Experimental and numerical study of the ballistic performance of steel fibre-reinforced explosively welded targets impacted by a spherical fragment

Steel fibres were used to reinforce the layered targets with surface-to-surface combination. The two- and three-layer metal targets with a total thickness of 5 mm were fabricated by explosive welding. The damage mechanism and the anti-penetration performance of the targets were studied experimentally and numerically using the LS-DYNA 3D finite element code. The effects of layer number and fibre spacing density on the anti-penetration performance were discussed. The results show that the failure modes of the steel front plate were shearing and plugging, and that the failure mode of the aluminium rear plate was ductile prolonging deformation when the tied interface failed by tension (or shearing and plugging when the interface remained connected) for the two-layer target. For the three-layer target, the failure modes of the steel front plate and the aluminium middle plate were shearing and plugging, while the steel rear plate failed by ductile prolonging deformation. At the same time, the steel-fibres failed by bending and tensile deformation. The anti-penetration performance of the three-layer composite targets was better compared with the performance of the two-layer targets when the areal density and fibre spacing density were equal. The reinforced fibres will improve the anti-penetration performance of the targets, and the ballistic resistance decreased with an increase in the fibre spacing distance.     

陶瓷/金属复合靶抗侵彻性能的数值模拟方法研究

采用自主开发的欧拉型二维爆炸与冲击问题仿真软件EXPLOSION-2D对钨杆侵彻陶瓷/金属复合靶板进行了数值模拟研究。为了描述陶瓷材料的损伤特性,在软件中嵌入JH-2本构模型及通过平板撞击实验结果拟合得到的高压状态方程。在质点网格法的基础上,给出了在欧拉算法下脆性材料累积损伤、破坏的数值算法。采用上述模型及算法研究了不同陶瓷片厚度条件下陶瓷/金属复合靶板的抗侵彻性能,分析了陶瓷靶损伤演化规律和侵彻过程。数值模拟结果与DOP(侵彻深度实验)结果吻合得较好,验证了该文模型和算法的有效性。     

装甲防护材料抗侵彻性能研究现状

目的分析装甲防护材料抗侵彻性能的研究现状,为改进复合装甲的结构设计提供参考。方法对装甲防护材料的抗侵彻研究现状进行论述,并对其应用情况进行分析。结果分别阐述了金属材料(装甲钢、铝合金和钛合金)、陶瓷复合靶板以及纤维增强复合材料(玻璃纤维、芳纶纤维和超高分子量聚乙烯纤维)的抗侵彻研究现状,并介绍了其应用情况。结论随着战场环境的日益更新和武器装备的飞速发展,单一的装甲防护材料已难以适应战场环境的不断变化,装甲防护材料将朝着强韧化、轻量化、智能化及多功能化发展。     

陶瓷棒填充点阵金属夹层结构的制备及抗侵彻实验

为提高轻量化复合装甲的抗侵彻能力,提出了内部填充陶瓷棒并由混杂短切玻璃纤维的环氧树脂封装的点阵金属夹层防护结构。首先,通过弹道冲击实验研究了陶瓷棒填充点阵金属夹层防护结构的抗弹丸侵彻能力;然后,结合失效模式和吸能效率,综合分析了该夹层防护结构的抗侵彻机制。结果表明:陶瓷棒填充点阵金属夹层防护结构的主要失效模式包括点阵金属结构和混杂填充材料的拉伸断裂、陶瓷棒的破裂、面板和背板的局部剪切破坏以及背板的总体弯曲变形。在球形弹丸侵彻过程中,由于点阵金属结构的塑性大变形和剪切扩孔、陶瓷棒和环氧树脂的断裂破坏以及面板的宏观弯曲变形,防护结构的抗侵彻能力得到大幅提高。研究结果可为新型轻质复合装甲的防护设计提供一定参考。      

Optimization of bond strength between gold alloy and porcelain through a composite interlayer obtained by powder metallurgy

The purpose of this study was to evaluate the influence of a composite interlayer (at the metal-ceramic interface) on the shear bond strength of a metal-ceramic composite when compared with a conventional porcelain fused to metal (PFM).Several metal-ceramic composites specimens were produced by hot pressing. To identify which was the best composition for the interlayer several composites, with different relations of metal/ceramic volume fraction, were bonded to metal and to ceramic substrates. The bond strength of the composites to substrates was assessed by the means of a shear test performed in a universal test machine (crosshead speed: 0.5 mm/min) until fracture. Some interfaces of fractured specimens as well as undestroyed interface specimens were examined with optical microscope and scanning electron microscope (SEM/EDS).The shear bond strength results for all composites bonded to metal and to ceramic substrates were significantly higher (>150 MPa) than those registered in the upper range of conventional porcelain fused to metal (PFM) techniques (∼80 MPa). The use of a composite interlayer proved to enhance metal/ceramic adhesion in 160%.     

