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Volume 1: Development and Characterization of Multifunctional Materials; Modeling, Simulation, and Control of Adaptive Systems; Integrated System Design and Implementation最新文献

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Smart Trailing Edges for Wind Turbines 风力涡轮机的智能后缘
J. Riemenschneider, M. Pohl, R. Unguran, V. Petrović, M. Kühn, A. Haldar, Hinesh Madhusoodanan, E. Jansen, R. Rolfes
In order to reduce the “cost of energy” for wind turbines it is an ongoing trend to increase the rotor diameter, which increases fatigue loads in the blade root area. Thus, a critical prerequisite for increased rotor diameter is the reduction of loads, which can be utilized by passive and active measures. This paper is giving an overview of current research work towards the use of a flexible trailing edge for load reduction as it is being pursued in the German national SmartBlades project. The active trailing edge is designed to change the lift of the outer blade in a way to counteract sudden changes caused by gusts or wind shear. Areas that are covered include the simulation towards the load reduction potential of such flexible trailing edges, the structural design of the trailing edge itself as a compliant mechanism, its experimental validation and fatigue investigation as well as multistable approaches for the design of such trailing edge flaps.
为了降低风力涡轮机的“能量成本”,增加转子直径是一个持续的趋势,这增加了叶片根部区域的疲劳载荷。因此,增加转子直径的关键先决条件是减少负载,这可以通过被动和主动措施加以利用。本文概述了目前在德国国家SmartBlades项目中使用柔性后缘来减少负载的研究工作。主动后缘的设计是为了改变外叶片的升力,以抵消阵风或风切变引起的突然变化。涵盖的领域包括对这种柔性后缘的减载潜力的模拟,后缘本身作为一种柔性机构的结构设计,其实验验证和疲劳研究,以及设计这种后缘襟翼的多稳态方法。
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引用次数: 7
Design of a Beam-Based Variable Stiffness Actuator via Shape Optimization in a CAD/CAE Environment 基于CAD/CAE环境下形状优化的梁式变刚度驱动器设计
Pietro Bilancia, G. Berselli, U. Scarcia, G. Palli
Industrial robots are commonly designed to be very fast and stiff in order to achieve extremely precise position control capabilities. Nonetheless, high speeds and power do not allow for a safe physical interaction between robots and humans. With the exception of the latest generation lightweight arms, purposely design for human-robot collaborative tasks, safety devices shall be employed when workers enter the robots workspace, in order to reduce the chances of injuries. In this context, Variable Stiffness Actuators (VSA) potentially represent an effective solution for increasing robot safety. In light of this consideration, the present paper describes the design optimization of a VSA architecture previously proposed by the authors. In this novel embodiment, the VSA can achieve stiffness modulation via the use of a pair of compliant mechanisms with distributed compliance, which act as nonlinear springs with proper torque-deflection characteristic. Such elastic elements are composed of slender beams whose neutral axis is described by a spline curve with non-trivial shape. The beam geometry is determined by leveraging on a CAD/CAE framework allowing for the shape optimization of complex flexures. The design method makes use of the modeling and simulation capabilities of a parametric CAD software seamlessly connected to a FEM tool (i.e. Ansys Workbench). For validation purposes, proof-concept 3D printed prototypes of both non-linear elastic element and overall VSA are finally produced and tested. Experimental results fully confirm that the compliant mechanism behaves as expected.
工业机器人通常被设计得非常快速和僵硬,以实现极其精确的位置控制能力。然而,高速度和高功率并不允许机器人和人类之间进行安全的物理互动。除了最新一代的轻量化手臂是专门为人机协同任务设计的外,当工人进入机器人工作空间时,必须配备安全装置,以减少受伤的机会。在这种情况下,可变刚度执行器(VSA)可能是提高机器人安全性的有效解决方案。鉴于这一考虑,本文描述了作者先前提出的VSA架构的设计优化。在这个新颖的实施例中,VSA可以通过使用一对具有分布式柔度的柔性机构来实现刚度调制,这些机构充当具有适当扭矩-挠度特性的非线性弹簧。这种弹性单元由细长梁组成,其中性轴由非平凡形状的样条曲线描述。梁的几何形状是通过利用CAD/CAE框架来确定的,允许对复杂挠曲进行形状优化。该设计方法利用了参数化CAD软件与FEM工具(即Ansys Workbench)无缝连接的建模和仿真能力。为了验证目的,最后制作并测试了非线性弹性元件和整体VSA的概念验证3D打印原型。实验结果充分证实了柔性机构的性能符合预期。
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引用次数: 4
Numerical Techniques to Model Fractional-Order Nonlinear Viscoelasticity in Soft Elastomers 软弹性体分数阶非线性粘弹性数值模拟技术
P. Miles, G. Pash, W. Oates, Ralph C. Smith
Dielectric elastomers are employed on a wide variety of adaptive structures. Many of these soft elastomers exhibit significant rate-dependencies in their response. Accurately quantifying this viscoelastic behavior is non-trivial and in many instances a nonlinear modeling framework is required. Fractional-order operators have been applied to modeling viscoelastic behavior for many years, and recent research has shown fractional-order methods to be effective for nonlinear frameworks. This implementation can become computationally expensive to achieve an accurate approximation of the fractional-order derivative. In this paper, we demonstrate the effectiveness of using quadrature techniques in approximating the Riemann-Liouville definition for fractional derivatives in the context of developing a nonlinear viscoelastic model.
