Large Strain Research Articles

Comparing the Impacts of Strain Types on Oxygen-Vacancy Formation in a Perovskite Oxide via Nanometer-Scale Strain Fields.

The utilization of an in-plane lattice misfit in an oxide epitaxially grown on another oxide with a different lattice parameter is a well-known approach to induce strains in oxide materials. However, achieving a sufficiently large misfit strain in this heteroepitaxial configuration is usually challenging, unless the thickness of the grown oxide is kept well below a critical value to prevent the formation of misfit dislocations at the interface for relaxation. Instead of adhering to this conventional approach, here, we employ nanometer-scale large strain fields built around misfit dislocations to examine the effects of two distinct types of strains─tension and compression─on the generation of oxygen vacancies in heteroepitaxial LaCoO3 films. Our atomic-level observations, coupled with local electron-beam irradiation, clarify that the in-plane compression notably suppresses the creation of oxygen vacancies, whereas the formation of vacancies is facilitated under tensile strain. Demonstrating that the defect generation can considerably vary with the type of strain, our study highlights that the experimental approach adopted in this work is applicable to other oxide systems when investigating the strain effects on vacancy formation.

Dynamic modeling and analysis of viscoelastic hard-magnetic soft actuators with thermal effects

Hard-magnetic soft materials (HMSMs) are a class of magnetoactive smart polymers capable of sustaining a high residual magnetic flux density and can undergo large actuation strains under an external magnetic excitation. Due to these exceptional characteristics, soft actuators based on HMSMs hold enormous potential for remote-controlled applications. The temperature and viscoelasticity considerably influence the performance of these materials during the operation. This work aims to develop an analytical framework for modeling the dynamic behavior of a planar hard-magnetic soft actuators (HMSA) considering temperature and viscoelastic effects. The constitutive behavior of the viscoelastic HMSA is described by employing an incompressible neo-Hookean model in conjunction with a Zener rheological model and the Rayleigh dissipation function. The dynamic governing differential equations of motion are derived by utilizing the non-conservative form of the Euler–Lagrange equation. This study delves into the collective influence of temperature and viscoelastic properties on the stability, periodicity, and resonance characteristics of nonlinear vibrations exhibited by HMSM-based planar actuator subjected to dynamic magnetic loading, presenting the findings through time-history responses, Poincaré maps, and phase-plane plots. The presented results can help in the efficient and robust design of HMSM-based actuators and can also serve as an initial step toward the development of advanced actuators exposed to dynamic loading under variable temperatures for diverse applications in the fields of engineering and medicine.

New strain configuration of convergence in the Arabia-Eurasia collisional zone: A comprehensive analysis of large shear zones inferred from geodetic and seismic observations

A new strain configuration is presented concerning the ongoing convergence deformation field in the Turkish-Iranian High Plateau (TIHP), E Anatolia-NW Iran. The strain configuration is derived from the contribution of geodetic strain-rate fields using GPS velocity data to reveal new constraints not documented previously in the region. This provides good evidence for novel “highland shear strain zones” by analysis of the combination of interpolated GPS velocity fields and seismological observations with maximum principal strain axes. Both the strain-rate fields and rotational elements of the estimated geodetic deformation exhibit juxtaposed, patchy strain rate partitioning in E Anatolia-NW Iran. These comprise both compressional strain lobes combined with local extensional areas and large shear strain fields in the core of the collision where the rotation rate fields present an unexpected propagation zone of continuous, counterclockwise rotation towards the W. The main results define approximately N-S- and W-E-trending, large, continuous, diagonal shear strain patterns with high total strain rate and maximum shear strain rate, consistent with right-lateral strike-slip and normal focal mechanisms. These are the Longitudinal Shear Zone (LSZ) extending from S to N and dividing the TIHP into the E Anatolia and NW Iran blocks, and the right-lateral Transcurrent Shear Zone (TSZ) extending from E (NW Iran) to W (E Anatolia). These differential movements of the inconsistent LSZ and TSZ shape both the highly buoyant plateau topography and the area, which undergoes migration to the W with respect to stable Eurasia by means of plateau push. Geodetic deformation compatible with fault focal data indicates that the LSZ and TSZ, in the framework of thermal and mechanical changes in the structure of the lithospheric thickness beneath the TIHP, are invaded and shaped by flowing mantle material that triggers and drives lateral escape of convergent crustal blocks, and configures the convergence with a shear-dominated deformation regime. The shear regime is primarily driven by NE- and NW-directed mantle flow fields and associated buoyancy forces due to slab fragmentation and tears in the region, exerting dominant control over the differential evolution of the LSZ and TSZ patterns. The new strain configuration for this convergence illuminates “the highland tectonics of large shear zones” resulting from slab thinning or its absence, and challenges conventional tectonic strain models in the TIHP.

