The role of the adhesive layer in the ballistic performance of ceramic multi-layer armour system is complex and multi-faceted,often with trade-offs between single-and multi-hit performance.However,research focused on ...The role of the adhesive layer in the ballistic performance of ceramic multi-layer armour system is complex and multi-faceted,often with trade-offs between single-and multi-hit performance.However,research focused on untangling the underlying impact of varying adhesive cohesive or adhesion properties is limited and sometimes appears to provide conflicting conclusions.Comparison between the available studies is also often difficult due to variations in armour systems or ballistic testing being conducted.This review scrutinises the available research,identifying six critical properties of an adhesive layer in determining ballistic performance:elastic modulus,fracture strain,acoustic impedance,tensile bond strength,shear bond strength,and thickness.The impact of each of these properties on ballistic performance is discussed in detail,with clear description of the underlying processes involved,allowing clear optimisation goals to be established depending on the ceramic armour specification.展开更多
The ballistic performance,and behaviour,of an armour system is governed by two major sets of variables,geometrical and material.Of these,the consistency of performance,especially against small arms ammunition,will dep...The ballistic performance,and behaviour,of an armour system is governed by two major sets of variables,geometrical and material.Of these,the consistency of performance,especially against small arms ammunition,will depend upon the consistency of the properties of the constituent materials.In a body armour system for example,fibre diameter,areal density of woven fabric,and bulk density of ceramic are examples of critical parameters and monitoring such parameters will form the backbone of associated quality control procedures.What is often overlooked,because it can fall into the User’s domain,are the interfaces that exist between the various products;the carrier,the Soft Armour Insert(SAI),and the one or two hard armour plates(HAP1 and HAP2).This is especially true if the various products are sourced from different suppliers.展开更多
The stability of single layer armour units on low crested and submerged breakwaters has been investigated in 2D hydraulic model tests. Armour unit movements including settlements, rocking and displacements have been d...The stability of single layer armour units on low crested and submerged breakwaters has been investigated in 2D hydraulic model tests. Armour unit movements including settlements, rocking and displacements have been determined. The effect of freeboard, packing density and wave steepness on the armour layer stability on crest, front and rear slope has been investigated. Armour units were mostly displaced in the most upper part of the seaward slope and at the seaward side of the crest. Damage on the crest was progressing towards the rear slope. About 40% to 50% larger armour units are required on the seaward slope and crest of low crested structures （as compared to conventional high crested breakwaters）. About 35% larger armour units are required on the rear slope. Larger armour units are not required on submerged breakwaters if the water depth on the crest exceeds 40% of design wave height.展开更多
This paper is investigating the use of composite armour reinforced by nanomaterials, for the protection of light armoured(LAV) and medium armoured military vehicles(MAV), and the interaction between the composite mate...This paper is investigating the use of composite armour reinforced by nanomaterials, for the protection of light armoured(LAV) and medium armoured military vehicles(MAV), and the interaction between the composite materials and high-performance ballistic projectiles. Four armour materials, consisted of front hybrid fibre reinforced polymer cover layer, ceramic strike-face, fibre reinforced polymer intermediate layer and the metal matrix composite reinforced backplate, were manufactured and assembled by adhesive technology. The proposed laminated protection system is suitable for armoured ground vehicles;however, it could be used as armour on ground, air and naval platforms. The design of the protection system, including material selection and thickness, was elaborated depending on the performance requirements of Level 4 + STANAG 4569 military standard(projectile 14.5 mm × 114 mm API B32) and especially on a design philosophy which is analysed with the specifications. The backplate of this new composite is a hybrid material of Metal Matrix Composite(MMC) reinforced with carbon nanotubes(CNTs), manufactured with the use of powder metallurgy technique. The composite backplate material was morphologically, mechanically and chemically analysed. Results show that all plates are presenting high mechanical properties and ballistic characteristics, compared to commonly used armour plates. Real military ballistic tests according to AEP-STANAG 4569 were carried out for the total composite armour systems. After the ballistic tests, AA2024-CNT3 showed the best protection results, compared with the other plates(AA2024-CNT1 and AA2024-CNT2), with the projectile being unable to fully penetrate the composite plate.展开更多
Insulated underground cables have the potential to reduce power outages, maintenance costs, and transmission losses compared to overhead lines.</span><span style="font-family:""> </span&g...Insulated underground cables have the potential to reduce power outages, maintenance costs, and transmission losses compared to overhead lines.</span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">On the other hand, they are exposed to several risks and physical damages, since they are buried in the ground. Though the cables are armoured in order to provide mec</span><span style="font-family:Verdana;">hanical protection and achieve tensile strength, and also to provide effective conductance of earth fault currents.</span></span><span style="font-family:""> </span><span style="font-family:Verdana;">The main purpose of this paper is to introduce insulated underground cables, armouring process, and to analyze the induced currents in metallic parts such as sheath and armour </span><span style="font-family:Verdana;">that causeohmic losses which are categorized mainly in two groups as circulating current and eddy current. This paper presents a review on analytical techniques used to analyze the effect of magnetic fields, andcalculate the losses in </span><span style="font-family:Verdana;">the armour of the cables,</span><span style="font-family:""> </span><span style="font-family:Verdana;">besides providing the strategies and solutions used for armour loss reduction.展开更多
