Civil infrastructure systems research: hazard mitigation and intelligent material systems

This article presents a review of recent-important developments in the field of intelligent material and fluid systems. Intelligent material and fluid systems, sometimes referred to as smart materials and fluids, can adjust their behavior to changes of external or internal parameters analogously to biological systems. In these systems, sensors, actuators and controllers are seamlessly integrated with structural materials at the macroscopic or mesoscopic level. In general, sensors and actuators are made of functional materials and fluids such as piezoelectric materials, magnetostrictive materials, shape memory alloys, polymer hydrogels, electro- and magneto-rheological fluids and so on. This article is specifically focused on the design of intelligent material and fluid systems used to control the deformation, vibration and fracture of composite materials and structures.

Semi-analytic modelling of transversely isotropic magneto-electro-elastic materials under frictional sliding contact

The 20th International Conference on Adaptive Structures and Technologies (ICAST) was held on 20–22 October 2009 in Hong Kong. This special section of Smart Materials and Structures is derived from the research papers presented at the conference. Of the 106 papers presented at the conference, 11 papers were reviewed and accepted for this special section, following the regular review procedures of the journal. This special section is focused on smart materials, multifunctional composites, and applications on morphing structures. Smart materials. Smart materials are the foundation of adaptive structures and intelligent systems. The development of new materials will lead to significant improvement in various applications. Three articles are focused on the fabrication of new materials and investigation of their behaviors: Barium strontium zirconate titanate ((Ba1-xSrx)(ZrxTi1-x)O3; BSZT, x = 0.25 and 0.75) ceramics with a highly crystalline structure were fabricated using the combustion technique. The microstructure of BSZT powders exhibited an almost-spherical morphology and had a porous agglomerated form. Polyaniline (PANI)/clay nanoparticles with unique core-shell structure were synthesized via Pickering emulsion polymerization. By dispersing PANI/clay nanoparticles in silicone oil, the ER fluid was made. Magnetic field effects were investigated on the deposition rate and surface morphology of chromium nitride coatings deposited by magnetron sputtering for superior hardness, excellent wear and oxidation resistance. The surface morphology of chromium nitride films was also examined by a scanning electron microscope (SEM). Multifunctional composites. Composites are made from two or more constituent materials so they can combine the best properties of different materials. Five papers deal with fabrication, testing, and modeling of various multifunctional composites: A new active structural fiber (ASF) was fabricated by coating a single carbon fiber with a concentric PZT (PbZr0.52Ti0.48O3) shell using electrolytic deposition. This new ASF is expected to have broader applications due to the higher piezoelectric coupling effect with the use of carbon fiber and PZT. The sol-gel technique was employed to deposit lead zirconium titanium (PZT) and silica composite film onto a copper (Cu)/polyimide (PI) flexible structure. The fabricated PZT-silica composite films were then used for flexible actuator and sensor applications. Interfacial properties and hydrophobicity of multifunctional Ni-nanopowder/epoxy composites were evaluated for self-sensing and actuation. The effects of water content on the actuation performance of ionic polymer–metal composites (IPMCs) were investigated experimentally. Multiscale modelling of a composite electroactive polymer structure was developed, in particular for tubular actuators. The models were validated with experimental data. Morphing structures. Three papers relate to morphing skins and structures. Several issues including stiffness and energy consumption were explored: Composite corrugated structures were used as morphing skin panels (MSPs) in the trailing edge region of a scaled morphing aerofoil section. Wind tunnel testing was carried out to demonstrate the MSP concept. Optimization of a variable-stiffness skin was performed for morphing high-lift devices. The objective is to design the structure to have high enough stiffness to withstand aerodynamic loading and yet low enough stiffness to enable morphing. The aerodynamic and actuation loads were taken into consideration during the optimization. Two adaptive and morphing structures were proposed for low-energy consumption or even energy-harvesting green buildings with the use of an optimization process. Searching for optimal solutions was done by means of an evolutionary technique while the compatibility of the resulting configurations of the adaptive envelope was ensured by the virtual force density method. We would like to thank all of the authors for their significant contributions to this special section for Smart Materials and Structures. We are also grateful to all of the reviewers and associate editors who handled the reviews for their time and effort. I would like to express my sincere appreciation to Professor E Garcia, Editor-in-Chief, for his encouragement by providing the opportunity to make this special section. I am indebted to IOP Publishing for their strong support and the staff, in particular publisher Natasha Leeper, for their special attention and excellent service.

