Internal Stress Distribution Research Articles

High-entropy two-dimensional metal phosphorus trichalcogenides boost high-performance potassium ion storage devices via electrochemical reconstruction

We investigate the influence of configurational entropy on the cycling performance of 2D metal phosphorus trichalcogenides (MPS3) when utilized as anodes in potassium-ion devices. High yield, two-dimensional high-entropy CoVMnFeZnPS3 (HEPS3) with thickness ranging from 6 to 10 nm was synthesized via a vacuum solid-state method. HEPS3 enables efficient potassium-ion transport and intercalation at the interface of electrodes, thanks to the high-entropy effects arising from the interaction of various metal ions on the K+ binding energy. HEPS3 potassium-ion anodes outperform their medium-entropy (CoMnFePS3 (ME3PS3) and CoMnFeZnPS3 (ME4PS3)), CoFePS3 (LE2PS3), and FePS3 (LEPS3) counterparts, exhibiting a high reversible capacity of 524 mAh g−1, impressive high-rate capability up to 10 A g−1, and exceptional cycling stability over 1000 cycles. Our findings indicate that the electrochemical reconstruction of HEPS3 during cycling is crucial for achieving high-performance potassium-ion batteries. In situ-formed metal alloy layers act as catalysts, offering not only suitable adsorption energy to prevent the shuttle effect but also promoting the complete conversion of polysulfides. Furthermore, cations uniformly dispersed across the 2D plane create a "lattice distortion effect," imparting the structure with high mechanical stability and allowing for even distribution of internal stress generated in the electrode during the K+ insertion/extraction process, which in turn suppresses electrode pulverization and prevents the aggregation of MPCh3 layers. This work proposes a novel strategy for significantly enhancing potassium-ion storage performance through the electrochemical activation of high-entropy layered metal phosphides, thus opening a new horizon of 2D material design principle in energy storage devices.

Dynamic response characteristics of grooved cylindrical shells in Taylor impact experiments

Buffer energy absorbing structures have very high use value in daily life, industrial production, aerospace and other fields. Cylindrical shells are used as a highly efficient buffer and energy absorbing structure due to their own structure and good mechanical properties. Taylor impact experiments were conducted on three types of structural cylindrical shells (non grooved, inner grooved, and outer grooved) and numerical model was also established to study and analyze the dynamic response characteristics of the three types of structural cylindrical shells. Finally, the deformation mechanism of the cylindrical shell was analyzed theoretically to explore the impact of grooving treatment on the deformation of the cylindrical shell. The results show that with the increase of impact velocity, the length of the cylindrical shells of the three structures decreased, and the diameter of the impact end and the maximum diameter increased. Each of the three specimens had a convergence velocity(convergence velocity: The impact end diameter of cylindrical shell is the initial impact velocity at the maximum diameter), that is, when the impact velocity was greater than or equal to the convergence velocity, its maximum diameter was equal to the diameter of the impact end. When the impact velocity exceeded a certain value, the deformation modes of the three types of cylindrical shells changed. The comparison of experimental and simulation results proved the effectiveness of the numerical model. The maximum stress was always above the impact end face. It was concluded from the theoretical analysis Due to the stress concentration at the groove, the stress distribution and internal stress distribution of the cylindrical shell were affected, which in turn affected the deformation and energy absorption capacity of the cylindrical shell. At the same impact velocity, the outer grooved cylindrical shell has the shortest buffer time and the BW specimen had the most gentle buffer curve before 35μs .

Structural assessment investigations of the DEMO Divertor shielding components with reference to RCC-MRx

• This paper relates the activity on structural analysis (integrity assessment) carried on the DEMO divertor cassette shielding components. The first step has regarded the evaluation of electromagnetic, thermal and mechanical loads. The structural analysis has focused attention on the integrity assessment of the shielding components (Shielding Liner, inboard and outboard reflector Plates) and their attachment systems. The elastic design-by-analysis rules of the RCC-MRx design code have been adopted. The verification has been performed for monotonic and cyclic loads (primary and secondary damages) under both negligible and significant irradiation conditions. Even though the assessment is not complete, important findings have allowed to refine the geometry of the shielding components to improve the internal stress distribution. The procedures foreseen by the RCC-MRx design rules (elastic analysis) have been constructed to compare the calculated stress values against the allowable ones.. This work describes the structural integrity assessment performed on a part of the DEMO Divertor Cassette, starting from the evaluation of electromagnetic, thermal and mechanical loads. The study focused on the shielding components (Shielding Liner, Inboard and Outboard Reflector Plates) and their attachments on the cassette. The assessment is made applying the elastic design-by-analysis rules of the RCC-MRx design code. The verification has been made for monotonic and cyclic loads (primary and secondary damages) under both negligible and significant irradiation conditions. The assessment is not complete because the verification against the fatigue damage has not been considered, but the overall findings allow to plan some improvements related to the shielding components to decrease the internal stress distribution. The elastic analysis performed according to the RCC-MRx design rules allows to compare the calculated stress values with the allowables.

