An overview of smart technology

In recent years there has been a seemingly ever-increasing use of the synonymous adjectives ‘smart’ and ‘intelligent’ to describe a diverse range of materials, structures, systems and technologies.^1-4 The origin of this terminology can be dated to the early 1980s when researchers working mainly in the US, and funded predominantly from defence budgets, began to examine the potential of combining advanced materials and sensors with powerful and compact computers to produce futuristic systems able to monitor their operating environment in real time and respond appropriately. Public awareness of this technology was given an enormous boost by the prominence given to use of ‘smart’ munitions during the Gulf war. Various articles appearing in popular science journals^5–7 and broadsheet newspapers in the months following the successful conclusion of this conflict served to maintain interest and it became fashionable to examine the use of ‘smart’ technology in industrial applications far removed from those originally envisaged in aerospace and defence. Various dedicated university research groups were formed at around this time (among the first in the UK being the Smart Structures Research Institute at Strathclyde University), often bringing together academics who had been working on ‘smart’ technologies for several years without realising it! Over the last five years researchers working in most of the major industrial sectors have given at least some thought to how they might apply ‘smart’ technology, important areas being in transport, building, civil infrastructure, biomedicine, sport and leisure, power generation and oil, gas and petrochemical. Packaging has not been left out of this process, with the prospects for ‘intelligent packaging’ being assessed most notably by CEST and Pira International in a report prepared in 1992 under DTI funding.⁸ Interest in ‘smart’ packaging has been sustained over the four years since this pioneering study, with the focus of attention gradually shifting from abstract conjecture to practical application. Notwithstanding the attention now being devoted to all things ‘smart’, the underlying concepts are still only poorly understood in many quarters and the word must warrant some sort of prize for the proportion of times that it is inaccurately applied. This paper presents a systematic definition of ‘smart’ technology and goes on to review very briefly some of the major advances being made under this technological umbrella. The UK's Defence Research Agency (DRA), like its American counterparts, has been active in ‘smart’ technology from its earliest days and has, for obvious reasons, concentrated mainly on aerospace and defence applications. However, with the launch in April 1994 of the DRA's Structural Materials Centre (SMC), committed explicitly to promoting wealth creation via the dual (i.e. military and civil) use of technology, there has been a conscious effort to identify wider opportunities for the exploitation of the contributing ‘smart’ technologies. Some ideas relevant to packaging which are currently being developed in conjunction with the DRA's Packaging Authority are outlined, together with an invitation for interested companies to participate in various DRA-led joint development programmes. © 1997 John Wiley & Sons, Ltd.     

埋入光纤对CFRP抗弯性能影响实验研究

埋入光纤传感器的碳纤维复合材料作为一种智能材料,集智能,耐腐蚀及比强度高等优异性能于一体而倍受关注.其应用的前提是二者的相容性.在应用中,CFRP主要承担弯曲载荷,所以在我们的实验中,仅对埋入光纤对CFRP弯曲性能的影响作研究.通过埋入不同直径光纤,不同光纤埋入方向,不同光纤涂层以及不同光纤根数等对CFRP弯曲强度影响的试验,以确定埋入光纤对CFRP弯曲性能影响的程度以及如何使之减到最小,为工程优化应用提供依据.     

智能材料工艺与结构中的先进传感器的发展

建立复合材料成型过程的智能化在线监控系统,有效地调整生产工艺,科学设计和优化生产工艺,可以有效地提高生产质量,降低生产成本。除生产工艺智能化外,还需建立材料结构的智能化体系,从复合材料固化成型、材料生产到材料应用整个过程均实现智能化,将开辟材料科学研究的新途径。建立智能材料工艺与结构体系需要先进的性能优良的传感器,本文以智能材料体系为背景阐述了各种传感器技术性能及发展方向。     

Modeling of the thermopiezoelastic behavior of prismatic smart composite structures made of orthotropic materials

Asymptotic homogenization models for prismatic smart composite structures are derived and the effective elastic, piezoelectric, and thermal expansion coefficients are obtained. The actuation coefficients characterize the intrinsic transducer nature of active smart materials that can be used to induce strains and stresses in a coordinated fashion. Examples of such actuators employed with smart composite material systems are derived from piezoelectric, magnetostrictive and some other materials. The constituents of the smart structures are assumed to exhibit orthotropic characteristics. The original problem for the regularly non-homogeneous smart composite structure reduces to a system of three simpler types of problem, called unit cell problems. It is precisely these unit cell problems that enable the determination of the aforementioned coefficients. These effective coefficients are universal in nature and can be used to study a wide variety of boundary value problems associated with a smart structure of a given geometry.     

