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During undrained cyclic loading, clayey soils experience substantial stiffness and strength degradation when subjected to shear amplitudes exceeding a critical threshold. This paper presents an enhanced bounding surface rate‐independent plasticity model, an evolution of the previous SANICLAY model, tailored to capture this specific behavior during cyclic loading. A distinguishing feature of the proposed model is the introduction of an activation mechanism. This mechanism triggers degradation modeling based on the applied cyclic shear amplitude. To measure this amplitude, the activation mechanism incorporates a novel state variable that serves as a proxy for the applied cyclic stress. The effectiveness of the proposed model is demonstrated by comparing it to experimental data from various materials subjected to cyclic shearing under undrained conditions. The study encompasses a broad range of constant strain or stress amplitudes. Compared to the reference model, the proposed model exhibits improved predictive accuracy for the stress‐strain response of clays at small amplitudes of cyclic loading and large number of cycles. Furthermore, it accounts for strength degradation due to cyclic loading. [ABSTRACT FROM AUTHOR]

Three‐dimensional multi‐axial warp knitted (3D MWK) reinforced composites are important components of advanced structural composites. The interfacial bonding between fiber and matrix is key to achieving high mechanical properties. In this work, graphene oxide (GO) and poly(oxypropylene) diamines (D400) were grafted on glass fiber (GF) multi‐axial warp knitted (MWK) fabrics to construct a "flexible‐rigid" structure. The surface morphologies of GF were characterized by SEM and EDS. Then, 3D MWK‐reinforced composites were prepared based on four kinds of modified fabrics using the VARTM method. The in‐plane compression properties were obtained at different high temperatures and their failure modes were analyzed. The strain–stress curves showed that the composites exhibited brittle fracture modes. D400 and GO‐modified multi‐scale composites exhibited outstanding compression properties. The strength of the related composited was improved by 55.78%, 76.78%, 52.19%, and 56.78% compared to that of desized composite at 30°C, 60°C, 120°C and 150°C, respectively. The damage to D400‐GO modified and D400 modified composites was the most serious, where shear fracture modes were obvious in addition to layer debonding features. This protocol provides a potential strategy to manufacture of D400 and GO‐modified hierarchical reinforced composites. Highlights: The modified 3D MWK glass fabrics based on poly(oxypropylene) diamines (D400) and graphene oxide (GO) were prepared.The compressive properties of 3D desized, D400‐, D400‐GO‐, and GO‐MWK fabrics reinforced epoxy composites were obtained and analyzed at different temperatures of 30°C, 60°C, 120°C, and 150°C.The failure mechanisms of 3D desized, D400‐, D400‐GO‐, and GO‐MWK fabrics reinforced epoxy composites at different temperatures were analyzed. [ABSTRACT FROM AUTHOR]

Composite materials are actively used as protection against electromagnetic fields, as conductors and to remove excess heat from microcircuits and boards. Such products are often subjected to mechanical stress during operation, and stretched polymer‐film composite materials suffer from deterioration in electrical conductivity, which leads to loss of electrically conductive properties. In this work, the effect of mechanical deformation (stretching) on electrical conductivity properties was studied. A predictive model was built based on Boltzmann statistics, which allows predicting the loss of electrically conductive properties when materials are under mechanical stress. The resulting model was refined by introducing coefficients calculated using an ensemble regression machine learning method. The mean absolute percentage error of the predicted electrical conductivity value for the materials under mechanical stress is about 5%–20%. Highlights: Stretching influence on conductivity and shielding.An expression for description and prediction resistance during stretching.Machine learning for predictive modeling. [ABSTRACT FROM AUTHOR]

3D woven tubular composites (3D‐WTC), known for their lightweight and high‐strength characteristics, are widely used in various energy‐absorbing components. To enhance the energy absorption capacity of 3D‐WTC, this study conducted a mechanical analysis of bamboo tube structures and proposed concentric circular nested biomimetic structures with "single tube + double ribs" and "double tubes + double ribs." 3D woven tubular composites with bamboo‐structures (3DWTC‐Bamboo) were fabricated using the vacuum‐assisted resin transfer molding (VARTM) process. Axial compression tests were conducted using a universal testing machine to reveal and discuss the energy absorption capacity and failure modes of 3DWTC‐Bamboo. The results showed that 3DWTC‐Bamboo with a "double tube + double ribs" concentric circular nested biomimetic structures performed exceptionally, with a peak load of 28.93KN and specific energy absorption of 7.74 J·g−1. The failure mode was a hybrid of "rib folding + tube wall buckling." Finally, finite element analysis of the stress distribution during the compression of 3DWTC‐Bamboo was conducted using ABAQUS, which validated the experimental results. In summary, this work provides a reference for structural innovation in 3D‐WTC and further expands its application in the field of energy absorption. Highlights: Propose "single tube + double ribs" and "double tubes + double ribs" structures.Introducing the "rib" structures to enhance the local strength/stiffness.Test results show that 3DWTC‐Bamboo has great potential in energy absorption.The "ribs" can increase the local strength/stiffness of the tube structures. [ABSTRACT FROM AUTHOR]

Drilling glass fiber reinforced polymer matrix (GFRP) composites typically causes burrs, splintering, and microcracks within the GFRP structure, as well as delamination, fiber pull‐out, and thermal degradation of the polymer matrix. Designing and manufacturing molded‐hole GFRP components, as opposed to drilling, has recently been proposed as a promising method for overcoming the issues associated with drilling, for which there is limited research. Specifically, the mechanical response of molded‐hole GFRP has not been fully addressed in the literature. In the present study, molded and drilled GFRP composites with epoxy matrix were fabricated by hand lay‐up, and then the samples were analyzed utilizing experimental and numerical analysis techniques. Stress and strain analyses of GFRP samples were performed in Ansys Transient Structural Analysis. Although the fiber orientations of the layer geometries [0°/90°] and 3D models were the same, an additional layer was defined in the direction of the fiber orientation [45°/−45°] of molded‐hole composites to simulate the fiber accumulation effect. Experimental findings revealed that the flexural strength of molded composites was 12% greater than that of drilled composites. According to the numerical analysis, 98.7% proximity was achieved between the experimental and numerical results. Thus, the present study has provided numerical modeling to understand the flexural strength of molded composites for the first time, which will contribute to the increased use of molded composites in numerous applications in the fields of aerospace, automotive, and marine. Highlights: Drilled‐ and molded‐hole GFRP composites were produced by hand lay‐up.Flexural properties of the composites were examined via 4P bending tests.Flexural strength of molded composites was higher than that of drilled ones.98.7% proximity was achieved between the experimental and FEM results.A unified FEM method is proposed for the molded‐hole composites. [ABSTRACT FROM AUTHOR]