ConspectusSmart soft materials have one or more characteristics that can be significantly altered in convertible fashions by external stimuli, such as light, moisture, mechanical force, temperature, electric/magnetic fields, pH, and so on. These materials can lead to widespread application in multifunctional smart devices. Recently, various smart soft materials have been developed under the inspiration of the intriguing multiscale structures, adaptive mechanisms, and dynamic responses of natural life, with an aim to further design advanced material systems with novel, intriguing, and unprecedented properties.Herein, inspired by the fascinating visual display strategies and adaptive mechanisms in animals and plants, we have fabricated a series of smart soft material-based devices that can respond to external stimuli with instantaneous and reversible fashions in optical, electrical, mechanical, and/or shape deformation signals. These devices can be fabricated for widespread applications, including smart windows, encryption devices, thermal camouflage, wearable strain sensors, anticounterfeit tabs, 3D stretchable electronics, dynamic displays, rewritable media, human–machine interfaces, and so on. The key to successfully achieving those intriguing characteristics in these smart material systems lies in the function-orientated structural design, which integrates bioinspired design and surface engineering with multiscale architecture as the crucial elements. In this Account, we provide a summary, with a main focus on our own work, of the recent advances in the bioinspired smart soft materials fabricated on the basis of 2D or 3D film–substrate multilayered structures. These materials are characterized by convertible topographies like dynamic cracks, folds, stimuli-responsive wrinkles, and other analogous structures. Those topographies are responsible for the dynamic stimuli-responsive optical, electrical, and mechanical properties demonstrated in the system, such as strain-dependent light scattering effect, mechanical tunable light shielding properties, moisture/mechanically/photothermally tunable surface reflectance, moisture/mechanically responsive resistance, etc. Besides, those 2D functional materials can be further evolved into shape adaptive 3D structures via strain relaxation methods. These systems demonstrate high design flexibility, excellent reversibility, and wide applicability, which can pave new routes for designing next generation smart soft materials equipped with versatile, tunable, adaptable, and interactive stimuli-responsive properties.

The civil engineering industry is increasingly focused on enhancing structural resilience to meet the demands of modern construction and environmental challenges.This paper entails the integration of new materials -like UHPC, FRP, and smart material systems -with state-of-the-art computational methods (e.g.FEA) as well as machine learning algorithms to predict up-to-date D&A from a broad source of natural hazards collectively called multi-hazards involving earthquakes).All these developments when combined, allows designers to create more durable and less rigid structures that better resist loading from the outside (e.g., earthquakes or extreme climatic events).This approach helps in saving the life span of infrastructures and also increases sustainability by reducing frequent work on repairs and replacements.This approach not only extends the lifespan of infrastructures but also contributes to sustainability by reducing the need for frequent repairs and replacements.The paper further discusses case studies demonstrating successful applications of these technologies, offering insights into their practical implementation and future potential in civil engineering.

The Army Research Office (ARO) has been supporting projects focusing onbasic research in the area of smart materials and adaptive structures overrecent years. A major emphasis of the ARO's Structures and DynamicsProgram has been on the theoretical, computational, and experimental analysisof smart structures and structural dynamics, damping, active control, andhealth monitoring as applied to rotorcraft, electromagnetic antennastructures, missiles, land vehicles, and weapon systems. The variety ofresearch projects supported by the program have been primarily directedtowards improving the ability to predict, control, and optimize the dynamicresponse of complex, multi-body deformable structures. The projects in thefield of smart materials and adaptive structures have includedmulti-disciplinary research conducted by teams of several faculty members aswell as research performed by individual investigators.This paper begins with a brief discussion of smart or active materials, i.e. materials having capabilities of sensing changes from the surroundingenvironment and actively responding to those inputs in an effective manner.Integrating these materials in structures makes them `smart', i.e. itprovides them with the capability to respond to the external stimuli to compensatefor undesired effects and/or to enhance the desired effects. The terms`active', `smart', `adaptive', and `intelligent' are frequently usedinterchangeably in this context. This discussion is followed by illustrationsfrom several current ARO-sponsored research projects related to smartmaterials and adaptive structures. A summary of significant results based uponthese investigations is given next. Finally, directions of potential futureresearch in the smart materials and adaptive structures area are discussed.