Surface evaluation of carbon fibre composites using wavelet texture analysis

Strong and lightweight fibre reinforced polymeric composites now dominate the aerospace, marine and low-volume automotive sectors. The surface finish on exterior composite panels is of critical importance for customer satisfaction. This paper describes the application of wavelet texture analysis (WTA) to the task of automatically classifying the surface finish of Carbon Fibre Reinforced Plastic (CFRP) samples into two quality grades. Automatic classification was successful for all but four samples out of 14,400 classification trial configurations, representing 403,200 sample classification attempts (28 attempts per configuration). This work establishes the principle of WTA as a basis for automatic surface finish classification of composite materials.     

铁性智能材料的计算机模拟进展

形状记忆合金、压电和磁致伸缩三类智能材料具有从序参量到畴结构到宏观性质平行的物理性质,将三类智能材料作为一个统一体进行研究是目前国际研究趋势。将三类智能材料进行综合,探寻其共同的物理基础以指导新材料开发是如今铁性智能材料面临的最大挑战。缺陷作为重要的改性手段,在铁性智能材料微结构演化、相稳定、宏观性能方面起到重要作用。重点介绍缺陷在三类智能材料中的重要作用的理论研究及计算机模拟的研究进展以及存在的问题,为寻找高性能化铁性智能材料提供理论方向。     

Influence of SiC particles distribution on mechanical properties and fracture of DRA alloys

In the last 20 years a new class of metal matrix composite material (DRA – Discontinuously Reinforced Aluminum) with aluminum alloy matrix and SiC particles as secondary phase has been developed. The most important step during composite production is the homogenization process of metal and ceramic powder particles. Quantitative analysis of a SiC particles distribution in the aluminum alloy matrix (CW67) was used to determine the optimum homogenization parameters of different powders. It was found out that the level of mixture homogeneity largely depends on the amount of mixing dish filling, homogenization time and characteristics of reinforcing particles. By introducing the concept of homogeneity index, it was shown that the lowest values of the mentioned parameter correspond to the best uniformity of SiC particles in the CW67 matrix. Composite with the lowest value of homogeneity index was the one with 5 vol.% of SiC, homogenized during 60 min and the amount of mixing dish filling of 20 vol.%. This composite displayed the best values of mechanical properties and fracture resistance.     

Non-equilibrium synthesis of new materials

Over the last few decades it has become apparent that metallic materials produced by conventional casting processes have reached their limit. Some improvements have been obtained by rapidly cooling bulk alloys but major increases have required the development of rapid solidification processes. However, more radical approaches, such as mechanical alloying (MA) and physical vapour deposition (PVD), are also being explored and these are the subject of this paper. This paper describes the physical basis behind the development of MA and PVD in the Structural Materials Centre and presents the results of some materials development programmes on aluminium, magnesium and titanium based materials.     

高分子阻尼材料的研究进展

本文介绍了高分子阻尼材料的研究进展,包括复合阻尼材料、智能阻尼材料等.展望了高分子阻尼材料的发展前景.     

Evaluation of quasi-isotropic plate and cylindrical shell fabricated with green composite sheets

Conventional fiber reinforced plastics (FRPs) have some problems in the case of disposal. Their combustion disposal discharges the carbon dioxide in the air because resins of FRPs are made of fossil fuel. In the case of disposal into the ground, these FRPs remain semi-permanently without decomposing. Therefore, green composites are now developed and are studied as one of less the environmental burden materials. In this study, two kinds of continuous green composite sheets, which were composed of Kenaf fibers or Linen fibers as reinforcement and biodegradable poly butylene succinate (PBS) resin as a matrix, were fabricated with a pultrusion molding. Since the PBS resin is a thermoplastic resin, the PBS/KENAF or PBS/LINEN composite sheets can be treated as intermediate materials such as Carbon Fiber Reinforced Plastic prepregs. In order to apply the PBS/KENAF or PBS/LINEN composite sheets to structural components, quasi-isotropic plates and cylindrical shells were fabricated and evaluated.     

