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Coalesce of photovoltaic effect with converse piezoelectric effect will turn into a photostrictive phenomenon. The current study conceptualizes a 1-3 photostrictive composite consists of a photovoltaic polymer as matrix and fibers of piezoelectric material. The proposed artificial photostrictive composite is capable of replacing lead-based naturally occurring photostrictive material, not only opening a potential for new applications but also caters to tailor the desired properties. Present study employs poly{4,8-bis[5-(2-ethyl-hexyl)thiophen-2-yl]benzo[1,2-b:4,5-b’]dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl) carbonyl] thieno[3,4-b] thiophene-4,6-diyl} (PTB7-Th) as organic photovoltaic polymer and Pb(Mg1/3Nb2/3)O3-0.35PbTiO3 (PMN-35PT) as the fibers. A representative volume element technique (RVE) is employed to embrace the local variation of multi-physics properties. The actuation response of cantilever and simply supported beam bonded to photostrictive composite patch is accurately predicted by finite element method, while discretizing the structure with degenerated shell element. Photostrictive composite with 60% volume fraction of fibers, arranged in square pattern have deflected the cantilever tip to 1.95 mm. Therefore, we provide 1-3 photostrictive composite as a solution for future wireless and lightweight vibration control applications.

The increasing obligatory demand for clean and environment-friendly alternates for refrigeration and air-conditioning has made solid-state refrigeration more alluring for researchers of the relevant fields. The flexocaloric effect is a mechanism providing solid-state refrigeration in mechanically loaded samples. In this work, we explore the potential of functionally graded (FG) dielectric material with Ba0.67Sr0.33TiO3 (BST) and polyvinylidene fluoride (PVDF) as its constituents to impart the cooling effect via the flexocaloric effect. A theoretical analysis based on the phenomenological thermodynamic theory of caloric effects is performed. The entropy and temperature changes (adiabatic) are derived by including flexoelectricity-induced polarization in Maxwell’s relation for the electrocaloric effect. An average temperature change of 1.82 K was achieved under an applied pressure of 100 MPa, which is not possible in conventionally used homogeneous trapezoid samples. The flexocaloric effect is observed to increase sharply with increasing load due to quadratic proportionality of temperature change with strain gradient. Further, the material composition can be tailored for increased entropy and temperature change by omitting the pure BST and PVDF phases at the top and bottom.

Simultaneous action of photovoltaic effect and converse piezoelectric effect will induce the photostrictive effect. In contrast to the naturally occurring photostrictive material, the present study proposes a 0-3 photostrictive composite. The current photostrictive composite comprises of poly{4,8-bis[5-(2-ethyl-hexyl) thiophen-2-yl] benzo[1,2-b:4,5-b′] dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethyl-hexyl) carbonyl] thieno[3,4-b] thiophene-4,6-diyl} (PTB7-Th) as organic photovoltaic polymer matrix and Pb(Mg1/3Nb2/3)O3-0.35PbTiO3 (PMN-35PT) as the particulates. The current study shows that the present 0-3 photostrictive composite is a suitable alternative for the most popular lead-based photostrictive material. While evaluating all the effective elastic, dielectric, piezoelectric, and pyroelectric properties of 0-3 photostrictive composite, the effect of local fluctuations was incorporated in representative volume element (RVE) using the finite element method. A finite element formulation using a degenerated shell element is derived to simulate the actuation response of the proposed 0-3 photostrictive composite. Numerical studies have been performed on cantilever and simply supported beams. The maximum tip and center deflection of cantilever beam and simply supported beam bonded with 0-3 photostrictive patch is 9.75×10−4 mm and 1.22×10−4 mm, respectively. The maximum value of the effective piezoelectric coefficient d31eff, effective thermal expansion coefficient αeff, effective Young’s modulus E1eff, and effective pyroelectric coefficient peff of proposed 0-3 photostrictive composite are −3.81×10−13 m/V, 4.59×10−4 °C−1, 1.63×109 N/m2, and 7.57×10−5 C/m2 K, respectively, obtained at 25% volume fraction of particulates. This study opens possibilities of photostrictive coupling in composites.

Photostriction is a multiphysics phenomenon comprising of both photovoltaic effect and converse piezoelectric effect. The extensively researched photostrictive material is lead lanthanum zirconate titanate, i.e., Pb0.92La0.08(Zr0.65Ti0.35)0.98O3 (PLZT) ceramic. In contrast to the traditional approaches of improving deflection response, the current study proposes a 0–3 composite model to substantially enhance the effective material properties, which in turn significantly improves the deflection response. A computational framework based on finite element analysis is employed to 0–3 photostrictive composite of PLZT as matrix and Pb(Mg1/3Nb2/3)O3-0.35PbTiO3 (PMN-35PT) as the inclusions. The representative volume element (RVE) or unit cell technique is used to incorporate the local variation of constituent properties and to calculate photostrictive properties such as effective elastic, dielectric, piezoelectric, and pyroelectric properties. An opto-electro-thermo-mechanical finite element formulation was engaged to get the actuation response of photostrictive material bonded to cantilever and simply supported beam. The maximum deflection for cantilever beam attached to photostrictive composite patch having 25% inclusions volume fraction in 0–3 composite is found to be 38% more in comparison to pure PLZT material. It is established that the opto-electro-mechanical 0–3 composite actuators possess high potential in lightweight, compact and wireless actuation applications.

