Macro Fiber Composite Actuators Research Articles

Modal characteristics of a cantilever beam with the free-end immersed in a magnetorheological fluid

This paper presents modal characteristics of a flexible cantilever beam with its free-end immersed in a magnetorheological (MR) fluid. Immersing the beam in MR fluid allows to change boundary conditions of the free-end by controlling the magnetic field intensity across MR fluid. Hence, the modal characteristics of the beam, such as natural frequency are varied as a function of the magnetic field applied to MR fluid domain. First, a thin cantilever beam was manufactured according to a design comprising a macro fiber composite (MFC) actuator for the beam excitation. Then, the dynamic responses of the beam were measured under two conditions: the free-end vibrating in air and the free-end immersed in MR fluid with different magnetic field intensities. The changes in the dynamic characteristics, such as resonance frequency, damping ratio, and resonant amplitude were evaluated and compared for various conditions. A significant reduction in the natural frequency was observed when the free-end of the beam was immersed in MR fluid and changed further when coil current was applied. In addition, the multiphysics simulation of the system was performed using finite element method. The numerical results of the dynamic response of the system showed good agreement with experimental results.

Understanding the guided waves propagation behavior in timber utility poles

Guided stress waves are considered one of the most efficient and reliable techniques that provide sufficient quantitative and qualitative assessment. In this study, we focused on scrutinizing the propagation behavior of guided waves in western white pine timber poles, experimentally, and numerically using COMSOL Multiphysics. Macro fiber composites (MFCs), due to their flexibility and convenience to install on curved profiles, were used to actuate and sense guided waves along the tested specimens. Various solutions for wave mode tuning and characterization have been tested for traction free and embedded boundary conditions. The behavior of propagating wave modes was analyzed and compared in the two boundary conditions tested. Also, the excitation frequency, based on the dispersion curves generated for transversely isotropic timber, was selected to ensure the presence of favorable propagating (for instance longitudinal modes) modes with minimal dispersion. Undesirable wave modes—such as flexural modes (non-axisymmetric)—were eliminated by a ring design composed of multiple MFC actuators coupled around the pole’s circumference. The remaining propagating longitudinal modes and their reflections, such as modes L(0,1) and L(0,2) propagating at nearly 1000 m/s and 800 m/s respectively, were significantly enhanced by the actuation of the ring which could be effectively used for the assessment process. The results demonstrated the complexity of the propagating modes in circular timber structures and the importance of the ring design in the excitation of the selected modes of interest and damping unwanted ones.

New Efficient Technique for Finite Element Modeling of Macro Fiber Composite Piezoelectric Materials

A lot of interest to simulate piezocomposite actuators with finite element method has been increased recently. However, there are still open questions regarding the modeling methodology, accuracy, and computational time cost. In this work, a new technique for modeling macro fiber composite piezoelectric actuator by finite element analysis is proposed. The presented technique models the piezocomposite actuator as a simple monolithic piezoceramic material with just two electrodes along its longitudinal extremes instead of using the actual large number of electrodes which results in very fine finite element mesh with high computational time cost. The proposed technique is validated successfully by comparing its results with those of the actual detailed model as well as with the published experimental results and manufacturer’s data.

Active vibration control analysis in smart composite structures using ANSYS

Piezoelectric Macro-Fiber Composite (MFC) utilization is increasing in engineering fields due to its strong actuation forces and high flexibility. In this paper, piezoelectric ( ) type (M8528-P1) patches are applied for active control of a cantilever composite beam. A linear coupled finite element model for piezoelectric MFC actuation of the composite beam was developed based on the APDL-ANSYS codes by using linear piezoelectric constitutive equations to study smart composite beam behavior in open and closed-loop cases. Active vibration control response of laminated composite beams with various stacking sequence configurations was examined, and the results were compared. In this, the proportional type (kp) of control algorithms is utilized, and in the summary of work refined two sets of finite element models. The first set their laminates to have an orientation (0 with 90), and others have an orientation (0 with 45). When the control signal applied with the gain (kp) to a system increases, the rise time generally decreases, the actuator voltages for different control gain for all cases are observed with the increase in the proportional constant. The findings of this study indicate that the composite beams composed from (0/90) stacking sequence sets had reached stability state faster than the composite beams composed from (0/45) stacking sequence sets.

