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This paper presents a thorough study of the strain response of different types of electroceramics during dynamical electrical loading. It highlights important aspects to take into account in the experimental methodology and outlines general guidelines for the discussion and interpretation of the results. The contributions of piezoelectric effect, electrostriction and ferroelectric/ferroelastic domain switching to the strain produced during the application of an alternating electric field are discussed by describing the strain-electric field (S-E) loops of different dielectric ceramics in which each of these contributions are predominant. In particular, attention is given to the description of the strain evolution in the characteristic "butterfly loops" typically shown by ferroelectric materials. The strain-polarization loop is indicated as a useful means to reveal the interconnection between strain and polarization state during dynamical electrical loading. Strain rate is suggested as a powerful tool to obtain more detailed information regarding the mechanisms of the electric field-induced strain.

This paper presents a theoretical description of the effects of strain induced by out-of-plane deformations on charge distributions and transport on graphene. A review of a continuum model for electrons using the Dirac formalism is complemented with elasticity theory to represent strain fields. The resulting model is cast in terms of scalar and pseudo-magnetic fields that control electron dynamics. Two distinct geometries, a bubble and a fold, are chosen to represent the most commonly observed deformations in experimental settings. It is shown that local charge accumulation regions appear in deformed areas, with a peculiar charge distribution that favors occupation of one sublattice only. This unique phenomenon that allows to distinguish each carbon atom in the unit cell, is the manifestation of a sublattice symmetry broken phase. For specific parameters, resonant states appear in localized charged regions, as shown by the emergence of discrete levels in band structure calculations. These findings are presented in terms of intuitive pictures that exploit analogies with confinement produced by square barriers. In addition, electron currents through strained regions are spatially separated into their valley components, making possible the manipulation of electrons with different valley indices. The degree of valley filtering (or polarization) for a specific system can be controlled by properly designing the strained area. The comparison between efficiencies of filters built with this type of geometries identifies extended deformations as better valley filters. A proposal for their experimental implementations as component of devices, and a discussion for potential observation of novel physics in strained structures are presented at the end of the paper.

Strain provides information about local behavior of structural components, and is one of the most concerned parameters in the structural health monitoring (SHM) of civil structures. It plays an important role in the condition assessment of bridges in terms of fatigue or yielding of the structural material, safety reserve or reliability of structural components, etc. The Wind And Structural Health Monitoring System (WASHMS) deployed on the suspension Tsing Ma Bridge (TMB) in Hong Kong has hitherto operated continuously for 17 years. As part of the WASHMS, 110 strain gauges were installed on the bridge to measure the dynamic strain response of the TMB. Based on the strain measurement data acquired in 2012, the structural condition of the TMB is evaluated by addressing the following issues: (1) Evaluation of the characteristics of stress responses in structural members on different deck cross-sections and comparison with the results obtained in 1999. (2) Statistical analysis of daily maximum stresses in different members and comparison with the design values (designated stresses) due to live loads at both serviceability limit state (SLS) and ultimate limit state (ULS). (3) Evaluation of the inner forces of monitored structural members and the corresponding strength utilization factors (SUFs). The assessment results obtained in the present study can be used as a reference or guideline for scheduling the bridge inspection and maintenance activities.

In this paper, the electrical and optical properties of single-layer MoS₂ and single-layer WS₂ in three strain states: biaxial tension, biaxial compression, biaxial tension and compression are systematically studied. All calculations are based on the first-principle of density functional theory. The results show that after biaxial tension strain, biaxial compression strain, and biaxial tension-compression strain are applied, the atomic structure, energy band structure, and optical absorption coefficient will show disparate changing trends. When the biaxial tension and compression strain intensity is less than 15%, the bond length, bond angle, and light absorption peak will have little fluctuation with the increase of strain intensity. However, compared with the other two strain states, these two crystal structures are the most volatile at this time. In addition, when 15% biaxial tensile strain is applied, the two crystals can still maintain their kinetic stability.

