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Showing papers in "Journal of Intelligent Material Systems and Structures in 2011"


Journal ArticleDOI
TL;DR: In this paper, the authors classify the shape morphing parameters that can be affected by planform alteration (span, sweep, and chord), out-of-plane transformation (twist, dihedral/gull, and span-wise bending), and airfoil adjustment (camber and thickness).
Abstract: Aircraft wings are a compromise that allows the aircraft to fly at a range of flight conditions, but the performance at each condition is sub-optimal. The ability of a wing surface to change its geometry during flight has interested researchers and designers over the years as this reduces the design compromises required. Morphing is the short form for metamorphose; however, there is neither an exact definition nor an agreement between the researchers about the type or the extent of the geometrical changes necessary to qualify an aircraft for the title ‘shape morphing.’ Geometrical parameters that can be affected by morphing solutions can be categorized into: planform alteration (span, sweep, and chord), out-of-plane transformation (twist, dihedral/gull, and span-wise bending), and airfoil adjustment (camber and thickness). Changing the wing shape or geometry is not new. Historically, morphing solutions always led to penalties in terms of cost, complexity, or weight, although in certain circumstances, thes...

1,068 citations


Journal ArticleDOI
TL;DR: In this paper, the authors present an extensive review of seismic applications of shape memory alloys (SMAs) for building and bridge structural engineering, including shape memory and superelastic effects.
Abstract: Shape memory alloys (SMAs) are a class of alloys that possess numerous unique characteristics. They offer complete shape recovery after experiencing large strains, energy dissipation through hysteresis of response, excellent resistance to corrosion, high fatigue resistance, and high strength. These features of SMAs, which can be exploited for the use in control of civil structures subjected to seismic events, have attracted the interest of many researchers in structural engineering over the past decades. This article presents an extensive review of seismic applications of SMAs. First, a basic description of two unique effects of SMAs, namely shape memory and superelastic effect, is provided. Then, the mechanical characteristics of the most commonly used SMAs are discussed. Next, the material models proposed to capture the response of SMAs in seismic applications are briefly introduced. Finally, applications of SMAs to buildings and bridges to improve seismic response are thoroughly reviewed.

336 citations


Journal ArticleDOI
TL;DR: In this article, the galloping of a bar with triangular cross section attached to a cantilever beam is proposed as an alternate power source for these wireless sensor nodes, and the maximum power output of 53 mW was measured at a wind velocity of 11.6 mph.
Abstract: There has been increasing interest in wireless sensor networks for a variety of outdoor applications including structural health monitoring and environmental monitoring. Replacement of batteries that power the nodes in these networks is maintenance intensive. A wind energy–harvesting device is proposed as an alternate power source for these wireless sensor nodes. The device is based on the galloping of a bar with triangular cross section attached to a cantilever beam. Piezoelectric sheets bonded to the beam convert the mechanical energy into electrical energy. A prototype device of size approximately 160 × 250 mm was fabricated and tested over a range of operating conditions in a wind tunnel, and the power dissipated across a load resistance was measured. A maximum power output of 53 mW was measured at a wind velocity of 11.6 mph. An analytical model incorporating the coupled electromechanical behavior of the piezoelectric sheets and quasi-steady aerodynamics was developed. The model showed good correlati...

234 citations


Journal ArticleDOI
TL;DR: In this article, the problem of vibration-based energy harvesting using piezoelectric transduction for civil infrastructure system applications with a focus on moving load excitations and surface strain fluctuations is formulated.
Abstract: This article formulates the problem of vibration-based energy harvesting using piezoelectric transduction for civil infrastructure system applications with a focus on moving load excitations and surface strain fluctuations. Two approaches of piezoelectric power generation from moving loads are formulated. The first one is based on using a bimorph cantilever located at an arbitrary position on a simply supported slender bridge. The fundamental moving load problem is reviewed and the input to the cantilevered energy harvester is obtained to couple with the generalized electromechanical equations for transient excitation. The second approach considers using a thin piezoceramic patch covering a region on the bridge. The transient electrical response of the surface patch to moving load excitation is derived in the presence of a resistive electrical load. The local way of formulating piezoelectric energy harvesting from two-dimensional surface strain fluctuations of large structures is also discussed. For a thi...