介电弹性体广泛应用于各种自适应结构。许多软弹性体在其响应中表现出显著的速率依赖性。准确地量化这种粘弹性行为是非常重要的,在许多情况下需要一个非线性建模框架。分数阶算子已经应用于粘弹性行为建模很多年了,最近的研究表明分数阶方法对非线性框架是有效的。为了获得分数阶导数的精确近似值,这种实现在计算上可能会变得非常昂贵。在本文中,我们证明了在建立非线性粘弹性模型的背景下,使用正交技术近似分数阶导数的Riemann-Liouville定义的有效性。
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引用次数: 3
On the Potential of Using the Small Punch Test for the Characterization of SMA Behavior Under Multi-Axial Loading Conditions 利用小冲孔试验表征SMA在多轴载荷条件下的性能的潜力
B. Kiefer, J. Hein, M. Abendroth, H. Biermann, S. Henkel, T. Niendorf, P. Krooß, Y. Chemisky
This work presents a first investigation of the small punch test (SPT) as a possible method to identify material parameters for shape memory alloy (SMA) behavior. In comparison to more common tests, the SPT has advantages in setup simplicity, small sample size, uncomplicated shape, and the possibility of specimen clamping, while offering controlled multi axial loading. Different loading scenarios are described and executed. The parameters of an established SMA model are subsequently (partially) calibrated from the measured SPT force-deflection curves. For some loading regimes, the effective response curves suggest the occurrence of damage events. To investigate the underlying microscale failure mechanisms, a first SEM study was conducted. These first results underline that the SPT is a promising efficient and inexpensive characterization method to support SMA constitutive model development under multiaxial loading — including aspects of damage, fracture and fatigue.
这项工作提出了小冲孔试验(SPT)作为一种可能的方法来识别形状记忆合金(SMA)行为的材料参数的第一次调查。与更常见的测试相比,SPT具有设置简单,样本量小,形状不复杂,试样夹紧的可能性,同时提供可控的多轴加载等优点。描述和执行不同的加载场景。随后(部分)根据测得的SPT力-挠度曲线校准已建立的SMA模型的参数。在某些加载状态下,有效响应曲线表明损伤事件的发生。为了研究潜在的微尺度破坏机制,进行了第一次扫描电镜研究。这些初步结果强调,SPT是一种有前途的高效且廉价的表征方法,可以支持SMA在多轴载荷下的本构模型开发,包括损伤、断裂和疲劳等方面。
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引用次数: 0
Experimental Validation of Adaptive Control for a Shape Memory Alloy Actuated Lightweight Robotic Arm 形状记忆合金驱动轻型机械臂自适应控制的实验验证
Serket Quintanar-Guzman, S. Kannan, H. Voos, M. Darouach, M. Alma
This article presents the experimental validation of a Direct Adaptive Control for angular position regulation of a lightweight robotic arm. The robotic arm is single degree-of-freedom (DOF) system, actuated by two Shape Memory Alloy (SMA) wires. The proposed adaptive control is capable of adapting itself to the hysteretic behavior of SMA wires and update its behavior to deal with the changing parameters of the material over time. The closed-loop approach is tested experimentally showing its effectiveness to deal with the highly nonlinear dynamics of the SMA wires. These results are discussed and compared with a classical control approach. The updated design and hardware development and modeling of the robotic arm are shown.