This paper introduces a new kind of armour block - hexagon multihole block on sloping breakwater. It has great characteristics such as good interlocking, strong resistance against waves and saving concrete. Through th...This paper introduces a new kind of armour block - hexagon multihole block on sloping breakwater. It has great characteristics such as good interlocking, strong resistance against waves and saving concrete. Through the hydraulic model test, the mechanism of stability of the block has been proved and the relations between stability and wave height, wave period, water depth, slope, laying method, porosity and cushion have been found. The effect of weight on steadiness have also been discovered. Finally, the method of design and some formulas are given.展开更多
During this research, experimental rolled homogeneous armour steel was cast, annealed and laser cut to form an appliqué plate. This Martensitic–Bainitic microstructure steel grade was used to test a novel means ...During this research, experimental rolled homogeneous armour steel was cast, annealed and laser cut to form an appliqué plate. This Martensitic–Bainitic microstructure steel grade was used to test a novel means of engineering lightweight armour. It was determined that a laser cutting speed of 1200 mm/min produced optimum hole formations with limited distortion. The array of holes acts as a double-edged solution, in that they provide weight saving of 45%, providing a protective advantage and increasing the surface area. Data collected were used to generate laser cut-edge hole projections in order to identify the optimum cutting speed, edge condition, cost and deformation performance. These parameters resulted in the generation of a surface, with less stress raising features. This can result in a distribution of stress across the wider surface. Provided that appropriate process parameters are used to generate laser cut edges, then the hardness properties of the surface can be controlled. This is due to compressive residual stresses produced in the near edge region as a result of metallurgical transformations. This way the traverse cutting speed parameter can be adjusted to alter critical surface characteristics and microstructural properties in close proximity to the cut-edge. A relationship was identified between the width of the laser HAZ and the hardness of the cut edge. It is the thickness of the HAZ that is affected by the laser process parameters which can be manipulated with adjusting the traverse cutting speed.展开更多
We evaluate an adaptive optimisation methodology,Bayesian optimisation(BO),for designing a minimum weight explosive reactive armour(ERA)for protection against a surrogate medium calibre kinetic energy(KE)long rod proj...We evaluate an adaptive optimisation methodology,Bayesian optimisation(BO),for designing a minimum weight explosive reactive armour(ERA)for protection against a surrogate medium calibre kinetic energy(KE)long rod projectile and surrogate shaped charge(SC)warhead.We perform the optimisation using a conventional BO methodology and compare it with a conventional trial-and-error approach from a human expert.A third approach,utilising a novel human-machine teaming framework for BO is also evaluated.Data for the optimisation is generated using numerical simulations that are demonstrated to provide reasonable qualitative agreement with reference experiments.The human-machine teaming methodology is shown to identify the optimum ERA design in the fewest number of evaluations,outperforming both the stand-alone human and stand-alone BO methodologies.From a design space of almost 1800 configurations the human-machine teaming approach identifies the minimum weight ERA design in 10 samples.展开更多
This is a very timely review of body armour materials and systems since new test standards are currently being written, or reviewed, and new, innovative products released. Of greatest importance, however, is the recen...This is a very timely review of body armour materials and systems since new test standards are currently being written, or reviewed, and new, innovative products released. Of greatest importance, however, is the recent evolution, and maturity, of the Ultra High Molecular Weight Polyethylene fibres enabling a completely new style of system to evolve e a stackable system of Hard Armour Plates. The science of body armour materials is quickly reviewed with emphasis upon current understanding of relevant energy-absorbing mechanisms in fibres, fabrics, polymeric laminates and ceramics. The trend in ongoing developments in ballistic fibres is then reviewed, analysed and future projections offered. Weaknesses in some of the ceramic grades are highlighted as is the value of using cladding materials to improve the robustness, and multi-strike performance, of Hard Armour Plates. Finally, with the drive for lighter, and therefore smaller, soft armour systems for military personnel the challenges for armour designers are reported, and the importance of the relative size of the Hard Armour Plate to the Soft Armour Insert is strongly emphasised.展开更多
Industrial applications of aluminium and its alloys are restricted because of their poor tribological properties. Thermal spraying, laser surfacing, electron beam welding are the most widely used techniques to alter t...Industrial applications of aluminium and its alloys are restricted because of their poor tribological properties. Thermal spraying, laser surfacing, electron beam welding are the most widely used techniques to alter the surface morphology of base metal. Preliminary studies reveal that the coating and layering of aluminium alloys with ceramic particles enhance the ballistic resistance. Furthermore, among aluminium alloys,7075 aluminium alloy exhibits high strength which can be compared to that of steels and has profound applications in the designing of lightweight fortification structures and integrated protection systems. Having limitations such as poor bond integrity, formation of detrimental phases and interfacial reaction between reinforcement and substrate using fusion route to deposit hard particles paves the way to adopt friction stir processing for fabricating surface composites using different sizes of boron carbide particles as reinforcement on armour grade 7075 aluminium alloy as matrix in the present investigation. Wear and ballistic tests were carried out to assess the performance of friction stir processed AA7075 alloy. Significant improvement in wear resistance of friction stir processed surface composites is attributed to the change in wear mechanism from abrasion to adhesion. It has also been observed that the surface metal matrix composites have shown better ballistic resistance compared to the substrate AA7075 alloy. Addition of solid lubricant Mo S2 has reduced the depth of penetration of the projectile to half that of base metal AA7075 alloy. For the first time, the friction stir processing technique was successfully used to improve the wear and ballistic resistances of armour grade high strength AA7075 alloy.展开更多