123 citations


Journal ArticleDOI
TL;DR: In this paper, the possibility of using piezoelectric energy harvesters as energy scavenging devices in highway bridges was investigated, where the structural vibration due to the motion of a load (vehicle) on the bridge was considered.
Abstract: This article investigates the possibility of piezoelectric energy harvesters as energy scavenging devices in highway bridges. The structural vibration due to the motion of a load (vehicle) on the b...

116 citations


Journal ArticleDOI
TL;DR: In this paper, gradient cellular centresymmetric auxetic configurations are evaluated as potential cores for aeroengine fan blades, and optimized to reduce the dynamic response for the first three fundamental modes.
Abstract: In this study, gradient cellular centresymmetric auxetic configurations are evaluated as potential cores for aeroengine fan blades, and optimized to reduce the dynamic response for the first three fundamental modes. Auxetic (negative Poisson’s ratio) re-entrant cellular beams are modeled, manufactured, and tested to assess their natural frequencies and mode shapes. Gradient versions of these beams with a varying internal cell angle are then designed to be incorporated as fillers in a baseline fan blade model. The optimized configurations of the gradient core lead to a substantial decrease of the mass of the fan blade, reduction of the dynamic modal displacements, and a lowering of the first three natural frequencies within the admissible frequency bandwidth.

115 citations


Journal ArticleDOI
TL;DR: In this paper, the design and experimental characterization of an electromagnetic transducer for energy harvesting from large structures (e.g., multistory buildings and bridges), for which the power levels can be above 100 W and disturbance frequencies below 1 Hz.
Abstract: This article reports on the design and experimental characterization of an electromagnetic transducer for energy harvesting from large structures (e.g., multistory buildings and bridges), for which the power levels can be above 100 W and disturbance frequencies below 1 Hz. The transducer consists of a back-driven ballscrew coupled to a permanent-magnet synchronous machine with power harvesting regulated via control of a four-quadrant power electronic drive. Design considerations between various subsystems are illustrated and recommendations in terms of minimal values are made for each design metric. Developing control algorithms to take full advantage of the unique features of this type of transducer requires a mechanical model that can adequately characterize the device’s intrinsic nonlinear behavior. A new model is proposed that can effectively capture this behavior. Comparison with experimental results verifies that the model is accurate over a wide range of operating conditions. As such, the model can...

107 citations


Journal ArticleDOI
TL;DR: In this article, a piezoelectric element is sandwiched between a proof mass and a base subjected to sinusoidal excitation, and the resulting relative motion is analyzed.
Abstract: Conventional energy harvester typically consists of a piezoelectric element, which is sandwiched between a proof mass and a base subjected to sinusoidal excitation. The resulting relative motion be...

104 citations


Journal ArticleDOI
TL;DR: The morphing air inlet is a structure with shape-changing capability as mentioned in this paper, which can "snap" open and closed and not require any external holding force to maintain its geometry.
Abstract: The morphing air inlet is a structure with shape-changing capability Shapes include that which is flush with an aerodynamic surface and also a submerged divergent channel suitable for use in an aircraft cooling system The air inlet structure is multistable in order that it can ‘snap’ open and closed and not require any external holding force to maintain its geometry Structural multistability is achieved using a novel combination of material prestress and bending stiffness tailoring Analytical and finite element models are developed in order to explain how this multistability is achieved and to predict the actuator requirements and bending strains within the structure The air inlet design is autoclave manufactured from carbon fiber reinforced plastic and tested as a proof-of-concept demonstrator The bending stiffness tailoring enables the structure to fulfill the conflicting requirements of large deformations, low mass, and high stiffness to withstand external loads The simple construction also aids ease of maintenance and reliability The morphing demonstrator behaves as a one degree-of-freedom system enabling simple actuation solutions, such as inflatable bladders, to be feasible