Analysis of ceramic/metal armour systems

A combined numerical and experimental study for the analysis of ceramic/metal composite armour system against 40.7 g steel projectiles has been performed. The ballistic performance of the add-on lightweight armours was examined by varying the thickness of tiles, while maintaining equal areal density of the system. A numerical study using smoothed particle hydrodynamics scheme is promising since the major distinguishing features of composite armour systems such as, projectile erosion, crack propagation, ceramic conoid formation and failure of backing plate, are successfully captured. Simulation results for ballistic limits appear to match fairly well with the test values and reveal an optimum value of the front plate to back plate thickness ratio.     

Flyweight,Superelastic, Electrically Conductive,and Flame‐Retardant 3D Multi‐Nanolayer Graphene/Ceramic Metamaterial

A ceramic/graphene metamaterial (GCM) with microstructure‐derived superelasticity and structural robustness is achieved by designing hierarchical honeycomb microstructures, which are composited with two brittle constituents (graphene and ceramic) assembled in multi‐nanolayer cellular walls. Attributed to the designed microstructure, well‐interconnected scaffolds, chemically bonded interface, and coupled strengthening effect between the graphene framework and the nanolayers of the Al₂O₃ ceramic (NAC), the GCM demonstrates a sequence of multifunctional properties simultaneously that have not been reported for ceramics and ceramics–matrix–composite structures, such as flyweight density, 80% reversible compressibility, high fatigue resistance, high electrical conductivity, and excellent thermal‐insulation/flame‐retardant performance simultaneously. The 3D well‐ordered graphene aerogel templates are strongly coupled with the NAC by the chemically bonded interface, exhibiting mutual strengthening, compatible deformability, and a linearly dependent relationship between the density and Young's modulus. Considerable size effects of the ceramic nanolayers on the mechanical properties are revealed in these ceramic‐based metamaterials. The designed hierarchical honeycomb graphene with a fourth dimensional control of the ceramic nanolayers on new ways to scalable fabrication of advanced multifunctional ceramic composites with controllable design suggest a great potential in applications of flexible conductors, shock/vibration absorbers, thermal shock barriers, thermal insulation/flame‐retardant skins, and porous microwave‐absorbing coatings.     

多层异质复合结构的动力学响应及抗侵彻性能

为研究多层异质复合结构动力学响应及抗侵彻性能,利用霍普金森试验装置,对不同材料排布顺序及含泡沫铝夹芯的多层复合结构进行冲击加载,通过贴在入射杆和透射杆上的应变片测得入射波、反射波、透射波波形,验证数值仿真模型正确性;结合数值模拟,研究不同结构对试件内部应力波传播特性和应力场分布影响规律;依据复合结构动力学响应特征,设计复合靶板并进行抗侵彻试验,分析靶板塑性变形特征及抗侵彻耗能机制;通过数值模拟分析泡沫铝夹芯厚度对防护性能影响。结果表明,装甲钢后置复合结构及含泡沫夹芯结构有助于减缓应力集中,减小陶瓷损伤面积;泡沫铝夹芯过厚难以为靶板变形提供支撑,降低抗侵彻阻力;五种夹芯厚度h=2 mm、h=5 mm、h=10 mm、h=20 mm、h=30 mm中,h=10 mm对应多层异质复合靶防护性能最优。      

Ti/Al3Ti金属间化合物基层状复合材料抗侵彻性能数值模拟

采用LS-DYNA非线性有限元软件对Ti/Al₃Ti金属间化合物基层状（MIL）复合材料靶板的弹道侵彻过程进行了数值模拟。考察了等厚度下Ti体积分数、层数和材料梯度分布对复合材料抗侵彻性能的影响。结果表明,Ti体积分数约为20%时,靶板的抗侵彻性能最好。随着层数的增加,复合材料靶板的抗侵彻性能逐渐增强;但超过25层后,靶板的抗侵彻性能逐渐趋于稳定。不同铺层结构功能梯度板的抗侵彻性能相差较大,正向铺层梯度板的抗侵彻性能明显优于等厚均质复合材料靶板。     