The study of complex oxides and oxide heterostructures has dominated the field of experimental and theoretical condensed matter research for the better part of the last few decades. Powerful experimental techniques such as molecular beam epitaxy and pulsed laser deposition have made fabrication of oxide heterostructures with atomically sharp interfaces possible, whereas more and more sophisticated handling of exchange and correlations within first principles methods including density functional theory (DFT) supplemented with Hubbard U corrections and hybrid functionals, and beyond DFT techniques such as dynamical mean field theory (DMFT) have made understanding of such correlated oxides and oxide interfaces easier. The emergence of the high-mobility two-dimensional electron gas with fascinating properties such as giant photoconductance, large negative magnetoresistance, superconductivity, ferromagnetism, and the mysterious coexistence of the latter two have indeed caught the attention of condensed matter community at large. Similarly, strain tuning of oxides have generated considerable interest particularly after the recent discovery of piezoelectric methods of strain generation. Theoretical understanding and prediction of the possible exotic phases emerging in such complex oxides both under strain and in heterostructures will eventually lead to better design of device applications in this new emerging field of oxide electronics, along with possible discovery of exotic physics in condensed matter systems, which may be of wider significance! In this review, we briefly look at theoretical studies of novel phenomena in oxides under strain and oxide heterostructure, and try to understand the role of exchange and particularly correlation in giving rise to such exotic electronic states. This review though primarily focuses on the theoretical aspects on understanding the different mechanism of the phenomena of emergence of exotic phases, does provide a unique overview of the experimental literature as well, accompanied by the theoretical understanding such that relevant device applications can be envisaged.

The two-dimensional transition-metal dichalcogenides (2D TMDs) WX₂ (S, Se, Te) have received extensive attention and research since they have excellent physical properties and have been widely used in the fields of photoelectronics. Monolayer (ML) WX₂ has excellent physical properties and can be modified by simple strain. Using the first principles based on density functional theory (DFT), this paper mainly studies the electronic properties of ML WS₂, WSe₂ and Wte₂. We also study the stabilities of three ML structures, the changes of Raman spectra and the movement of Raman peaks under biaxial tensile and compressive strains. Under the control of strain not only does the bandgap changes, but also the band properties shift between the direct bandgap and the indirect bandgap. With the increase of strain, bond length and bond angle change in the opposite trend. At the same time, we also studied the phonon dispersion relations of WX₂ under different strains. We found that three structures showed good thermodynamic stabilities under the tensile strain (1–10%). When the compressive strain is 2%, one of the acoustic modes of WS₂ or Wse₂ becomes imaginary at $\mathrm{\Gamma }$ point, which indicates the structural instability. When tensile strain Raman summit blueshifts and when compressive strains, the redshift occurs.

Yttria nanoparticles are synthesized by co-precipitation method and as-prepared nanoparticles are annealed at various temperatures. The as-prepared and annealed particles are characterized by X-ray diffraction and transmission electron microscope (TEM). Here we estimated the lattice strain, crystallite size, deformation stress, and deformation energy density for annealed (800°C) yttrium oxide nanoparticles by Williamson-Hall-Isotropic Strain Model (W-H-ISM), W-H-Anisotropic Strain Model (W-H-ASM) and W-H-Energy Density Model (W-H-EDM) based on W-H plot from powder X-ray diffraction data. The shape and size of the nanoparticles are determined using TEM. The results of the estimated crystallite size of yttria nanoparticles by various methods agreed with the TEM results.

First-principles calculation has been performed to investigate the effect of strain on the magnetic moment of Fe-doped MoTe₂ monolayer. Our results show that the Fe-doped MoTe₂ monolayer is semiconductor with the magnetic moment of 2.037 ${\mu }_{\mathrm{\text{B}}}$. By analyzing the density of states, we find that the magnetic moment is mainly contributed by the Fe atom. When the biaxial strain is applied along the layer, the results show that the magnetic moment is almost unchanged when the compressive strain is under 5% and tensile strain is under 7%. However, as the strain increases, the magnetic moment decreases to almost zero with compressive strain larger than 7%, and the magnetic moment begins to increase with the tensile strain larger than 8%, which indicates the different effects of compressive strain and tensile strain on the magnetism of Fe-doped MoTe₂.