88 citations


Journal ArticleDOI
TL;DR: In this paper, the behavior of two sets of woven fiberglass/epoxy specimens, one with embedded and one with surface-mounted piezoelectric wafer transducers (lead zirconate titanate), were tested under axial tensile fatigue at high stress ratio, and the transducers were interrogated in pitch-catch mode at different stages of the specimens' life, while they were subjected to the mean test load (the testing machine is paused).
Abstract: The need to understand and monitor the integrity of structural components made of composite materials is becoming critical, due to an increase of the use of composites in aerospace, civil, wind energy, and transportation engineering. Off-the-shelf piezoelectric transducers embedded inside the composites or bonded onto the structure surface are a pos- sible solution for on-line structural health monitoring and non-destructive evaluation: they can be used to generate Lamb waves, which are able to detect damage. This article focuses on the behavior of two sets of woven fiberglass/epoxy specimens, one with embedded, one with surface-mounted piezoelectric wafer transducers (lead zirconate titanate). The specimens are tested under axial tensile fatigue at high stress ratio, and the transducers are interrogated in pitch-catch mode at different stages of the specimens' life, while they are subjected to the mean test load (the testing machine is paused). A novel signal processing technique based on wavelet thresholding/denoising and Gabor wavelet transform is discussed. This technique identifies changes in boundary conditions, loading/unloading prior to damage and during damage. It appears to correlate the contour area changes with the so-called characteristic damage state observed in the literature in composite laminates under tensile fatigue.

85 citations


Journal ArticleDOI
TL;DR: In this article, an analytical electromechanical model is proposed to predict the deflection, voltage, and power output of a proposed low-frequency micro-harvesting structure.
Abstract: An analytical electromechanical model is proposed to predict the deflection, voltage, and the power output of a proposed low-frequency micro-harvesting structure. The high natural frequencies of th...

Journal ArticleDOI
TL;DR: Periodic, shunted piezoelectric patches are applied for the control of wave propagation in beams in this article, where the patches are shunted through resonant circuits featuring a single and multiple resonances.
Abstract: Periodic, shunted piezoelectric patches are applied for the control of wave propagation in beams. The patches are shunted through resonant circuits featuring a single and multiple resonances. The p...

Journal ArticleDOI
TL;DR: In this paper, the performance of a combined shunted periodic piezoelectric patch array with a cantilever beam was analyzed by investigating the velocity amplitude of the beam upstream and downstream of the array section and the number of control elements in the array.
Abstract: The use of both shunted piezoelectric elements and periodic arrays have been investigated independently as well as used in conjunction to modify the vibration of a system Piezoelectric patches bonded to a cantilever beam which is shunted with an active circuit, specifically a negative capacitance shunt, can control broadband flexural vibrations of a structure Also, periodic arrays integrated into a structure allow for modification of propagating waves through the mechanical ‘‘stop-bands’’ The performance of a combined shunted periodic piezoelectric patch array will be analyzed in this study by investigating the velocity amplitude of the beam upstream and downstream of the array section and the number of control elements in the array The negative capacitance shunts caused a global spatial average velocity reduction of 5 dB at the modal peaks from 500 to 5000 Hz The reduction is shown to be greater in the downstream section of the beam Also, by increasing the number of patches in the array, the attenu

Journal ArticleDOI
TL;DR: In this paper, a continuous span morphing wing is described, which consists of two primary components: (1) zero-Poisson ratio morphing core and (2) fiber-reinforced elastomeric matrix composite skin with a nearly zero Poisson ratio in-plane.
Abstract: Recent developments in morphing aircraft research have motivated investigation into conformal morphing systems, that is, shape change without discrete moving parts or abrupt changes in the airfoil profile. In this study, implementation of a continuous span morphing wing is described. The system consists of two primary components: (1) zero-Poisson ratio morphing core and (2) fiber-reinforced elastomeric matrix composite skin with a nearly zero-Poisson ratio in-plane. The main goal for improved air vehicle efficiency was a nominal 100% change in area of the active wing section with less than 2.54 mm out-of-plane deflection under representative aerodynamic loading. Objectives of this study included exploring fabrication techniques for advanced morphing core shapes (i.e., having airfoil-shaped cross-section), exploiting customizable design parameters of in-house fabricated skin and core material, designing a prototype wing structure such that integration with a candidate UAV was feasible, and experimentally e...

Journal ArticleDOI
TL;DR: In this paper, the airfoil camber at the wing trailing edge on a full scale wing of a civil regional transportation aircraft is controlled by substituting a traditional sparsified shape memory alloys (SMAs).
Abstract: Multiple flight regimes during typical aircraft missions mean that a single unique optimized configuration, that maximizes aerodynamic efficiency and maneuverability, cannot be defined. Discrete components such as ailerons and flaps provide some adaptability, although they are far from optimal. Wing morphing can significantly improve the performance of future aircraft, by adapting the wing shape to the specific flight regime requirements, but also represents a challenging problem: the structure has to be stiff to maintain its shape under loads, and yet be flexible to deform without collapse. One solution is to adopt structural elements made of smart materials; Shape Memory Alloys (SMAs) have demonstrated their suitability for many static applications due to their high structural integration potential and remarkable actuation capabilities.In this work, the airfoil camber at the wing trailing edge on a full scale wing of a civil regional transportation aircraft is controlled by substituting a traditional sp...

