Experimental and theoretical characterization on creep behavior of 1−3 piezocomposites subjected to a constant electric field and mechanical pre-stress is carried out. For curved surfaces or systems undergoing large deformations, piezo-ceramics are unsuitable since these are brittle in nature. Hence, piezo-composites are used as replacements. Creep is an important aspect with these systems due to a softer viscoelastic matrix involved. Electrical and electro-mechanical creep are studied for these systems. Electrical creep is observed to be maximum at the coercive field. Also, it is inferred that the volume fraction of fiber in 1−3 piezocomposites affects the system performance. The electro-mechanical creep is observed to reduce exponentially with increasing compressive pre-stress. Mechanical depolarization effect is observed during compressive loading. A thermodynamically-consistent macro-mechanical model is proposed to capture the creep behavior of 1−3 piezo-composites. It is found that the model predictions are in agreement with the experimental observations. © 2018 Elsevier Ltd and Techna Group S.r.l.

Arunachalakasi Arockiarajan

Department of Applied Mechanics

Ratnadeep Pramanik

Depolarization

Electric fields

Compressive loading

Electro-mechanical

Experimental approaches

MECHANICAL DEPOLARIZATION

MECHANICAL MODEL

PIEZOCOMPOSITES

Theoretical modeling

VISCOELASTIC MATRIX

Creep

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IIT Madras

Ceramics International

1–3 piezocomposites are extensively used for sensor, actuator, naval and aerospace applications owing to their enhanced electromechanical coupling, wider bandwidth and reliability. However, their performance gets adversely affected when they are subjected to combined static and dynamic loads that initiate both creep and fatigue damage, simultaneously. 1–3 piezocomposites undergo damage due to creep–fatigue interactions because of the passive and viscoelastic polymer matrix and inherent domain switching mechanisms. In this work, experiments are conducted to obtain the electromechanical response of 1–3 piezocomposites subjected to electrical fatigue and mechanical compressive creep loads. It is observed that, the electromechanical response degrades with increase in number of electrical fatigue cycles, matrix volume fraction and mechanical compressive pre-stress. A nonlinear phenomenological combined creep–fatigue damage model is developed within a thermodynamic framework to account for the creep–fatigue interactions in 1–3 piezocomposites. The model predictions are found to be in agreement with the experimental observations. © 2019, Springer Nature B.V.

Meccanica

Mechanics of 1–3 piezocomposites subjected to creep–fatigue loads

Piezocomposites find extensive use in sensors and actuators, naval applications, etc. owing to their characteristic coupling between electro-mechanical domains. These materials being relatively soft and ductile show a viscoelastic response to applied thermo-mechano-electrical loads. This causes a drift in the system response and creep is observed, which affects system efficiency. During prolonged service periods, self-heating occurs. Often, piezocomposites are subjected to mechanical pre-stresses prior to electrical input. To understand the response of 1–3 piezocomposites under these intricate loading conditions, experiments are performed to study the electro-mechanical response of 1–3 piezocomposites under thermo-mechano-electrical creep loads. Mechanical depolarisation is observed during the creep process. Creep strain is observed to increase with matrix volume fraction, mechanical pre-stress, electric field and temperature. A decrement in creep polarisation is seen with the increase in matrix volume fraction, mechanical pre-stress and temperature. The system performance is observed to be strongly dependent on the fibre volume fraction. A hybrid model is proposed within a thermodynamic framework to predict the creep response of 1–3 piezocomposites under thermo-mechano-electrical loads. The model is simultaneously representative of the macroscopic phenomenological details and mesoscopic electro-mechanical insights. While the free energy potential and domain switching concepts are characteristic of macroscopic modelling, the representative volume element (RVE) and its description with regard to domain wall resistance can be related to the mesoscopic length scales. The model predictions are found to be in agreement with the experimental observations. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group.

Philosophical Magazine

A hybrid phenomenological model for thermo-mechano-electrical creep of 1–3 piezocomposites

1-3 piezocomposites are often subjected to mechanical pre-stress under elevated temperatures in naval and offshore applications, actuators, and so on, where the presence of the ductile epoxy matrix causes considerable creep in the system. This deteriorates the system efficiency and its overall performance. To address this issue, experiments are performed to capture the electromechanical response for thermo-mechanical creep of 1-3 piezocomposites for different fiber volume fractions under various thermal loads, wherein mechanical depolarization is observed. The piezo-coupling coefficient is observed to degrade. Higher thermal loads resulted in an increase in creep strain coupled with a decrease in creep polarization. A Kelvin–Voigt fractal derivative viscoelastic model is used to capture the creep strain. The creep strain is decomposed into ferroelastic and anelastic parts. The evolution of creep polarization is obtained using the ferroelastic component of the creep strain. The model predictions are found to be in agreement with the experimental observations. © The Author(s) 2019.