This paper presents active vibration control of smart cantilever beam using poling tuned piezoelectric actuator. The vibrating response of piezo-laminated cantilever beam is modeled using a lumped ...

Improvement in operating characteristics of piezoelectric materials, one of the most extensively used dielectric materials, is a major focus of research among materials scientists. Present work puts forward, a novel approach for achieving enhanced piezoelectricity in ferroelectric materials by manipulating electrode placement during poling. Three unique poling configurations, abbreviated as PC1, PC2, and PC3 are developed for exploiting the dependence of effective piezoelectric properties on spatially varying poling direction. Finite element method based numerical simulations are performed to evaluate the electric field distribution, poling direction, and their effect on effective piezoelectric coupling coefficients of PMN–0.35PT (Pb(Mg1/3Nb2/3)O3–0.35PbTiO3) piezoelectric ceramic. A two-phase solution process is developed to evaluate the local orientation of dipoles for each poling configuration and subsequently computing effective piezoelectric properties of the material in an average sense. Parametric studies are carried out to analyze the effect of aspect ratio R of sample and electrode to sample length ratio, r on effective piezoelectric properties. PC1 yields an increase of up to 135% in the magnitude of the transverse coupling coefficient $$({e}_{31}^{eff})$$ and an 8% increase in effective longitudinal coupling coefficient $$({e}_{33}^{eff})$$ while PC2 is observed to exhibit a maximum enhancement of 164% in the magnitude of $${e}_{31}^{eff}$$ and 11.2% in the magnitude of $${e}_{33}^{eff}$$ . PC3, presented as a special case, yields zero values of piezoelectric coefficients in an average sense but can result in a highly elevated net output for bending applications, owing to favorable spatial variation in stresses and associated piezoelectric coefficients.

In this article, active vibration control of a piezo laminated smart structure is presented using poling tuned piezoelectric material. To improve the performance of existing materials and utilize the actuation potential of different modes of operation ( d31, d33, and d15), simultaneously, the poling direction of the piezoelectric materials is altered and an optimum poling direction is found. Poling tuned piezoelectric patches at the top and bottom layers of the structure are mounted which act as sensors and actuators, respectively. The computational technique used for calculating the time history of the structure is a finite element method. A fuzzy logic controller is developed to compute the appropriate actuator signal as output while taking sensor voltage and its derivative as input. The controlled response due to this fuzzy logic controller is calculated for different piezoelectric materials under consideration and the performance of these materials in active vibration control is compared. Influence of poling angle on the controlled response of the structure is scrutinized and is found to vary from material to material. A large enhancement due to poling tuning is seen in the properties of Pb(Mg1/3Nb2/3)O3-0.35PbTiO3 (PMN-0.35PT), whereas other materials show very less improvement or even decay in the properties.

Only a few piezoelectric materials interact with light owing to their wide bandgap, which leaves researchers with very few options. The high piezoelectric coupling coefficient of lead lanthanum zirconate titanate, i.e., PLZT (Pb0.92La0.08(Zr0.65Ti0.35)0.98O3), makes it very popular amongst the research fraternities. In this paper, piezoelectric coupling coefficient is further improved by designing a 1–3 composite of PLZT as matrix and fibers of PMN35PT (Pb(Mg1/3Nb2/3)O3–0.35PbTiO3). First, a finite element method is applied to representative volume elements of 1–3 photostrictive composites to determine the elastic, piezoelectric, pyroelectric, and thermal expansion coefficient. Secondly, degenerated shell element-based finite element formulation is used to simulate the actuation response of host structure bonded with 1–3 photostrictive composite, while prescribed with cantilever and simply supported boundary conditions. It is observed that the 1–3 composite of PLZT and PMN-35PT has 15% higher piezoelectric coupling coefficient and its pyroelectric coefficient is 7.5 times of PLZT material. Keeping the constant geometrical and boundary conditions, the structure equipped with the proposed 1–3 photostrictive composite produces a 74.8% enhanced actuation response.

A technique known as poling direction tuning is proposed to improve the material performance of piezoelectric based actuators. The piezoelectric material used in actuation applications of thin structures operates in d31 mode; hence, a method is devised to increase the value of piezoelectric coefficient, d31. Poling direction of the piezoelectric material is altered to activate d31, d33, and d15 modes, simultaneously. The performance of actuator is evaluated at different poling angle and poling angle for best performance is found. A simply supported plate with a layer of actuator piezoelectric material at the bottom is used for simulation studies. The computational technique used for calculating the time history of the structure is a finite-element method. The controlled shape using a fixed actuator voltage is calculated for different piezoelectric materials under consideration. Influence of poling angle on the shape control of the structure is scrutinized and is found to vary from material to material. A large enhancement due to poling tuning is seen in the properties of Pb(Mg1/3Nb2/3)O3-0.35PbTiO3 (PMN-0.35PT), whereas other materials show very less improvement or even decay in the properties.