Journal ArticleDOI
TL;DR: In this article, a requirement formulation based on a time-series of spanwise lift distributions on a morphing wing, representing the mission profile of the aircraft as a whole, is presented.
Abstract: The design of an airfoil structure involves the disciplines of aerodynamics and structural mechanics, both of which are considered in the design methodology presented in this article. The approach described in this article starts from a requirement formulation based on a time-series of spanwise lift distributions on a morphing wing, representing the mission profile of the aircraft as a whole. This allows to specify goals based directly on aerodynamic performances instead of prescribing fixed geometrical shapes. Using the aero-structural analysis tool presented here, together with a parametrization representing the airfoil outer shape as well as its mechanical properties, allows the formulation of a combined aero-structural optimization problem. Promising aerodynamic and structural morphing performances have been obtained by applying the method to a morphing concept using Dielectric Elastomers (DEs) as actuators. Although the coupled physics are considered and a detailed material model has been used, resul...

Journal ArticleDOI
TL;DR: In this paper, the free and forced vibration characteristics of an FGPM beam under thermo-electro-mechanical loads using the higher-order shear deformation beam theory were investigated.
Abstract: This article presents the free and forced vibration characteristics of an FGPM beam under thermo-electro-mechanical loads using the higher-order shear deformation beam theory. The beam properties a...

Journal ArticleDOI
TL;DR: In this paper, external vibration energy can be used to assist with the actuation between stable states, which is of interest in the case when surface bonded macrofiber composites (MFC) actuators are employed as actuation system.
Abstract: Composite laminate plates designed to have two statically stable configurations have been the focus of recent research, with a particular emphasis on morphing applications. In this article, we consider how external vibration energy can be used to assist with the actuation between stable states. This is of interest in the case when surface bonded macrofiber composites (MFC) actuators are employed as the actuation system. Typically, these type of actuators have been found to require considerably high voltage inputs to achieve significant levels of actuation authority. Therefore, assisting the actuation process will allow lower voltages and/or stiffer plates to be actuated. Two bi-stable plates with different thickness, [0(4) - 90(4)](T) and [0(2) - 90(2)](T), are tested. The results show a significant reduction in the force required to change state for the case where dynamic excitation provided by an MFC actuator is used to assist the process. This strategy demonstrates the potential of dynamically assisting actuation as a mechanism for morphing of bi-stable composites.

Journal ArticleDOI
TL;DR: In this article, the great interest in developing morphing airfoils is mainly based on their capability to adapt their shape to optimize some specific aircraft performance indices during the mission, however, they do not consider the effect of the shape on the performance of the aircraft.
Abstract: The great interest in developing morphing airfoils is mainly based on their capability to adapt their shape to optimize some specific aircraft performance indices during the mission. Nevertheless, ...

Journal ArticleDOI
TL;DR: In this paper, a magnetorheological elastomer (MRE)-based semi-active (SA) vibration isolator is developed and tested in real-time with a SA controller.
Abstract: A magnetorheological elastomer (MRE-based semi-active (SA) vibration isolator is developed and tested in real-time with a SA controller, illustrating the feasibility of MRE-based isolators. While several researchers have applied MREs to tunable vibration absorbers (TVAs), little work has been done using MREs in primary isolation systems. Further, in cases where TVAs were developed, few SA controllers were implemented in proof of concept experiments. This article presents a magnetically biased MRE-based vibration isolator, which enables the device to have a fail-safe operation in the event of a power failure. To test the effectiveness of the MRE isolator, a SA controller is developed to minimize the payload velocity. A comparison by simulation of variable modulus and damping systems is also presented. Finally, experimental results are given, showing that the MRE isolator and SA controller system reduce resonances and payload velocities by 16-30% when compared to passive systems.

