Macro Fiber Composite Research Articles

Role of Flexible Macro Fibre Composite (MFC) Actuator on Bragg Wavelength Tuning in Microstructure Polymer Optical Fibre Long Period Grating for Strain Sensing Applications*

The microstructure polymer optical fibre (mPOF) inscribed long period grating (LPG) offers a wide field of application in strain sensors arena within the materials elastic limit. Flexible innovative macro fibre composite (MFC) actuator generates electromechanical force under DC driving voltage. We propose a novel method for Bragg wavelength blue shifting through stretch tuning of mPOF LPG in axial direction under applied DC voltage on attached MFC with LPG. The grating period of mPOF LPG changes refractive index and causes blue shift of Bragg grating fibre wavelength. The shifting governs on the values of generated electromechanically strain transfer from flexible MFC to mPOF LPG and they have potential applications in strain sensor.

An Investigation on Dynamic Signals of MFC and PVDF Sensors: Experimental Work

In the present paper, identification of dynamic sensing characteristics of macrofiber composite (MFC) and polyvinylidene fluoride (PVDF) is carried out via experimental investigation. As a first step, basic characteristics and operating principles of MFC and PVDF are briefly reviewed. Then, a clamped aluminum beam structure is prepared and experimental setup for vibration signal test is established with shaker system. Both MFC and PVDF are attached on the top and bottom surface of the beam structure, respectively, and connected to data acquisition system. In order to verify the operating bandwidth, frequency responses of the smart beam structure are obtained from 0 Hz to 5 kHz under sine sweep excitation. For the identification of dynamic sensing characteristics, experiments for linearity, durability, and robustness are conducted. It is observed that both MFC and PVDF have excellent sensing performance in measuring dynamic response and monitoring structural vibration.

Bayesian Techniques to Quantify Parameter and Model Uncertainty for a Macro-Fiber Composite Model

Piezoceramic-based Macro-Fiber Composites (MFCs) are cost-competitive and highly efficient actuators/sensors that are currently being considered for aerospace, aeronautic, automotive, and industrial applications. Due to the constituent lead zirconate titanate (PZT) material, MFCs exhibit constitutive nonlinearities and hysteresis that must be characterized in models to achieve their full capability. A modeling framework for a flexible structure with MFC actuators operating in hysteretic regimes was recently introduced to quantify a range of rate-dependent hysteretic behavior (Hu et al., 2013). In that work, the homogenized energy model (HEM) for ferroelectric hysteresis was combined with Euler-Bernoulli theory to construct a dynamic MFC model. The HEM facilitates efficient implementation, which is important for quantitative model comparisons with data and real-time model-based control. A Bayesian framework was employed to quantify the uncertainty that model and measurement errors imbue upon parameters. It was revealed that some of the model parameters are highly correlated. In this paper, we will use the newly introduced framework to investigate the uncertainty of the model response. The parameter uncertainty will be propagated through the model using a sampling method to quantify the uncertainty associated with model predictions for various operating regimes. Response uncertainties quantified in this manner can be subsequently incorporated in control techniques such as sliding mode designs to improve stabilization and tracking capabilities of robust control algorithms.

Application of Macrofiber Composite for Smart Transducer of Lamb Wave Inspection

Macrofiber composite (MFC) has been developed recently as a new type of smart material for piezoelectric transducers. It shows advantages over traditional piezoelectric ceramic materials (PZT) including the method of application, sensitivity, and cost. It can be embedded on the structure, which provides the possibility to monitor the structural health in real time. In this paper, the feasibility of this transducer for the Lamb wave inspection has been experimentally explored. A pair of MFC patches is bonded on a 2 mm thick aluminum plate, and it has been demonstrated that the dispersive characteristics of S0 and A0 modes, generated and detected by MFC patches, agreed well with the theory. The influence of the bonding condition of the transducer was also tested to show that rigid bonding is required to assure a high amplitude signal. In order to illustrate the performance of defect detection, an artificial defect fabricated on the surface of a specimen was inspected in the pitch-catch mode. The results showed that the MFC transducer is a promising Lamb wave transducer for nondestructive testing (NDT) and structural health monitoring (SHM).

W042001 スマート構造を用いた高精度宇宙構造システムの実現に向けて(【W04200】知的材料・構造システムの現状と今後の展開,機械材料・材料加工部門企画,ワークショップ)

In order to realize a high accuracy space structure system, shape and vibration controls using smart structures are studied. Two prototypes of smart reflectors were developed and investigated. One was a long smart beam system equipped with Macro Fiber Composites (MFCs) and the other was a smart reconfigurable reflector equipped with smart actuators. The smart actuator was designed for the smart reconfigurable reflector and it consisted of a piezoelectric stack actuator and a displacement magnification mechanism. Experiments of the shape and vibration controls of the long smart beam were carried out and their performance were investigated. The performance of the smart actuator was also investigated through numerical simulations and experiments. The results are reported in this paper.