Analysis of Novel Morphing Trailing Edge Flap Actuated by Multistable Laminates

This paper presents an analysis of a novel morphing trailing edge flap design for a wind turbine rotor blade with embedded multistable composite plates. Morphing trailing edge devices are promising candidates for reducing loads in variable wind conditions and turbulent flows as well as capable of changing the shape rapidly. The application of multistable laminates allows large deformations with modest actuation demand, without the need for a continuous supply of energy. They can undergo snap-through with the help of Macro Fiber Composites actuator patches. A rectangular multistable plate is designed with the optimal location of actuators, aiming at two-way snap-through without the loss of bistability. A multi-objective derivative-free optimization scheme is used to minimize the snap-through voltages and maximize the out-of-plane displacements. The designed multistable plates with actuators are embedded at a suitable location of the morphing trailing edge flap. As the multistable plates snap, the flap deflects to a new position. The mechanism of the new morphing concept is simulated and analyzed with finite element tools.

Dynamic control of kinematically excited laminated, thin-walled beam using macro fibre composite actuator

In this study, the problem of vibration reduction in a cantilever beam under kinematic excitation is considered. Numerical studies and laboratory tests are performed on a composite beam with an embedded macro fibre composite actuator. Select methods of vibration reduction, that is, proportional (P), derivative (D), and PD controls, are presented. The properties of the control system are described using the first-order inertial term. The experimental results are used to identify the time constant and verify the proposed concept. Finally, the possibility of vibration control is demonstrated numerically using the finite element model.

Research on active vibration control of flexible wing based on MFC actuator

An active vibration control scheme was proposed based on Macro Fiber Composite (MFC) actuators for the bending and torsional vibration control of large flexible lightweight wing structures. Firstly, a finite element modeling and modal analysis of a flexible wing are carried out. Further, the number, type, and location distribution of the MFC actuators bonded on the supported beam of the wing are designed. Then, the actuated characteristics of the two kinds of MFC actuators required for bending and torsional vibration controls was theoretically analyzed. The simulation model of the overall vibration control system was also finally obtained. Finally, through ANSYS simulation analysis, the vibration control effect of the current control system on the first two-order low-frequency modal response of the wing structure is given. The simulation results show that the proposed active vibration control scheme has specific feasibility and effectiveness.

Oscillating performance and propulsion mechanism of biomimetic underwater oscillatory propulsion by resonant actuation of macro fiber composites

An oscillatory propulsion driven by the resonant actuation of macro fiber composites is proposed. Specifically, the propulsion is modeled as a cantilever internally actuated by bonded macro fiber composite actuators, with a passive attachment. Underwater oscillating performances of the proposed device are investigated experimentally. Experimental results show that the maximum oscillating magnitude and velocity of the propulsion are 4.20 mm and 163.5 mm/s. Computational fluid dynamic simulations for the formation of the vortices caused by the oscillating structure are conducted. The maximum instantaneous and mean thrusts of the propulsion in the stable periods are 4.72 mN and 1.87 mN, respectively. The initiation, development, separation, and propagation stages of the vortex caused by the oscillating structure are revealed. The phenomenon of the reverse Karman vortex street is observed. The location and distribution of the vortices are also indicated. A high-velocity region between the neighboring counterrotating vortices is detected from the cycle-averaged velocity fields. The maximum flow velocity in the region is approximately 1.5 times the oscillating velocity of the propulsion. Furthermore, a jet, resembled by the flow, ejects from the propulsion tip and spreads out backwards. The propulsion travels forward by the reaction force of the pseudo-jet. Those results may be helpful for the studies on biomimetic underwater propulsion devices.

Modeling of macro fiber composite actuated laminate plates and aerofoils

This article investigates the modeling of macro fiber composite-actuated laminate plates with distributed actuator patches. The investigation details an analytical and finite element modeling, with experimental validation of the bending strain and deflection of an epoxy E-glass fiber composite laminate. An analytical approach is also developed to estimate the plate deflection from the experimental strain measurements. The analytical method uses direct integration of single dimensional plate bending moments obtained by strain-induced shear moments from the macro fiber composite actuators. Finite element analysis software was used with the composite laminate modeled in ANSYS ACP. The results from both analytical and numerical models show good agreement with the experimental results, with strain values agreeing within 20 ppm and the maximum difference in deflection not exceeding 0.1 mm between models. Finally, an application of the analytical model for developing morphing aerofoil designs is demonstrated.