Journal ArticleDOI
TL;DR: In this paper, the design assessment of an innovative flap architecture for a variable-camber tra... is presented, where the authors came to the definition of a novel morphing architecture acting as high-lift device.
Abstract: Several flight regimes occurring during a typical aircraft mission make it impossible to define a unique optimized wing configuration able to maximize aerodynamic efficiency, maneuverability, and stability in every flight condition. Components like ailerons and flaps, in some way, guarantee a certain level of adaptability, being far from optimal. Wing morphing can strongly improve the aerodynamic efficiency of future aircraft by assuring an optimal adaptive behavior which best fits the specific flight regime requirements. Such an approach, in spite of related benefits, presents a challenging problem: the same structure rigid enough to keep its shape under the aerodynamic loads has to largely deform itself without undergoing structural collapses. In the frame of a research project funded by Alenia Aeronautica S.p.A., the authors came to the definition of a novel morphing architecture acting as high-lift device.In this study, the design assessment of an innovative flap architecture for a variable-camber tra...

Journal ArticleDOI
TL;DR: In this article, the non-linear dynamics of an adaptive tuned vibra- tion absorber (ATVA) with a shape memory alloy (SMA) element is analyzed and the influence of hysteretic behavior due to stress-induced phase transformation is considered.
Abstract: The tuned vibration absorber (TVA) is a well-established passive vibration control device for achieving vibration reduction of a primary system subjected to external excitation This contribution deals with the non-linear dynamics of an adaptive tuned vibra- tion absorber (ATVA) with a shape memory alloy (SMA) element Initially, a single-degree of freedom oscillator with an SMA element is analyzed showing the general characteristics of its dynamical response Then, the analysis of an ATVA with an SMA element is carried out Initially, small amplitude vibrations are considered in such a way that the SMA element does not undergo a stress-induced phase transformation Under this assumption, the SMA influ- ence is only caused by stiffness changes corresponding to temperature-induced phase trans- formation Afterwards, the influence of the hysteretic behavior due to stress-induced phase transformation is considered A proper constitutive description is employed in order to cap- ture the general thermomechanical aspects of the SMAs The hysteretic behavior introduces complex characteristics to the system dynamics but also changes the absorber response allow- ing vibration reduction in different frequency ranges Numerical simulations establish com- parisons of the ATVA results with those obtained from the classical TVA

Journal ArticleDOI
TL;DR: In this paper, a new approach is proposed to effectively detect the initiation and progression of structural damage by combining the global dynamic and the local electromechanical impedance (EMI) techniques, using the same set of surface-bonded piezoelectric ceramic (PZT) patches as sensors.
Abstract: In this article, a new approach is proposed to effectively detect the initiation and progression of structural damage by combining the global dynamic and the local electromechanical impedance (EMI) techniques, using the same set of surface-bonded piezoelectric ceramic (PZT) patches as sensors. The PZT patches are used to determine the natural frequencies and the strain mode shapes of the structure (for use in the global dynamic technique) as well as to acquire the electromechanical admittance signature (for use in the EMI technique) to facilitate an improved damage assessment. Occurrence and location of the incipient damage are determined using the EMI technique, whereas for moderate to severe damages, the location and the severity are arrived at through the global dynamic technique. Finally, damage severity is determined in terms of the original stiffness of structure using the strain mode shapes directly determined using the PZT patches. The proposed technique is illustrated using two specimens—a 4-m lo...

Journal ArticleDOI
TL;DR: In this paper, the complex response of the IPMC-like body to electrical and mechanical stimuli is set within the context of the 3-D theory of linear elasticity, and a field of chemically induced distortions is included in the model; these mechanical distortions and the derivation of the final PDE equations of the multiphysics problem are thermodynamically consistent.
Abstract: The modeling of the complex response of the IPMC-like body to electrical and mechanical stimuli is set within the context of the 3-D theory of linear elasticity. A field of chemically induced distortions is included in the model; these mechanical distortions and the derivation of the final PDE equations of the multiphysics problem are thermodynamically consistent. Some results of the numerical experiments are revisited through an original analysis of the stress distribution along the IPMC-like body.

Journal ArticleDOI
TL;DR: In this paper, a base-isolation system using magnetorheological (MR) elastomers was investigated. Magnetic elastomer is a new class of smart materials whose elastic modulus or stiffness can be adjusted dependi...
Abstract: This article investigates a smart base-isolation system using magnetorheological (MR) elastomers, which are a new class of smart materials whose elastic modulus or stiffness can be adjusted dependi...

