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"Smart structures"
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Multiphysics design of programmable shape-memory alloy-based smart structures via topology optimization
We present a novel multiphysics and multimaterial computational design framework for shape-memory alloy-based smart structures. The proposed framework uses topology optimization to optimally distribute multiple material candidates within the design domain, and leverages a nonlinear phenomenological constitutive model for shape-memory alloys (SMAs), along with a coupled transient heat conduction model. In most practical scenarios, SMAs are activated by a nonuniform temperature field or a nonuniform stress field. This framework accurately captures the coupling between the phase transformation process and the evolution of the local temperature field. Thus, the resulting design framework is able to optimally tailor the two-way shape-memory effect and the superelasticity response of SMAs more precisely than previous algorithms that have relied on the assumption of a uniform temperature distribution. We present several case studies, including the design of a self-actuated bending beam and a gripper mechanism. The results show that the proposed framework can successfully produce SMA-based designs that exhibit targeted displacement trajectories and output forces. In addition, we present an example in which we enforce material-specific thermal constraints in a multimaterial design to enhance its thermal performance. In conclusion, the proposed framework provides a systematic computational approach to consider the nonlinear thermomechanical response of SMAs, thereby providing enhanced programmability of the SMA-based structure.
Journal Article
Active Disturbance Rejection Control for Piezoelectric Smart Structures: A Review
The piezoelectric smart structures, which can be labeled as the cream of the crop of smart structures without overstatement, are strongly impacted by a large number of uncertainties and disturbances during operation. The present paper reviews active disturbance rejection control (ADRC) technologies developed for application in piezoelectric smart structures, focusing on measurement, analysis, estimation, and attenuation of uncertainties/disturbances in systems. It first explained vast categories of uncertainties/disturbances with their adverse influences. Then, after a brief introduction to the application of basic ADRC in smart structures, a thorough review of recently modified forms of ADRC is analyzed and classified in terms of their improvement objectives and structural characteristics. The universal advantages of ADRC in dealing with uncertainties and its improvement on the particularity of smart structures show its broad application prospects. These improved ADRC methods are reviewed by classifying them as modified ADRC for specific problems, modified ADRC by nonlinear functions, composite control based on ADRC, and ADRC based on other models. In addition, the application of other types of active anti-disturbances technologies in smart structures is reviewed to expand horizons. The main features of this review paper are summarized as follows: (1) it can provide profound understanding and flexible approaches for researchers and practitioners in designing ADRC in the field and (2) light up future directions and unsolved problems.
Journal Article
Piezoelectric Actuators in Smart Engineering Structures Using Robust Control
In this study, piezoelectric patches are used as actuators to dampen structural oscillations. Damping oscillations is a significant engineering challenge, and the use of piezoelectric patches in smart structures allows for a reduction in oscillations through sophisticated control methods. This analysis involved H-infinity (H∞) robust analysis. H∞ (H-infinity) control formulation is a robust control design method used to ensure system stability and performance under disturbances. When applied to piezoelectric actuators in smart structures, H∞ control aims to design controllers that are robust to variations in system dynamics, external disturbances, and modeling uncertainties, while meeting specified performance criteria. This study outlines the piezoelectric effects and advanced control strategies. A structural model was created using finite elements, and a smart structural model was analyzed. Subsequently, dynamic loads were applied and oscillation damping was successfully achieved by employing advanced control techniques.
Journal Article
Smart Metamaterial Based on the Simplex Tensegrity Pattern
In the present paper, a novel cellular metamaterial that was based on a tensegrity pattern is presented. The material is constructed from supercells, each of which consists of eight 4-strut simplex modules. The proposed metamaterial exhibits some unusual properties, which are typical for smart structures. It is possible to control its mechanical characteristics by adjusting the level of self-stress or by changing the properties of structural members. A continuum model is used to identify the qualitative properties of the considered metamaterial, and to estimate how the applied self-stress and the characteristics of cables and struts affect the whole structure. The performed analyses proved that the proposed structure can be regarded as a smart metamaterial with orthotropic properties. One of its most important features are unique values of Poisson’s ratio, which can be either positive or negative, depending on the applied control parameters. Moreover, all of the mechanical characteristics of the proposed metamaterial are prone to structural control.
Journal Article
Smart Structures
Synthesizing knowledge acquired as a result of significant research and development over recent years, Smart Structures clearly illustrates why these structures are of such intense current interest. Gaudenzi offers valuable insight into both how they behave and how and at what cost they could be designed and produced for real life applications in cutting edge fields such as vibration control, shape morphing, structural health monitoring and energy transduction. Smart Structures offers a basic and fundamental description of smart structures from the physical, mathematical and engineering viewpoint. It explains the basic physics relating to the behaviour of active materials, gives the mathematical background behind the phenomena, and provides tools for numerical simulation. It also offers an insight into considerations related to the manufacturing, assembly and integration of smart structures. Smart Structures is divided into 5 sections: in the first part a definition of smart structures is proposed, the motivation for developing a smart structure presented and the basic physics of active materials such aspiezoelectrics, electrostrictives, magnetostrictives and shape memory alloys briefly recalled. A second part is devoted to the mathematical modelling of piezoelectric bodies. The third part discusses actuation and sensing mechanisms based on which the active part of a smart structure will produce \"results\" on the passive one. The fourth part deals with active composites at the micromechanical and macromechanical level, and the fifth part is devoted to applications of smart structures with examples taken from the aerospace field. This introduction to smart structures will be useful both for structural and mechanical designers, and for students and researchers at graduate level or beyond. The diverse industries involved in this rapidly evolving field include aerospace, automotive and bioengineering.
eBook
μ-Analysis and μ-Synthesis Control Methods in Smart Structure Disturbance Suppression with Reduced Order Control
In this study, we created an accurate model for a homogenous smart structure. After modeling multiplicative uncertainty, an ideal robust controller was designed using μ-synthesis and a reduced-order H-infinity Feedback Optimal Output (Hifoo) controller, leading to the creation of an improved uncertain plant. A powerful controller was built using a larger plant that included the nominal model and corresponding uncertainty. The designed controllers demonstrated robust and nominal performance when handling agitated plants. A comparison of the results was conducted. As an example of a general smart structure, the vibration of a collocated piezoelectric actuator and sensor was controlled using two different approaches with strong controller designs. This study presents a comprehensive simulation of the oscillation suppression problem for smart beams. They provide an analytical demonstration of how uncertainty is introduced into the model. The desired outcomes were achieved by utilizing Simulink and MATLAB (v. 8.0) programming tools.
Journal Article
The vibration suppression of solar panel based on smart structure
This paper provides a solution to the active vibration control of a microsatellite with two solar panels. At first, the microsatellite is processed as a finite element model containing a rigid body and two flexible bodies, according to the principles of mechanics, and that the dynamic characteristics are solved by modal analysis. Secondly, the equation involving vibration control is established according to the finite element calculation results. There are several actuators composed of macro fibre composite on the two solar panels for outputting control force. Furthermore, the control voltage for driving actuator is calculated by using fuzzy algorithm. It is clear that the smart structure consists of the flexible bodies and actuators. Finally, the closed-loop control simulation for suppressing harmful vibration is established. The simulation results illustrate that the responses to the external excitation are decreased significantly after adopting fuzzy control.
Journal Article