The proximal femoral nail antirotation device (PFNA) is a typical implant to the treatment of intertrochanteric fractures. However, re-fracture of the femur shaft after nailing are usually been reported. The purpose of this study was to investigate the biomechanical features in the healed proximal femur at different stages in the healing process. Stress and strain distributions, total strain energy density (SED) along the femur and PFNA were analyzed in walking and stair climbing. Results showed remarkable stress concentration occurred near the locking bolt hole with retained PFNA, decreased after PFNA removal. Stair climbing resulted in higher strain at the locking bolt hole than normal walking. The conclusion can be drawn that non-removal of PFNA after healing may result in high fractural risk near locking bolt on femoral shaft. Meanwhile, stair climbing should be avoided during healing.

The effects of biaxial strain parallel to the (001) plane on the electronic structures and optical properties of Ge are calculated using the first-principles plane-wave pseudopotential method based on density functional theory. The screened-exchange local-density approximation function was used to obtain more reliable band structures, while strain was changed from −4% to $+$4%. The results show that the bandgap of Ge decreases with the increase of strain. Ge becomes a direct-bandgap semiconductor when the tensile strain reaches to 2%, which is in good agreement with the experimental results. The density of electron states of strained Ge becomes more localized. The tensile strain can increase the static dielectric constant distinctly, whereas the compressive strain can decrease the static dielectric constant slightly. The strain makes the absorption band edge move toward low energy. Both the tensile strain and compressive strain can significantly increase the reflectivity in the range from 7 eV to 14 eV. The tensile strain can decrease the optical conductivity, but the compressive strain can increase the optical conductivity significantly.

In this study, a molecular dynamics (MD) study has been performed on composition and temperature dependences of mechanical properties of CdTe${}_{1-x}$Se${}_x$ ($x=0.25$, 0.50 and 0.75) nanowires with a diameter of 6.93 nm. The simulation results show that CdTe${}_{0.75}$Se${}_{0.25}$ nanowire seems to be more ductile, whereas CdTe${}_{0.25}$Se${}_{0.75}$ nanowire seems to be more brittle at 1 K. Moreover, the temperature and composition exert significant effects on the mechanical properties of CdTeSe nanowires under stretching. We conclude that the dominancy of Se atoms yields a higher stability and strength at the lower temperature of 1 K, whilst it is the same for the nanowires with both higher Te and Se contents at the higher temperature of 300 K. The radial distribution functions (RDFs) have also been calculated for the CdTeSe nanowires based on the pair separation distance at 1 and 300 K.

The elastic and photocatalytic properties of multiferroic material InFeO₃ under strain are calculated through density functional theory. The calculated results indicate that the intrinsic InFeO₃ and the strained InFeO₃ meet the mechanical stability conditions and hold a relatively larger elastic coefficient than popular multiferroic material BiFeO₃. The calculated bandgap and band edge of InFeO₃ under tensile strain show that InFeO₃ could be a high-efficiency photocatalytic hydrogen production material. InFeO₃ under tensile strain holds the ability of photocatalytic water splitting to produce hydrogen with excellent ferroelectric, mechanical properties and absorption of visible light.

We present first-principles calculations to study the stability and electronic properties of stanene on WS₂ hybrid structure. It can be seen that the stanene is bound to WS₂ substrate with an interlayer distance of about 3.0 Å with a binding energy of −51.8 meV per Sn atom, suggesting a weak interaction between stanene and WS₂. The nearly linear band dispersion character of stanene can be preserved with a sizeable band gap in stanene on WS₂ hybrid structure due to the difference of onsite energy induced by WS₂ substrate, which is more helpful to the on–off current ratio in the logical devices made of stanene/WS₂. Moreover, the band gaps, the position of Dirac point with respect to Fermi level, and electron effective mass (EEM) of stanene on WS₂ hybrid structure can be tuned by the interlayer distance, external electric field and strains. These results indicate that stanene on WS₂ hybrid structure is a promising candidate for stanene-based field-effect transistor (FET) with a finite band gap and high carrier mobility.