Journal ArticleDOI
TL;DR: In this paper, separated carbon nanotubes (CNTs) aggregations were bridged by short carbon fibers in the conductive polymer composites, where a styrene-based shape memory polymer (SMP) was selected as the matrix resin.
Abstract: In this article, separated carbon nanotubes (CNTs) aggregations were bridged by short carbon fibers in the conductive polymer composites, where a styrene-based shape memory polymer (SMP) was selected as the matrix resin. Due to the synergistic effect of hybrid fillers, the electrical resistivity of the SMP composites was significantly decreased in comparison with those with only CNTs embedded. Benefits offered by the hybrid fillers to the electrical, mechanical, and shape memory properties of the developed conductive SMP composites were experimentally demonstrated in detail. The additionally acquired shape memory capability could expand the application scope of traditional conductive polymer composites.

Journal ArticleDOI
TL;DR: In this article, a cellular hexagonal morphology and kirigami techniques are used to produce a wingbox for morphing applications, which can be completely or partially folded, providing some shape-adapting capabilities for possible morphological applications.
Abstract: This study introduces the design and manufacturing of a wingbox based on a cellular hexagonal morphology and produced using kirigami techniques. The wingbox is manufactured in autoclave-cured woven Kevlar fabric using ply-cutting patterns designed around an airfoil profile. The cellular wingbox can be completely or partially folded, providing some shape-adapting capabilities for possible morphing applications. A numerical and analytical evaluation of the torsional stiffness of the wingbox with novel elastomeric face skins is also performed.

Journal ArticleDOI
TL;DR: A finite element analysis and design of the morphing cellular structure is presented, ensuring that the local strains in the elastic ligaments of the cellular structure do not exceed the maximum allowable, even as the section undergoes a large global strain.
Abstract: Chord extension morphing of helicopter rotors has recently been shown to be highly beneficial for stall alleviation, with the ability to reduce power near the envelope boundaries and increase maximum gross weight, altitude, and speed capability of the aircraft. This article presents a morphing mechanism to extend the chord of a section of the helicopter rotor blade. The region aft of the leading-edge spar contains a morphing cellular structure. In the compact state, the edge of the cellular structure aligns with the trailing edge of the rest of the blade. When the morphing cellular structure is in the extended state, the chord of that section of the blade is increased by 30%. In transitioning from compact to extended states, the cellular structure slides along the ribs which define the boundaries of the morphing section in the spanwise direction. The cellular section has mini-spars running along the spanwise direction to attach the flexible skin and provide stiffness against camber-like deformations due t...

Journal ArticleDOI
TL;DR: In this article, the non-dimensional analysis of adaptive magnetorheological energy absorbers (MREAs) for drop-induced shock mitigation was performed using a single-degree-of-freedom system with an MREA.
Abstract: This study addresses the non-dimensional analysis of adaptive magnetorheological energy absorbers (MREAs) for drop-induced shock mitigation. The control objective to ensure that the payload mass comes to rest at the end of the available stroke of the MREA, that is, a ‘soft landing.’ The governing equation of motion of a single-degree-of-freedom system with an MREA was derived. The Bingham number was defined and its effect on the system response was examined. A comprehensive non-dimensional analysis was conducted using non-dimensional stroke, velocity and acceleration, where Bingham number and time constant were key parameters. An optimal Bingham number - based on drop velocity, payload mass, and passive damping - minimized the drop-induced shock loads transmitted to the payload by utilizing maximum damper stroke.

Journal ArticleDOI
TL;DR: In this article, the authors examined four conventional vibration suppression control laws and four hybrid modifications of these laws using a switching method, and determined which of these eight controllers results in the least amount of power flow to the actuator to have the same settling time under free vibrations.
Abstract: The research study presented here examines four conventional vibration suppression control laws and four hybrid modifications of these laws using a switching method. The motivation is to determine which of these eight controllers results in the least amount of power flow to the actuator to have the same settling time under free vibrations. The reason to look at reduced energy controllers is the idea that in some applications, very little energy is available for control, yet passive and semi-active methods cannot meet performance demands. In particular, the eventual goal is to reduce transient vibrations of smart structures using energy obtained from harvesting and/or low-power storage devices (batteries or super capacitors), as often desirable in aerospace systems. The four conventional active control systems compared in this study are Positive Position Feedback (PPF) control, Proportional Integral Derivative (PID) control, non-linear control, and Linear Quadratic Regulator (LQR) controls. A hybrid versio...