Interface engineering at the nanoscale: Synthesis of low‐energy boundaries

The low toughness and structural stability of nanostructured materials is strongly related to the numerous grain boundaries and interfaces. This necessitates new design strategies to inherently improve the grain boundaries. Amongst other concepts the use of low‐energy boundaries has turned out to provide the most comprehensive improvement of the property spectrum targeting on ductility, toughness, as well as thermal and microstructural stability upon mechanical loading. Cyclic high‐pressure torsion (CHPT) is one prosperous technique to synthesis low‐angle boundaries (LAGB) at the nanoscale, enabling the production of high‐strength materials. We present here an in‐depth analysis of the structural evolution focusing on the effect of different strain amplitudes and accumulated strains as well as crystal structure to understand how these parameters need to be adjusted to optimize the fraction of LAGBs. Different than expected from classical fatigue testing, the crystal structure seems to play a minor role for the cell structure evolution at comparably large strain amplitudes. It is therefore a strong asset that CHPT is feasible to produce nanostructures LAGB boundaries in both FCC and BCC structures. Furthermore, by optimizing the geometry of the anvils, it enables homogenous structural sizes in the entire sample as in contrast to other techniques the strain gradient impact on LAGB formation can be overcome.This article is protected by copyright. All rights reserved.

The extended scaling laws of the mechanical properties of additively manufactured body-centered cubic lattice structures under large compressive strains

Additively manufactured lattice structures are porous light-weight structures with mechanical properties that are dictated both from the topology and the parent material properties. When printed from metals, these structures can withstand large continuous plastic deformation. In this paper, we focus on body-centered cubic (BCC) lattice structures under compression up to large deformation strains, and we propose relations between the slenderness ratio of struts and the following mechanical properties: Young's modulus, yield strength, hardening rate of the structure and the densification strain. We perform a systematic study using finite element modelling (FEM) to find how both material properties and lattice structures are affecting the effective mechanical properties of BCC lattice structures under compression. Based on this analysis we propose the scaling laws of the mechanical properties. The scaling laws can be explained as an extension of the Gibson-Ashby power law relations for bend-dominated structures with non-slender beams. We also discuss how rounding the connections between the struts using fillets affects the scaling laws. We demonstrate the scaling laws in the analysis of experimental results, showing the accuracy and limitations of the scaling laws in predicting the mechanical properties, with an emphasis on large deformations. In the analysis, we use experimental values published in literature, and we also present here experimental results of lattice structures printed from Inconel 718.

High performance magnesium-based plastic semiconductors for flexible thermoelectrics

Low-cost thermoelectric materials with simultaneous high performance and superior plasticity at room temperature are urgently demanded due to the lack of ever-lasting power supply for flexible electronics. However, the inherent brittleness in conventional thermoelectric semiconductors and the inferior thermoelectric performance in plastic organics/inorganics severely limit such applications. Here, we report low-cost inorganic polycrystalline Mg3Sb0.5Bi1.498Te0.002, which demonstrates a remarkable combination of large strain (~ 43%) and high figure of merit zT (~ 0.72) at room temperature, surpassing both brittle Bi2(Te,Se)3 (strain ≤ 5%) and plastic Ag2(Te,Se,S) and organics (zT ≤ 0.4). By revealing the inherent high plasticity in Mg3Sb2 and Mg3Bi2, capable of sustaining over 30% compressive strain in polycrystalline form, and the remarkable deformability of single-crystalline Mg3Bi2 under bending, cutting, and twisting, we optimize the Bi contents in Mg3Sb2-xBix (x = 0 to 1) to simultaneously boost its room-temperature thermoelectric performance and plasticity. The exceptional plasticity of Mg3Sb2-xBix is further revealed to be brought by the presence of a dense dislocation network and the persistent Mg-Sb/Bi bonds during slipping. Leveraging its high plasticity and strength, polycrystalline Mg3Sb2-xBix can be easily processed into micro-scale dimensions. As a result, we successfully fabricate both in-plane and out-of-plane flexible Mg3Sb2-xBix thermoelectric modules, demonstrating promising power density. The inherent remarkable plasticity and high thermoelectric performance of Mg3Sb2-xBix hold the potential for significant advancements in flexible electronics and also inspire further exploration of plastic inorganic semiconductors.