本文对轻型机械臂角位置调节的直接自适应控制进行了实验验证。机械臂为单自由度(DOF)系统,由两条形状记忆合金(SMA)导线驱动。所提出的自适应控制能够适应SMA丝的滞后行为,并更新其行为以处理随时间变化的材料参数。通过实验验证了闭环方法对SMA丝高度非线性动力学的处理效果。讨论了这些结果,并与经典控制方法进行了比较。介绍了机械臂的最新设计、硬件开发和建模。
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引用次数: 0
A Piezocomposite Trailing-Edge for Subsonic Aircraft 一种用于亚音速飞行器的压电复合材料后缘
C. Wright, O. Bilgen
This paper examines the feasibility of piezocomposite morphing airfoils and trailing edge control surfaces subjected to large dynamic pressures. Piezocomposite airfoils have been shown to be feasible on small unmanned aerial vehicles, subject to relatively low dynamic pressures, operating in the Reynold’s number range of 50k to 250k. The operating range of interest in this paper has a cruising Reynold’s number range between 250k and 1M subject to relatively large wing loading. This range of Reynold’s numbers has not been explored in detail due to the large aerodynamic loads produced. Based on the authors’ previous research on small unmanned aircraft, the proposed concept is a variable-camber airfoil that employs a continuous inextensible surface and surface-bonded piezocomposite actuators. To achieve camber-morphing, multiple piezocomposite actuating elements are applied to the upper and lower surfaces. A case study is performed to determine the design parameters of the airfoil. The parameters to be varied include the substrate thickness of the baseline airfoil, leading edge, and piezocomposite bonded areas. In addition, the positions of the piezocomposites are varied. The analysis is performed using a coupled fluid-structure interaction model assuming static aeroelastic behavior. A voltage sweep is conducted on each airfoil design while being subjected to 70 m/s free stream velocity. The sweep examines the lift coefficient and lift-to-drag ratio of the airfoil over the full operational range. This research lays the groundwork for determining the feasibility of piezocomposite morphing airfoil and trailing edge concepts for use in applications subject to large dynamic pressures.
研究了大动压作用下压电复合材料变形翼型和后缘控制面的可行性。压电复合材料翼型已被证明在小型无人机上是可行的,受相对较低的动压影响,在雷诺数50k至250k范围内运行。在较大的机翼载荷下,本文感兴趣的工作范围为250k ~ 1M的巡航雷诺数范围。由于产生了很大的空气动力载荷,雷诺数的这个范围还没有被详细探讨。基于作者之前对小型无人机的研究,提出了一种采用连续不可扩展表面和表面粘合的压电复合材料作动器的变弧度翼型的概念。为了实现弯曲变形,多个压电复合材料驱动元件应用于上下表面。进行了一个案例研究,以确定翼型的设计参数。要改变的参数包括基材厚度的基线翼型,前缘,和压电复合材料粘结区。此外,压电复合材料的位置是不同的。采用假定静力气动弹性行为的流固耦合模型进行分析。电压扫描是进行在每个翼型设计,同时受到70米/秒自由流速度。扫描检查升力系数和升阻比的翼型在整个操作范围。这项研究奠定了基础,确定可行性的压电复合材料变形翼型和后缘的概念,用于应用受大动压力。
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引用次数: 0
Fabrication and Testing of Kirigami-Inspired Multi-Stable Composites 基里伽米激发多稳定复合材料的制备与测试
Aditya Lele, O. Myers, Suyi Li
This paper aims at highlighting the fabrication procedures and proof-of-concept tests of a Kirigami inspired multi-stable composite laminate. Bistable composites consisting of asymmetric fiber layout have shown great potentials for shape morphing and energy harvesting applications. However, a patch of such a bistable composite is limited to very simple deformation when being snapped between its two stable equilibria (or states). To address this issue, this study investigates the idea of utilizing Kirigami, the ancient art of paper cutting, into the design and fabrication of bistable composite laminates. Via combining multiple patches of laminates and cutting according to prescribed Kirigami pattern, one can create a structure with multiple stable states and sophisticated deformation paths between them. This can significantly expand the application potentials of the multi-stable composites. This paper details the fabrication procedures for an elementary unit cell in the envisioned Kirigami composite and the results of proof-of-concept experiments, which measure the force required to switch the Kirigami composite between its different stable states. Preliminary results confirm that the Kirigami unit cell possesses multiple stable states depending on the underlying fiber layout. Each patch in the Kirigami composite could be snapped independently between stable states without triggering any undesired snapping in other patches. Moreover, a transient propagation of curvature change is observed when a patch in the Kirigami composite is snapped between its stable states. Such a phenomenon has not been reported in the bistable composite studies before. Results of this paper indicate that Kirigami is a powerful approach for designing and fabricating multi-stable composites with a strong appeal for morphing and adaptive systems. This paper highlights the feasibility and novelty of combining Kirigami art and bistable adaptive composites.