The concept of an adaptive aircraft wing, i.e., whose shape parameters such as camber, span-wise twist, and thickness can be varied to optimize the wing shape for various flight conditions, has been extensively studied by numerous researchers. While the aerodynamic benefits (in terms of increased lift/drag ratios, improved maneuverability, and delayed flow separation) have been analytically and experimentally established, the complexity and weight penalty of the designs and actuation using smart materials could potentially alleviate the shortcomings of prior designs, leading the way to a more practical `smart' adaptive wing which responds to changes in flight and environmental conditions by optimally modifying its shape. A summary of recent work in the area of adaptive wing concepts incorporating smart structures technologies is presented. Emphasis is placed on continuing research at Northrop Grumman under a United States Defense Advanced Research Projects Agency contract entitled `Smart Structures and Materials Development-Smart Wing,'. Limitations and potential benefits of adaptive wing designs, applications and advantages of smart material actuators and sensors, and results of recent tests are discussed. Recommendations for future work required to develop an operational smart adaptive wing are also outlined.

Building on the research performed during the DARPA/AFRL/NASA Smart Wing Phase 1 program (Kudva, J.N. et al. (July 1999). Overview of the DARPA/AFRL/NASA Smart Wing Program, SPIE Symposium on Smart Structures and Materials, Newport Beach, CA, Vol. 3674, pp. 230 6; Martin, C.A. et al. (1999). Smart Materials and Structures Smart Wing Phase 1 Final Report, AFRL-ML-WP-TR-1999-4162, Air Vehicles Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, OH.) sought to improve vehicle aerodynamic efficiency using control surfaces actuated by smart materials, the goal of the Phase 2 effort was to develop larger scale, smart hingeless control surfaces capable of high-rate actuation and quantify their performance benefits at test conditions representative of operational flight environments. To achieve this goal, a 30-percent geometric scale, full-span wind tunnel model of a proposed Northrop Grumman Corporation (NGC) Uninhabited Combat Air Vehicle (UCAV) was designed and tested. The model incorporated conventional, hinged control surfaces on the left side and smart, hingeless control surfaces on the right to allow incremental aerodynamic performance comparisons; including lift increment due to unit control surface deflection (CL), and roll moment due to unit control surface deflection (Cld). This paper describes the design, fabrication, system integration, and ground test results of the Smart Wing Phase 2 model. Topics that are covered include: (1) wind tunnel model selection; (2) analysis and design procedure; (3) smart control surface integration; (4) model instrumentation; and (5) static load and Ground Vibration Test (GVT) results and correlation.

Objectives: The paper presents significant application of smart materials and their implementation in modern structures. The application of shape memory alloys, piezoelectric and magnetostrictive materials are provided in this paper for the readers. It also defines the architectural perspective in order to assess how architecture can develop with the advancement of smart materials. Methods: The scientific utilization of smart structural mechanics in the design, construction and preservation of infrastructures needs attention in civil engineering aspect. Smart meters are important components of next generation structures because they enable remote metering of energy consumption. The influence of TiO2 coated plastering mortar, in its fresh state has good thermal performance in building wall model and makes the building thermally efficient. Additionally it includes the sustainable use and potential contribution of Zero Energy Building (ZEB) principle towards achieving smart cities. Findings: It is found that these technological strides can be used for better reliability and overall safety of any structure. Thus the structural integrity, firmness and long term benefits are taken care of. Finally we came up with the conclusion that the effectiveness of using smart materials in smart structures can become an agent in building “towards a new architecture”. Applications: These materials are useful in creating a sustainable environment which are eco-friendly and leads to less energy consumption which is a boon to our societyKeywords: Magnetostrictive Materials, Piezoelectric Materials, Shape Memory Alloys, Smart Meters, ZEB

Smart textiles are one of the areas that provides added value to textile materials. It is a sector that has been developed with new technologies, new fibers, and textile materials. The production of smart or intelligent textiles cooperate with other branches of science like nanotechnology, materials science, design, electronics, and computer engineering, etc. Smart textiles are classified into three groups as passive smart textiles, active smart textiles and ultra smart textiles according to their performance characteristics. Passive smart textiles are the first generation of smart textiles and sense the external conditions; for instance, UV protecting clothing, conductive fibers, etc. As active smart textiles respond to external conditions, ultra smart textiles sense, react, and adopt themselves to conditions. Shape memory materials, chromic materials, heat storage, and thermo-regulated fabrics are the typical applications of active smart textiles.