Hybrid-Microstructure-Based Soft Network Materials with Independent Tunability of Mechanical Properties over Large Deformations.

Introducing auxetic metamaterials into stretchable electronics shows promising prospects for enhancing the performance and innovating the functionalities of various devices, such as stretchable strain sensors. Nevertheless, most existing auxetics fail to meet the requirement of stretchable electronics, which typically include high mechanical flexibility and stable Poisson's ratio over large deformations. Moreover, despite being highly advantageous for application in diverse load-bearing conditions, achieving tunability of J-shaped stress-strain response independent of negative Poisson's ratio remains a significant challenge. This paper introduces a class of hybrid-microstructure-based soft network materials (HMSNMs) consisting of different types of microstructures along the loading and transverse directions. The J-shaped stress-strain curve and nonlinear Poisson's ratio for HMSNMs can be tuned independently of each other. The HMSNM provides much higher strength than the corresponding existing metamaterial while offering a nearly stable negative Poisson's ratio over large strains. Both mechanical properties under infinitesimal and large deformations can be well-tuned by geometric parameters. Fascinating functionalities such as shape programming and stress regulation are achieved by integrating a set of HMSNMs in series/parallel configurations. A stretchable LED-integrated display capable of displaying dynamic images without distortion under uniaxial stretching serves as a demonstrative application.

Bidirectional large strain monitoring using a novel graphene film-based patch antenna sensor

This study proposes a rectangular microstrip patch antenna sensor based on a high-conductivity graphene film for bidirectional strain detection in structural health monitoring (SHM). By using a highly conductive graphene film instead of traditional metal foil to produce a patch antenna, the antenna possesses a higher flexibility and a larger sensing range. The mechanical, electromagnetic, and radiative properties were investigated. The strain sensing principle based on the resonant frequency offset of the graphene film antenna was proposed. The relationships between the resonant frequency shift and structural strain were quantitatively explored through theoretical deductions, finite element simulations, and experiments. According to the experimental results, the shift in the resonant frequency was linearly related to the lateral and longitudinal strains. The sensitivity coefficients for the lateral and longitudinal strains were 2.2037 kHz/μϵ and 3.6198 kHz/μϵ, respectively. The thermal strain can be distinguished based on the linear resonant frequency-temperature relationship. The results demonstrated the advantages and prospects of the proposed novel patch antenna for SHM.

Enhanced perturbation measurement range chirped pulse ϕ-OTDR for distributed static measurements using feedback frequency-shift compensation technology

Chirped-pulse phase-sensitive optical time-domain reflectometry (CP-ϕOTDR) is a newly developed distributed optical fiber sensing (DOFS) technology that can measure physical quantities across the length of optical fiber. The measurement of perturbations as strain or temperature changes is performed by comparing the time domain trace of Rayleigh backscattered (RBS) light with a reference trace. However, large strain or temperature fluctuations or laser frequency noises necessitate frequent updates of the reference, and short-term change measurements must be integrated to obtain absolute strain or temperature, which introduces a 1/f noise component due to the combination of noise with each cumulative change. In this study, we propose a novel CP-ϕOTDR system based on frequency-shift compensation (FSC) technology. This system utilizes real-time feedback control of the central frequency of the incident laser to compensate for time domain trace distortion caused by large perturbations. It overcomes the limitations associated with the total chirp bandwidth and eliminates the 1/f noise component by obviating the need for frequent updates of the reference trace. The measuring range for perturbations is only limited to the wavelength range supported by the integrated optical devices, typically on the order of nanometers, corresponding to at least tens of Kelvin in temperature fluctuations or hundreds of micro-strains. To validate the effectiveness, we conducted a temperature measurement experiment involving a 1 K variation, which is about 90 times the maximum measurable perturbation that the original CP-ϕOTDR system can demodulate with the reference unchanged. The results demonstrate that the FSC method significantly expands the perturbation measurement range of the CP-ϕOTDR system.