It has been proved that the construction of interconnected armour on superhydrophobic surface could significantly enhance the mechanical robustness.Here,a new kind of armour with frame/protrusion hybrid structure was ...It has been proved that the construction of interconnected armour on superhydrophobic surface could significantly enhance the mechanical robustness.Here,a new kind of armour with frame/protrusion hybrid structure was achieved by nanosecond laser technology.Then,this armoured superhydrophobic surface demonstrated excellent durability,which could withstand linear abrasion(~3 N press)800 cycles,water jet test(1.0 MPa pressure)40 times and 100℃treatment 18 days.Particularly,the armoured superhydrophobic sample shows outstanding anti-icing ability,which can speed up the supercooled water dropping(no adhesion within 2 h),increase the freezing delay time by~3 times and maintain low adhesion force(less than 35 kPa)after 30 icing/de-icing cycles.Further finite element analysis and theoretical modeling proved that the developed frame/protuberance hybrid structure could effectively enhance the durability.The relatively low surface accuracy in this study can significantly reduce processing cost,which provides a bright future for the practical application of armour superhydrophobic materials.展开更多
Armour grade quenched and tempered steel closely confirming to AISI 4340 is well known for its superior ballistic performance and hence used in the fabrication of combat vehicles. The traditional fillers like austenit...Armour grade quenched and tempered steel closely confirming to AISI 4340 is well known for its superior ballistic performance and hence used in the fabrication of combat vehicles. The traditional fillers like austenitic stain- less steel showed poor ballistic performance of these welded joints as compared to the base metal. Attempts have been made to deposit hardfaced interlayer between austenitic stainless steel weld metals. Though this method, mar-- ginal improvements in ballistic performance can be yielded, and cracks were observed in between base metal and hardfaced layer. Thickness of the hardfaced interlayer plays a vital role for the effective ballistic performance. Thus, an attempt has been made to investigate the effect of hardfaced interlayer thickness on ballistic performance of ar- mour steel welds. The results of effect of buttering, low hydrogen ferritic （LHF） filler and three different hardfaced layer thicknesses （4, 5.5 and 7 ram） on ballistid performance of shielded metal arc welded armour steel joints were given.展开更多
Austenitic stainless steel(ASS) and High nickel steel(HNS) welding consumables are being used for welding Q&T steels, as they have higher solubility for hydrogen in austenitic phase, to avoid hydrogen induced crac...Austenitic stainless steel(ASS) and High nickel steel(HNS) welding consumables are being used for welding Q&T steels, as they have higher solubility for hydrogen in austenitic phase, to avoid hydrogen induced cracking(HIC) but they are very expensive. In recent years, the developments of low hydrogen ferritic steel(LHF) consumables that contain no hygroscopic compounds are utilized for welding Q&T steels. Heat affected zone(HAZ) softening is another critical issue during welding of armour grade Q&T steels and it depends on the welding process employed and the weld thermal cycle. In this investigation an attempt has been made to study the influence of welding consumables and welding processes on metallurgical characteristics of armour grade Q&T steel joints by various metallurgical characterization procedures. Shielded metal arc welding(SMAW) and flux cored arc welding(FCAW) processes were used for making welds using ASS, LHF and HNS welding consumables. The joints fabricated by using LHF consumables offered lower degree of HAZ softening and there is no evidence of HIC in the joints fabricated using LHF consumables.展开更多
It is important to understand how ballistic materials respond to impact from projectiles such that informed decisions can be made in the design process of protective armour systems. Ballistic testing is a standards-ba...It is important to understand how ballistic materials respond to impact from projectiles such that informed decisions can be made in the design process of protective armour systems. Ballistic testing is a standards-based process where materials are tested to determine whether they meet protection, safety and performance criteria. For the V50ballistic test, projectiles are fired at different velocities to determine a key design parameter known as the ballistic limit velocity(BLV), the velocity above which projectiles perforate the target. These tests, however, are destructive by nature and as such there can be considerable associated costs, especially when studying complex armour materials and systems. This study proposes a unique solution to the problem using a recent class of machine learning system known as the Generative Adversarial Network(GAN). The GAN can be used to generate new ballistic samples as opposed to performing additional destructive experiments. A GAN network architecture is tested and trained on three different ballistic data sets, and their performance is compared. The trained networks were able to successfully produce ballistic curves with an overall RMSE of between 10 and 20 % and predicted the V50BLV in each case with an error of less than 5 %. The results demonstrate that it is possible to train generative networks on a limited number of ballistic samples and use the trained network to generate many new samples representative of the data that it was trained on. The paper spotlights the benefits that generative networks can bring to ballistic applications and provides an alternative to expensive testing during the early stages of the design process.展开更多
A-Jacks are concrete armor units that are used in both open channel and coastal applications.In open channel applications,they are used for bank and toe protection,flow and grade control,bridge pier scour protection,e...A-Jacks are concrete armor units that are used in both open channel and coastal applications.In open channel applications,they are used for bank and toe protection,flow and grade control,bridge pier scour protection,energy dissipation,and habitat.These small units may be fabricated in standard block machines.In coastal applications,A-Jacks are used in breakwaters,jetties,revetments,and habitat development.Coastal units are generally much larger and more robust than the small open channel units.This paper focuses on coastal applications and in particular,combines results on three topics:(1)recent hydraulic model studies,(2)alternative fabrication methods,and(3)bundle placement construction methods.Hydraulic models studies were conducted that examined the standard random and uniform placement methods,and also the bundle placement method.In bundle placement,3~20 A-Jacks are banded together,lifted with a spreader bar,and placed as a single crane pick.This significantly decreases installation time during construction.It also provides a more hydraulically stable placement technique.The hydraulic model tests examined the bundle stability in random waves for cases where the binding remains in tack and is removed.The geometry of A-Jacks enables a variety of fabrication techniques.One option is to fabricate the A-Jacks as two pieces using flat forms and then grout the two pieces together.Flat forms may be used in conventional block machines for A-Jacks sizes up to 1.3 m.Larger sizes may be wet cast in flat forms or gang forms.The A-Jacks geometry has been recently modified to increase grouting efficient and strength.Large A- Jacks may also be cast in a single piece using 'clam shell' type forms.展开更多