Research on actuation performance of macro fiber composites based on third order shear deformation theory

Macro fiber composite (MFC) is a new type of high-performance smart piezoelectric material with an ultrathin section, which is used to decrease vibration and the noise of plate and shell structures due to high output and good flexibility. At present, the classical plate theory (CPT) has been adopted to study actuation performance of MFC. It does not consider shear deformation of an MFC integrated plate structure and cannot obtain the actuation force distribution of MFC, so that the accurate exerting position of the actuation force cannot be obtained. To solve this problem, this paper proposes that the third order shear deformation theory (TSDT) should be used to deduce the MFC actuation force formula which considers shear deformation of the MFC integrated plate structure and introduces a local displacement distribution function to ensure that the adhered interface between the MFC and the plate satisfy deformation compatibility and stress balance. Consider the end displacement calculation of an MFC integrated beam structure, for example. The comparison among the MFC actuation force formula based on TSDT, the MFC actuation force formula based on CPT, and the MFC integrated beam experiment indicates that the first can obtain higher calculation accuracy. On the basis of studying the MFC actuation force formula, the actuation simulation calculation of the plate by MFC is performed through making MFC equivalent to the actuation force and bending moment acting on plate structure to carry out the actuation experiment of an MFC integrated plate structure under the actuation of harmonic voltage of different amplitude values. The result shows that the experiment well matches the acceleration time history of simulation.

Experiment and Modeling on Macro Fiber Composite Stress-Induced Actuation Function Degradation

The effect of stress depolarization will cause actuation function degradation of a piezoelectric actuator, which can eventually trigger function failure of the piezoelectric smart structure system. In the present study, we experimentally demonstrate the degradation process of the actuation function of the Macro Fiber Composite (MFC) piezoelectric actuator. Actuation function degradation data of MFC actuators undergoing cyclic loads with four different stress amplitudes have been measured. Based upon the experimental results, the radial basis function (RBF) neural network learning algorithm was adopted to establish a neural network model, in order to predict the actuation function degenerative degree of the MFC actuator, undergoing arbitrary cyclic load within the concerned stress amplitude range. The maximum relative error between the predicted result and our experimental result is 4%.

Underwater oscillation performance and 3D vortex distribution generated by miniature caudal fin-like propulsion with macro fiber composite actuation

Underwater biomimetic propulsion systems that mimic the BCF (Body and/or Caudal Fin) fishes have attracted considerable attention. A miniature caudal fin-like propulsion device, whose design is based on the morphology and kinematics of the koi fish, is proposed in this paper. The propulsion is actuated by flexible fiber-based piezoelectric actuators, Macro Fiber Composite (MFC). A vacuum fabrication procedure is employed to bond the components of the proposed device. The underwater oscillation performances of the proposed propulsion at different steady-state sinusoidal excitations are experimentally investigated. Computational fluid dynamic (CFD) analysis is conducted to investigate the three-dimensional flow generated by the oscillation propulsion system. A simplified model, where the internal bending moment provided by the MFC actuators is replaced by a shear force, is created based on the obtained experimental data. The CFD simulations demonstrate that the maximum instantaneous and mean thrusts generated by the propulsion system during the stable period are 21.5 and 9.5 mN, respectively. These are consistent with the Lighthill’s elongated-body theory. Then, the uneven spatial distributions of the instantaneous vorticity around the propulsion are visualized, using seven two-dimensional planes intersecting at various locations. The CFD results suggest that the vorticity distributions around the trailing and leading edges of the caudal fin considerably differ because of the fin’s unique shape. A reverse Karman vortex street pattern is observed behind the trailing edge of the caudal fin. This indicates a thrust-producing pattern. On the other hand, a Karman vortex street pattern is distinctly observed before the leading edge. This indicates a drag-producing pattern. The geometry and shape effects of the caudal fin-like propulsion device are identified consequently. Those obtain results may be beneficial for the design of underwater vehicles with oscillation fin-like propulsion system.

Active multimode vibration control of a smart structure using macro fiber composite actuators based on ANFIS

In this study, vibration control was achieved using macro fiber composite actuators initiated by feedback from polyvinylidene difluoride (PVDF) membrane sensors. First, the structure mode was found using the finite element method after which simulation of the effect of piezoelectric actuators on the structure as well as a feasibility investigation was carried out. The ANSYS Workbench was used for parametric design and to determine the best position for the actuators. Structure vibration in different modes was measured using PVDF membrane sensors for feedback control and to investigate the vibration reduction effect achieved with three individual controllers. The pros and cons of active vibration reduction control were also examined in several different modes. The experimental results obtained with several types of vibration reduction control were compared: Type-1 fuzzy control, Type-1 adaptive fuzzy control, and the vibration reduction effect of an adaptive neuro-fuzzy inference system. The results showed that the adaptive neuro-fuzzy inference system controller was the best choice under the experimental conditions used in this study.