本文重点介绍了一种基里伽米启发的多稳定复合材料层压板的制造过程和概念验证试验。由非对称纤维组成的双稳态复合材料在形状变形和能量收集方面具有很大的应用潜力。然而,这种双稳态复合材料的一小块在其两个稳定平衡(或状态)之间断裂时仅限于非常简单的变形。为了解决这一问题,本研究探讨了将古老的剪纸艺术Kirigami运用到双稳态复合层压板的设计和制造中。通过组合多块层压板并按照规定的基里伽米模式切割,可以创建具有多个稳定状态和它们之间复杂变形路径的结构。这将极大地拓展多稳定复合材料的应用潜力。本文详细介绍了设想的Kirigami复合材料中一个基本单元的制造过程,以及概念验证实验的结果,该实验测量了在不同稳定状态之间切换Kirigami复合材料所需的力。初步结果证实,基里伽米细胞具有多种稳定状态,这取决于底层纤维的布局。Kirigami复合材料中的每个贴片都可以在稳定状态之间独立地断裂,而不会触发其他贴片中的任何不希望的断裂。此外,当基里伽米复合材料中的一个贴片在其稳定状态之间被折断时,观察到曲率变化的瞬态传播。这种现象在双稳态复合材料研究中未见报道。结果表明,Kirigami是设计和制造多稳定复合材料的一种强有力的方法,具有很强的变形和自适应系统的吸引力。强调了基里伽美艺术与双稳态自适应复合材料相结合的可行性和新颖性。
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引用次数: 1
Data-Driven Modeling Techniques to Estimate Dispersion Relations of Structural Components 估计结构构件色散关系的数据驱动建模技术
V. V. S. Malladi, M. Albakri, P. Tarazaga, S. Gugercin
Dispersion relations describe the frequency-dependent nature of elastic waves propagating in structures. Experimental determination of dispersion relations of structural components, such as the floor of a building, can be a tedious task, due to material inhomogeneity, complex boundary conditions, and the physical dimensions of the structure under test. In this work, data-driven modeling techniques are utilized to reconstruct dispersion relations over a predetermined frequency range. The feasibility of this approach is demonstrated on a one-dimensional beam where an exact solution of the dispersion relations is attainable. Frequency response functions of the beam are obtained numerically over the frequency range of 0–50kHz. Data-driven dynamical model, constructed by the vector fitting approach, is then deployed to develop a state-space model based on the simulated frequency response functions at 16 locations along the beam. This model is then utilized to construct dispersion relations of the structure through a series of numerical simulations. The techniques discussed in this paper are especially beneficial to such scenarios where it is neither possible to find analytical solutions to wave equations, nor it is feasible to measure dispersion curves experimentally. In the present work, actual experimental data is left for future work, but the complete framework is presented here.
色散关系描述了弹性波在结构中传播的频率依赖性。由于材料的不均匀性、复杂的边界条件和被测结构的物理尺寸,实验确定结构部件(如建筑物的地板)的色散关系可能是一项繁琐的任务。在这项工作中,利用数据驱动的建模技术来重建预定频率范围内的色散关系。在一维光束上证明了这种方法的可行性,其中色散关系可以得到精确的解。在0-50kHz的频率范围内,用数值方法得到了波束的频响函数。然后,利用矢量拟合方法构建数据驱动的动力学模型,建立基于沿梁16个位置的模拟频响函数的状态空间模型。然后通过一系列数值模拟,利用该模型构建结构的色散关系。本文讨论的技术特别适用于既无法找到波动方程的解析解,又无法通过实验测量色散曲线的情况。在目前的工作中,实际的实验数据留给以后的工作,但这里给出了完整的框架。
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引用次数: 4
Design of a Leading Edge Morphing Based on Compliant Structures in the Framework of the CS2-AIRGREEN2 Project CS2-AIRGREEN2项目框架下基于柔性结构的前缘变形设计
A. Gaspari, A. Gilardelli, S. Ricci, A. Airoldi, F. Moens
This paper summarizes the results obtained in the framework of Clean Sky 2 REG-IADP, AIRGREEN on the development of a dedicated morphing device, i.e. a Leading Edge morphing. This device, designed so to be installed on a advanced, twin prop, regional aircraft, is conceived to guarantee high lift conditions together with a smoothed and continuous skin surface, especially important due to the presence of a laminar wing. The design of a such as complex devices required a multi-disciplinary approach, able to combine the aerodynamic performances and the structural ones related to the compliant structures concept adopted for the internal structure. The paper includes an overview of all the design challenges, the adopted solutions and finally the obtained numerical assessments.