Personal body armour is one of the most important pieces of equipment to protect human beings from various critical and fatal injuries.In today’s modern world,various organizations including law enforcement and secur...Personal body armour is one of the most important pieces of equipment to protect human beings from various critical and fatal injuries.In today’s modern world,various organizations including law enforcement and security service have made it mandatory for their personnel to wear personal protection system while on field duty.However,the systems should comprise an improved ballistic performance,light-weighted,flexible as well as comfortable panel not only to be accepted with a wider range but also for effective performances of the consumer.Generally,the overall performances of the protective body armour could be affected by various parameters including armour design techniques,type of materials used and finishing of the panels.The current paper aims to critically review state-of-art for armour panel design techniques and the different perspective body armour materials.The paper starts by discussing the different body armour and its category.Later,the different states of technology for armour panel design(mostly for women),its problems and the possible solutions will be cited.Later,the commonly used different polymeric fibrous and the future possible advanced materials including carbon nanotube(CNT),Graphene CNT and shear thickening fluids(STFs)treated materials for developing the reinforced body armour panel will be discussed.The authors believe that this paper will enlighten useful guidelines and procedures about the different panel design techniques and current and promising future materials for researchers,designers,engineers and manufacturers working on the impact resistance body armour field.展开更多
The depth of penetration(DOP)method is a well-known ballistic test method for characterisation and ranking of ceramic armour materials.The ceramic tile is bonded to a backing material of semi-infinite thickness,and th...The depth of penetration(DOP)method is a well-known ballistic test method for characterisation and ranking of ceramic armour materials.The ceramic tile is bonded to a backing material of semi-infinite thickness,and the penetration depth of the projectile gives a measure of the performance of the ceramic.There is,however,an inherent variability in the results from this test method.In this work,the accuracy and the variability of the DOP method has been investigated in a round robin exercise.Six ballistic test centres took part in the exercise.A test protocol was developed,in which the threat type(projectile and impact conditions)and a procedure on how to prepare the targets were specified.The targets consisted of alumina tiles of two different thicknesses that were bonded to polycarbonate backing cubes.Two different 7.62 mm armour piercing projectiles were employed;one with a hard steel core and one with a tungsten carbide core.The projectiles and the other materials all came from single material batches in order to avoid batch-to-batch variations in material properties.These materials were distributed between the ballistic test centres.The test results of the different ballistic test facilities were collected and compared.There was not a lot of variation between the average DOP values obtained at each laboratory,but the variation in penetration depth between shots was high.The consequence of this variation may be less confidence in the test results,and a statistical method was used to evaluate the required number of tests that are sufficient to obtain an average result with high confidence.In most cases,the required number of tests is much higher than what is practically feasible.This work was conducted as part of the European Defence Agency-project CERAMBALL.展开更多
Through hydraulic model experiment and site investigation, this paper has derived a calculation formula of dry-laid stone armour layer thickness of rubble mound breakwaters for fishery harbours. The influences of the ...Through hydraulic model experiment and site investigation, this paper has derived a calculation formula of dry-laid stone armour layer thickness of rubble mound breakwaters for fishery harbours. The influences of the friction force between stone blocks and the variations of wave length or period and water depth are considered in the formula. The calculated results of several existing structures are in good agreement with field data. This formula is more practical than those ever published both at home and abroad, and has been adoptted by the technical standards of aquatic projects published by the Ministry of Agriculture of China. It is applicable for the calculation of dry-laid stone armour layer of breakwater for small- or medium-size harbours.展开更多
Intermetallic aluminide compounds possess several potential advantages compared to alloyed steels,like enhanced oxidation resistance,lower density and the omittance of critical raw materials.Iron aluminides,compared t...Intermetallic aluminide compounds possess several potential advantages compared to alloyed steels,like enhanced oxidation resistance,lower density and the omittance of critical raw materials.Iron aluminides,compared to other transition metal-aluminides of TM_(3)-Al type,although having a higher density compared to titan-aluminides,have a lower density compared to nickel-aluminides,but also a higher ductility than both alternatives,making this material potentially effective in ballistic protection application.Density-wise,this material may be a worthy alternative to armour steels,which was the aim of this study.Two materials,Fe_(3)Al intermetallic compound(F3A-C)and Armox 500 armour steel were ballistically tested against tungsten-carbide(WC)armour-piercing ammunition,in accordance with STANAG 4569.After ballistic testing,microhardness and metallographic testing were performed,revealing differences in strain hardening,crack propagation mode and exit hole morphology.F3A-C ballistic resistance is similar to that of armour steel,in spite of the lower tensile and impact mechanical properties,relying on a considerably higher strain hardening rate,thermal properties and a lower density.展开更多