Earthquakes that rupture several faults occur frequently within the shallow lithosphere but are rarely observed for intermediate‐depth events (70–300 km). On 29 November 2007, the Mw7.4 Martinique earthquake struck the Lesser Antilles Island Arc near the deep end of the Wadati‐Benioff‐Zone. The sparse regional seismic network of 2007 previously hampered a detailed examination of this unusually complex event. Here, we combine seismic data from different studies with regional moment tensor inversion results and 3D full‐waveform modeling. We show that the earthquake is a doublet consisting of dip‐slip and strike‐slip motion along two oblique structures, both activated under extensional stress along the strike of the slab. Comparison with tectonic reconstructions suggests that the earthquake ruptured along a re‐activated ridge‐transform segment of the subducted Proto‐Caribbean spreading ridge. The unprecedented resolution of the source process highlights the influence of pre‐existing structures on localizing slab deformation also at intermediate‐depth. Plain Language Summary: Some earthquakes in continents and near the ocean floor are known to break multiple, differently oriented, faults. Such compound earthquakes are rarely observed in subducted plates in the intermediate‐depth region between 70 and 300 km. Intermediate‐depth earthquake mechanics and stress state are possibly different from shallower earthquakes, and maybe they hinder complex events. On 29 November 2007, the Mw7.4 Martinique earthquake occurred at a depth of ∼150 km, near the deep end of the regional seismic zone below the Lesser Antilles Arc. The regional seismic network in 2007 was relatively sparse; it revealed the earthquake had a complex mechanism but did not previously allow for an in‐depth study. In this study, we combine different types of data and methods, including full waveform information, based on a recently derived 3D regional velocity model. Our analyses shows that the Martinique earthquake consisted of at least two distinct sub‐events on perpendicular faults in the subducted plate—a source doublet. By comparing the orientations of the doublet faults with plate tectonic reconstructions, we infer that this intermediate‐depth earthquake broke along a fossil plate‐boundary. This indicates that such structures remain structural weaknesses even after subduction. Key Points: Moment tensor solutions, aftershock activity, back‐projection, and source‐time function suggest a complex rupture of the 29 November 2007, Mw7.4 Martinique earthquakeRegional Moment Tensor modeling and aftershock cross‐correlation identified the event as a source doubletEarthquake likely re‐activated a fossil ridge‐transform structure associated with the subducted Proto‐Caribbean spreading ridge [ABSTRACT FROM AUTHOR]

West Africa continues to host a growing number of low and intermediate‐magnitude earthquakes (M2‐5) along its passive margins, and its continental interior. Earthquake activity in these regions raises the need to comprehend the causes and the tectonic controls of the seismicity. Unfortunately, such studies are rare. Here, we apply single‐station inversion techniques to constrain fourteen focal mechanisms, computed after compiling a set of high‐quality waveforms. We describe the connection between seismicity, the contemporary stress field, anthropogenic activity and Holocene fault scarps in the region. Our results indicate transpressive stresses acting on the inherited brittle structures in the passive margins. We also observe a compressive regime in the intracontinental failed rifts. We attribute the seismicity to the reactivation of "weak" faults in the Neoproterozoic and Mesozoic failed rifts, the passive transform structures, and the intracratonic Precambrian brittle shear zones. Plain Language Summary: Earthquakes have occurred in West Africa, in the interior and the edges of regions that host several brittle structures. The causes and the mechanisms of this seismicity have not been comprehensively investigated. Hence, the characteristics of the regional tectonics are not fully established. In this study, we resolve the properties of the source of earthquakes, and the regional stress field. Our description of the sources of earthquakes matches the geometry of inherited brittle shear zones and failed rifts. The results indicate a strong influence of transpressive stress transfers from the ocean to the passive margins of West Africa. In the continental interior, especially, the West African Belt, the stress is compressional in the E‐W direction, consistent with stress orientations in adjoining regions. An extensional earthquake is observed in Mali, within the Gourma failed rift. We find that the seismicity of West Africa and the variations of the stress can be explained by the combination of preexisting faults, plate forces, ocean‐continent stress transfer, and density heterogeneity across the geologic domains. Key Points: Improved constraints on stress regimes and stress orientations from inversion of new focal mechanisms of M < 5.5 earthquakesNew focal mechanisms obtained from classical and novel approach based on single station waveform inversionEarthquakes in West Africa are rupturing the passive margin faults, intracontinental failed rift faults, and brittle shear zones [ABSTRACT FROM AUTHOR]

In the manufacturing of fiber‐reinforced composite materials, the preforming stage of dry fiber fabric entails compaction operations carried out under constant pressure, a specific preforming temperature, and in‐plane tension. Throughout this process, permanent deformation and creep/recovery behavior are observed in the fabric, correlating with factors such as time, sustained pressure, temperature, and in‐plane tension. Effective control of fiber volume fraction and material composition necessitates a thorough comprehension of these phenomena as well as the capacity to predict them with accuracy. To solve this, a viscoelastic‐plastic model was put forth, which provides an account of the viscous effects on the fabric during its stages of compression and recovery. The proposed model incorporates changed Burgers units to manage time‐dependent deformations and plastic units to address permanent deformations. Through the application of a single set of parameters, the model precisely and comprehensively characterizes through‐thickness creep/recovery behavior of preformed dry fiber fabrics under varying conditions, including creep stress, temperature, and in‐plane tension. To enhance the practical utility of the model, an application has been developed and validated against experimental data conducted under diverse test conditions. The results demonstrate consistency between experimental curves and model‐predicted curves across various compression scenarios. Highlights: A viscoelastic‐plastic model was proposed with a single parameter set.Stress, temperature, and in‐plane tension all exacerbated creep/recovery.Model captures temp. and time‐related creep/recovery with in‐plane tension.The model has been transformed into a practical application tool. [ABSTRACT FROM AUTHOR]

The carbon/glass hybrid rod exhibits high tensile strength, light weight, and strong corrosion resistance. However, the bottleneck of interlayer splitting exists in the interlayer hybrid rod, severely impeding safe operation. To solve the problem of rod splitting, this paper proposed a new scheme of an intralayer carbon/glass hybrid rod. Based on the material constitutive model, a full‐scale simulation model was developed. The stress distribution and deformation of the hybrid rod were analyzed and the progressive damage mechanism of the hybrid rod was explained. The results indicated that, for the intralayer carbon/glass hybrid rod, (a) the ultimate experimental tensile load witnessed a significant increase, rising by 14.0% from 452.4 to 515.7 kN compared to the interlayer hybrid rod; (b) the numerical model predicted the tensile load of 525.9 kN, with an error of 1.9% compared to the test result, meeting engineering accuracy requirements; (c) the elastic deformation stage saw a 146.7% increase from 280.2 to 691.3 MPa in the maximum axial stress of the carbon‐fiber layer, and a 120% increase from 89.8 to 198.0 MPa in the maximum radial stress of the glass fiber layer as the tensile displacement increased from 0.16 to 0.32 mm. In conclusion, the intralayer carbon/glass hybrid rod proposed in this paper can significantly improve the tensile strength compared to the interlayer hybrid rod, which can accelerate the application of carbon/glass hybrid rods in oil and gas fields. Highlights: According to the problem of interlayer splitting in the interlayer carbon/glass hybrid rods, a novel scheme of an intralayer carbon/glass hybrid rod was proposed.Based on the material constitutive model, a full‐scale simulation model of an intralayer carbon/glass hybrid rod was developed to analyze the stress distribution and deformation response under tensile load.The dynamic progressive damage analysis method for intralayer carbon/glass hybrid rods was proposed to reveal the damage evolution mechanism. [ABSTRACT FROM AUTHOR]