Journal of Intelligent Material Systems and Structures

Experimental characterization and viscoelastic modeling for thermo-mechanical creep of 1-3 piezocomposites

Composite structures which show magneto-electric (ME) coupling behavior have a wide range of engineering applications. In this work, a composite structure comprising of a ferroelectric and a magnetostrictive material is taken for investigation. First, the nonlinear responses of the ferroelectric material and the magnetostrictive material are studied separately by experiments. In order to predict the nonlinear response, a thermodynamically consistent macroscopic model is proposed for the ferroic materials. Model parameters are then estimated from the experimental data, and the simulated results based on the proposed model are presented. Results from the theoretical model are in agreement with the experimental data. Subsequently, a homogenization procedure is introduced to find out the nonlinear response of a layered ME composite structure, and the obtained results are discussed. © 2017, Springer-Verlag Wien.

Acta Mechanica

Nonlinear magneto-electro-mechanical response of layered magneto-electric composites: theoretical and experimental approach

Depending on the maximum amplitude of externally applied cyclic electric fields, ferroelectric ceramics show minor or major hysteresis. The materials also show asymmetric butterfly hysteresis in a prepoled material. Aiming at capturing these behaviour in a phenomenological constitutive model, a multi-surface modelling approach for ferroelectrics is introduced. In this paper, with the note on the motivation for a multi-surface model related to the results of new experimental investigations and also to experimental data reported in the literature, the constitutive relation for a rate dependent multi-surface ferroelectric model is developed. Following this, a brief graphical illustration shows how this model captures the objective phenomena. Consequently, the numerical implementation of the model to capture experimental results is demonstrated. Finally, the performance of this model to represent behaviour of decaying polarisation offset of electrically fatigued specimen is shown. © 2016 Informa UK Limited, trading as Taylor & Francis Group.

A multi-surface model for ferroelectric ceramics - Application to cyclic electric loading with changing maximum amplitude

Experiments are conducted to measure the effective properties and also the time dependent behaviour of 1-3 piezocomposites and bulk piezoceramics subjected to cyclic electric field at room temperature under quasi static loading condition in the non-linear regime. Experimental dielectric and butterfly hysteresis show that 1-3 piezocomposite exhibits the time dependent behaviour. Hence a viscoelastic based numerical model has been proposed to predict the time dependent effective properties of 1-3 piezocomposites and bulk piezoceramics. The predicted effective properties are incorporated in the proposed 3D finite element based micromechanical model to predict the time dependent non-linear electromechanical behaviour of 1-3 piezocomposites and compared with experimental observations. The experimental and simulated results show that the presence of epoxy polymer constituent in 1-3 piezocomposite has an influence on the non-linear time dependent electromechanical response of 1-3 piezocomposite. © 2014 Elsevier Ltd and Techna Group S.r.l.

Finite element modelling on time dependent ferroelectric behaviour of 1-3 piezocomposites

The viscoelastic behaviour of 1-3 piezocomposites with different volume fractions and bulk piezoceramics is studied under thermal environment subjected to electrical loading. Experiments are conducted to measure the temperature dependent effective properties based on IEEE standards and time dependent thermo-electromechanical response of 1-3 piezocomposites and piezoceramic subjected to high cyclic electrical loading under elevated thermal environment. The temperature dependent effective properties are predicted using the proposed numerical model based on unit cell approach and implemented into the viscoelastic model to predict the time dependent thermo-electro-elastic effective properties. The predicted effective properties are incorporated in a finite element based 3-D micromechanical model to predict the time dependent thermo-electro-mechanical performance behaviour of 1-3 piezocomposites. Comparison between the experiments and simulations shows that this model can reproduce the characteristics of time dependent non-linear electromechanical response under thermal environment. It is observed that the variation in fiber volume fraction and elevated operating temperature has a significant influence on the response of the 1-3 piezocomposites. © 2014 AIP Publishing LLC.

Fulltext

Journal of Applied Physics

Viscoelastic modeling and experimental characterization of thermo-electromechanical response of 1-3 piezocomposites

A study is carried out to compare the non-linear behaviour of 1-3 piezocomposites with different volume fractions and bulk piezoceramics. Experiments are conducted to measure the electrical displacement and strain on piezocomposites and ceramics under high cyclic electrical loading. A thermodynamically consistent framework, combining the phenomenological and micromechanical models, is developed to predict the coupled behavior. Volume fractions of three distinct uni-axial variants (instead of six variants) are used as internal variables to describe the microscopic state of the material. In this model, the grain boundary effects are taken into account by introducing the back fields (electric field and stress) as non-linear kinematic hardening functions. In order to calculate the effective properties (elastic, piezoelectric, and dielectric constants) of piezocomposites for different volume fractions, an analytical model based on equivalent layered approach is proposed. The predicted effective properties are incorporated in the proposed model, and the classical hysteresis (electrical displacement versus electric field) as well as butterfly curves (strain versus electric field) is simulated. Comparison between the experiments and the simulations shows that this model can reproduce the characteristics of non-linear coupled response. It is observed that the variation in fiber volume fraction has a significant influence on the response of the 1-3 piezocomposites. © 2012 American Institute of Physics.

Journal	Data powered by TypesetCeramics International
Publisher	Data powered by TypesetElsevier Ltd
ISSN	02728842
Open Access	No