Fracture behaviors of the 1500 MPa-grade anti-oxidation hot-stamped steel: Measurement, numerical simulation and experimental validation

Ultra-high strength hot-stamped steel has been increasingly and widely used for the improvement of the collision safety and lightweight level. The 1500 MPa-grade anti-oxidation hot-stamped steel (AHS-1500), as a newly developed hot-stamped steel, is promising in the automotive industry due to its advantages of anti-oxidation, high strength, high hardenability, and no coating. It is necessary to figure out its fracture failure behaviors and further predict the fracture risk for promoting the large-scale application. In this paper, the fracture behaviors of the AHS-1500 steel plate are investigated by experiments and simulation. The fracture tests are conducted under static and dynamic loads by considering various stress states, namely uniaxial tension, notched static tension, shear, punching, center-hole static tension, and VDA bending. The fracture failure behaviors are obtained. Moreover, an Swift+Hockett-Sherby combined hardening model is adopted to extrapolate the post-necking flow stress to obtain the stress-strain relation at large strains. A fracture failure model is further established based on the GISSMO fracture failure criterion to accurately describe the failure behaviors under various stress states. The nonlinear fracture failure strain and the necking instability strain are determined with the consideration of the influence of element size and strain rate. Finally, the three-point bending experiment of a cap beam part is conducted and simulated to verify the effectiveness of the proposed model. The simulated results match the experimental ones very well, with the absolute relative errors of only 1.4 % and 4.6 % for the peak force and peak displacement, respectively. This research is favourable for contributing to high-precision numerical analysis for the design of automotive structural components and providing technical support for large-scale promotion of the AHS-1500 steel.

Shear strengthening of reinforced concrete beams completely wrapped by large rupture strain (LRS) FRP

An experimental work on the shear strengthening of reinforced concrete (RC) beams completely wrapped by large rupture strain (LRS) FRP is presented in this paper. A total of 14 three-point bending tests were carried out on simply supported RC beams, with a focus on the impacts of the shear span-to-depth ratio (1.53, 2.25, and 3.01) and FRP reinforcement ratio (0.37 %, 0.75 %, and 1.12 %) on the shear behavior of RC beams strengthened with LRS FRP. For the beams with a median length, the ductility coefficients increased by 81 %, 154 %, and 335 % with the increase in FRP reinforcement ratio. For the long beams, the ductility coefficients increased by 116 %, 286 %, and 470 % as the FRP reinforcement ratio improved. The ductility markedly improved with the increase in shear span-to-depth ratio. PET FRP’s fracture was not found at the ultimate state, and the improvement in mid-span deflection after the peak state was mainly contributed by the shear deformation. The strengthened specimens exhibited a ductile shear failure mode. For the short RC beams, the shear capacity was slightly enhanced, and the ductility was not improved after being strengthened. The strengthened short RC beams still showed a brittle diagonal compression failure mode. The experimental shear contribution of PETT FRP was compared with the prediction of the existing design guidelines. Finally, an effective strain model of PET FRP, including the shear span-to-depth ratio effect, was proposed and verified with the experimental results.