Influence of water on bond behavior between CFRP sheet and natural calcareous stones

In this paper the effect of a long term immersion in water on bond durability is analyzed when FRPs (Fiber Reinforced Plastic) are externally applied to a masonry substrate. In the performed research a substrate made by natural calcareous stones, strengthened by CFRP (Carbon Fiber Reinforced Plastic) sheets has been analyzed. For a better comprehension of water effect on the adhesive bond between stone and CFRP, the same treatments were performed to the constituent materials, namely epoxy resins, CFRP sheets and stones. To this aim mechanical tests were carried out on stone, composite materials and epoxy resins before and after their immersion in water, evaluating the effects of this agent on the properties of the materials. The influence of the aging in water on the interface stone-reinforcement was analyzed in terms of bond strength, maximum bond stress, optimal bond length, slip-bond stress relationship and mode of failure. In addition the possibility of calibrating design relationships, taking into account the influence of environmental conditions is discussed. Detailed results on adhesives and composites aged in water have been reported in a previous paper while in the present work the significant decay of the mechanical properties of the stone is specifically investigated. With regard to the conditioning treatment a reduction of the bond strength has been observed (up to 26%) as well as a similar decrease of the maximum bond stress; in addition the aged specimens have shown a more fragile behavior. On the basis of the obtained results the empirical coefficient, reported in the available Italian Guidelines, to determine the FRP-masonry bond strength seems still effective when the system FRP-masonry is aged in water once the properties of the aged materials are considered in the provided relationships.     

Electrochemical Properties of Carbon Electrodes Modified with Cobalt Hexacyanoferrate and Nickel Hexacyanoferrate Nanoparticles

Inorganic Materials - C/KCoHCF-1, C/KNiHCF-2, C/KNiCoHCF-3, and C/KCoNiHCF-4 composite materials have been produced via surface modification of activated carbon. Structural characteristics of the...     

Material design and shape memory properties of smart composites composed of polymer and ferromagnetic shape memory alloy particles

Ferromagnetic shape memory alloys (FSMAs) such as NiMnGa are expected to be new practical actuator materials with high driving frequency by magnetic field and large strain due to the shape memory effect (SME). However, the brittleness and poor workability of FSMAs, especially at a polycrystalline state, are serious problems and should be improved for a practical use. From this viewpoint a smart composite has been designed by a combination of a polymer matrix and FSMA particles (FSMAP), and a systematic investigation has been done for a NiMnGa-FSMAP/epoxy smart composite. This paper summarizes the design concept and some experimental results of the smart composite. It is pointed out that the single-crystal NiMnGa-FSMAP are easily made by mechanical crush due to the brittleness of FSMAs, and microstructural control is also possible by applying magnetic field during curing. Experimental study revealed that the NiMnGa-FSMAP/epoxy smart composites exhibit both tensile ductility and SME, and that shape memory properties become improved by decreasing particle size of FSMAP. It is concluded that the FSMAP/polymer smart composite has a large potential to be a new practical actuator material.     

Influence of water on bond behavior between CFRP sheet and natural calcareous stones