The small‐scale‐dependent nonlinear dynamical attributes of microplate‐type laminated piezoelectric systems of harvesting energy subjected to a triangular mechanical actuation are explored in the current exploration. The core of harvesting systems is supposed to be made of nanocomposites reinforced by randomly oriented carbon nanotubes (CNTs) having various degrees of agglomeration coated by piezoelectric layers. In this regard, the microplate‐type systems of harvesting energy are modeled via a quasi‐3D plate theory combined with the modified strain gradient elasticity in the presence of various microsize‐dependent strain gradient tensors. Thereafter, the solution of the developed coupled electromechanical size‐dependent nonlinear problem is obtained numerically by utilizing the meshless collocation approach employing incorporation of the polynomial and radial basis functions to remove any feasible singularity for the associated moment matrices. It comes to the conclusion that by elevating the quantity of CNTs disclosed within the clusters, the significance of the microsize dependency in the achieved voltage enhances from 22.06% to 22.73% toward the simply supported bridge‐type context, and from 33.00% to 33.92% toward the clamped bridge‐type context. Highlights: Development of a microstructural‐dependent quasi‐3D shear flexible energy harvester model.Incorporating the roles of various strain gradient tensors in the nonlinear dynamics of microharvesters.Size‐dependent time‐histories of achieved voltage from triangular mechanical‐loaded microharvesters.Influence of the CNT reinforcement clustering on the nonlinear dynamic performance. [ABSTRACT FROM AUTHOR]

To facilitate the on‐demand release of hydrophilic antibiotics for accelerated repair of infected wounds, a self‐powered wound dressing incorporating a "Lock‐ON/OFF" electric field (EF)‐driven drug release mechanism combined with electrical stimulation (ES) therapy is presented. When subjected to mechanical stress, the drug exhibits controlled, slow‐release behavior, achieving a remarkable cumulative release rate of 88.57%—89 times higher than the non‐mechanical stress group. Conversely, in the absence of mechanical stress, the drug remains unreleased, maintaining a 0% cumulative release rate in a fully closed state. The dressing utilizes its piezoelectric effect to establish an electric field, enabling precise control of hydrophilic drug release by regulating the electrostatic balance between the drug carrier and the drug. Moreover, the piezoelectric field acts as an exogenous electric field, remodeling the endogenous electric field of the wound, and accelerating wound closure. Combining EF‐driven drug release with ES result in a 1.26 fold improvement in wound healing compared to ES alone. This study addresses precision therapy limitations in fully automated diagnosis and treatment, paving the way for advancements in remote diagnosis, wireless therapy, and on‐demand precision medicine. [ABSTRACT FROM AUTHOR]

Mechanoluminescence (ML) is luminescence induced due to mechanical stress, providing intuitive responses to strain‐related events. Piezoelectricity is the conversion of mechanical strain into electrical signals, offering a quantitative measurement of force/deformation. Combining ML and piezoelectricity within a single device provides a comprehensive understanding of mechanical events, providing qualitative and quantitative information about strain‐related phenomena. A ZnS:Cu/polydimethylsiloxane (PDMS) composite and a biocompatible silk fibroin/PDMS composite are prepared to generate ML and electrical signals, respectively. An innovative method for obtaining powder from silk fabrics is employed. The microstructure and composition of silk fibroin powder are also examined via X‐ray diffraction and Fourier Transform Infrared (FTIR) spectroscopy. Mechanical stimuli such as pressure, stretching, twisting, bending, vibration, and rubbing are applied to the device to demonstrate optical and electrical responses. Under pressure, a voltage of 3.82 V and an output current of 201.6 nA are generated at a force of 1 N. Furthermore, a handwritten test is conducted to qualitatively visualize letters based on ML effects and explore the feasibility of using artificial intelligence to classify voltage signals generated during writing into their corresponding letters. This biocompatible, dual‐modal self‐powered sensor demonstrates broad applicability in wearable technology, biomechanics, human–machine interaction, security, and energy harvesting. [ABSTRACT FROM AUTHOR]

Hardening of carbon steel products by austenitization and immersion in a quenching medium is a widely used heat treatment to obtain a hard and strong martensitic structure. To avoid the undesired consequences, such as residual stresses or insufficient hardening depth, the cooling rates must be accurately measured and controlled. This can be achieved using the impinging water jet quenching technique. The aim of this work is to perform hardening of four low‐alloyed 70 mm cylindrical carbon steel bars, using impinging water jet quenching technique with different jet flow rates, and to analyze its effect on thermal evolution and residual stresses. The temperature evolution during quenching experiments is recorded and used as input to a comprehensive quenching model to predict phase transformations, final hardness, and residual stresses of cylindrical bars. All four quenching experiments result in a fully hardened martensitic state. Furthermore, a decrease in jets' flow rate, within a certain interval, results in different thermal histories and in lower compressive residual stresses on the surface. The results from quenching simulations show promising hardness, microstructure, and residual stress predictions that are validated by hardness measurements, optical microscopy, and residual stress analysis using X‐Ray diffraction method. [ABSTRACT FROM AUTHOR]

In this article, the microstructure and mechanical properties of the Fe–0.31C–6.86Mn–3.53Al steel and DP980 and 22MnB5 steel dissimilar/similar joints by fiber laser welding are studied. Based on experimental results, fusion zone (FZ) of transformation‐induced plasticity (TRIP)‐welded joint mainly consists of 77 vol% martensite and 23 vol% ferrite. The FZ of TRIP‐DP980 and TRIP‐22MnB5 welds mainly consist of martensite. The hardness profile of weld cross‐section exhibits significant asymmetry, and softening zones hardness of TRIP‐DP980 and TRIP‐22MnB5 accounts for 82% and 64% of DP980 and 22MnB5 base materials (BM), respectively. However, no softening zone is observed on TRIP steel side, primarily due to the lack of martensite in TRIP BM. The tensile results showed that welding efficiency of TRIP‐TRIP reached 99%, but elongation of welded specimen is only 50% of TRIP BM due to the high hardness and brittleness of FZ region. TRIP‐DP980 and TRIP‐22MnB5 joints did not fail in softening zone, because the constraint stress is generated on both sides of softening zone to inhibit the plastic deformation in softening zone during tensile process. The tensile stress is distributed on the surface of tensile specimens and concentrated in BM on the side with low yield strength (YS), resulting in the final fracture. [ABSTRACT FROM AUTHOR]