Experimental and constitutive model investigation on the tensile mechanical properties of polyurea at wide strain-rate range

Polyurea is extensively utilized as a protective coating material for structures under impact and blast loadings, owing to its significant large tensile deformation capability and strain hardening effect. In this study, the tensile performance of polyurea was experimentally and theoretically investigated. Firstly, rational geometric shapes and dimensions were designed, and a series of quasi-static and dynamic uniaxial tensile tests were conducted to obtain the nonlinear stress-strain curves at different strain rates. The results indicated a notable strain-rate effect in polyurea, with an increase in elastic modulus and tensile stress as the strain rate increased. Moreover, as the strain rate escalates, the strain hardening effect becomes more pronounced, thereby enhancing the protective capabilities of polyurea. Subsequently, an existing hyperelastic model, namely the Mooney-Rivlin (MR) model, was modified to incorporate the strain rate effect, resulting in a non-linear visco-hyperelastic constitutive model. Furthermore, the proposed constitutive model and parameters were validated by simulating existing tensile and blast tests using the finite element (FE) program LS-DYNA. This work could provide a reference for the design of structural protection.

Stress–strain curve and elastic behavior of the fibrotic lung with usual interstitial pneumonia pattern during protective mechanical ventilation

Patients with acute exacerbation of lung fibrosis with usual interstitial pneumonia (EUIP) pattern are at increased risk for ventilator-induced lung injury (VILI) and mortality when exposed to mechanical ventilation (MV). Yet, lack of a mechanical model describing UIP-lung deformation during MV represents a research gap. Aim of this study was to develop a constitutive mathematical model for UIP-lung deformation during lung protective MV based on the stress–strain behavior and the specific elastance of patients with EUIP as compared to that of acute respiratory distress syndrome (ARDS) and healthy lung. Partitioned lung and chest wall mechanics were assessed for patients with EUIP and primary ARDS (1:1 matched based on body mass index and PaO2/FiO2 ratio) during a PEEP trial performed within 24 h from intubation. Patient’s stress–strain curve and the lung specific elastance were computed and compared with those of healthy lungs, derived from literature. Respiratory mechanics were used to fit a novel mathematical model of the lung describing mechanical-inflation-induced lung parenchyma deformation, differentiating the contributions of elastin and collagen, the main components of lung extracellular matrix. Five patients with EUIP and 5 matched with primary ARDS were included and analyzed. Global strain was not different at low PEEP between the groups. Overall specific elastance was significantly higher in EUIP as compared to ARDS (28.9 [22.8–33.2] cmH2O versus 11.4 [10.3–14.6] cmH2O, respectively). Compared to ARDS and healthy lung, the stress/strain curve of EUIP showed a steeper increase, crossing the VILI threshold stress risk for strain values greater than 0.55. The contribution of elastin was prevalent at lower strains, while the contribution of collagen was prevalent at large strains. The stress/strain curve for collagen showed an upward shift passing from ARDS and healthy lungs to EUIP lungs. During MV, patients with EUIP showed different respiratory mechanics, stress–strain curve and specific elastance as compared to ARDS patients and healthy subjects and may experience VILI even when protective MV is applied. According to our mathematical model of lung deformation during mechanical inflation, the elastic response of UIP-lung is peculiar and different from ARDS. Our data suggest that patients with EUIP experience VILI with ventilatory setting that are lung-protective for patients with ARDS.

Yield locus and texture evolution of AA7475-T761 aluminum alloy under planar biaxial loading: An experimental and analytical study

AA7475 aluminum alloy is used as a structural material in aerospace and automobile applications where complex loading conditions are applicable. The material properties under multi-axial loading are recommended for efficient component design. Hence, the mechanical behaviour of AA7475-T761 aluminium alloy was investigated through planar biaxial tensile tests. The yield locus evolution and plastic strain direction were measured at higher plastic strain values (up to 7 %) at various load ratios. The yield loci were constructed and compared with existing yield criteria. Yld2000–2d yield criterion demonstrated accurate predictions with a deviation of approximately 1 %, highlighting its effectiveness in capturing the yield behavior of AA7475. Microstructure analysis using Electron Backscatter Diffraction (EBSD) was conducted to understand the misorientation evolution under the multi-axial loading. Bulk-texture analysis was performed using X-ray diffraction method. Texture analysis revealed that uniaxial deformation favoured the development of Cube and Inverse-Copper textures, while biaxial deformation yielded split Inverse-Goss texture formation. Fractography study shows very different fracture surfaces of biaxial samples compared to uniaxial samples. Overall, this study contributes to a comprehensive understanding of the yield behavior, microstructure, and texture evolution of AA7475-T761 aluminium alloy under different loading conditions at very large strains.