This research proposes a novel nature-based design of a new concrete armour unit for the cover layer of a rubblemoundbreakwater. Armour units are versatile with respect to shape, orientation, surface condition details...This research proposes a novel nature-based design of a new concrete armour unit for the cover layer of a rubblemoundbreakwater. Armour units are versatile with respect to shape, orientation, surface condition details, and porosity.Therefore, a detailed analysis is required to investigate the exact state of their hydraulic interactions and structuralresponses. In this regard, the performance results of several traditional armour units, including the Antifer cube,Tetrapod, X-block and natural stone, are considered for the first step of this study. Then, the related observed resultsare compared with those obtained for a newly designed (artificial coral) armour unit. The research methodology utilizesthe common wave flume test procedure. Furthermore, several verified numerical models in OpenFOAM code areused to gain the extra required data. The proposed armour is configured to provide an effective shore protection as anenvironmental-friendly coastal structure. Thus it is designed with a main trunk including deep grooves to imitate thetypical geometry of a coral type configuration, so as to attain desirable performance. The observed results and ananalytic hierarchy process (AHP) concept are used to compare the hydraulic performance of the studied traditionaland newly proposed (artificial coral) armour units. The results indicate that the artificial coral armour unit demonstratesacceptable performance. The widely used traditional armour units might be replaced by newer designs for betterwave energy dissipation, and more importantly, for fewer adverse effects on the marine environment.展开更多
基金funding for this research was provided by Netherlands Ministry of Defence
文摘The role of the adhesive layer in the ballistic performance of ceramic multi-layer armour system is complex and multi-faceted,often with trade-offs between single-and multi-hit performance.However,research focused on untangling the underlying impact of varying adhesive cohesive or adhesion properties is limited and sometimes appears to provide conflicting conclusions.Comparison between the available studies is also often difficult due to variations in armour systems or ballistic testing being conducted.This review scrutinises the available research,identifying six critical properties of an adhesive layer in determining ballistic performance:elastic modulus,fracture strain,acoustic impedance,tensile bond strength,shear bond strength,and thickness.The impact of each of these properties on ballistic performance is discussed in detail,with clear description of the underlying processes involved,allowing clear optimisation goals to be established depending on the ceramic armour specification.
文摘The ballistic performance,and behaviour,of an armour system is governed by two major sets of variables,geometrical and material.Of these,the consistency of performance,especially against small arms ammunition,will depend upon the consistency of the properties of the constituent materials.In a body armour system for example,fibre diameter,areal density of woven fabric,and bulk density of ceramic are examples of critical parameters and monitoring such parameters will form the backbone of associated quality control procedures.What is often overlooked,because it can fall into the User’s domain,are the interfaces that exist between the various products;the carrier,the Soft Armour Insert(SAI),and the one or two hard armour plates(HAP1 and HAP2).This is especially true if the various products are sourced from different suppliers.
文摘The stability of single layer armour units on low crested and submerged breakwaters has been investigated in 2D hydraulic model tests. Armour unit movements including settlements, rocking and displacements have been determined. The effect of freeboard, packing density and wave steepness on the armour layer stability on crest, front and rear slope has been investigated. Armour units were mostly displaced in the most upper part of the seaward slope and at the seaward side of the crest. Damage on the crest was progressing towards the rear slope. About 40% to 50% larger armour units are required on the seaward slope and crest of low crested structures （as compared to conventional high crested breakwaters）. About 35% larger armour units are required on the rear slope. Larger armour units are not required on submerged breakwaters if the water depth on the crest exceeds 40% of design wave height.
基金the Research and Development department of EODH SA and has been co-financed by the European Regional Development Fund of the European Union and Greek national funds through the Operational Program Competitiveness,Entrepreneurship and Innovation,under the call RESEARCH-CREATE-INNOVATE(project code:T1EDK-04429).
文摘This paper is investigating the use of composite armour reinforced by nanomaterials, for the protection of light armoured(LAV) and medium armoured military vehicles(MAV), and the interaction between the composite materials and high-performance ballistic projectiles. Four armour materials, consisted of front hybrid fibre reinforced polymer cover layer, ceramic strike-face, fibre reinforced polymer intermediate layer and the metal matrix composite reinforced backplate, were manufactured and assembled by adhesive technology. The proposed laminated protection system is suitable for armoured ground vehicles;however, it could be used as armour on ground, air and naval platforms. The design of the protection system, including material selection and thickness, was elaborated depending on the performance requirements of Level 4 + STANAG 4569 military standard(projectile 14.5 mm × 114 mm API B32) and especially on a design philosophy which is analysed with the specifications. The backplate of this new composite is a hybrid material of Metal Matrix Composite(MMC) reinforced with carbon nanotubes(CNTs), manufactured with the use of powder metallurgy technique. The composite backplate material was morphologically, mechanically and chemically analysed. Results show that all plates are presenting high mechanical properties and ballistic characteristics, compared to commonly used armour plates. Real military ballistic tests according to AEP-STANAG 4569 were carried out for the total composite armour systems. After the ballistic tests, AA2024-CNT3 showed the best protection results, compared with the other plates(AA2024-CNT1 and AA2024-CNT2), with the projectile being unable to fully penetrate the composite plate.
文摘Insulated underground cables have the potential to reduce power outages, maintenance costs, and transmission losses compared to overhead lines.</span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">On the other hand, they are exposed to several risks and physical damages, since they are buried in the ground. Though the cables are armoured in order to provide mec</span><span style="font-family:Verdana;">hanical protection and achieve tensile strength, and also to provide effective conductance of earth fault currents.</span></span><span style="font-family:""> </span><span style="font-family:Verdana;">The main purpose of this paper is to introduce insulated underground cables, armouring process, and to analyze the induced currents in metallic parts such as sheath and armour </span><span style="font-family:Verdana;">that causeohmic losses which are categorized mainly in two groups as circulating current and eddy current. This paper presents a review on analytical techniques used to analyze the effect of magnetic fields, andcalculate the losses in </span><span style="font-family:Verdana;">the armour of the cables,</span><span style="font-family:""> </span><span style="font-family:Verdana;">besides providing the strategies and solutions used for armour loss reduction.