To find the suitable deformation temperature range for the as‐cast Fe–5.5Cr–5.5Ni–3.0Al–0.27C high‐strength lightweight steel, the thermal mechanical behavior and the dependent microstructure characteristics are studied to investigate the high‐temperature mechanical response of the steel. In the results, it is shown that the microstructure of the steel owns a dendrite framework consisting of the martensite dendrite and the interdendritic austenite, among which precipitations of NiAl, Ni3Al, and δ‐Fe are induced by high‐temperature deformation. The flow stress dependence of deformation temperature shows two different variation tendencies, corresponding to the varied deformation mechanisms of strain‐induced precipitation of second phases and δ‐Fe nucleation, and then resulting in different variation of dislocation density. It is found that a periodical fluctuation of flow stress appears as the alternative occurrence of first rise and then drop followed by drop and rise, and the phenomenon is inferred to be caused by local dynamic recrystallization in the dendrites and the neighboring interdendritic spacings. [ABSTRACT FROM AUTHOR]

The element‐free Galerkin (EFG) meshfree method is employed in this research to compute strain fields based on discrete displacement data obtained from digital image correlation (DIC). To validate the method's accuracy, both simulated images with highly heterogeneous deformations and real tests conducted on notched specimens with known solutions are initially employed. The study then investigates the strain field near the crack tip in an AISI 1020 steel specimen through a multiscale experiment. From the macroscale experiment, the strain data are used to determine the crack‐tip plastic zone size, and the solution is compared with predictions from linear‐elastic fracture mechanics. The stress intensity factor is also determined. Furthermore, the high strain gradient ahead of the crack tip is determined from the microscale experiment and compared against commercial DIC software. Experimental results confirm the effectiveness of the proposed formulation in crack tip analysis. Highlights: Enhancing the calculation of strain fields is achieved through a meshfree formulation.The method is validated using simulated and experimental images with heterogeneous deformations.The large strain gradient near a fatigue crack tip is evaluated. [ABSTRACT FROM AUTHOR]

In this paper, the creep‐fatigue responses of the nickel‐based superalloy Inconel 718 have been investigated by conducting hybrid stress–strain‐controlled creep‐fatigue interaction (HCFI) loading experiments at 650°C with different dwell stresses and dwell periods. Deformation responses demonstrate that stress dwell leads to complex cyclic responses, such as an increase in softening rate and changes in inelastic strain rate. Then, a novel creep equivalent stress determination method is proposed based on stress relaxed characteristics. After modifying the continuum damage mechanics (CDM) model with this method, accurate prediction results of the creep‐fatigue cyclic life under strain‐controlled creep‐fatigue loading and HCFI loading can be obtained. Finally, the damage evolutions of Inconel 718 under HCFI loading are analyzed by CDM model. The results of damage evolution indicate that the trend of damage accumulation under different test conditions is consistent with the trend of inelastic strain in the material. Highlights: The creep‐fatigue responses of Inconel 718 under HCFI loading are investigated.A creep equivalent stress determination method based on stress relaxation is proposed.Accurate life prediction results obtained under various loadings at high temperature. [ABSTRACT FROM AUTHOR]

In practical mechanical components, the characteristic of geometric discontinuous generates non‐uniform energy field near the notch, which affects the local damage evolution process of the notched specimens. Therefore, it is particularly crucial to formulate a parameter that can characterize such inhomogeneous state distribution. First, a strain energy density gradient factor is introduced to describe the complexity of strain energy density distribution near the notch. Meanwhile, a size effect factor is given considering the strain energy gradient factor and notch geometry parameter. Then, taking into account the impact of phase difference, a direct damage parameter considering non‐proportionality of different multiaxial load levels is developed. Furtherly, the modified strain energy density parameter is determined. Finally, the comparison between the proposed model and the other three models emphasizes the advantages of the model. Highlights: A strain energy density gradient factor is given for the fatigue analysis of notched specimens.A calculation method of equivalent strain energy density is proposed.Several key factors affecting the fatigue life of notched specimens are considered.A general procedure for fatigue life prediction of notched specimens is presented. [ABSTRACT FROM AUTHOR]

The classical Mohr–Coulomb criterion has an extremely wide range of applications in the field of engineering geology, while it cannot accurately characterize rock failure under high confining stresses. Therefore, a nonlinear modification is implemented based on the Mohr–Coulomb criterion for achieving wider usage in all stress environments. The cohesion and internal friction angle are firstly calculated by regression based on the triaxial experiments of diorite and other typical rocks in different confining stress ranges, and the variation modes of cohesion and internal friction angle are then formalized and integrated into the classical Mohr–Coulomb criterion. Using the experimental results of 435 triaxial compression tests in existing publications, the predictions of the modified criterion are compared with those of the previous nonlinear criteria, which show that the predicted values of the modified criterion are in good agreement with the measured strength. Compared with the previous nonlinear criteria, the modified criterion has a wider application range and always maintains a higher accuracy. Highlights: A modified nonlinear Mohr–Coulomb criterion is proposedThe accuracy of the proposed criterion is verified by 435 triaxial tests.The proposed criterion shows a higher accuracy than previous nonlinear criteria [ABSTRACT FROM AUTHOR]

The strong sensitivity of velocity to stress observed in many sandstones originates from the response of stress‐sensitive discontinuities such as grain contacts and microcracks to a change in effective stress. If the change in stress is anisotropic, then the change in elastic wave velocities will also be anisotropic. Characterization of stress‐induced elastic anisotropy in sandstones may enable estimation of the in situ three dimensional stress tensor with important application in solving problems occurring during drilling, such as borehole instability, and during production, such as sanding and reservoir compaction. Other applications include designing hydraulic fracture stimulations and quantifying production‐induced stresses which may lead to rock failure. Current methods for estimating stress anisotropy from acoustic anisotropy rely on third‐order elasticity, which ignores rock microstructure and gives elastic moduli that vary linearly with strain. Elastic stiffnesses in sandstones vary non‐linearly with stress. Using P‐ and S‐wave velocities measured on Gulf of Mexico sandstones, this non‐linearity is found to be consistent with a micromechanical model in which the discontinuities are represented by stress‐dependent normal and shear compliances. Stress‐induced anisotropy increases with increasing stress anisotropy at small stress but then decreases at larger stresses as the discontinuities close and their compliance decreases. When the ratio of normal‐to‐shear compliance of the discontinuities is unity, the stress‐induced anisotropy is elliptical, but for values different from unity, the stress‐induced anisotropy becomes anelliptic. Although vertical stress can be obtained by integrating the formation's bulk density from the surface to the depth of interest, and minimum horizontal stress can be estimated using leak‐off tests or hydraulic fracture data, maximum horizontal stress is more difficult to estimate. Maximum horizontal stress is overpredicted based on third‐order elasticity using measured shear moduli, with estimates of pore pressure, vertical stress and minimum horizontal stress as input. The non‐linear response of grain contacts and microcracks to stress must be considered to improve such estimates. [ABSTRACT FROM AUTHOR]