弹体侵彻陶瓷/金属复合靶板问题的研究

针对弹体侵彻陶瓷/金属复合靶板的问题,将弹体的墩粗变形、陶瓷面板碎裂及陶瓷锥的形成变化和金属背板的变形结合起来,建立了可变形弹体垂直侵彻陶瓷/金属靶板的理论分析模型。利用大型非线性有限元程序LS-DYNA3D,对平头弹侵彻陶瓷/金属复合靶板的问题进行数值模拟,得到了陶瓷/金属复合靶板受弹体侵彻的变形过程。最后给出了典型位置的位移随时间的变化曲线,理论模型分析结果和数值模拟结果与实验结果进行了对比,吻合很好。说明理论分析模型的正确性和数值模拟结果的可靠性,可以为复合靶板的设计提供有利依据。     

弹体高速侵彻陶瓷复合厚靶的计算模型研究

针对平头弹高速撞击陶瓷复合厚靶的问题,以集中质量法为基础并考虑靶体的内摩擦效应对Fellows模型加以改进,建立侵彻过程的理论计算模型并利用Matlab编程求得不同撞击速度下弹体侵彻复合靶体的侵彻深度,模型得到了试验结果和数值计算结果的验证。参数分析的结果表明,陶瓷厚度的增加可提高复合靶体的抗侵彻能力,但随着初始撞击速度的提高,弹体的侵彻深度增长曲线趋于平缓。     

Lithium–Graphite Paste: An Interface Compatible Anode for Solid‐State Batteries

All‐solid‐state batteries (ASSBs) with ceramic‐based solid‐state electrolytes (SSEs) enable high safety that is inaccessible with conventional lithium‐ion batteries. Lithium metal, the ultimate anode with the highest specific capacity, also becomes available with nonflammable SSEs in ASSBs, which offers promising energy density. The rapid development of ASSBs, however, is significantly hampered by the large interfacial resistance as a matched lithium/ceramic interface that is not easy to pursue. Here, a lithium–graphite (Li–C) composite anode is fabricated, which shows a dramatic modification in wettability with garnet SSE. An intimate Li–C/garnet interface is obtained by casting Li–C composite onto garnet‐type SSE, delivering an interfacial resistance as low as 11 Ω cm². As a comparison, pure Li/garnet interface gives a large resistance of 381 Ω cm². Such improvement can be ascribed to the experiment‐measured increased viscosity of Li–C composite and simulation‐verified limited interfacial reaction. The Li–C/garnet/Li–C symmetric cell exhibits stable plating/striping performance with small voltage hysteresis and endures a critical current density up to 1.0 mA cm^?2. The full cell paired with LiFePO₄ shows stable cycle performance, comparable to the cell with liquid electrolyte. The present work demonstrates a promising strategy to develop ceramic‐compatible lithium metal‐based anodes and hence low‐impedance ASSBs.     

Interaction between silicon carbide and a nickel-based superalloy at elevated temperatures

A study has been made of the reaction of hot-pressed SiC and a nickel-based superalloy at temperatures between 700 and 1150° C. Under conditions of reduced oxygen pressure at the reaction interface, obtained by applying pressure to the couple, some degree of reaction was observed in both metal and ceramic at all temperatures studied. Preliminary studies utilizing the same techniques at 1000° C with a Si-SiC ceramic composite, Si₃N₄, MgO, Al₂O₃, and SiO₂ also indicated some degree of reaction in the metal for all ceramics examined.     

高性能梯度复合管制备及界面接合机理研究

本文研究了AlCrFe—FeCr—FeAl高性能梯度复合管中金属过渡层与金属基体接合界面组织结构，及其对力学性能的影响。结果表明：利用金属间化合物作为梯度过渡层，使得基体与内衬层形成牢固的冶金结合。使复合管的力学性能显著提高；同时，高硬度的金属过渡层与陶瓷层组成的双层复合结构，使得复合管的使用寿命显著延长。     

Numerical and Experimental Investigation on the Self-Healing Potential of Interpenetrating Metal–Ceramic Composites

An interpenetrating metal ceramic composite (IMCC) has been investigated regarding the potential as well as the feasibility of self-healing. Triggered by heating, cracks in the damaged composite located mainly in the Al₂O₃ ceramic or at the interface could be filled and closed by the liquid AlSi10Mg metal alloy. This healing procedure promises to reduce stress concentrations at crack tips and to improve the mechanical properties compared to the predamaged composite. Two different numerical approaches have been introduced to investigate this assumption and the potential of self-healed IMCCs for a best case scenario: 1) A simple 2D model to analyze the reduction of stress concentrations in front of a crack tip within the ceramic due to healing and 2) a 3D model based on CT-scan reconstructed microstructures to study how macroscopic mechanical properties can be restored depending on the amount of predamage. Further, the self-healing approach has been investigated experimentally for the same composite. Despite the fact that experimental self-healing of the investigated IMCC is only moderately feasible so far, the study shows the great potential that can still be exploited in order to extend the service life time of IMCC engineering components.     