文摘This paper introduces a new kind of armour block - hexagon multihole block on sloping breakwater. It has great characteristics such as good interlocking, strong resistance against waves and saving concrete. Through the hydraulic model test, the mechanism of stability of the block has been proved and the relations between stability and wave height, wave period, water depth, slope, laying method, porosity and cushion have been found. The effect of weight on steadiness have also been discovered. Finally, the method of design and some formulas are given.
基金the support of Swansea University during the pursuit of this research
文摘During this research, experimental rolled homogeneous armour steel was cast, annealed and laser cut to form an appliqué plate. This Martensitic–Bainitic microstructure steel grade was used to test a novel means of engineering lightweight armour. It was determined that a laser cutting speed of 1200 mm/min produced optimum hole formations with limited distortion. The array of holes acts as a double-edged solution, in that they provide weight saving of 45%, providing a protective advantage and increasing the surface area. Data collected were used to generate laser cut-edge hole projections in order to identify the optimum cutting speed, edge condition, cost and deformation performance. These parameters resulted in the generation of a surface, with less stress raising features. This can result in a distribution of stress across the wider surface. Provided that appropriate process parameters are used to generate laser cut edges, then the hardness properties of the surface can be controlled. This is due to compressive residual stresses produced in the near edge region as a result of metallurgical transformations. This way the traverse cutting speed parameter can be adjusted to alter critical surface characteristics and microstructural properties in close proximity to the cut-edge. A relationship was identified between the width of the laser HAZ and the hardness of the cut edge. It is the thickness of the HAZ that is affected by the laser process parameters which can be manipulated with adjusting the traverse cutting speed.
文摘We evaluate an adaptive optimisation methodology,Bayesian optimisation(BO),for designing a minimum weight explosive reactive armour(ERA)for protection against a surrogate medium calibre kinetic energy(KE)long rod projectile and surrogate shaped charge(SC)warhead.We perform the optimisation using a conventional BO methodology and compare it with a conventional trial-and-error approach from a human expert.A third approach,utilising a novel human-machine teaming framework for BO is also evaluated.Data for the optimisation is generated using numerical simulations that are demonstrated to provide reasonable qualitative agreement with reference experiments.The human-machine teaming methodology is shown to identify the optimum ERA design in the fewest number of evaluations,outperforming both the stand-alone human and stand-alone BO methodologies.From a design space of almost 1800 configurations the human-machine teaming approach identifies the minimum weight ERA design in 10 samples.
文摘This is a very timely review of body armour materials and systems since new test standards are currently being written, or reviewed, and new, innovative products released. Of greatest importance, however, is the recent evolution, and maturity, of the Ultra High Molecular Weight Polyethylene fibres enabling a completely new style of system to evolve e a stackable system of Hard Armour Plates. The science of body armour materials is quickly reviewed with emphasis upon current understanding of relevant energy-absorbing mechanisms in fibres, fabrics, polymeric laminates and ceramics. The trend in ongoing developments in ballistic fibres is then reviewed, analysed and future projections offered. Weaknesses in some of the ceramic grades are highlighted as is the value of using cladding materials to improve the robustness, and multi-strike performance, of Hard Armour Plates. Finally, with the drive for lighter, and therefore smaller, soft armour systems for military personnel the challenges for armour designers are reported, and the importance of the relative size of the Hard Armour Plate to the Soft Armour Insert is strongly emphasised.
基金Financial assistance from Armament Research Board, New Delhi, India
文摘Industrial applications of aluminium and its alloys are restricted because of their poor tribological properties. Thermal spraying, laser surfacing, electron beam welding are the most widely used techniques to alter the surface morphology of base metal. Preliminary studies reveal that the coating and layering of aluminium alloys with ceramic particles enhance the ballistic resistance. Furthermore, among aluminium alloys,7075 aluminium alloy exhibits high strength which can be compared to that of steels and has profound applications in the designing of lightweight fortification structures and integrated protection systems. Having limitations such as poor bond integrity, formation of detrimental phases and interfacial reaction between reinforcement and substrate using fusion route to deposit hard particles paves the way to adopt friction stir processing for fabricating surface composites using different sizes of boron carbide particles as reinforcement on armour grade 7075 aluminium alloy as matrix in the present investigation. Wear and ballistic tests were carried out to assess the performance of friction stir processed AA7075 alloy. Significant improvement in wear resistance of friction stir processed surface composites is attributed to the change in wear mechanism from abrasion to adhesion. It has also been observed that the surface metal matrix composites have shown better ballistic resistance compared to the substrate AA7075 alloy. Addition of solid lubricant Mo S2 has reduced the depth of penetration of the projectile to half that of base metal AA7075 alloy. For the first time, the friction stir processing technique was successfully used to improve the wear and ballistic resistances of armour grade high strength AA7075 alloy.
基金supported by Beijing Nature Science Foundation(3232054)National Nature Science Foundation of China(51977079)+4 种基金Key Laboratory of Icing and Anti/De-icing of CARDC(Grant No.IADL 20210401)the Central Guidance on Local Science and Technology Development Fund of Hebei Province(226Z1204G)the Top Young Innovative Talents of Colleges and Universities of Higher Learning Institutions of Hebei(BJ2021095)Youth Elite Scientists Sponsorship Program by Chinese Society for Electrical Engineering(CSEE-YESS-2017002)the Fundamental Research Funds for the Central Universities(2020MS115).