Development, modeling and application of piezoelectric fiber composites

Piezoelectric materials are capable of actuation and sensing and have been used in a wide variety of smart devices and structures. Active fiber composite and macro fiber composite are newly developed types of piezoelectric composites, and show superior properties to monolithic piezoelectric wafer due to their distinctive structures. Numerous work has focused on the performance prediction of the composites by evaluation of structural parameters and properties of the constituent materials with analytical and numerical methods. Various applications have been explored for the piezoelectric fiber composites, including vibration and noise control, health monitoring, morphing of structures and energy harvesting, in which the composites play key role and demonstrate the necessity for further development.

Ultrasound Flow Sensor Based on Arrays of Piezoelectric Transducers Integrated in a Composite

The functionalization of fiber-reinforced polymer composites by integration of piezoelectric transducers allows for both the measurement and the excitation of guided waves within the component. A common use for guided waves in composite components is nondestructive examination. In the presented work, however, the radiation of ultrasound waves from the surface of the component due to guided waves in the component is utilized. Glass fiber-reinforced polypropylene (GF/PP) plates with integrated arrays of piezoelectric macro fiber composite (MFC) transducers are used as ultrasound transmitter and receiver. The plates are then set up as facing walls of a rectangular duct and the sound transit times between the plates are measured. From the measured sound transit times, the velocity of gas flow inside the composite duct is determined. In that way, a flow sensor integrated in the walls of a flow channel, e.g. an air duct, made of composites is built. This paper focuses on the manufacturing of such an integrated flow sensor.

B35 圧電振動発電で駆動する振動状態監視装置の開発に関する研究(M-OS3-1 制御/センシング,M-OS3 スマート構造システム,「海を越え,国を越え,世代を超えて!」)

In this study, we have developed a sensor prototype for vibration acceleration monitoring driven by the authors' proposed vibration energy harvester. It uses a commercial LTC3588 energy harvesting chip with capacitors and the piezo-bimorph cantilever-type energy harvester consists of the surface bonded two Macro-Fiber Composites. The power consumption of the acceleration sensor was typically 1[mW], and the driving current was typically 0.4[mA]. For vibration condition monitoring applications of industrial rotating machinery, we assumed that the typical casing or pedestal vibration amplitude of the rotating machinery was 0.71[mm/s] (RMS) according to ISO standard. This low intensity excitation condition was the input for experimental evaluation of the developed sensor prototype. The sensor prototype was able to measure the vibration acceleration of approximately 17[s] under the vibration input of 0.026[G] (RMS) at approximately 56[Hz] every two minutes. Approximately 12% of the input of vibration energy was used for driving the acceleration sensor. Therefore, estimated overall energy transfer efficiency was about 12%. The experimental results indicate the feasibility of the sensor prototype driven by piezocomposite vibration energy harvester.

Modeling Fiber Composites during the Cure Process for Piezoelectric Actuation

Analytical, numerical, and experimental modeling methods are presented to predict deformation after the cure process of thin unsymmetric laminates for piezoelectric actuation. During fabrication, laminates deform to several post-cure room temperature shapes. Thin cross-ply laminates deform to a circular cylindrical post-cure shape while thicker laminates deform to a saddle shape. Post-cure shapes are dependent on ply orientation, thickness, and material properties. Because, CLT alone does not always predict the correct post-cure room temperature shape of the thin composite laminates, an extension of CLT with the Rayleigh-Ritz technique and potential energies are used to better predict these shapes. Finite element models are used to predict the post-cure room temperature shapes. Thin composite laminates are modeled coupling heat transfer and structural mechanics, which are necessary for modeling the cure process. Modeling the fabrication process captured important data such as residual stresses from the cure process, room temperature shapes, and bi-stability of the composite laminates. To validate these analytical and numerical results, experiments were con- ducted using macro-fiber composite (MFC) patches for morphing the laminates. The experimental piezoelectric morph- ing results relate well to analytical and numerical results.

On the Actuation Authority of Adaptive Sandwich Beam with Composite Actuators: Coupled Finite Element Analysis

A two noded active sandwich beam element is formulated by employing layerwise Timoshenko’s beam theory. Displacement continuity conditions are imposed between different layers of the sandwich. This element is used to model an adaptive sandwich beam with macro-fiber composite (MFC) as extension actuator and shear actuated fiber composite (SAFC) as shear actuator. Influence of thickness and volume fraction of the active fiber (PZT-5A and single crystal PMN-PT) in the composite actuators on the actuation performance of the sandwich beam is investigated. Based on several numerical experiments, it is found that the PMN-PT based shear actuators give maximum actuation authority for the volume fraction of the fibers in the range of 80%-85%, whereas in case of PZT-5A based shear actuators the actuation authority remains maximum for the fiber volume fractions 80% and above.