On the cyclic torsion behavior of extruded AZ61A magnesium alloy tube

This work investigated the cyclic torsional behaviors of extruded AZ61A Mg alloy tubes through experiments and simulations. To capture the Bauschinger effect, the elastic viscoplastic self-consistent model with the twinning and detwinning scheme, together with a torsion-specific finite element approach was improved by adding a back-stress. A unique Swift effect with the “butterfly” shape was observed and reasonably reproduced by our model. Furthermore, the relative activities of deformation mechanisms, internal stress distributions, and twin volume fraction distributions under cyclic torsion were discussed. The findings could be beneficial to the design, manufacturing, and service of Mg alloys, particularly under cyclic torsion.

Relationship between Internal Stress Distribution and Microstructure in a Suspension-Sprayed Thermal Barrier Coating with a Columnar Structure

The suspension plasma spray (SPS) method is expected to become a novel coating method because it can achieve various microstructures using a suspension with submicron spray particles. Thermal barrier coatings (TBCs) with a columnar structure, which might achieve high strain tolerance, can be obtained using the SPS technique. This study evaluated the internal stress distribution of the suspension-plasma-sprayed thermal barrier coating (SPS-TBC) with different columnar structures using hybrid measurement using high-energy synchrotron X-ray diffraction analysis and laboratory low-energy X-rays. The relationship between the microstructure and the internal stress distribution of the SPS-TBC was discussed on the basis of the experimental results. In addition, the in-plane internal stress was decreased by decreasing the column diameter. The thin columnar microstructure of the SPS-TBC has superior strain tolerance. The internal stresses in the SPS-TBC are periodic decrements caused by stress relaxation in porous layers in its column.

Early-age deformation of hydrophobized metakaolin-based geopolymers

This study presents a novel strategy to simultaneously mitigate the early-age shrinkage and achieve hydrophobization of metakaolin-based geopolymer (MKG) pastes through the incorporation of organic admixtures including polydimethylsiloxane (PDMS) and sodium methylsilicate (SMS). The pore structure, wettability, moisture/water adsorption capacity, and internal moisture distribution are investigated through different techniques including MIP and LF-NMR. Results indicate that the autogenous shrinkage of MKG paste is reduced by 91.2 % and 41.6 % when adding 5 % PDMS and replacing with 20 % SMS, and the water contact angle increases to approximately 130° and 140°, respectively. The addition of organic admixtures significantly reduces the moisture adsorption and surface tension of the MKG matrix, and thus internal water tends to be transported into larger pores, leading to less liquid-vapor meniscus and lower capillary stress. Moreover, an underlying mechanism is proposed to explain the shrinkage mitigation of hydrophobized MKG paste, accounting for the moisture transfer tendency and internal stress distribution.

Influence of Superstructure Pouring Concrete Volume Deviation on Bridge Performance: A Case Study

Due to factors such as casting, mold making, and construction errors, the actual size of the bridge structure will inevitably deviate from the designed size and dimension, and the amount of deviation between the two volumes is generally random and the location of the deviation is not fixed. However, this phenomenon that occurs in the actual practice has not been paid enough attention within existing studies. From a theoretical point of view, the apparent size of concrete will directly affect the cross-sectional stiffness, especially for statically indeterminate structures. This effect will be further reflected in the internal force and stress distribution of the structure. In addition, the variation of the poured volume of the bridge superstructure can also influence the dead-load effect of the bridge structure. Therefore, the influence of pouring concrete volume deviation (PCVD) on the cross-sectional stiffness of large-span continuous reinforced concrete rigid-frame (CRCR) bridges was first stressed and investigated in this paper. Field data of PCVD were monitored by measuring demolished sections with tools that ensure accuracy, and a sensitivity analysis was conducted to analyze the effect of PCVD on the cross-sectional stiffness at different locations. Statistical analysis of the measured data concluded that PCVD has a significant influence on the internal-force distribution and structural stiffness of the bridge, up to 30%. Finally, a theoretical method that considers the influence of PCVD was proposed based on the field monitoring data and the statistical analysis results.