文摘It has been proved that the construction of interconnected armour on superhydrophobic surface could significantly enhance the mechanical robustness.Here,a new kind of armour with frame/protrusion hybrid structure was achieved by nanosecond laser technology.Then,this armoured superhydrophobic surface demonstrated excellent durability,which could withstand linear abrasion(~3 N press)800 cycles,water jet test(1.0 MPa pressure)40 times and 100℃treatment 18 days.Particularly,the armoured superhydrophobic sample shows outstanding anti-icing ability,which can speed up the supercooled water dropping(no adhesion within 2 h),increase the freezing delay time by~3 times and maintain low adhesion force(less than 35 kPa)after 30 icing/de-icing cycles.Further finite element analysis and theoretical modeling proved that the developed frame/protuberance hybrid structure could effectively enhance the durability.The relatively low surface accuracy in this study can significantly reduce processing cost,which provides a bright future for the practical application of armour superhydrophobic materials.
基金the Armament Research Board(ARMREB), New Delhi,Government of India for providing financial support to carry out this investigation through a research and development project, No.ARMREB/MAA/2008/93
文摘Armour grade quenched and tempered steel closely confirming to AISI 4340 is well known for its superior ballistic performance and hence used in the fabrication of combat vehicles. The traditional fillers like austenitic stain- less steel showed poor ballistic performance of these welded joints as compared to the base metal. Attempts have been made to deposit hardfaced interlayer between austenitic stainless steel weld metals. Though this method, mar-- ginal improvements in ballistic performance can be yielded, and cracks were observed in between base metal and hardfaced layer. Thickness of the hardfaced interlayer plays a vital role for the effective ballistic performance. Thus, an attempt has been made to investigate the effect of hardfaced interlayer thickness on ballistic performance of ar- mour steel welds. The results of effect of buttering, low hydrogen ferritic （LHF） filler and three different hardfaced layer thicknesses （4, 5.5 and 7 ram） on ballistid performance of shielded metal arc welded armour steel joints were given.
基金Armament Research Board (ARMREB), New Delhi for funding this project work (Project no. MAA/03/ 41)
文摘Austenitic stainless steel(ASS) and High nickel steel(HNS) welding consumables are being used for welding Q&T steels, as they have higher solubility for hydrogen in austenitic phase, to avoid hydrogen induced cracking(HIC) but they are very expensive. In recent years, the developments of low hydrogen ferritic steel(LHF) consumables that contain no hygroscopic compounds are utilized for welding Q&T steels. Heat affected zone(HAZ) softening is another critical issue during welding of armour grade Q&T steels and it depends on the welding process employed and the weld thermal cycle. In this investigation an attempt has been made to study the influence of welding consumables and welding processes on metallurgical characteristics of armour grade Q&T steel joints by various metallurgical characterization procedures. Shielded metal arc welding(SMAW) and flux cored arc welding(FCAW) processes were used for making welds using ASS, LHF and HNS welding consumables. The joints fabricated by using LHF consumables offered lower degree of HAZ softening and there is no evidence of HIC in the joints fabricated using LHF consumables.
基金supported by the Engineering and Physical Sciences Research Council [grant number: EP/N509644/1]。
文摘It is important to understand how ballistic materials respond to impact from projectiles such that informed decisions can be made in the design process of protective armour systems. Ballistic testing is a standards-based process where materials are tested to determine whether they meet protection, safety and performance criteria. For the V50ballistic test, projectiles are fired at different velocities to determine a key design parameter known as the ballistic limit velocity(BLV), the velocity above which projectiles perforate the target. These tests, however, are destructive by nature and as such there can be considerable associated costs, especially when studying complex armour materials and systems. This study proposes a unique solution to the problem using a recent class of machine learning system known as the Generative Adversarial Network(GAN). The GAN can be used to generate new ballistic samples as opposed to performing additional destructive experiments. A GAN network architecture is tested and trained on three different ballistic data sets, and their performance is compared. The trained networks were able to successfully produce ballistic curves with an overall RMSE of between 10 and 20 % and predicted the V50BLV in each case with an error of less than 5 %. The results demonstrate that it is possible to train generative networks on a limited number of ballistic samples and use the trained network to generate many new samples representative of the data that it was trained on. The paper spotlights the benefits that generative networks can bring to ballistic applications and provides an alternative to expensive testing during the early stages of the design process.
文摘A-Jacks are concrete armor units that are used in both open channel and coastal applications.In open channel applications,they are used for bank and toe protection,flow and grade control,bridge pier scour protection,energy dissipation,and habitat.These small units may be fabricated in standard block machines.In coastal applications,A-Jacks are used in breakwaters,jetties,revetments,and habitat development.Coastal units are generally much larger and more robust than the small open channel units.This paper focuses on coastal applications and in particular,combines results on three topics:(1)recent hydraulic model studies,(2)alternative fabrication methods,and(3)bundle placement construction methods.Hydraulic models studies were conducted that examined the standard random and uniform placement methods,and also the bundle placement method.In bundle placement,3~20 A-Jacks are banded together,lifted with a spreader bar,and placed as a single crane pick.This significantly decreases installation time during construction.It also provides a more hydraulically stable placement technique.The hydraulic model tests examined the bundle stability in random waves for cases where the binding remains in tack and is removed.The geometry of A-Jacks enables a variety of fabrication techniques.One option is to fabricate the A-Jacks as two pieces using flat forms and then grout the two pieces together.Flat forms may be used in conventional block machines for A-Jacks sizes up to 1.3 m.Larger sizes may be wet cast in flat forms or gang forms.The A-Jacks geometry has been recently modified to increase grouting efficient and strength.Large A- Jacks may also be cast in a single piece using 'clam shell' type forms.