本文总结了在Clean Sky 2 regg - iadp, AIRGREEN框架下关于专用变形装置(Leading Edge morphing)研制的研究成果。该装置的设计目的是安装在先进的双支柱支线飞机上,旨在保证高升力条件以及光滑连续的表面,特别是由于层流机翼的存在,这一点尤为重要。如此复杂的装置的设计需要多学科的方法,能够将气动性能和与内部结构所采用的柔性结构概念相关的结构性能结合起来。本文概述了所有的设计挑战,采用的解决方案,最后得到了数值评估。
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引用次数: 5
Tailoring and Characterization of the Liquid Crystalline Structure of Cellulose Nanocrystals for Opto-Electro-Mechanical Multifunctional Applications 纤维素纳米晶体液晶结构的裁剪与表征及其在光电机械多功能应用中的应用
Inseok Chae, A. Meddeb, Z. Ounaies, Seong H. Kim
Liquid crystalline (LC) behaviors of cellulose nanocrystal (CNC), derived from wood, cotton or other cellulose-based biopolymers, have been actively investigated due to their unique optical properties and their superb mechanical properties, which open up potential applications in bioelectronics and biomedical engineering. In particular, many attempts have been made to control phase and orientation of LC-CNCs because they are critical factors deciding optical and mechanical properties, and electromechanical performances. Through the applications of mechanical force, electric field and magnetic field, some degree of success has been achieved; however, realizing homogeneous arrangements of CNCs that can be exploited at the macroscale is still elusive, owing to a variety of intermolecular interactions. The characterizations of the LC phase and orientation of CNCs are also challenging due to their complex biological structures. In this report, we introduce approaches to control the phase and orientation of LC-CNCs through the self-assembly, mechanical force and electric field. The liquid crystalline behaviors of CNCs in polar solvents and at the air/water interface are discussed. Translational and rotational behaviors of CNCs under DC electric field are also investigated as a function of their surface charge and dipole moment. In addition, we introduce a nonlinear optical process, namely, sum frequency generation (SFG) spectroscopy, for the structural characterization of LC-CNCs. Using SFG, we can analyze not only crystal phase and structure, but also polar ordering of CNCs which plays a key role in determining their electromechanical performances. Development of cellulose-based smart materials will expand the spectrum of available functional materials that are lightweight, flexible, mechanically tough, and thermally stable at moderately high temperatures (up to 300°C).
摘要以木材、棉花等纤维素基生物聚合物为原料制备的纤维素纳米晶体(CNC),由于其独特的光学性能和优异的力学性能,在生物电子学和生物医学工程中具有潜在的应用前景,因此其液晶(LC)行为一直受到人们的积极研究。特别是,由于相位和取向是决定光学和机械性能以及机电性能的关键因素,人们已经进行了许多尝试来控制lc - cnc的相位和取向。通过机械力、电场和磁场的应用,取得了一定程度的成功;然而,由于各种分子间相互作用,实现可以在宏观尺度上利用的cnc的均匀排列仍然是难以捉摸的。由于其复杂的生物结构,表征cnc的相和取向也具有挑战性。在本报告中,我们介绍了通过自组装、机械力和电场来控制lc - cnc的相位和方向的方法。讨论了cnc在极性溶剂和空气/水界面上的液晶行为。研究了直流电场作用下cnc的平移和旋转行为与表面电荷和偶极矩的关系。此外,我们还介绍了一种非线性光学过程,即和频产生(SFG)光谱,用于lc - cnc的结构表征。利用SFG不仅可以分析cnc的晶相和结构,还可以分析cnc的极性排序,这是决定cnc机电性能的关键因素。基于纤维素的智能材料的开发将扩大可用功能材料的范围,这些功能材料重量轻,柔韧,机械韧性强,并且在中等高温(高达300°C)下热稳定。
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引用次数: 0
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Volume 1: Development and Characterization of Multifunctional Materials; Modeling, Simulation, and Control of Adaptive Systems; Integrated System Design and Implementation
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