Lamb wave transducers made of piezoelectric macro-fiber composite

During recent years, an intensive research activity concerning the application of Lamb waves (LWs) for SHM has been observed. LWs may be generated and sensed using different types of transducers, and their selection is essential for the SHM system's performance. Results of the investigation of three types of transducers based on macro-fiber composite (MFC) are presented in this paper; two types of commercially available MFC actuators are compared with a novel type of custom-designed interdigital transducer also based on the MFC substrate. After a short presentation of the piezoelectric transducer designed for SHM applications, details concerning the proposed interdigital transducer design are provided. Beampatterns of the investigated transducers are first compared using numerical FEM simulations, and next, the numerically obtained beampatterns are verified experimentally using laser vibrometry. In the final part of this paper, advantages and disadvantages of the investigated transducers are discussed. Copyright © 2012 John Wiley & Sons, Ltd.

Modeling hysteresis and creep behavior of macrofiber composite–based piezoelectric bimorph actuator

Macrofiber composite–based bimorph actuators inherit the nonlinear properties of hysteresis and creep of piezoelectric materials, which limit the accuracy in real-time control. Many hysteresis models have been proposed, and generalized Maxwell slip model consisting of a series of nonlinear elements is one of the simplest and most efficient operators to describe symmetrical hysteresis. However, these hysteresis operators do not contain the creep behavior of piezoelectric materials. In this study, a hybrid model including a generalized Maxwell slip operator, a creep operator, and a dynamic model is developed to characterize a macrofiber composite–based piezoelectric bimorph actuator. The generalized Maxwell slip operator is used to describe the hysteresis, the creep operator is used to describe the creep behavior, and a transfer function is used to describe the dynamic model. Each nonlinear element in the creep operator is made up of a diode, a resistance, and a capacitance. The experiment results show that the proposed model can accurately predict the hysteresis, creep, and dynamic behaviors of the macrofiber composite–based piezoelectric bimorph actuator.

Fatigue life characterization for piezoelectric macrofiber composites

In an effort to aid the investigation into lightweight and reliable materials for actuator design, a study was developed to characterize the temperature-dependent lifetime performance of a piezoelectric macrofiber composite (MFC). MFCs are thin rectangular patches of polyimide film, epoxy and a single layer of rectangular lead zirconium titanate (PZT) fibers. In this study, the useful life of the MFC is characterized to determine the effect of temperature on the performance of the composite as it is fatigued by cyclic piezoelectric excitation. The test specimen consists of the MFC laminated to a cantilevered stainless steel beam. Beam strain and tip displacement measurements are used as a basis for determining the performance of the MFC as it is cyclically actuated under various operating temperatures. The temperature of the beam laminate is held constant and then cycled to failure, or 250 million cycles, in order to determine the useful life of the MFC over a temperature range from − 15 to 145 °C. The results of the experiments show a strong temperature dependence of the operational life for the MFC. Damage inside the composite was identified through in situ visual inspection and during post-test microstructural observation; however, no degradation in operational performance was identified as it was cyclically actuated up to the point of failure, regardless of temperature or actuation cycle number.

Application of piezoelectric macro-fiber-composite actuators to the suppression of noise transmission through curved glass plates

This paper analyzes the possibility of increasing the acoustic transmission loss of sound transmitted through planar or curved glass shells using attached piezoelectric macro fiber composite (MFC) actuators shunted by active circuits with a negative capacitance. The key features that control the sound transmission through the curved glass shells are analyzed using an analytical approximative model. A detailed analysis of the particular arrangement of MFC actuators on the glass shell is performed using a finite element method (FEM) model. The FEM model takes into account the effect of a flexible frame that clamps the glass shell at its edges. A method is presented for the active control of the Young's modulus and the bending stiffness coefficient of the composite sandwich structure that consists of a glass plate and the attached piezoelectric MFC actuator. The predictions of the acoustic transmission loss frequency dependencies obtained by the FEM model are compared with experimental data. The results indicate that it is possible to increase the acoustic transmission loss by 20 and 25 dB at the frequencies of the first and second resonant modes of the planar and curved glass shells, respectively, using the effect of the shunt circuit with a negative capacitance.

Evaluation of polarization of embedded piezoelectrics by the thermal wave method

This work demonstrates the benefit of the thermal wave method for the evaluation of the polarization state of embedded piezoelectrics. Two types of samples were investigated: A low-temperature co-fired ceramics (LTCC)/lead zirconate titanate (PZT) sensor-actuator and a macro-fiber composite (MFC) actuator. At modulation frequencies below 10 Hz, the pyroelectric response was governed by thermal losses to the embedding layers. Here, the sample behavior was described by a harmonically heated piezoelectric plate exhibiting heat losses to the environment characterized by a single thermal relaxation time.