文摘Personal body armour is one of the most important pieces of equipment to protect human beings from various critical and fatal injuries.In today’s modern world,various organizations including law enforcement and security service have made it mandatory for their personnel to wear personal protection system while on field duty.However,the systems should comprise an improved ballistic performance,light-weighted,flexible as well as comfortable panel not only to be accepted with a wider range but also for effective performances of the consumer.Generally,the overall performances of the protective body armour could be affected by various parameters including armour design techniques,type of materials used and finishing of the panels.The current paper aims to critically review state-of-art for armour panel design techniques and the different perspective body armour materials.The paper starts by discussing the different body armour and its category.Later,the different states of technology for armour panel design(mostly for women),its problems and the possible solutions will be cited.Later,the commonly used different polymeric fibrous and the future possible advanced materials including carbon nanotube(CNT),Graphene CNT and shear thickening fluids(STFs)treated materials for developing the reinforced body armour panel will be discussed.The authors believe that this paper will enlighten useful guidelines and procedures about the different panel design techniques and current and promising future materials for researchers,designers,engineers and manufacturers working on the impact resistance body armour field.
基金conducted as part of the European Defence Agency-project CERAMBALL,contract number B 1091 GEM1 GP
文摘The depth of penetration(DOP)method is a well-known ballistic test method for characterisation and ranking of ceramic armour materials.The ceramic tile is bonded to a backing material of semi-infinite thickness,and the penetration depth of the projectile gives a measure of the performance of the ceramic.There is,however,an inherent variability in the results from this test method.In this work,the accuracy and the variability of the DOP method has been investigated in a round robin exercise.Six ballistic test centres took part in the exercise.A test protocol was developed,in which the threat type(projectile and impact conditions)and a procedure on how to prepare the targets were specified.The targets consisted of alumina tiles of two different thicknesses that were bonded to polycarbonate backing cubes.Two different 7.62 mm armour piercing projectiles were employed;one with a hard steel core and one with a tungsten carbide core.The projectiles and the other materials all came from single material batches in order to avoid batch-to-batch variations in material properties.These materials were distributed between the ballistic test centres.The test results of the different ballistic test facilities were collected and compared.There was not a lot of variation between the average DOP values obtained at each laboratory,but the variation in penetration depth between shots was high.The consequence of this variation may be less confidence in the test results,and a statistical method was used to evaluate the required number of tests that are sufficient to obtain an average result with high confidence.In most cases,the required number of tests is much higher than what is practically feasible.This work was conducted as part of the European Defence Agency-project CERAMBALL.
文摘Through hydraulic model experiment and site investigation, this paper has derived a calculation formula of dry-laid stone armour layer thickness of rubble mound breakwaters for fishery harbours. The influences of the friction force between stone blocks and the variations of wave length or period and water depth are considered in the formula. The calculated results of several existing structures are in good agreement with field data. This formula is more practical than those ever published both at home and abroad, and has been adoptted by the technical standards of aquatic projects published by the Ministry of Agriculture of China. It is applicable for the calculation of dry-laid stone armour layer of breakwater for small- or medium-size harbours.
基金support by the project entitled"Interdisciplinarity in Materials Science and Joining Technologies"from the Department of Production Engineering,Faculty of Technical Sciences Novi Sad,Serbia。
文摘Intermetallic aluminide compounds possess several potential advantages compared to alloyed steels,like enhanced oxidation resistance,lower density and the omittance of critical raw materials.Iron aluminides,compared to other transition metal-aluminides of TM_(3)-Al type,although having a higher density compared to titan-aluminides,have a lower density compared to nickel-aluminides,but also a higher ductility than both alternatives,making this material potentially effective in ballistic protection application.Density-wise,this material may be a worthy alternative to armour steels,which was the aim of this study.Two materials,Fe_(3)Al intermetallic compound(F3A-C)and Armox 500 armour steel were ballistically tested against tungsten-carbide(WC)armour-piercing ammunition,in accordance with STANAG 4569.After ballistic testing,microhardness and metallographic testing were performed,revealing differences in strain hardening,crack propagation mode and exit hole morphology.F3A-C ballistic resistance is similar to that of armour steel,in spite of the lower tensile and impact mechanical properties,relying on a considerably higher strain hardening rate,thermal properties and a lower density.
文摘This research proposes a novel nature-based design of a new concrete armour unit for the cover layer of a rubblemoundbreakwater. Armour units are versatile with respect to shape, orientation, surface condition details, and porosity.Therefore, a detailed analysis is required to investigate the exact state of their hydraulic interactions and structuralresponses. In this regard, the performance results of several traditional armour units, including the Antifer cube,Tetrapod, X-block and natural stone, are considered for the first step of this study. Then, the related observed resultsare compared with those obtained for a newly designed (artificial coral) armour unit. The research methodology utilizesthe common wave flume test procedure. Furthermore, several verified numerical models in OpenFOAM code areused to gain the extra required data. The proposed armour is configured to provide an effective shore protection as anenvironmental-friendly coastal structure. Thus it is designed with a main trunk including deep grooves to imitate thetypical geometry of a coral type configuration, so as to attain desirable performance. The observed results and ananalytic hierarchy process (AHP) concept are used to compare the hydraulic performance of the studied traditionaland newly proposed (artificial coral) armour units. The results indicate that the artificial coral armour unit demonstratesacceptable performance. The widely used traditional armour units might be replaced by newer designs for betterwave energy dissipation, and more importantly, for fewer adverse effects on the marine environment.