A three-dimensional (3D) digital image correlation (DIC) method is presented for measuring the deformations of vinyl chloride-coated metal (VCM) multilayer sheets and their composites. The calculations and the principle of strain and deformation measurements using the DIC method are described. A VCM multilayer sheet consists of a substrate [steel plate cold commercial (SPCC) and steel plate cold elongation (SPCE)] and a clad (a VCM film). The corresponding deformations of VCM deep-drawing multilayer sheets (SPCE as a substrate and a VCM film as a clad), VCM nondeep-drawing multilayer sheets (SPCC as a substrate and a VCM film as a clad), nondeep-drawing substrates (SPCC), deep-drawing substrates (SPCE) and clads (VCM films) were captured along the x- and y-directions in uniaxial tension experiments and using the DIC method. The maximal measured strains along the x-direction for the VCM deep-drawing multilayer sheets, VCM nondeep-drawing multilayer sheets, nondeep-drawing substrates, deep-drawing substrates and clads were, respectively, 637.835%, 132.210%, 31.688.632%, 107.102%, and 118.937%. The maximal measured strains along the $y$-direction were 739.028%, −11.174%, −9.678%, −13.273% and 12.120%, respectively. These data show that the mechanical properties of VCM multilayer sheets are better than those of their substrates and clads. The effectiveness and accuracy of the presented DIC method for VCM multilayer sheet measurements were confirmed in a series of experiments.

A comprehensive theoretical study has been carried out to examine the electronic and thermoelectric properties of As$XY$ (where $X=\mathrm{\text{S}}$, Se; $Y=\mathrm{\text{Cl}}$, Br, and I) monolayers. The lattice constants of these monolayers are optimized to determine their most stable configurations. The electronic and thermoelectric characteristics of these monolayers are calculated using state-of-the-art computational methods. Specifically, the first-principles calculations in combination with semiclassical Boltzmann transport theory were employed to gain insights into their behavior. One of the crucial findings of the study is the observation of an indirect band nature in all the studied monolayers. This characteristic provides valuable information about the materials’ electronic behavior and potential applications. Furthermore, the impacts of tensile and compressive strains on these monolayers are investigated. Interestingly, we observed changes in the band value when strain is applied, which opens up exciting possibilities for engineering their electronic properties. Importantly, despite these changes, the band nature of the monolayers remains consistent. In particular, it is found that the AsSI monolayer exhibits a remarkable enhancement in the Seebeck coefficient, both in the unstrained state and under a compressive strain of 4% in the p-type region. This enhancement leads to a higher power factor (PF), suggesting that AsSI monolayers could be promising candidates for efficient thermoelectric devices. Overall, these findings highlight the potential of strain engineering to tailor the electronic properties of As$XY$ monolayers, offering exciting opportunities for their application in thermoelectric devices. This research contributes valuable insights into the design and optimization of novel materials for future energy conversion and electronic applications.

The aim of this study was to enhance head-injury prediction, this paper investigated the behavior of cerebrospinal fluid (CSF) in finite element (FE) modeling. Nine different material properties selected according to material definitions and property values were used to represent CSF in FE head models. To evaluate the influence of CSF material parameters on brain mechanical responses, the models were validated against available cadaver experiment data. Results showed that coup pressure increased whereas contrecoup pressure decreased when the head sustained purely translational impact with increased bulk modulus when CSF was modeled as fluid. However, with increased bulk modulus, coup pressure, contrecoup pressure and relative skull-brain motions decreased under rotational impact. When CSF was assumed to be an elastic material, coup pressure increased whereas contrecoup pressure decreased with increased elastic modulus when the head was subjected to purely translational impact. However, the variation trend was not obvious during head rotation. Results also indicated that when subjected to brain strain and von Mises stress, the model was prone to underestimate brain injury when CSF was modeled as an elastic material, especially during purely translational impact to the head. The model with CSF as fluid reduced the strain rate of brain, which was more likely to be realistic than the model with CSF as a viscoelastic material. These findings suggested that significantly higher values of the bulk modulus of CSF modeled as fluid were needed to predict intracranial dynamic responses and brain injury during head impact.