Preparation of Gradient Polyurethane and Its Performance for Flexible Sensors.

Flexible sensors are prone to the problems of slow recovery rate and large residual strain in practical use. In this paper, a polyurethane functional composite with a gradient change in elastic modulus is proposed as a flexible sensor to meet the recovery rate and residual strain without affecting the motion. Different hard and soft segment ratios are used to synthesize a gradient polyurethane structure. The conductive percolation threshold was obtained between 45 wt% and 50 wt% of flake silver powder. Both gradient polyurethane and gradient polyurethane composites demonstrated that gradient materials can increase the recovery rate and reduce residual strain. The gradient polyurethane composites had a tensile strength of 3.26 MPa, an elastic modulus of 2.58 MPa, an elongation at break of 245%, a sensitivity coefficient of 1.20 at 0-25% deformation, a sensitivity coefficient of 11.38 at 25-75% deformation, a rate of recovery of 1.95 s at a time, and a resistance to fatigue (over 1000 cycles at a fixed strain of 20% showed a stable electrical response). The sensing performance under different cyclic strain frequencies was also investigated. The process has practical applications in the field of wearable skin motion and health monitoring.

Critical parameters governing elastocaloric effect in polyisoprene rubbers for solid-state cooling

The aim of this work is to study the critical parameters governing the eCe (elastocaloric effect) of poly-isoprene rubber (NR and IR) in use conditions of a cooling device, i.e. under partial cyclic loading. The effect of mechanical cyclic loading parameters (pre-extension ratio, waveform and frequency) on eCe was first studied. It shows that the eCe increases when the mimimum pre-extension ratio is increased and frequency is lowered from 1Hz to 0.001Hz, as it promotes strain-induced crystallization. However, it also leads to a decrease in potential cooling power, from 7 to 0.01 MW/m3 (i.e. 8 kW/kg to 0.01 kW/kg). At intermediate frequency (f ≈ 0.1 Hz), the comparison of square and triangular waveforms demonstrated that the former enables greater temperature variation. This is due to its holding step (at maximum extension ratio), which maximizes crystallization but also promotes stress relaxation, resulting in increased mechanical losses. Consequently, the square and triangular loadings have a COPmat of 12 and 25, with a temperature variation of 4.2K and 3.6K, respectively. Regarding the formulation, rubbers that do not have a great tendency to crystallize such as synthetic polyisoprene rubber seem to have the best COPmat, while to maximize ΔT, the best of our formulations are NR crosslinked with sulfur and having a crosslink density close to 1.5 × 10−4 mol/cm3, which combine large strain induced crystallization and entropic elasticity. This material has a COPmat of about 27 and allows a ΔT≈4K, i.e.performance comparable to that of the best Shape Memory Alloys (at equivalent COPmat).

Photocycloaddition of Zero-Dimensional Metal Halide Hybrids with Reversible Photochromism.

In this work, two zero-dimensional (0D) metal halide hybrids L2ZnBr4 [1, L = (E)-4-(2-(1H-pyrrol-3-yl)vinyl)-1-methylpyridin-1-ium] and L6Pb3Br12 (2) were prepared, which demonstrated photochromism and photoinduced cracking. Upon irradiation at 450 nm, a single crystal-to-single crystal transformation occurred as a result of the [2 + 2] photocycloaddition of L. Interestingly, compared to the complete photocycloaddition of L in 1, only two-thirds of L monomers could be photodimerized in 2 because of the difference in L orientation. 1 shows reversible photochromic behavior including rapid response time, few cracks, high conversion rate, and good reaction reversibility, while 2 exhibits no significant color change but distinct photoinduced cracking because of the large local lattice strain induced by inhomogeneous and anisotropic deformation. Moreover, the photocycloaddition of L results in the distinct shift of photoluminescence of 1 and 2, attributed to the variation in conjugation of π electrons and distortion of metal halide clusters. As a proof-of-concept, reversible optical writing is demonstrated for 1. These findings provide new insights into the design of stimuli-responsive multifunctional materials.