In this paper the effect of a long term immersion in water on bond durability is analyzed when FRPs (Fiber Reinforced Plastic) are externally applied to a masonry substrate. In the performed research a substrate made by natural calcareous stones, strengthened by CFRP (Carbon Fiber Reinforced Plastic) sheets has been analyzed. For a better comprehension of water effect on the adhesive bond between stone and CFRP, the same treatments were performed to the constituent materials, namely epoxy resins, CFRP sheets and stones. To this aim mechanical tests were carried out on stone, composite materials and epoxy resins before and after their immersion in water, evaluating the effects of this agent on the properties of the materials. The influence of the aging in water on the interface stone-reinforcement was analyzed in terms of bond strength, maximum bond stress, optimal bond length, slip-bond stress relationship and mode of failure. In addition the possibility of calibrating design relationships, taking into account the influence of environmental conditions is discussed. Detailed results on adhesives and composites aged in water have been reported in a previous paper while in the present work the significant decay of the mechanical properties of the stone is specifically investigated. With regard to the conditioning treatment a reduction of the bond strength has been observed (up to 26%) as well as a similar decrease of the maximum bond stress; in addition the aged specimens have shown a more fragile behavior. On the basis of the obtained results the empirical coefficient, reported in the available Italian Guidelines, to determine the FRP-masonry bond strength seems still effective when the system FRP-masonry is aged in water once the properties of the aged materials are considered in the provided relationships.     

Carbon fibre reinforced composite waste: An environmental assessment of recycling,energy recovery and landfilling

The environmental benefits of recycling are assessed against other end-of-life (EOL) treatments for Carbon Fibre Reinforced Plastic (CFRP) waste. Recycling via pyrolysis, incineration with energy recovery, and disposal via landfilling are compared. To account for physical changes to materials from use and recycling, equivalence between recycled and virgin materials is calculated based on the ability to produce a short fibre composite beam of equivalent stiffness. Secondary effects of using Recycled Carbon Fibre (RCF) in a hypothetical automotive application are also analysed. Results underline the ecological constraints towards recycling CFRPs and demonstrate that benefits from recycling are strongly linked to the impacts of the selected recovery process, the materials replaced by RCF in a secondary application, and also to the type of secondary application in which they are used.     

导电高分子材料在隐身技术中的应用

隐身技术是一项跨学科的综合技术，它涉及到电磁、材料、能量转换、信息处理等学科和技术。本文简单介绍了材料隐身的隐身机理及材料隐身技术对材料的要求，说明了导电高分子材料是隐身材料的优选材料之一，综述了导电高分子材料在雷达隐身、红外隐身技术中的应用。     

NiMnGa铁磁性形状记忆合金颗粒/树脂智能复合材料的研究进展*

介绍了NiMnGa铁磁性形状记忆合金颗粒/树脂智能复合材料的制备、温度场和磁场响应特性以及阻尼性能的最新研究进展.与NiMnGa多晶材料相比,NiMnGa铁磁性形状记忆合金颗粒/树脂智能复合材料具有很好的加工成型性能,克服了NiMnGa多晶材料的脆性,同时表现出良好的温度场响应特性和阻尼性能,是一种很有发展前景的新型驱动器材料和阻尼材料.在磁场响应方面,新型铁磁性形状记忆合金(NiCoMnIn、NiCoMnSb、NiCoMnGa)/树脂智能复合材料将是未来研究的重点.     

压电陶瓷/聚合物复合材料的制备工艺及其性能研究进展

本文首先介绍了压电材料的种类和基本性能,然后介绍了在不同的应用背景下压电陶瓷／聚合物复合材料的十种连通方式,综述了这类压电材料的制备工艺,较全面地总结了前人对这类压电材料的性能研究工作,展望了这类压电材料的应用前景和发展方向     

Assembling DNA into Advanced Materials: From Nanostructured Films to Biosensing and Delivery Systems

The past decade has witnessed a rapid expansion in the design and assembly of engineered materials for biological applications. However, such applications place limitations on the molecular building blocks that can be used. Requirements for polymer‐based building blocks include biocompatibility, biodegradability, and stimuli‐responsive behavior. Many traditional polymers used in materials science are limited in at least one of these areas, so new polymers need to be explored. As we outline here, DNA is one such polymer that shows promise in developing the next generation of ‘smart’ materials for biomedical and diagnostic applications.     

Development and Trend of Advanced Polymer Composites as Structural Materials in Korea

A brief review of recent research and development of advanced polymeric composite materials in Korea is discussed. This paper also introduces the government research institutes and universities doing active research on composite materials. Aerospace companies are developing many advanced composite materials for defense, aerospace, transportation, and industrial applications. The anticipated applications of polymer composite materials as a structural materials are also discussed.