Simulation Analysis of Bionic Robot Fish Based on MFC Materials

With the development of marine resources, research on underwater robots has received unprecedented attention. The discovery and application of new smart materials provide new ideas for the research of underwater robots, which can overcome the issues of traditional underwater robots and optimize their design. A macro fiber composite (MFC) is a new type of piezoelectric fiber composite that combines actuators and sensors. The material has excellent deflection, good flexibility, and a high electromechanical coupling coefficient. Bionic mechatronics design is an effective way to innovate mechatronics in the future and can significantly improve mechatronics system performance. As an important issue for the design of bionic mechatronics, it is necessary to make robots as soft as natural organisms to achieve similar biological movement with both higher efficiency and performance. Compared with traditional rigid robots, the design and control of a soft robotic fish are difficult because the coupling between the flexible structure and the surrounding environment should be considered, which is difficult to solve due to the large deformation and coupling dynamics. In this paper, an MFC smart material is applied as an actuator in the design of bionic robotic fish. Combined with the piezoelectric constitutive and elastic constitutive equations of the MFC material, the voltage-drive signal is converted to a mechanical load applied to the MFC actuator, which makes the MFC material deform and drives the movement of the robotic fish. The characteristics of caudal fin motion during the swimming process of the bionic robotic fish were analyzed by an acoustic-solid coupling analysis method. The motion control analysis of the bionic robotic fish was carried out by changing the applied driving signal. Through numerical analysis, a new type of soft robotic fish was designed, and the feasibility of using an MFC smart material for underwater bionic robotic fish actuators was verified. The new soft robotic fish was successfully developed to achieve high performance.

Experimental analysis of active–passive vibration control on thin-walled composite beam

In the study presented, active and passive vibration control techniques for a thin-walled composite beam were developed and experimentally analysed. An MFC (Macro Fibre Composite) actuator was used, together with the magnetic forces between two permanent cuboidal magnets (passive vibration control) for vibration damping applications. After the experiments conducted with active vibration control (MFC actuator), it was found that in all cases, the vibration damping of the analysed system was much higher at its resonant frequency. Nevertheless, due to the experimental results, it could be concluded that active and passive vibration control systems were efficient for thin-walled composite beam vibration amplitude control. Methodology for thin-walled composite beam vibration control analysis was developed and presented in the article.

Modeling, analysis, and control of MFC sandwiched laminate panel flutter with general layups and arbitrary boundary conditions

In this paper, a new solution approach based on Lagrange multipliers is developed for aeroelastic panel flutter analysis of rectangular composite plates sandwiched by two Macro Fiber Composites (MFCs). The smart panel has general stacking sequences and subjected to the elastic edge restraints. By utilizing the assumed mode technique, the displacements and electric potentials are expanded using formerly determined mode shapes. Afterward, the potential and kinetic energies of the problem are achieved and by employing the Lagrange equation, the discretized equations of the motion are obtained. The supersonic aerodynamic load is modeled through the well-known piston theory and included within the equations by means of the non-conservative force term of the Lagrange equation. Deriving the equations is more simplified thanks to the orthogonality of the Legendre polynomials. Finally, the input voltage of the MFC actuator is determined through the proportional or velocity feedback control algorithms based on the sensor output. The capability and credibility of the proposed approach are confirmed by comparing the results with those achieved by the FEM. The method is used to investigate the effects of MFCs orientations on the panel flutter boundaries of smart plates.

Suppressing high-order surface errors of an active carbon fiber reinforced composite reflector using two types of actuators

Active feedback control is a feasible approach for maintaining the desired shape of a reflector. An architecture for an active reflector is presented in which both piezoelectric ceramic transducer (PZT) and macrofiber composite (MFC) actuators are introduced to reduce both the global and local (high-order) surface errors. An electromechanical finite element model with two types of actuators is developed using the Hamilton principle. An optimal shape controller is then developed to minimize the reflector surface error. Lower-order orthogonal Zernike polynomials are derived in a unit hexagon. The polynomials are considered to be the basic error modes of a reflector and are used to optimize the length of the PZT actuators. The arrangement of MFC actuators can be optimized in a single triangular component of the reflector because the deflections they induced are very local. An experiment is conducted to verify the performance of MFC actuators in a triangular component. The improvement in the control efficiency of the active reflector is demonstrated by two numerical examples.