Piezoelectric materials play an important role in powering nano and microelectromechanical systems. However, these are often limited by their low sensing, actuation, and power outputs. This study proposes a novel poling direction arrangement theoretically in the piezoelectric materials which enhances the output parameters drastically. The poling angle was graded from bottom to top surface of element in linear fashion which helps in utilizing the bending and shear stresses efficiently. The sensing, actuation and energy harvesting performance of Pb[ZrxTi1‐x]O3 in graded mode was compared with those obtained from operating in transverse and shear modes. It was found from finite element simulations that a maximum sensing voltage of 11.85 V was been obtained in graded mode which was around 15 times higher than that obtained in shear mode. Likewise, a maximum strain of 8.2 μm/m and a tip displacement of 34.3 μm was observed in the graded mode. Eventually, the maximum power of 0.12 W was harvested from graded mode harvester followed by shear mode harvester where only : 1.6 × 10−3 W could be harvested. However, the associated challenge with such study is the fabrication and graded poling of piezoelectric which still is an unexplored research area for scientific fraternity.

Flexoelectric energy conversion, due to its universality and size dependence, is a potential candidate for applications in self-sustainable micro-electromechanical systems/nano-electromechanical systems. This study presents the performance indices for assessing flexoelectricity-driven energy conversion in micro-scale piezoelectric (non-centrosymmetric) and non-piezoelectric (centrosymmetric) dielectric materials. Electromechanical coupling coefficients for geometry selection and figures of merit for material selection for the two most common modes of operations, i.e., transverse mode as in bending of beams and longitudinal mode as in the compression of non-uniform cross section structures, are derived. An interplay of flexoelectricity and piezoelectricity in different circumstances is assessed for three different materials, namely, barium titanate (BaTiO3), Er-doped BST ceramic (Ba1-xTi0.96Sn0.04O3 + x mol. % Er), and polyvinylidene difluoride (PVDF), for transverse and longitudinal modes. In the transverse mode, BaTiO3 and BST are found to dominate at a beam thickness of 5 μm, while at 100 μm, PVDF shows substantially higher magnitudes of electromechanical coupling coefficients. A similar trend for the electromechanical coupling coefficient is observed in the longitudinal mode. PVDF has a very low magnitude of figure of merit in the transverse mode as compared to the other two materials (0.65% of BST and 0.71% of BaTiO3), while in the longitudinal mode, the figure of merit of PVDF exceeds the other two materials by a large magnitude (197 times of BST and 285 times of BaTiO3).

Various strategies to achieve superior converse flexoelectric response, qualitatively and quantitatively, in dielectric materials are presented. For the qualitative aspect, a novel approach for achieving converse flexoelectric effect independent of geometry or material composition of dielectric materials, by having modified electrical boundary conditions is presented. The theoretical investigation of the proposed methodology is presented and compared with the existing methods (functional grading and trapezoid-shaped sample). Later, the hybrid configurations of existing methods with the proposed strategy are analyzed and are found to enhance the actuation in some cases while decreasing in others, suggesting the possibility of a quantitatively superior effect. While the proposed method of varying electric field direction is established as an alternative to existing methods to induce electric field gradient, the FGM is found to exhibit up to 380% actuation of the closest non-hybrid strategy, i.e. trapezoid geometry.

In the present study, a functionally graded material (FGM) based dielectric composite is investigated for direct and converse flexoelectric effects induced due to material inhomogeneity. An Isogeometric analysis based formulation is employed to effectively capture the gradient terms appearing in the electro-elastic coupling constitutive laws of flexoelectricity. Non-uniform stresses and strains generated due to non-uniform elastic properties in the domain induce flexoelectricity inherently without any special geometric and/or boundary conditions. A two-dimensional (2D) FGM structure made by the combination of polyvinylidene fluoride (PVDF) and barium titanate (BaTiO3) is studied under mechanical and thermal loading conditions for its flexoelectric response. The induced polarization and voltage along with its dependence on grading index (n) is analyzed. Further, to extend the study to converse flexoelectricity, the mechanical response of the FG flexoelectric material under an applied electric potential is studied. Finally, the actuation of the structure by an applied electric field is studied. As high as 10% actuation of original displacement is observed for higher values of n. Effectiveness of the grading concept to induce flexoelectric response is established through numerical studies. Longitudinal and transverse modes of flexoelectricity are scrutinized and the concept of grading is proved to inherently induce the flexoelectricity in dielectrics without special geometric modifications.

In the present study, the temperature fluctuations in tissues based on Penne’s bio-heat transfer equation is investigated by applying the Laplace and Hankel transforms. To get the solution in a physical form, a numerical inversion technique has been applied. The temporal and spatial distribution of temperature is investigated with the effect of relaxation time and is presented graphically.