New concepts for the assessment of concrete slab interfacial effects in pavement design and analysis

For many years, concrete pavement construction, whether new or overlay, has been done with a variety of layer interfaces ranging from strongly cemented having a high degree of shear strength to completely unstabilised having only internal frictional resistance between the individual particles. In this regard, both past and present design methodologies have been limited in their capability to address the bond between the slab and the underlying layers – essentially considering either unbonded or fully bonded conditions for design purposes. However, this limitation ignores a wide range of partially bonded conditions that can exist between these two limits that may consist of a variety of combinations of different levels of friction and adhesion. For most instances of design, unbonded conditions are principally hypothetical where qualification of the amount of adhesive strength and frictional restraint that develops along the interface between the slab and the underlying layer is the key to the characterisation of slab behaviour resulting in varying degrees of partial bond. This paper addresses a framework to model the effects of the concrete pavement slab–subbase interface for design purposes based on research relative to these and other factors as they may pertain to the prediction of short- and long-term performance.     

Electric field-assisted and field-depressed segregation of reactive metals to the bonding interface in braze alloy joining

Segregation of reactive metals at the bonding interface has been observed in various ceramic and/or metal joints bonded with reactive metal-bearing braze alloys. When a d.c. of 20 mAcm⁻² is applied to the ceramic/braze/ceramic system at a brazing temperature of, say, 1373 K, the electric field assists the segregation at the braze-ceramic interface on the cathode side and suppresses the segregation at the interface on the anode side. This may imply that reactive metal atoms in the braze can migrate as a cation. E.m.f. measurement on the ceramic (AIN or ZrB₂)-metal foil systems with increasing temperature shows that a negative e.m.f. to the ceramic pole appears from about 900 K for AIN and from 500 K for ZrB₂, as does the thermally stimulated current in polymers. These temperatures coincide well with those where the electrical conductivity of AIN and ZrB₂, respectively, begins to increase with increasing temperature. Therefore, it is considered that the polarization of the ceramics may take place and assist the migration, and consequently segregation, of reactive metals in braze alloys to the braze-ceramic interface during brazing.     

A review of advanced proton-conducting materials for hydrogen separation

This paper provides a comprehensive overview of developments and recent trends in H₂ separation technology that uses dense proton–electron conducting ceramic materials and their associated membranes. Various proton–electron conducting materials and their associated membranes are summarized and classified into several important categories, such as Ni-composite proton-conducting materials, as well as tungstate-based, BaPrO₃-based, LaGaO₃-based, and niobate/tantalite composite metal oxide-based ceramic materials/membranes. Various membrane designs, including asymmetric ceramic membranes (supported and self-supported) and surface-modified membranes, are also reviewed. Several important properties of ceramic materials and membranes, such as proton and electron conductivity and performance (i.e., H₂ transport flux and lifetime stability), are also discussed. To highlight the technical progress in this area, all possible ceramic materials and associated membranes are summarized, along with their properties and performance, to help readers quickly locate the information they are looking for. Based on this review, several challenges hindering the maturation of this technology are analyzed in depth, and possible research directions for overcoming these challenges are suggested.     

Microstructure in titanium carbonitride cermets

Abstract

Titanium carbonitride cermets were fabricated by conventional powder metallurgy techniques, producing a microstructure characterised by very fine grains, exhibiting a core–rim structure, bonded with a metallic phase. Transmission electron microscopy was used to characterise the crystalline structure and orientation relationship of the ceramic and metallic phases. The results show that the core and rim phases have the same crystalline structure and orientation relationship, as well as similar lattice parameters. Specific orientation relationships were observed at ceramic/metal and ceramic/ceramic interfaces.     

Flat friction stir spot welding of low carbon steel by double side adjustable tools

2 mm low carbon steel plates were successfully welded by the flat friction stir spot welding(FSSW) using double side adjustable tools, by which the keyhole formed in the conventional FSSW was eliminated and a flat surface on both the top and bottom sides of the welded joints was obtained. In addition, the hook shape usually generated in the conventional FSSW was eliminated by this technique, and the unbonded interface was parallel to the surface of the sheets. Owing to the enlarged bonded interface width by eliminating the keyhole and the intermixed interface by the adjustable probe, the plug fracture occurred under all the welding conditions in the present study. Due to the suppression of the thickness thinning and elimination of the hook shape, the joint performance was improved in the plug fracture mode. The shear tensile performance was considered to strongly depend on the microstructure in the tip area of the unbonded interface and the maximum shear fracture load of 23.0 kN was achieved in this study.