Determination of Magnetic Structures in Magnetic Microwires with Longitudinally Distributed Magnetic Anisotropy.

We studied the magnetic properties of a glass-covered amorphous microwire that was stress-annealed at temperatures distributed along the microwire length. The Sixtus-Tonks, Kerr effect microscopy and magnetic impedance techniques have been applied. There was a transformation of the magnetic structure across the zones subjected to annealing at different temperatures. The annealing temperature distribution induces the graded magnetic anisotropy in the studied sample. The variety of the surface domain structures depending on the longitudinal location has been discovered. Spiral, circular, curved, elliptic and longitudinal domain structures coexist and replace each other in the process of magnetization reversal. The analysis of the obtained results was carried out based on the calculations of the magnetic structure, assuming the distribution of internal stresses.

Homogeneous cooling control technology for high-strength low-alloy hot-rolled strip

ABSTRACT Heterogeneities of transverse temperature during laminar cooling of high-strength low-alloy hot-rolled strip can cause heterogeneous distribution of microstructure, mechanical property and internal stress. Edge masking is a control technology that can be used to improve laminar cooling heterogeneities. In this paper, different edge masking schemes were set up based on the transverse transformation characteristics of the strip. The results show that a slow cooling of 7.1 s during transformation could reduce the heterogeneity of grain size, internal stress and microhardness at the edge and middle of the strip. In addition, the relationship model between grain size and six variables such as transformation start temperature was established by PCA. It provided a new idea for the construction of a microstructure prediction model under nonlinear cooling.

Construction of an Arrhenius constitutive model for Mg-Y-Nd-Zr-Gd rare earth magnesium alloy based on the Zener-Hollomon parameter and objective evaluation of its accuracy in the twinning-rich intervals

According to a high-temperature compression test of rare earth magnesium alloy (WE43), a strain-compensated constitutive model of the Arrhenius equation based on Zener-Hollomon parameters was established, and the rheological behaviors were predicted. The model exhibited relatively serious prediction distortion in the low-temperature and high-strain rate parameter interval, and its accuracy was still unsatisfactory even after modification by a correction operator considering the coupling of temperature and strain rate. The microstructure characterization and statistical analysis showed that a large number of twinning occurred in the parameter intervals with prediction deviation. The occurrence of twinning complicated the local internal stress distribution by drastically changing the crystal orientation and led to significant fluctuations in the macroscopic strain-stress and hardening curves relative to the rheological processes dominated by the dislocation and softening mechanisms, making the logarithm of the strain rate and stress deviate from the linear relationship. This twinning phenomenon was greatly influenced by the temperature and strain rate. Herein, the influence mechanism on twinning behavior was analyzed from the perspective of the interaction of dislocation and twinning.

Numerical investigation of the application of voxel based meshes for stochastic tow based discontinuous composites

Stochastic tow based discontinuous composites (STBDC) are fabricated from compression molding chips of chopped and slit pre-impregnated uni-directional carbon fiber reinforced polymer (CFRP) tape. The discontinuous mesostructure gives the material system increased moldability versus continuous fiber composites; however, this gives the material highly variable effective properties. For applications in finite element analysis, the mesostructural morph ology of STBDCs can be idealized using a non-conforming voxel-based mesh framework. The objective of this study is to investigate the effect of mesh coarsening on the elastic response of STBDC simulations. Furthermore, a method for the homogenization of the voxel based mesostructure is considered, with results compared against detailed simulations of the mesostructure. The results demonstrate that coarse mesostructures provide similar effective properties and internal stress distributions as detailed models. Furthermore, simulations with homogenized properties provide nearly identical results to detailed simulations for a fraction of the simulation time. • Voxel-based representative volume elements can be used to generate finite element models and calculate effective properties. • Chips size influences the magnitude of internal stress concentrations observed in representative volume elements. • Method for homogenization provides a similar elastic response as detailed representative volume elements. • Simulations capture the chip size effects on the effective modulus.

