共查询到20条相似文献，搜索用时 15 毫秒
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This paper deals with optimal shape control of functionally graded smart plate containing patches of piezoelectric sensors and actuators. The genetic algorithm (GA) is designed to search for optimal actuator voltage and displacement control gains for the shape control of the functionally graded material (FGM) plates. The work extends the earlier finite element formulations of the two leading authors, so that it can be readily treated using genetic algorithms. Numerical results have been obtained to study the effect of the shape control of the FGM plates under a temperature gradient by optimising (i) the voltage distribution for the open loop control, and (ii) the displacement control gain values for the closed loop feedback control. The effect of the constituent volume fractions of zirconia, through varying the volume fraction exponent n, on the optimal voltages and gain values has also been examined. 相似文献
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K-T. Lau 《Materials Science & Technology》2014,30(13):1642-1654
AbstractFibre-optic Bragg grating (FBG) sensors have been recognised as one of the smart localised and globalised structural health monitoring devices for many structural applications. A particular interest has been placed on embedding these sensors into advanced composites for in situ manufacturing process monitoring and then, lifetime structural health monitoring (SHM). There is no doubt that the need of maintaining structural integrity of these composites has been increased owing to an increasing use of carbon and glass fibre composites in real life structural and engineering applications. In the public transportation, the structural components of Airbus 350 XWB and Boeing 787 are made by over 50% of composite materials to replace traditional aluminium alloys. Electric vehicles have used lightweight carbon fibre composites as their chassis to overcome the weight penalty from batteries. With the advantages of high specific stiffness to weight ratio and good damping properties of polymer based composites, these composites are also used to reinforce and strengthen civil concrete structures that are located on the earthquake zones. In some critical engineering components, glass fibre composites with embedded shape memory alloy (SMA) wires are used for stiffness and shape controls during marginally operational conditions. Therefore, developing better SHM technologies is an urgent need to ensure the structural integrity and safety of structures. In this paper, FBG sensors for different SHMs are introduced and discussed. The use of the sensors with appropriate design for smart composites with sensing and actuating capacities is also presented. 相似文献
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Lidong Zhang Pancˇe Naumov Xuemin Du Zhigao Hu Juan Wang 《Advanced materials (Deerfield Beach, Fla.)》2017,29(37)
Materials that respond rapidly and reversibly to external stimuli currently stand among the top choices as actuators for real‐world applications. Here, a series of programmable actuators fabricated as single‐ or bilayer elements is described that can reversibly respond to minute concentrations of acetone vapors. By using templates, microchannel structures are replicated onto the surface of two highly elastic polymers, polyvinylidene fluoride (PVDF) and polyvinyl alcohol, to induce chiral coiling upon exposure to acetone vapors. The vapomechanical coiling is reversible and can be conducted repeatedly over 100 times without apparent fatigue. If they are immersed in liquid acetone, the actuators are saturated with the solvent and temporarily lose their motility but regain their shape and activity within seconds after the solvent evaporates. The desorption of acetone from the PVDF layer is four times faster than its adsorption, and the actuator composed of a single PVDF layer maintains its ability to move over an acetone‐soaked filter paper even after several days. The controllable and reproducible sensing capability of this smart material can be utilized for actuating dynamic elements in soft robotics. 相似文献
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Joselle M. McCracken Brian R. Donovan Timothy J. White 《Advanced materials (Deerfield Beach, Fla.)》2020,32(20):1906564
Machines are systems that harness input power to extend or advance function. Fundamentally, machines are based on the integration of materials with mechanisms to accomplish tasks—such as generating motion or lifting an object. An emerging research paradigm is the design, synthesis, and integration of responsive materials within or as machines. Herein, a particular focus is the integration of responsive materials to enable robotic (machine) functions such as gripping, lifting, or motility (walking, crawling, swimming, and flying). Key functional considerations of responsive materials in machine implementations are response time, cyclability (frequency and ruggedness), sizing, payload capacity, amenability to mechanical programming, performance in extreme environments, and autonomy. This review summarizes the material transformation mechanisms, mechanical design, and robotic integration of responsive materials including shape memory alloys (SMAs), piezoelectrics, dielectric elastomer actuators (DEAs), ionic electroactive polymers (IEAPs), pneumatics and hydraulics systems, shape memory polymers (SMPs), hydrogels, and liquid crystalline elastomers (LCEs) and networks (LCNs). Structural and geometrical fabrication of these materials as wires, coils, films, tubes, cones, unimorphs, bimorphs, and printed elements enables differentiated mechanical responses and consistently enables and extends functional use. 相似文献
