinforced laminas and (b) a monolithic E-glass mat reinforced composite laminate with a low MWCNT-content MWCNT-doped PVEE-matrix. The projectile/armor interaction simulation results show that both armor architectures yield a minimal (∼6%) increase in the Ballistic-Protection as measured by the armor V50, a velocity at which the probability of armor penetration by a given fragment is 50%. The results obtained are rationalized using a simple analysis of the effect of MWCNTs on the in-plane and the through-the-thickness properties of the armor.
B Pandurangan - One of the best experts on this subject based on the ideXlab platform.
-
the role of adhesive in the Ballistic structural performance of ceramic polymer matrix composite hybrid armor
Materials & Design, 2012Co-Authors: Mica Grujicic, B Pandurangan, B DentremontAbstract:Abstract Transient non-linear dynamics computational finite-element analyses are employed to investigate the role of the adhesive used in ceramic strike-face/composite back-face hybrid armor. The role of the adhesive is investigated under: (a) high loading-rate conditions accompanying impact of an armor-piercing projectile onto the armor structure; and (b) low loading rate conditions associated with the ingress of the loads which are generated at the road/tire contact interfaces and transmitted into the armor structure through the vehicle frame. The high loading-rate conditions were analyzed since they reveal the role of the adhesive under Ballistic impact scenarios which controls the overall penetration resistance of the armor. On the other hand, the low loading-rate conditions were analyzed since they may reveal the potential structural damage that armor may experience due to sustained in-service loads. Since structural thermoset-polymer-based adhesives suffer from inadequate ductility, only the case of flexible (elastomer-based) adhesives was considered. The following two specific aspects of the adhesive mechanical response are given special attention: (a) strain rate sensitivity and (b) the degree of volumetric compressibility. The results obtained show that while significant improvements in the Ballistic Protection performance and durability of hybrid armor can be attained by proper modifications in the adhesive layer mechanical properties, there is no single combination of these properties which simultaneously optimizes all the performance requirements.
-
A Computational Investigation of the Multi-Hit Ballistic-Protection Performance of Laminated Transparent-armor Systems
Journal of Materials Engineering and Performance, 2012Co-Authors: Mica Grujicic, B Pandurangan, N. CoutrisAbstract:Multi-hit Ballistic-Protection performance of a prototypical laminated glass/polycarbonate transparent armor is investigated using a series of transient nonlinear dynamics analyses of armor impact with a sequence of four M2AP full metal jacket (FMJ) armor-piercing bullets. All calculations were carried out using ABAQUS/Explicit commercial finite element program (ABAQUS Version 6.7, User Documentation, Dessault Systems, 2007), and the computational results obtained were compared to their experimental counterparts obtained by Dolan (Ballistic Transparent-armor Testing Using a Multi-hit Rifle Pattern, Bachelors, Thesis, Kettering University, December 2007). The comparison revealed that (a) The proposed computational procedure can reasonably well account for the observed multi-hit Ballistic-Protection performance of the laminated transparent armor; (b) The role of prior bullet hits in reducing armor’s Ballistic-Protection performance is clearly revealed; (c) The role of polycarbonate lamina in preventing glass fragments from entering the vehicle interior is clearly demonstrated; and (d) Experimentally observed inability of the transparent armor to defeat 0.50-caliber Fragment Simulating Projectiles (FSPs) is confirmed.
-
design and material selection guidelines and strategies for transparent armor systems
Materials & Design, 2012Co-Authors: Mica Grujicic, W C Bell, B PanduranganAbstract:Abstract As evidenced by the recent experience of the US Armed Forces involved in the missions in Iraq and Afghanistan, armoring military-vehicle windshields and side windows is a very challenging task. Apart from providing the required single-hit and multi-hit Ballistic Protection to the vehicle occupants, the armor must also possess and retain optical transparency and be compatible with on-board imaging and communications equipment. In addition, standard low cost and light-weight requirements are also critical in the design and engineering of transparent armor systems. At the present time, the design and fabrication of transparent armor systems is done almost exclusively using empirical, trial-and-error and legacy approaches. Consequently, new transparent armor system development lead times are long, the costs are quite high and many shortcomings of the systems become apparent only after they have been fielded. To help better understand and overcome this situation, a brief overview and discussion of the basic transparent armor architectures, functional layers and transparent materials is provided and a set of design and material selection guidelines is proposed.
Tore Børvik - One of the best experts on this subject based on the ideXlab platform.