The reliability requirements for mechatronics continue to increase. Traditional life test methods make it difficult to obtain the data required to assess or predict the reliability of these mechatronic products within a reasonable time. Accelerated life tests can speed up the failure process of the product by using accelerated stress conditions. And then test data is obtained to predict the reliable life of the product under normal service conditions through modeling and analysis. The test efficiency of the accelerated life tests is higher than that of the life test. So, the method of accelerated life tests has become a solution for life and reliability prediction of highly reliable and long‐life mechatronic products. However, mechatronic products usually undergo cyclic stress during service. The use of cyclic stress as an accelerating stress in accelerated life tests can provide a realistic representation of service conditions and achieve higher test efficiency. Cyclic stress accelerated life test is an accurate and efficient solution for predicting the life and reliability of such mechatronic products. Current relative research is focused on constant stress, step stress and sequential stress accelerated life tests. A great challenge in engineering is modeling and analysis of cyclic stresses accelerated life tests. In this paper, we first describe the cyclic stress accelerated life test profile and its key parameters, then propose model assumptions and establish a modelling and analysis method for cyclic stress accelerated life test data, followed by an illustrative example to apply and validate the proposed method. The research results can provide technical support for the life and reliability assessment of mechatronic products under cyclic stress service conditions. [ABSTRACT FROM AUTHOR]

Shear strength of damage zone, representing the stress threshold for rupture initiation, is a critical parameter in faulting mechanics. Despite its significance, the damage‐zone's shear strength has not been estimated in natural earthquake ruptures. Here we employed coseismic deformation and strain, kinematic slip model, and finite element modeling to determine the elastic properties and peak shear stress of coseismic damage zones along the 2021 Mw 7.4 Maduo earthquake. Through the analysis of the lowest shear stress resulting in surface ruptures and the highest stress without surface rupture, we constrained the strength within a range of 7–17 MPa. Our result is consistent with strength (5–16 MPa) of sandstone samples from laboratory tests, demonstrating the validity of this estimation. Although factors such as fault maturity and confining pressure influence strength variation, the strength can directly reflect the stress threshold required for macroscopic surface rupture formation in fault damage zones dominated by sandstone. Plain Language Summary: Shear strength of a fault damage zone inform us its ability to withstand shear stress before surface rupture occurs. This information often provides insights into the earthquakes rupture hazards near the Earth's surface. Natural earthquakes provide a perfect opportunity for us to address the question of "what is the shear strength of a fault damage zone." To this end, we require a set of comparative references: the utmost shear stress that a damage zone can withstand without surface rupture and the minimal one necessary for the zone to generate surface rupture. In this investigation, we studied the 2021 Maduo earthquake because it had multiple distinct surface rupture segments in some places but not in others. By comparing shear stress in these segments, we could figure out how strong the damage zones were. We used real observations and numerical simulations to estimate how much stress these damage zones can withstand. Our results indicate that, for damage zones embedded in intact sandstone with a Young's modulus of 15 GPa, its strength ranges from 7 to 17 MPa. Significantly, our study is the first to reveal the shear strength of damage zone from a nutural earthquake using geodetic data. Key Points: Shear modulus and shear stress for coseismic damage zone were determined using coseismic deformation and finite element modelEstimated shear strength from overlap range of coseismic stress between surface rupture and non‐rupture parts ranges from 7 to 17 MPaShear strength exhibits positive and negative correlations with confining pressure and fault maturity, respectively [ABSTRACT FROM AUTHOR]

Piezoelectric actuators are vital devices that convert electrical signals into mechanical strain, offering rapid and precise responses. Lead‐based piezoceramics have traditionally been the preferred choice for commercial piezoelectric actuators, while the low Curie temperature and the rising environmental concerns hinder their applications at high temperatures. In this study, a novel strategy is proposed to achieve high piezoelectric responses in lead‐free 0.67Bi1.05FeO3–0.33BaTiO3 (67BF‐33BT) ceramics with high Curie temperature by artificially generating a large internal bias field through repeat poling and aging treatments. A comprehensive exploration of how this internal bias field responds to applied electric fields and temperature variations has been conducted. The results suggest that the internal bias field originates from two aspects, one arises from the free charges that compensate for the depolarization field, while the other is attributed to the highly oriented defect dipoles. As a result of this internal bias field, the ceramics exhibit asymmetric strain–electric field (S–E) behaviors, resulting in a high strain (ε = 0.21%) and an extremely high piezoelectric coefficient (d33* = 1033.70 pm V−1) when subjected to low electric field (20 kV cm−1), along with good temperature stability from room temperature (RT) to 100 °C. [ABSTRACT FROM AUTHOR]

Piezocatalytic cancer therapy, in which piezoelectric nanomaterials generate reactive oxygen species (ROS) via piezocatalytic redox reactions under mechanical stress, has emerged as an effective strategy for cancer treatment. However, the inherent hypoxia in tumor microenvironments enormously restricts its efficacy. To address this issue, acid‐degradable Janus‐type multicompartmental carriers able to separately encapsulate piezocatalytic gold nanoparticle‐coated poly(ethylene glycol)‐modified zinc oxide nanorods (Au@P‐ZnO NRs) and O2‐generating catalase (CAT) are fabricated in this study using stop‐flow lithography (SFL). The CAT and Au@P‐ZnO NRs are sequentially released by modulating the composition ratios of acid‐cleavable monomers in the precursor solution during the SFL. The sequential release by the Janus carriers significantly increased the intracellular ROS levels under hypoxia conditions upon ultrasound irradiation owing to the O2 supplied by the CAT. An in vivo study showed that a single intratumoral injection of Janus particles encapsulating the CAT and Au@P‐ZnO NRs efficiently alleviated tumor hypoxia and substantially suppressed tumor growth. This study demonstrates that pH‐responsive, O2‐generating, and piezocatalytic Janus carriers have high potential for piezocatalytic therapy of hypoxic tumors and offers insights into using pH‐responsive Janus carriers for efficient hypoxia‐relieving piezocatalytic cancer therapy via the cascade of oxygenation and ROS generation. [ABSTRACT FROM AUTHOR]