Study of the response characteristics of the water–force coupling action of hard coal bodies in steeply inclined coal seams

Study of the pre-blast weakening of hard-top coal water injection is especially important to solve problems related to the low recovery rate of coal resources and frequent dynamic disasters due to the low degree of fragmentation of hard-top coal during high-stage fully mechanized top-coal caving in steeply inclined coal seams. With the application of rock mechanical tests and numerical simulations, this study carries out mechanical property testing on natural and water-saturated coal samples, investigates the effect of moisture on coal sample mechanical properties in meso-scale, and quantifies the degradation of coal samples under moisture due to mollification. It also reveals the interaction between water and acoustic emission signals based on the statistics of acoustic emission count and energy. A numerical model is established to analyze coal sample internal stress distribution features before and after water injection in macro-scale. Moreover, the detailed mitigating measures for top-coal water injection for engineering practice are designed. The results demonstrate that the mechanical properties of coal samples are significantly affected by moisture-induced degradation. The failure and collapse degrees of water-saturated samples are generally larger than those of natural samples. When the water content is higher, the acoustic emission count and energy of the coal sample are smaller—presenting a negative correlation. The internal stress of coal samples before and after water injection differs significantly. When subjected to water, the top-coal stress releases and transfers, and the peak value is significantly reduced. This study has verified in macro- and meso-scales that top coal can be fully weakened under water–force coupling. The findings of this study are of practical significance for safe and efficient mining and provide a reference for presplit weakening of hard-top coal during horizontal sublevel fully mechanized top-coal caving in steeply inclined coal seams.

Internal Stress Distribution in Suspension Plasma Sprayed Thermal Barrier Coating Subjected to in-plane Tensile Loading

Internal Stress Distribution in Suspension Plasma Sprayed Thermal Barrier Coating Subjected to in-plane Tensile Loading

Stress Induced Color and Pattern for Information Coding

AbstractOn the process of deforming polymer, its morphologies can be vividly observed and reflected via the internal stress distribution under the polarized light due to its special stretched birefringence, which gives a new way to store and read information. Inspired by this vivid character, a novel crosslinked polyurethane (PU) is designed and used as matrix for coding information, in which aluminum acetylacetonate works as the crosslinker to form dynamical crosslinked structure with coordinated bonds. By tailoring these two bonds via a region‐selective regulation, the information can be written in the crosslinked PU. Only under the polarized light, the coded information can be read as stress induced color on the deformed state. After its recovery, 2D pattern can be simultaneously formed on the surface of the film. Therefore, the information is expressed in multiple channels. Thanks to the dynamic character, the information can be also erased and rewritten. Therefore, it is a new method for information coding with a high security, which has a wide range of potential applications in data storage, anticounterfeiting labeling, information conversion, and other areas.

Analysis of effect of various coatings on stress distribution in tool material

The possibility of controlling the distribution of internal stresses and their magnitude due to the use of coatings on replaceable carbide plates of milling cutters is considered. It is established that this way of solving the problem is promising and can be used in industry.

Thermal-hydraulic-mechanical coupling mechanical behavior and acoustic emission characteristics of deep sandstone

Based on the deep in situ mining environments with ?three high?, a triaxial compression experiment of water-saturated sandstone under the conditions of 150?C, 110 MPa confining stress and 105 MPa pore water stress was carried out. The results show that the creep deformation stage produces a surge in acoustic emission energy when the radial deformation of sandstone changes from expansion to rapid compression, and the sandstone is sheared by a single crack when it is damaged. From deformation monitoring and acoustic emission energy analysis, the thermal-hydraulic-mechanical (THM) coupling environment will cause irreversible changes to the internal stress distribution, pore structure and mineral framework of sandstone. In the THM coupling experiment, the irreversible impact of the rock sample due to the long-term simulation of the "three high" environment and the difference caused by the impact on the final experimental results should be considered.