Motion planning and tracking control for coupled flexible beam structures

A systematic flatness-based motion planning approach for a structure consisting of coupled flexible bending beams is introduced. The beams are equipped with in-domain piezoelectric macro-fiber composite (MFC) actuators and are coupled by an elastic string, modeled as spring, which connects the tip masses of adjacent beams. This setup provides a challenging benchmark experiment to evaluate control concepts. Hamilton’s principle leads to the equations of motion involving spatially varying parameters due to the different material characteristics of the carrier structure and the attached MFC-actuators. The flat output is constructed by exploiting the spectral system representation and enables a differential parameterization of the system states and inputs. This parameterization transfers the motion planning problem into a trajectory assignment problem for the flat output. The resulting flatness-based feedforward control law is analyzed and evaluated at an experimental setup. To increase the performance and the robustness w.r.t. model uncertainties and external disturbances the flatness-based feedforward control is amended by a feedback controller with observer in the spirit of the two-degrees-of-freedom control approach.

Design optimization of multistable variable-stiffness laminates

Exploiting the anisotropic nature of composite laminates is a driving factor to improve the design regime of multistable structures. The concept of laminate tailoring is being taken a step ahead by allowing variation in fiber angle orientation within the ply planform. Such composite laminates known as variable stiffness (VS) composites have been reported to provide significant improvements in performance over constant stiffness designs. The phenomenon of snapping from one stable state to another is of paramount importance for multistable structures to be used in morphing applications. VS laminates allow the designer to tailor structural response according to the requirements of the morphing mechanism. This work presents a parametric study to explore designs by exploiting the tailoring options in VS laminates, with the objective of requiring low snap-through and snap-back voltages but at the same time enabling high out-of-plane displacements with the effective and efficient use of microfiber composites actuators. The fiber orientation of the layers of the VS laminate is assumed to vary linearly from the center to the edge of the plate. Design spaces of different laminates were investigated by varying the three angle parameters defining the VS laminates. Finite element analyses on snap-through and snap-back actions on the bistable nature of VS laminates were performed using the help of macro fiber composite actuators.

Experimental investigation into the nonlinear dynamics of a bistable laminate

An experimental study of the single-well and twin-well, also referred to as intra-well and inter-well, respectively, nonlinear dynamics of a bistable composite laminate is presented. An asymmetric four-ply [0/90/0/90] carbon fiber laminate with two cylindrical stable equilibria supported at its center and free at all boundaries is used for the experimental testing. The mechanical bistability makes the laminate able to snap from one stable equilibrium to the other when displacement reaches a critical value. This snapthrough motion is highly nonlinear and associated with large-amplitude vibrations. This property opens chances for bistable laminates in morphing and energy-harvesting applications. An electromechanical shaker is used to excite the laminate at its center by a controlled amplitude and frequency excitation. The dynamic response of the laminate is measured using a Polytec laser vibrometer. In addition, four macro-fiber composite actuators are attached to the laminate to measure the output voltage due to vibration and hence assess its energy-harvesting capability. The laminate’s natural frequencies and damping under small-amplitude excitations that would match the natural frequencies of an underlying linear system are experimentally identified. A primary resonance excitation of the first bending mode is carried out using amplitude sweep and frequency sweep. It is shown that in both cases, the response starts as a small-amplitude single-well vibration around the static equilibrium position. Varying the excitation amplitude or frequency, the response exhibits a period-doubling bifurcation associated with higher levels of vibration. As the excitation conditions are varied further, the laminate snaps from one equilibrium position to the other. This snapthrough motion is characterized to be of a frequency that is half the natural frequency of the excited mode. It is shown that the period-doubling cascade is responsible for the escape from the single-well to the twin-well response. A secondary Hopf bifurcation that creates a period-three motion and a chaotic snapthrough were also identified. Two low-frequency interesting modes that are attributed to the elasticity of the midpoint support, referred to as rocking modes, were identified using a hammer. These modes got repeatedly excited via subharmonic resonance of order two. In terms of the energy harvesting, the snapthrough motion was found to greatly enhance the energy extraction capability. The frequency band of significant power generation was found to be about 25% of the excitation frequency, which is a good ratio for a single excitation frequency.