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Shape memory alloys (SMAs) are widely utilized as an actuation source in microscale devices, since they have a simple actuation mechanism and high‐power density. However, they have limitations in terms of strain range and actuation speed. High‐speed microscale SMA actuators are developed having diamond‐shaped frame structures with a diameter of 25 µm. These structures allow for a large elongation range compared with bulk SMA materials, with the aid of spring‐like behavior under tensile deformation. These actuators are validated in terms of their applicability as an artificial muscle in microscale by investigating their behavior under mechanical deformation and changes in thermal conditions. The shape memory effect is triggered by delivering thermal energy with a laser. The fast heating and cooling phenomenon caused by the scale effect allows high‐speed actuation up to 1600 Hz. It is expected that the proposed actuators will contribute to the development of soft robots and biomedical devices. 相似文献
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Microrobotics has many potential applications, such as environmental remediation, in the biomedical arena. However, existing microrobots exhibit practical limitations including inadequate biocompatibility and imprecise control. Here, a microrobot made of shape memory alloy (SMA) actuator which can be driven by laser scanning to perform microscale motions is introduced. The 65 µm long microrobot having crawling‐like motion can demonstrate the movement with 10.0 µm s−1 of the maximum speed. The microrobot is controlled by a laser affording wireless, spatiotemporally selective capabilities. During actuation, the robot exhibits crawling‐like motions including trigger via the SMA as removal of adhesion to surface, propulsion induced by optothermal and optical trapping effects. Both theoretical predictions and experimental results confirm that the SMA microrobot can be actuated and controlled via laser scanning. The principle of SMA microrobots, and the optical actuation method, can be broadened to other applications that require deformable microscale structures suitable for mass production. 相似文献
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Rachael Granberry Kevin Eschen Brad Holschuh Julianna Abel 《Advanced Materials Technologies》2019,4(11)
Advances in actuating fabrics can enable a paradigm shift in the field of smart wearables by dynamically fitting themselves to the unique topography of the human body. Applications including soft wearable robotics, continuous health monitoring, and body‐mounted haptic feedback systems are dependent upon simultaneous body proximity and garment stiffness for functionality. Passive fabrics and fitting mechanisms are unable to conform around surface concavities and require either high elasticity or a multiplicity of closure devices to achieve garment fit. The design, manufacture, and validation of the first circumferentially contractile and topographic self‐fitting garments composed of NiTi‐based shape memory alloy (SMA) knitted actuators that dynamically conform to the unique shape and size of the wearer's body in response to a change of the garment's temperature is introduced. Advanced materials and systems innovations 1) enable novel garment manufacturing and application strategies, 2) facilitate topographical fitting (spatial actuation) through garment architectural design, and 3) provide tunable NiTi‐based SMA actuation temperatures to enable actuation on the surface of human skin. This research represents a paradigm shift for wearable applications by redefining garment fit to fully topographical conformation to the wearer through advanced materials and structures design. 相似文献
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智能材料与结构的发展研究 总被引：1，自引：0，他引：1
智能材料与结构是由世界发达国家在８０年代发展起来的一项高新技术，智能结构就是把传感器，致动器，光电器件和微型处理机等预先埋置在复合材料层压板内形成的。由于它奇特的功能和潜在的应用，目前已成为航空天部门专家和工程师们广为关心的课题。本文介绍了国外智能材料与结构的最新发展和应用，智能结构的组成和制造方法，最后讨论了目前存在的问题和我国开展智能结构发展研究的建议。 相似文献
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Charles A. Weinberg Song Cai Jeremy Schaffer Julianna Abel 《Advanced Materials Technologies》2020,5(6)
Improvements in multifunctional materials have led researchers to reinvigorate traditional textile structures by integrating emerging material technologies to offer novel solutions to diverse industries. However, there exist few multifunctional materials capable of being produced with micrometer diameters that can be spun into yarns for textile manufacturing, limiting the wearability and tunability of multifunctional textiles. Here, the creation of nickel‐titanium (NiTi) smart material‐based yarns is enabled by the availability of small diameter (≤10 µm) NiTi filaments that can survive the yarn spinning manufacturing process. NiTi microfilament yarns exhibit traditional superelastic and shape memory properties, and afford additional improvements to mechanical performance such as a tunable structural stiffness, plateau strength, and actuation contractions through the introduction of controllable geometric parameters—yarn count, surface twist angle, and manufacturing strains. This work concludes in a densely knitted, closed‐form textile with shape memory actuation and superelastic recovery. NiTi microfilament yarns and textiles have promising impacts in actuating and energy‐absorbing technologies for medical, robotics, aerospace, and defense applications. 相似文献
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NiTi形状记忆合金丝的电阻与应力,应变的关系研究 总被引：10，自引：3，他引：7
形状记忆合金是智能材料与结构中很有希望的驱动材料。本文研究了外加应力和残留应变对形状记忆合金ＮｉＴｉ丝的电阻的影响。研究发现，在３０℃下的恒温过程中，外加应力对ＮｉＴｉ丝电阻的影响可以分为两种情况，一种是在弹性变形过程中，电阻随着应力的增加呈线性增加；另一种是在发生组织变化的过程中，当发生应力诱发马氏体相变时，电阻降低；当发生马氏体孪生变形时，电阻随着应力的增加而增加。应变对电阻的影响表现为随着ＮｉＴｉ丝的残余应变量的增加，电阻线性地增加。 相似文献
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TiNi基高温形状记忆合金的马氏体相变与形状记忆效应 总被引：2，自引：0，他引：2
综述了Ti-Ni基高温形状记忆合金中的马氏体相变和形状记忆效应最近研究进展。Ti-Ni基高温形状记忆合金主要包括用Ti-Ni-Pd,Ti-Ni-Pt,Ti-Ni-Zr和Ti-Ni-Hf等。对Ti-Ni基高温形状记忆合金体材料、薄带和薄膜中的马氏体相变、组织结构、形状记忆效应以及超弹性性能等进行了评述和归纳。值得注意的是,通过适当的时效处理可调节相变温度,显著改善Ti-Ni-Hf高温形状记忆合金的开头记忆效应和超弹性性能,其主要原因在于时效的Ti-Ni-Hf合金中析出纳米级析出相导致基体强度升高。采取适当的制备和加工方法,提高合金的马氏体相变温度,改善合金的开头记忆效应,是当前TiNi基形状记忆合金研究的主要发展趋势。 相似文献