Failure behavior of tantalum electrolytic capacitors under extreme dynamic impact: Mechanical–electrical model and microscale characterization

Tantalum electrolytic capacitors have performance advantages of long life, high temperature stability, and high energy storage capacity and are essential micro-energy storage devices in many pieces of military mechatronic equipment, including penetration weapons. The latter are high-value ammunition used to strike strategic targets, and precision in their blast point is ensured through the use of penetration fuzes as control systems. However, the extreme dynamic impact that occurs during penetration causes a surge in the leakage current of tantalum capacitors, resulting in a loss of ignition energy, which can lead to ammunition half-burst or even sometimes misfire. To address the urgent need for a reliable design of tantalum capacitor for penetration fuzes, in this study, the maximum acceptable leakage current of a tantalum capacitor during impact is calculated, and two different types of tantalum capacitors are tested using a machete hammer. It is found that the leakage current of tantalum capacitors increases sharply under extreme impact, causing functional failure. Considering the piezoresistive effect of the tantalum capacitor dielectric and the changes in the contact area between the dielectric and the negative electrode under pressure, a force–electric simulation model at the microscale is established in COMSOL software. The simulation results align favorably with the experimental results, and it is anticipated that the leakage current of a tantalum capacitor will experience exponential growth with increasing pressure, ultimately culminating in complete failure according to this model. Finally, the morphological changes in tantalum capacitor sintered cells both without pressure and under pressure are characterized by electron microscopy. Broken particles of Ta–Ta2O5 sintered molecular clusters are observed under pressure, together with cracks in the MnO2 negative base, proving that large stresses and strains are generated at the micrometer scale.

Interfacially Enhanced Superconductivity in Fe(Te,Se)/Bi4Te3 Heterostructures.

Realizing topological superconductivity by integrating high-transition-temperature (TC) superconductors with topological insulators can open new paths for quantum computing applications. Here, a new approach is reported for increasing the superconducting transition temperature by interfacing the unconventional superconductor Fe(Te,Se) with the topological insulator Bi-Te system in the low-Se doping regime, near where superconductivity vanishes in the bulk. The critical finding is that the of Fe(Te,Se) increases from nominally non-superconducting to as high as 12.5K when Bi2Te3 is replaced with the topological phase Bi4Te3. Interfacing Fe(Te,Se) with Bi4Te3 is also found to be critical for stabilizing superconductivity in monolayer films where can be as high as 6K. Measurements of the electronic and crystalline structure of the Bi4Te3 layer reveal that a large electron transfer, epitaxial strain, and novel chemical reduction processes are critical factors for the enhancement of superconductivity. This novel route for enhancing TC in an important epitaxial system provides new insight on the nature of interfacial superconductivity and a platform to identify and utilize new electronic phases.

Test, design, and parametric analysis of a prefabricated industrial building with shape memory alloy (SMA) cable-restrained bearings for seismic resilience

This paper presents an in-depth discussion on the behavior and design of a novel shape memory alloy (SMA) cable-restrained natural rubber (hereinafter denoted as SMA-NR) bearing used for multi-stage seismic protection of an industrial building equipped with critical facilities. The study commences with a brief illustration of the working mechanism of the bearing, followed by an individual SMA cable test and a full-scale quasi-static test on an SMA-NR bearing specimen. The SMA cable specimen exhibits a unique flag-shaped hysteretic behavior with large recoverable strain. The SMA-NR bearing test results present a double-stage hysteretic behavior, i.e., initial horizontally flexible performance and cable-restrained state for structural safety. Through a verified numerical modelling, and taking three structural responses into consideration, i.e., peak absolute acceleration, peak bearing deformation, and residual bearing deformation, an extended parametric study is conducted, covering different bearing types and restraining elements (SMA or steel cables). The system-level analysis results highlight the benefit of the SMA cable-restrained strategy in seismic isolation performance, and show a favorable efficiency of this strategy in trade-off of critical responses. Furthermore, a representative single-degree-of-freedom (SDOF) model is developed and well validated, with a satisfactory agreement to the overall structural model. Seismic fragility analyses are finally conducted considering both far-field and near-fault ground motions, indicating that the SMA cable restrainer, serving as the last-defense strategy, could effectively balance the various dynamic responses of the superstructure.