Background: Shoulder and elbow motions can affect ulnar nerve strain. However, there is no evidence that links this kind of strain to specific activities. The purpose of this study was to examine ulnar nerve strain at the elbow resulting from normal daily activities.

Methods: This study was conducted using thirty fresh frozen cadaveric elbows from subjects who had no deformities or history of previous upper extremity surgery. Strain was calculated based on nerve elongation. Ulnar nerve strain at the elbow from motion related to common daily activities was measured in both normal nerves and nerves in which gliding motion was restricted. The results of these measurement were then compared.

Results: Activities related to extreme elbow and shoulder motions, such as cellular phone use, yielded an average strain of 6.3%. In addition, we found that nerve strain increased significantly in conditions in which gliding motion was restricted. Nerve strain due to motion associated with cellular phone use, for example, rose by 69.1%.

Conclusions: Elbow flexion and shoulder abduction in daily activities are associated with increases in ulnar nerve strain, but this may not cause permanent damage to the nerve. After nerve gliding motion had been restricted, nerves that normally exhibited less strain often had even increased higher levels of strain than those nerves that normally exhibited high strain.

The cracking of GaN films and the associated cracking of substrates are described. The geometry, structure, and evolution of fracture demonstrate that GaN films crack under tensile stress during growth and are subsequently overgrown and partially healed. The film cracks channel along the (1010)_GaN planes and also extend a distance of ~5 μm into the sapphire substrate. These incipient cracks in the substrate form a set of initial flaws that leads to complete fracture through the sapphire during cooling for sufficiently thick films. Each stage of this cracking behavior is well described by a fracture mechanics model that delineates a series of critical thicknesses for the onset of cracking that are functions of the film and substrate stresses, thicknesses, and elastic properties. Similar cracking behavior is found to occur independently of the choice of substrate between sapphire and SiC and is traced to a tensile stress generation mechanism early in the growth process, such as that provided by island coalescence. Cracking is the dominant stress relief mechanism, as opposed to dislocation generation or diffusion, because of the island growth mode and because of optimized growth temperatures at or below the brittle-to-ductile transition. Lateral epitaxial overgrowth (LEO) of GaN is shown to minimize substrate fracture even though film cracking remains unaffected. This effect explained in terms of the limits placed on the initial extent of insipient substrate cracks due to the LEO geometry.

In this study, we propose a new bilayer-laminated magnetoelectric (ME) composite consisting of magnetostrictive Ni and Tb${}_{0.3}$Dy${}_{0.7}$Fe₂ (Terfenol-D) plates and piezoelectric Pb(Zr,Ti)O₃ (PZT) plate. The Ni–Terfenol–D-Ni/PZT composite is constructed and compared with the traditional Terfenol-D/PZT composite. The bias magnetic field and the electric field frequency dependences of the converse ME (CME) coefficient were investigated. It is shown that the Ni–Terfenol-D–Ni/PZT exhibits a large CME coefficient of 6.2 × 10${}^{-7}$ s/m at the electric field frequency of 42 kHz under a low bias magnetic field of 230 Oe, which results from the highly concentrated flux induced by Ni and the stress-interaction between Ni and magnetostrictive Terfenol-D.

The effect of high-energy electron beam on the silicon carbide nanopowder’s structural parameters, strain and powder size was studied. The sample was irradiated with $\sim$2-MeV electron beam energy under different fluencies such as 1.13 ⋅ 10${}^{17}$, 1.89 ⋅ 10${}^{17}$, 2.79 ⋅ 10${}^{17}$ and 3.69 ⋅ 10${}^{17}$ cm${}^{-2}$ at the linear electronic accelerator. Initial and irradiated samples at various doses have been analyzed in the XRD. The nanostructural effects within FullProf are treated using the pseudo-Voigt profile function. The dependences of maximum strain and nanocrystallite size on irradiation dose were obtained and analyzed.