A three-phase anisotropic elastic elliptical inhomogeneity with internal linear stress and strain distributions

A three-phase anisotropic elastic elliptical inhomogeneity with internal linear stress and strain distributions

Analytical and numerical study of one-dimensional and two-dimensional stress distribution within an elastic semi-infinite material under the action of an arbitrary rectangular uniform loading

Purpose. The study of stress distribution within an elastic semi-infinite material under the action of an external loading is of great importance in the theory of elasticity. In most cases, the lack of knowledge about the stress distribution within a material can result in incomplete and inappropriate engineering designs, leading to unsatisfactory consequences. The latter include cracks and fractures, created inside the concrete segmental lining in TBM tunneling, as well as indentations that occur in floors due to the lack of pillar design not only in underground mining, but even in civil projects. This study focuses on the one-dimensional and two-dimensional internal stress distribution induced by arbitrary rectangular–square loading, in other words, that applied to an elastic semi-infinite material. Methods. Firstly, this paper uses an analytical method and, subsequently, a numerical method. In the analytical study, the point load equations of Boussinesq and Westergaard are used. Extending these equations to the rectangular loading area, four new equations are introduced. Using the Abaqus finite element software, the numerical study is performed in 3D space. Findings. The results show that the answers from the introduced equations are in high consistency with numerical ones. However, the result of the extended Boussinesq point load equation is closer to the answer obtained by the numerical method. Originality. Four new equations, presented in this paper, describe one-dimensional and two-dimensional stress distribution. Practical implications. The presented equations can provide a simple and convenient way to solve rectangular load problems in many cases such as foundation, civil and mining projects. This study uses initial information on specific segments in the Tabriz Metro line-2 Project.

The Influence of Mortar's Poisson Ratio and Viscous Properties on Effective Stiffness and Anisotropy of Asphalt Mixture.

This paper presents the results of a research study and analysis conducted to determine the degree of anisotropy of asphalt concrete in terms of its initial elastic properties. The analysis of asphalt concrete was focused on determining the effective constrained stiffness modulus in three mutually perpendicular directions based on the finite element method. The internal structure of the asphalt concrete was divided into the mortar phase and the mineral aggregate phase. Static creep tests using the Bending Beam Rheometer were conducted for the mortar phase to fit the rheological model. The aggregate arrangement and orientation were analysed using an image analytical technique for the mineral phase. The Finite Element Method (FEM) meshes were prepared based on grey images with an assumption of plane strain in 2D formulation. Using the FEM model, the tension/compression tests using selected characteristic directions were conducted, and the effective constrained stiffness moduli were estimated. This study showed a dominant horizontal direction for all coarse aggregates resulting from the normal force of the road roller and paving machines during laying and compaction on a road site. Depending on the values of the mortar's mechanical parameters and the load direction, the effective stiffness modulus might differ by ±20%. Based on the FEM analysis, this result was proven and commented on through an effective directional modulus evaluation and a presentation of internal stress distribution. Depending on the shape and orientation of the aggregates, it was possible to observe local "stress bridging" (transferring stresses from aggregate to aggregate when contacting). Moreover, the rheological properties of the mortar were considered by assuming two limiting situations (instantaneous and relaxed moduli), determining the bands of all possible solutions. In the performed FEM analysis, the influence of the Poisson ratio was also considered. The analysed asphalt concrete tends to be isotropic when the Poisson's mortar ratio is close to the value of 0.5, which agrees with the physical expectations. The obtained results are limited to particular asphalt concrete and should not be extrapolated to other asphalt mixture types without prior analysis.

Tunable Mechanics and Micromechanism in Close-Knit Silicide-in-SiO2 Core-Shell Nanowires.

Bending/tension mechanics is one of the core issues for nanowires in flexible free-standing transport and sensor applications, but it remains a challenge to tailor the mechanical performance beyond the inherent properties. Herein, based on structure engineering, silicon-based Mn5Si3@SiO2 nanocables are proposed and demonstrated as versatile nanosystems. Except for outstanding toughness, large ultimate strain, and great strength, they display diverse mechanical behaviors such as simplex elasticity, plasticity, and viscoelasticity under different external conditions. The tunable performances originate from synergetic effects between the core and shell components, like the atomic bonding transitional interface and space confinement, which induce optimizing internal stress distribution and the dislocation evolution mechanism in the core. The related mechanical performance is revealed carefully. The bending and tension dynamic picture, quantitative force curve, stress-strain dependence, and the corresponding lattice evolution are acquired by in/ex situ characterizations and measurements. These results contribute to nanowire mechanical design and also expand to strain-regulated three-dimensional multifunctional nanosystems.