-
surface strengthening using a self protective diffusion paste and its application for Ballistic Protection of steel plates
Materials & Design, 2009Co-Authors: Tore Børvik, D C Lou, J K SolbergAbstract:Abstract This paper deals with surface strengthening of steel plates using a self-protective diffusion paste. During the surface strengthening process, a paste containing carbon, boron or similar is applied on the steel surface. In addition to serving as a source for the various diffusion ingredients, the paste protects the steel against contact with the environment, so no packing or gas Protection is necessary. Thus, the handling is in general very simple, and the surface strengthening process can be performed in a conventional air furnace. The method provides the same type of surface strengthening that is obtained by more conventional methods. In this work, the main focus will be surface strengthening by carburizing, but also boronizing and boronizing followed by carburizing have been tested out. The methods have been applied to increase the Ballistic resistance of the low-strength carbon steel NVE36 (with nominal yield stress of 355 MPa) against impacts from small-arms bullets. An empirical model combining diffusion depth, heat-treatment temperature and soaking time was established on the basis of a series of experimental data. By means of this equation, the various heat-treatment parameters can be predicted when others are chosen. Ballistic perforation tests using 7.62 mm APM2 bullets showed that the low-strength carbon steel after surface strengthening obtained a Ballistic limit higher than that of Hardox 400, which is a wear steel with a yield stress of about 1200 MPa.
-
perforation resistance of five different high strength steel plates subjected to small arms projectiles
International Journal of Impact Engineering, 2009Co-Authors: Tore Børvik, A H ClausenAbstract:Abstract Thin plates of high-strength steel are frequently being used both in civil and military Ballistic Protection systems. The choice of alloy is then a function of application, Ballistic performance, weight and price. In this study the perforation resistance of five different high-strength steels has been determined and compared against each other. The considered alloys are Weldox 500E, Weldox 700E, Hardox 400, Domex Protect 500 and Armox 560T. The yield stress for Armox 560T is about three times the yield stress for Weldox 500E, while the opposite yields for the ductility. To certify the perforation resistance of the various targets, two different Ballistic Protection classes according to the European norm EN1063 have been considered. These are BR6 (7.62 mm Ball ammunition) and BR7 (7.62 mm AP ammunition), where the impact velocity of the bullet is about 830 m/s in both. Perforation tests have been carried out using adjusted ammunition to determine the Ballistic limit of the various steels. In the tests, a target thickness of 6 mm and 6 + 6 = 12 mm was used for Protection class BR6 and BR7, respectively. A material test programme was conducted for all steels to calibrate a modified Johnson–Cook constitutive relation and the Cockcroft–Latham fracture criterion, while material data for the bullets mainly were taken from the literature. Finally, results from 2D non-linear FE simulations with detailed models of the bullets are presented and the different findings are compared against each other. As will be shown, good agreement between the FE simulations and experimental data for the AP bullets is in general obtained, while it was difficult to get reliable FE results using the Lagrangian formulation of LS-DYNA for the soft core Ball bullet.
Henry Angelo Sodano - One of the best experts on this subject based on the ideXlab platform.
-
Aramid nanofibers for multiscale fiber reinforcement of polymer composites
Composites Science and Technology, 2018Co-Authors: Brendan A. Patterson, Angelica Okorom, Mohammad H. Malakooti, Jiajun Lin, Henry Angelo SodanoAbstract:While aramid fibers have been innovative for Ballistic Protection because of their high energy absorption, minimal usage has been applied to continuous fiber reinforced polymer (CFRP) composites in structural applications. One of the challenges with aramid fibers results from their processing, which yields smooth and chemically inert surfaces that limit the ability of the fibers to adhere to polymeric matrices. Here, it is shown that aramid nanofibers can adhere to the surface of macroscale aramid reinforcements to improve the strength of the composite interface and reinforce the matrix as well. Aramid nanofibers are formed through the dissolution of aramid fibers followed by isolation and dispersion into an epoxy matrix. When employed in CFRP, aramid nanofibers prove to be effective reinforcement agents through improvement in both matrix properties as well as modifying the interfacial shear strength, which leads to improved interlaminar shear strength and fracture toughness. The interface enhancements are attributed to hydrogen bonding and π-π coordination between the aramid nanofibers and the macro fibers providing improved transfer load from the fiber to the matrix. This work demonstrates that aramid nanofibers may provide the robust mechanical properties that are necessary for structural applications while utilizing a cost-effective and convenient nanoscale building block.
Orhan R Yildirim - One of the best experts on this subject based on the ideXlab platform.
-
investigation on the Ballistic impact behavior of various alloys against 7 62 mm armor piercing projectile
Materials & Design, 2008Co-Authors: Teyfik Demir, Mustafa Ubeyli, Orhan R YildirimAbstract:Abstract In this study, impact behavior of the aluminum alloys of 7075 and 5083 and the high-strength low-alloy steel, AISI 4140 was investigated under 7.62 mm armor piercing (AP) projectile experimentally. Various heat treatments were applied to the alloys AISI 4140 and 7075 to see the effect of hardness and strength on their Ballistic behaviors. Experimental results showed that among the investigated materials, the best Ballistic performance was attained with the alloy, 7075-T651 which maintained the Ballistic Protection with the areal density ⩾85 kg/m 2 .