SUMMARY: The nucleus is a central organelle of eukaryotic cells undergoing dynamic structural changes during cellular fundamental processes such as proliferation and differentiation. These changes rely on the integration of developmental and stress signals at the nuclear envelope (NE), orchestrating responses at the nucleo‐cytoplasmic interface for efficient genomic functions such as DNA transcription, replication and repair. While in animals, correlation has already been established between NE dynamics and chromatin remodeling using last‐generation tools and cutting‐edge technologies, this topic is just emerging in plants, especially in response to mechanical cues. This review summarizes recent data obtained in this field with more emphasis on the mechanical stress response. It also highlights similarities/differences between animal and plant cells at multiples scales, from the structural organization of the nucleo‐cytoplasmic continuum to the functional impacts of NE dynamics. Significance Statement: This is a comprehensive review of the recent developments in the area of nuclear envelope dynamics and its connection to chromatin modifications and remodeling focusing on the mechanical stress response. [ABSTRACT FROM AUTHOR]

The viscoelasticity of mechanically sensitive tissues such as periodontal ligaments (PDLs) is key in maintaining mechanical homeostasis. Unfortunately, PDLs easily lose viscoelasticity (e.g., stress relaxation) during periodontitis or dental trauma, which disrupt cell–extracellular matrix (ECM) interactions and accelerates tissue damage. Here, Pluronic F127 diacrylate (F127DA) hydrogels with PDL‐matched stress relaxation rates and high elastic moduli are developed. The hydrogel viscoelasticity is modulated without chemical cross‐linking by controlling precursor concentrations. Under cytomechanical loading, F127DA hydrogels with fast relaxation rates significantly improved the fibrogenic differentiation potential of PDL stem cells (PDLSCs), while cells cultured on F127DA hydrogels with various stress relaxation rates exhibited similar fibrogenic differentiation potentials with limited cell spreading and traction forces under static conditions. Mechanically, faster‐relaxing F127DA hydrogels leveraged cytomechanical loading to activate PDLSC mechanotransduction by upregulating integrin–focal adhesion kinase pathway and thus cytoskeletal rearrangement, reinforcing cell–ECM interactions. In vivo experiments confirm that faster‐relaxing F127DA hydrogels significantly promoted PDL repair and reduced abnormal healing (e.g., root resorption and ankyloses) in delayed replantation of avulsed teeth. This study firstly investigated how matrix nonlinear viscoelasticity influences the fibrogenesis of PDLSCs under mechanical stimuli, and it reveals the underlying mechanobiology, which suggests novel strategies for PDL regeneration. [ABSTRACT FROM AUTHOR]

Straintronics involves the manipulation and regulation of the electronic characteristics of 2D materials through the use of macro‐ and nano‐scale strain engineering. In this study, an atomic force microscope (AFM) coupled with an optical system is used to perform indentation measurements and tip‐enhanced photoluminescence (TEPL), allowing to extract the local optical response of a suspended monolayer membrane of ternary WSSe at various levels of deformation, up to strains of 10%. The photoluminescence signal is modeled considering the deformation, stress distribution, and strain dependence of the WSSe band structure. An additional TEPL signal is observed that exhibits significant variation under strain, with 64 meV per percent of elongation. This peak is linked to the highly strained 2D material lying right underneath the tip. The amplification of the signal and its relation to the excitonic funneling effect are discussed in a more comprehensive model. The diffusion caused by Auger recombination against the radiative excitonic decay will also be compared. TEPL is used to examine and comprehend the local physics of 2D semi‐conducting materials subjected to extreme mechanical strain. Chemical vapor deposition‐fabricated 2D ternaries possess high strain resistance, comparable to the benchmark MoS2, and a high Young's modulus of 273 GPa. [ABSTRACT FROM AUTHOR]

Biological activities take place in 3D environments, where cells interact in various directions in a defined, often microstructured, space. A sub‐millimeter‐sized stretching device is developed to mechanically stimulate a structurally restricted, soft multicellular microenvironment to investigate the effect of defined cyclic mechanical forces on a multicellular system. It consists of a multi‐material 3D microstructure made of Polydimethylsiloxane (PDMS) and gelatine‐based hydrogel, which is printed using the 2‐photon polymerization (2PP) method. The printed structures are first characterized microscopically and mechanically to study the effect of different printing parameters. Using 2PP, organotypic cell cultures are then directly printed into the hydrogel structures to create true 3D cell culture systems. These systems are mechanically stimulated with a cantilever by indenting at defined positions. The cells in the 3D organotypic cell culture change morphology and actin orientation when exposed to cyclic mechanical stretch, even within short timescales of 30 min. As proof of concept, a Medaka retinal organoid is encapsulated in the same structure to demonstrate that even preformed organoids can be stimulated by this method. The results highlight the capability of 2PP for manufacturing multifunctional soft devices to mechanically control multicellular systems at micrometer resolution and thus mimic mechanical stresses as they occur in vivo. [ABSTRACT FROM AUTHOR]

Alleviating bone loss is an essential way to prevent osteoporotic fractures. Proper exercise improves bone density without the side effects of long‐term medications, but the mechanism is unclear. Our study explored the role of Antxr1/LncRNA H19/Wnt/β‐catenin axis in the process of exercise‐mediated alleviation of bone loss. Here we discovered that moderate‐intensity treadmill exercise alleviates bone loss caused by ovariectomy and ameliorates bone strength accompanied by an increased lncRNA H19 expression. Concomitantly, Antxr1, a mechanosensitive protein was found downregulated by exercise but upregulated by ovariectomy. Interestingly, knockdown expression of Antxr1 increased lncRNA H19 expression and Wnt/β‐catenin signaling pathway in bone marrow mesenchymal stem cells, whereas overexpression of Antxr1 decreased lncRNA H19 expression and Wnt/β‐catenin signaling pathway. Hence, our study demonstrates the regulation of Antxr1/LncRNA H19/Wnt/β‐catenin axis in the process of mechanical strain‐induced osteogenic differentiation, which provides further mechanistic insight into the role of mechanical regulation in bone metabolism. [ABSTRACT FROM AUTHOR]

Bulk phosphorus oxynitride (PON), isoelectronic with SiO2, is confirmed to have many polymorphs as the latter. However, its 2D counterparts have not been studied. In this work, crystal structure exploration and property study are performed on 2D PON with the help of first‐principle calculation. Three 2D PON sheets are found with thermal, dynamical, and mechanical stability and all of them can be viewed as oxygen‐doped known 2D γ phosphorus nitride (γ‐PN). In the studies, it is indicated that they are indirect bandgap materials with gap values larger than 3 eV. The situations of orbital hybridization are discussed and their bonding properties are analyzed. Infrared vibrational spectra of these 2D materials are simulated and the vibrational modes at the Brillouin center are assigned by the factor group analysis. The reasons for the disappearance of some infrared peaks in the simulated spectra are revealed based on the calculated Born effective charges and vibrational eigenvectors. Their piezoelectric stress tensors are computed via density‐functional perturbation method and the piezoelectric strain tensors are also deduced via the calculated elastic constants. In the results, it is uncovered that these 2D PON sheets have considerably greater piezoelectric coefficients than the primitive 2D γ‐PN, which make them promising for nanopiezoelectric use. [ABSTRACT FROM AUTHOR]