Smart materials are the materials which have the ability to respond to changes in their condition or the environment to which they are exposed, in a useful and usually repetitive manner. Structures that incorporate smart materials are called as “Smart Structures”. Smart materials are developed which responds to environmental stimuli such as pressure, temperature and wind. Smart materials used in construction technology includes self healing coatings, smart concrete, shape shifting metals, transparent metals, aerogels etc which will change the construction technology in near future. A new material known as shape shifting material has been developed that once deformed will automatically return to its original shape when heated. Concrete is the major building material used in construction industry but it is vulnerable and starts to collapse when it comes in contact with environmental stimuli such as water, wind, stress and pressure. A new type of smart concrete contains dormant bacteria and when they come into contact with stimuli like water, they create limestone, filling up the cracks and thus creating a self-healing repair mechanism. The coatings, made with polymers internally react with one another when ruptured, thus creating a self-healing mechanism. Transparent metals and aerogels are the futuristic materials which will replace the conventional building materials and will play a crucial role in the development of smart cities. Identifying the conventional moiety between Materials Science and construction technology, the paper intent to show how these two fields are inherently connected. This paper provides a comprehensive review of the types of smart materials for construction technology, giving a new vision into innovative processes and techniques, providing new inspiration in the field of architectural design and construction technology.

Smart structure systems and smart materials technologies have a vital role in many types of manufacturing in this century. Various construction materials can considerably improve functioning. Smart Materials have a vital role in the evolution of building technology. These materials are part of a smart structural system that can detect its surroundings and perform like living systems. The study state and recognize the relation between adaptive structure system and construction materials “smart concrete” in the construction scope through analysis, new techniques and innovative methods. The study’s goal is to explore how these two professions are inextricably linked, developing ever more symbiotic as time goes on. The paper presented the various categories of smart structure systems and materials that have unique properties. Furthermore, the paper revealed the effective behavior of smart materials that take into consideration at every level of design progression of civil engineering.KeywordsAdaptive systemSmart materialsSmart concrete

In the present study, real-time measurement of internal and residual strains in GFRP laminates with an optical fiber strain sensor was performed in an autoclave molding. An Extrinsic Fabry-Perot Interferometric (EFPI) type optical fiber strain sensor was embedded into prepreg sheets before the molding. The ion viscosity and the temperature of the epoxy resin matrix were also measured simultaneously with the internal strain measurement. The results of the experiments showed that the internal and residual strain of GFRP laminates during the molding could be monitored by the optical fiber sensor embedded in the parallel direction to the reinforcing fibers. It was also found that the circumstances around the embedded optical fiber strain sensor should be taken into account for the interpretation of the measured internal and residual strain.

The vibrations of a structure having a vibration absorber without damper vanish at the anti-resonance frequency theoretically. Hence if the rigidity of the absorber is controlled to produce an anti-resonance state according to the forced frequency, the vibrations of the structure can be deleted for sinusoidal forces. However, external vibration force involves higher modes, in general, so the structure is excited by various frequencies. Hence it is difficult to delete the vibrations using the anti-resonance procedure. This paper presents a method to control vibration of structures by combining the auto-tuning control of anti-resonance and optimal dynamic absorbers. Theoretical results under the control have been presented. To validate the present method and the theoretical results, experimental tests have been performed.

Piezoelectric materials play an important role in smart material and structural systems, and high-performance piezoelectric actuators with larger force and displacement output are in demand. It was shown in our previous work that the hybrid sintering process using a 28 GHz microwave technique and hot pressing offers advantages over conventional technologies reference. It was also confirmed that the maximum achieved value of piezoelectric constant d31 of the specimens of the hybrid-sintering process is approximately 360×10-12 m/V, which is about 38% larger than 260×10-12 m/V, the d31 of the conventionally sintered specimens. In this study, the material properties, including electromechanical coupling factor, Young's modulus, frequency constant, Curie temperature and dielectric constant, of the specimens fabricated with the microwave sintering process were further investigated for different sintering temperatures. The Curie point Tc decreases, but the dielectric constant εr at Tc increases with the grain size of specimens for all sintering methods. The influence of grain size on Tc and εr can be attributed to the residual stress induced by the lattice mismatch between the cubic phase and the tetragonal-rhombohedral mixed phase.