Flexoelectricity is a size-dependent electromechanical mechanism coupling polarization and strain gradient. It exists in wide variety of materials, most noticeable for nanoscale objects, where gradients are higher. Simulations important to understand flexoelectricity because experiments at very small scales difficult, analytical solutions scarce. Here, we computationally evaluate the role response linear dielectric solids two-dimensions. We deal with higher-order coupled partial differential...

Abstract Bones generate electricity under pressure, and this electromechanical behavior is thought to be essential for bone's self‐repair remodeling properties. The origin of response attributed the piezoelectricity collagen, which main structural protein bones. In theory, however, any material can also voltages in strain gradients, thanks property known as flexoelectricity. work, flexoelectricity bone pure mineral (hydroxyapatite) are measured found same order magnitude; quantitative...

Abstract Converse flexoelectricity is a mechanical stress induced by an electric polarization gradient. It can appear in any material, irrespective of symmetry, whenever there inhomogeneous field distribution. This situation invariably happens piezoresponse force microscopy (PFM), which technique whereby voltage delivered to the tip atomic microscope order stimulate and probe piezoelectricity at nanoscale. While PFM premier for studying ferroelectricity nanoscale, here we show, theoretically...

Flexoelectricity is a universal property of all dielectrics by which they generate voltage in response to an inhomogeneous deformation. One the controversial issues this field concerns magnitude flexoelectric coefficients measured experimentally, greatly exceed theoretical estimates. Furthermore, there broad scatter amongst experimental measurements. The truncated pyramid compression method one common setups quantify flexoelectricity, interpretation relies on simplified analytical equations...

Cracks generate the largest strain gradients that any material can withstand. Flexoelectricity (coupling between gradient and polarization) must therefore play an important role in fracture physics. Here we use a self-consistent continuum model to evidence two consequences of flexoelectricity fracture: resistance increases as structural size decreases, it becomes asymmetric with respect sign polarization. The latter phenomenon manifests itself range intermediate sizes where piezo- compete....

The origin of "giant" flexoelectricity, orders magnitude larger than theoretically predicted, yet frequently observed, is under intense scrutiny. There mounting evidence correlating giant flexoelectriclike effects with parasitic piezoelectricity, but it not clear how piezoelectricity (polarization generated by strain) manages to imitate flexoelectricity strain gradient) in typical beam-bending experiments, since a bent beam the net zero. In addition changes sign space inversion insensitive...

Flexoelectricity is an electromechanical effect coupling polarization to strain gradients. It fundamentally differs from piezoelectricity because of its size-dependence and symmetry. generally perceived as a small noticeable only at the nanoscale. Since ferroelectric ceramics have particularly high flexoelectric coefficient, however, it may play significant role piezoelectric transducers shrink submicrometer scale. We examine this issue with continuum model self-consistently treating piezo-...

Piezoelectricity and flexoelectricity are two independent but not incompatible forms of electromechanical response exhibited by nanoscale ferroelectrics. Here, we show that can either enhance or suppress the piezoelectric cantilever depending on ferroelectric polarity lead to a diode-like asymmetric (two-state) response.

The mechanical properties of materials are insensitive to space inversion, even when they crystallographically asymmetric. In practice, this means that turning a piezoelectric crystal upside down or switching the polarization ferroelectric should not change its response. Strain gradients, however, introduce an additional source asymmetry has consequences. Using nanoindentation and contact-resonance force microscopy, study demonstrates response indentation uniaxial (LiNbO3 ) does polarity is...

Crack propagation during the indentation test of a ferroelectric single crystal is simulated using phase-field model. This model based on variational formulations brittle crack and domain evolution in materials. Due to high compressive stresses near indenter contact faces, modified regularized formulation fracture coupled with material prevent formation interpenetration compressed regions. The simulation results show that radial cracks perpendicular poling direction propagate faster than...

Abstract The novel coronavirus (COVID-19) has already spread to almost every country in the world and infected over 3 million people. To understand transmission mechanism of this highly contagious virus, it is necessary study potential factors, including meteorological conditions. Here, we present a machine learning approach effect temperature, humidity wind speed on number people three most populous autonomous communities Spain. We find that there moderate inverse correlation between...

The Finite Element Method (FEM) suffers from important drawbacks in problems involving excessive deformation of elements despite being universally applied to a wide range engineering applications. While dynamic remeshing is often offered as the ideal solution, its computational cost, numerical noise and mathematical limitations complex geometries are impeding widespread use. Meshless methods (MM), however, by not relying on mesh connectivity, circumvent some these limitations, while...

Omni directional mobile robots have been popularly employed in several applications especially soccer player considered Robocup competitions. However, omni navigation system, omni-vision system and omni-kick mechanism such not ever combined. This situation brings the idea of a robot with no head direction into existence, i.e. comprehensive robot. Such can respond more quickly it would be capable for sophisticated behaviors as ball passing or goal keeping. paper has tried to focus on...

The mass sensitivity of the piezoelectric surface acoustic wave (SAW) sensors is an important factor in selection best gravimetric for different applications. To determine this value without facing practical problems and long theoretical calculation time, we have shown that SAW can be calculated by a simple three-dimensional (3-D) finite-element analysis (FEA) using commercial platform. FEA data are used to calculate propagation speed, particle displacements, energy distribution on cuts...

In this study, a novel biopolymer based on poly(glycerol sebacic)-urethane (PGS-U) and its nanocomposites containing Cloisite@30B were synthesized by facile approach in which the crosslinking was created aliphatic hexamethylene diisocyanate (HDI) at room temperature 80 °C. Moreover, metronidazole tetracycline drugs selected as target loaded into PGSU nanocomposites. A uniform continuous microstructure with smooth surface is observed case of pristine PGS-U sample. The continuity all...

In multilayer ferroelectric actuators, electrode edges are the main source of fracture due to generation non-uniform electric fields in their vicinity. The fields, turn, induce incompatible strain and hence concentrated stresses, which may cause ceramic crack. this paper, crack initiation from is simulated using a phase-field model. This model based on variational formulations brittle propagation domain evolution materials. simulation results show different patterns depending bonding...

Omni directional mobile robots have been popularly employed in several applications especially soccer player Robocup competitions. However, control and self-localization of omni are important issues different teams the competitions used techniques to tackle it. Since it is very complicated calculate system transfer function as classic control, a simplified model would be helpful for estimating PID coefficients robots' position orientation control. The vision-based combined with odometry...

The mass sensitivity of the piezoelectric surface acoustic wave (SAW) sensors is an important factor in selection best gravimetric for different applications. To determine this value without facing practical problems and consuming long theoretical calculation time, we have shown that SAW can be calculated by a simple 3D finite element analysis (FEA) using ANSYS platform. FEA data were used to calculate propagation speed, particle displacements energy distribution on cuts various materials....