The biaxial tension–tension cyclic loading experiments were conducted on the cruciform specimens prepared using a silane‐modified polyurethane sealant to investigate their mechanical behavior. The finite element method was employed to validate the mechanical behavior of cruciform specimens under the biaxial cyclic loading conditions. It is shown that the highest stress concentration is in the central region of the cruciform specimens, indicating that the shape design of the specimen is suitable for the biaxial tension–tension cyclic tests. Additionally, the effects of loading path, mean stress, and stress amplitude on ratcheting strain and dissipated energy were analyzed through the experimental data. The experimental results demonstrated that the loading path had an influence on the mechanical behavior of the cruciform specimen. The additional ratcheting strain caused by the non‐proportional loading path was found to be loading path dependent of the adhesive. Moreover, the mean stress and stress amplitude greatly affected the strain response curves of the specimen under biaxial cyclic loading. The ratcheting strain and dissipated energy increased with increasing mean stress and stress amplitude; nevertheless, stress amplitude had more influence on the mechanical behavior than the mean stress. Highlights: The biaxial cyclic loading tests were conducted on the cruciform specimens.The effects on ratcheting strain and dissipated energy were analyzed.The loading path has influences on the mechanical response of the specimen.The mean stress and stress amplitude have effects on the strain response [ABSTRACT FROM AUTHOR]

Integrating photocatalytic technology with building materials is an imperative new trend in the green building field. Here, a novel Pd/ZnO nanorod array‐decorated ceramic tile has been designed for the first time, aiming to purify the surrounding environment. Because of the piezoelectric characteristics of ZnO nanorods, the environmental degradation efficiency of this tile‐based structure under light irradiation could be improved through injecting mechanical vibration stress. The unique piezo‐photocatalytic synergistic effect, due to the piezoelectric field created by bent ZnO nanorods and the Schottky junction formed by the noble metal Pd/ZnO heterostructures, could effectively separate the photoinduced carriers and reduce the rate of recombination, boosting the degradation efficiency. The tile‐based Pd/ZnO reaches the greatest catalytic efficiency of 75% for dye degradation in 30 min when ultrasonic and solar irradiation are applied simultaneously. Present results offer a fresh idea for creating novel piezo‐photocatalytic materials applied in eco‐friendly green buildings. [ABSTRACT FROM AUTHOR]

A suite of slate samples collected along a 2 km transect crossing the Lishan fault in central Taiwan were evaluated to assess the role of ductile deformation in natural graphitization at lower greenschist facies metamorphic conditions. The process of natural aromatization, or graphitization, of an organic precursor is well established as a thermally driven process; however, experimental studies have shown that the energy provided by deformation can substantially reduce the activation energy required for graphitization. This study provides a natural example of deformation‐induced graphitization. A strain gradient approaching the Lishan fault was established by scanning electron microscope imaging and X‐ray diffraction analysis of phyllosilicates and quartz that showed an increase in the strength of slaty cleavage development via dissolution‐precipitation processes. Thermal conditions were constrained to be near isothermal using calcite‐dolomite geothermometry. Raman spectroscopic results from carbonaceous material, including D1‐full width‐at‐half‐maximum (FWHM), G‐FWHM, Raman band separation (RBS), and a lesser‐known vibrational mode B2g‐FWHM, showed robust linear trends across the same sampling transect. However, the G‐FWHM parameter showed a trend opposite of that expected from thermally driven graphitization. The Raman results are interpreted to reflect a strain‐driven reduction in graphite crystallite size (decrease in G‐FWHM) but improvement in structural ordering in individual coherent domains. A multiple linear regression with an R2 value of 0.92 predicts the graphite D1‐FWHM values from the XRD‐derived ratio of muscovite populations and muscovite microstrain, demonstrating the concomitant recrystallization of silicates and carbonaceous material across the strain gradient, despite the disparate processes accommodating the deformation. This study demonstrates the role of deformation in natural graphitization and provides a new perspective on the use of graphite as a geothermometer in strongly deformed greenschist facies rocks. [ABSTRACT FROM AUTHOR]

Polymer network materials are interesting alternatives to thermoplastic polymers. Here, the preparation of polymer capsules is investigated, which are made from poly(ε‐caprolactone) (PCL) networks and are compartmentalized in a crosslinked PCL shell and a core that is suitable to enclose payloads of interest. Aided by microfluidic templating, PCL network capsules with a narrow size distribution (176 ± 5 µm) and thin shells (≈7.5 µm) are formed from 4‐arm star‐shaped 12 kDa PCL precursors by photoinitiator‐free UV light‐induced radical polymerization of methacrylate end‐groups. FITC‐BSA is encapsulated as a model protein. The physicochemical characterization of the capsules indicated a partial crosslinking of methacrylate endgroups into netpoints. Microscopy revealed a fraction of collapsed capsules that are discussed in the context of network stability and mechanical stress created at the capsule interfaces during solvent removal. The incubation of particles with human embryonic kidney (HEK) cells showed good cell compatibility, suggesting their potential use in biosciences and beyond. [ABSTRACT FROM AUTHOR]

As one of wavefield separation methods in elastic reverse time migration, the decoupled wave equation succeeds to separate the particle velocity of P‐ and S‐wave without mode crosstalk. However, it fails to decouple the stress of P‐ and S‐wave which encounters with the problem of crosstalk. To overcome the crosstalk, the paper has proposed the quasi‐stress equations to decouple the stress tensor wavefields of P‐ and S‐wave based on the decoupled stress–strain relationship. Because P‐ and S‐wave stress wavefields are second‐order tensors, different from the imaging method of vector decoupled particle velocity wavefields, a double dot product imaging condition is proposed to obtain scalar images. Based on the total source‐stress tensor wavefields and separated receiver‐stress tensor wavefields, we obtain the scalar images of quasi‐PP and quasi‐PS from the stress information by the double dot product imaging condition. Several numerical examples are evaluated to demonstrate the effectiveness of the separation of P‐ and S‐wave stress and advantage of the proposed imaging condition from the second‐order stress tensor wavefields. [ABSTRACT FROM AUTHOR]

The TC18 titanium alloy as an aviation landing gear material is famous for its high strength and hardenability. However, under the influence of the harsh service environment, its corrosion resistance is relatively poor. WC–12Co ceramic material is one of the most widely used surface strengthening materials, and the coatings are often produced by high velocity oxygen fuel (HVOF) thermal spraying. In the spraying, the deposition state of particles directly affects the quality and strengthening ability of coating. This study combined the correlation of flow field calculation and impact process of particles, and the particle flight characteristics were analyzed in the three‐dimensional HVOF spraying. The change law for temperature and velocity of particles was explored by changing the spraying distance, oxygen/fuel (O/F) ratio, and particle size. Based on the calculation results of flow field, a three‐dimensional random deposition model of WC–12Co multiparticle was established by the coupled Euler–Lagrange method, and the crystal inhomogeneity was introduced by the Voronoi method. Compared the flattening rate and spreading degree of particles deposition, the evolution law of temperature and stress–strain fields for coating and substrate during the deposition was revealed. [ABSTRACT FROM AUTHOR]