On the Development of a Damage Detection System using Macro-fibre Composite Sensors

Macro-fibre composite (MFC) sensors, originally developed as actuators by NASA, have been investigated for three components of a damage detection system for composite structures; actuation, sensing and energy harvesting. MFC sensors are constructed from piezoelectric fibres embedded in an epoxy matrix and offer greater flexibility than traditional sensors for embedding due to their low profile and low weight. It is proposed that embedded MFCs could be used to act as damage detectors, whilst energy either transmitted ultrasonically or harvested ambiently could be used to power the system. To assess the applicability of the MFCs a scale A320 composite wing was manufactured. Ten MFC sensors were embedded within the wing structure. Through a series of investigations on the wing the use of MFCs as part of an acousto-ultrasonic (AU) and Acoustic Emission (AE) damage detection system were investigated. Utilising AE source location and an AU cross-correlation techniques damage induced by impact was identified. In a further experiment the capability of transmitting and harvesting energy with the same embedded MFC actuators was completed. By impedance matching it was possible to improve the transmitted power. Furthermore an analysis of the MFCs ability to capture ambient vibrations, associated with aircraft structures, was completed. The completed experimental work demonstrated that it would be possible to embed sensors, energise them through active or passive vibration, and detect damage.

Optimal control methods for vertical and horizontal beam dynamics

An application of the Macro Fiber Composite (MFC) actuators for damping of a composite beam is presented in this paper. The effectiveness of vibration reduction by a selected control method is tested for vertical and horizontal position of the beam. The original model has been studied numerically by using Galerkin's discretisation method. The numerical results for the vertical and horizontal beams are compared.

Dynamic control for morphing of bi-stable composites

Adaptive structures have been the focus of much research due to performance gains not possible to achieve using conventional designs. Within this context, the idea of morphing promises augmented capabilities in terms of manoeuvrability, fuel efficiency and the ability to perform dissimilar tasks in an optimal manner. To achieve morphing, materials capable of changing shape requiring minimum actuation are necessary. Bi-stable composites are a type of composite structures which have two statically stable configurations. This bi-stability property, resulting from locked in-plane residual stresses, has attracted considerable attention from the adaptive structure community for morphing structures as actuation is no required to hold each stable configuration. The change between stable states is physically realised as a jump phenomenon or snap-through, which is strongly non-linear in nature. Morphing strategies exploiting snap-through have been studied showing encouraging preliminary results. This article exploits the dynamic response of bi-stable composites as a means of augmenting the actuation for morphing control. A morphing strategy targeting modal frequencies leading to snap-through of the structure is successfully developed. This results in a full-state configuration control by inducing and reversing snap-through as desired. The strategy is tested on a specimen using Macro Fiber Composites as smart actuators validating the proposed concept.

Damage detection for pipeline structures using optic-based active sensing

This study proposes an optics-based active sensing system for continuous monitoring of underground pipelines in nuclear power plants (NPPs). The proposed system generates and measures guided waves using a single laser source and optical cables. First, a tunable laser is used as a common power source for guided wave generation and sensing. This source laser beam is transmitted through an optical fiber, and the fiber is split into two. One of them is used to actuate macro fiber composite (MFC) transducers for guided wave generation, and the other optical fiber is used with fiber Bragg grating (FBG) sensors to measure guided wave responses. The MFC transducers placed along a circumferential direction of a pipe at one end generate longitudinal and flexural modes, and the corresponding responses are measured using FBG sensors instrumented in the same configuration at the other end. The generated guided waves interact with a defect, and this interaction causes changes in response signals. Then, a damage-sensitive feature is extracted from the response signals using the axi-symmetry nature of the measured pitch-catch signals. The feasibility of the proposed system has been examined through a laboratory experiment.

Morphing of Bistable Composite Laminates Using Distributed Piezoelectric Actuators

The use of bistable unsymmetric cross-ply laminates for morphing application has received growing attention in the last few years. So far, most studies use large rectangular piezoelectric Macro Fiber Composite (MFC) patches bonded at the center of the laminate to induce snap-through. However, the use of large rectangular MFC patches bonded in the center of the laminates significantly influences the shape of the laminate by greatly reducing the curvature at the midsection of the laminate where the MFC patches are bonded. This paper presents a study where narrow cocured MFC strips distributed over the entire surface are used to induce snap-through of unsymmetric cross-ply laminates. This MFC configuration allows having a more uniform curvature in the laminate. Since the strips are bonded on both sides, reverse snap-through should be obtained. The study was both theoretical and experimental. A finite element nonlinear analysis was used to predict the two stable cylindrical configurations and the snap-through induced by MFC actuation. For the experimental study, a laminate-MFC structure was manufactured and tested. The shapes were measured using a 3D image correlation system as a function of applied voltage. Good correlations for the cylindrical shape and displacement field were observed.