Plant responses to abiotic stresses are dynamic, following the unpredictable changes of physical environmental parameters such as temperature, water and nutrients. Physiological and phenotypical responses to stress are intercalated by periods of recovery. An earlier stress can be remembered as 'stress memory' to mount a response within a generation or transgenerationally. The 'stress priming' phenomenon allows plants to respond quickly and more robustly to stressors to increase survival, and therefore has significant implications for agriculture. Although evidence for stress memory in various plant species is accumulating, understanding of the mechanisms implicated, especially for crops of agricultural interest, is in its infancy. Rice is a major food crop which is susceptible to abiotic stresses causing constraints on its cultivation and yield globally. Advancing the understanding of the stress response network will thus have a significant impact on rice sustainable production and global food security in the face of climate change. Therefore, this review highlights the effects of priming on rice abiotic stress tolerance and focuses on specific aspects of stress memory, its perpetuation and its regulation at epigenetic, transcriptional, metabolic as well as physiological levels. The open questions and future directions in this exciting research field are also laid out. Summary statement: Priming has a significant effect on rice abiotic stress tolerance by inducing a memory. Stress memory in rice is perpetuated during its growth cycle or is transmitted to progeny and it is regulated at epigenetic, transcriptional, metabolic as well as physiological levels. [ABSTRACT FROM AUTHOR]

Lithium‐sulfur batteries utilizing sulfide solid electrolytes hold considerable potential for achieving both high energy density and enhanced safety. However, the substantial volume changes experienced by sulfur during cycling result in mechanical stress accumulation, leading to mechanical degradation and thereby degrading overall electrochemical performance. In this study, a stress‐buffer strategy is proposed to address this challenge by engineering a mechanically resilient crosslinked structure for the composite sulfur cathode. This structure is accomplished through the integration of a highly flexible thermoplastic elastomer (ethylene vinyl acetate, EVA), which enables stress release during sulfur volume variations by the repeated stretching and shrinking of EVA, thereby maintaining stable ionic/electronic diffusion channels within the electrode. By virtue of the mechanically stable architecture, the stress evolution experienced by the entire sulfur electrode is substantially reduced, witnessing a remarkable decrease of ≈33.7%. Consequently, the S‐EVA composite cathode demonstrates exceptional electrochemical performance, especially cycling stability. Notably, the S‐EVA composite cathode, with a high loading of 7.5 mg cm−2, exhibits stable cycling performance close to 3.0 mAh cm−2 within 50 cycles. This work not only offers novel insights into mitigating the mechanical stress within the electrode but also paves the way for developing durable high‐performance all‐solid‐state batteries. [ABSTRACT FROM AUTHOR]

While the Earth (rocky planet) can be approximated as an elastic body, it also possesses anelasticity, Q−1, which causes energy dissipation (intrinsic attenuation) during deformation. Rock deformation experiments have demonstrated that Q−1 shows a marked amplitude dependency for strain of >∼10−6, but seismic‐waves‐induced strain is generally much smaller than the threshold value. Therefore, all seismological analyses have assumed amplitude‐independent attenuation. However, theoretical models of dislocation‐induced attenuation have predicted amplitude‐dependent attenuation under high temperatures and pressures equivalent to the crustal and uppermost mantle conditions. This study investigates whether attenuation is actually independent of seismic‐wave amplitudes by a systematic analysis of a large number of spectral amplitudes of co‐located earthquake pairs with different observed amplitudes. We assume the ω2 source and circular crack models to correct for the source parameters of earthquakes. The obtained results suggest that amplitude‐dependent attenuation is required to explain the observations, which contradicts a long‐standing recognition that amplitude‐dependent attenuation is negligible for the propagation of seismic waves. Our model calculation further suggests that Q−1 is proportional to the seismic amplitude, A, whereby Q−1 ∝ A0.1–0.2, which introduces attenuation variations along a given raypath, with significantly enhanced attenuation near the hypocenter. Our result highlights the need to revisit and potentially rethink current models of the physical mechanisms influencing intrinsic attenuation. Plain Language Summary: When seismic waves propagate in the Earth, their strain energy is gradually lost by the energy dissipation due to grain‐boundary sliding or dislocations during internal deformation. This study investigates whether the energy of seismic waves loses during their propagation in the crust and uppermost mantle by the systematic analysis of large number of seismic waveforms. Our result reveals that the energy dissipation depends on amplitude of seismic waves with 0.1–0.2 power of the amplitude. This finding is different from a long‐standing common recognition that attenuation is independent for amplitudes comparable to seismic waves. Our results highlight the merit of revisiting conventional observations, models, and hypotheses in the Earth and planetary sciences, where all the existing studies have assumed amplitude‐independent energy dissipation. Key Points: We analyzed spectral ratios of co‐located earthquakes with different amplitudes to extract amplitude‐dependent attenuationThis study suggests that amplitude‐dependent attenuation occurs in the crust and the uppermost mantle during the seismic‐waves propagationSeismic attenuation is proportional to the amplitude to the power of 0.1–0.2 [ABSTRACT FROM AUTHOR]

Tonga is a convergent plate boundary between the Pacific and Australian plates and is the fastest and the most seismically active deep subduction system in the world. We focused on southern Tonga (south of latitude 22°S) and the mantle transition zone (depths of 410–670 km), where seismic activity forms two subparallel bands of events in the east and west. We performed stress analysis by inverting focal mechanisms of earthquakes available in the Global Centroid Moment Tensor catalog and revealed two distinct stress regimes in the slab. While the stress orientation in the eastern slab segment conforms to the down‐dip compressional stress along the entire slab, the stress orientation in the western slab segment is different, having the maximum compression in the vertical direction. This suggests that the western segment can represent a stagnant slab with flattening and bending, as proposed by modeling studies. Its connection with the younger actively subducting slab is supported by the horizontal westward shift at 520 km depth. The stress analysis also indicates substantially different fault orientations in both segments. In the actively dipping slab, the majority of activated faults are predominantly sub‐horizontal. However, they are significantly inclined from vertical in the stagnant slab segment. A higher scatter in fault orientations in the stagnant slab suggests deformation, fragmentation and rheological complexity resulting from bending and flattening. Plain Language Summary: Tonga is a part of Tonga‐Kermadec, the 2,550‐km long subduction system in SW Pacific. It represents a convergent plate boundary between the Pacific and Australian plates. It is the fastest converging and the most seismically active deep subduction in the world. In the mantle transition zone, especially at depths greater than 500 km, the geometry of the slab becomes complex, forming separated slab segments. We performed stress analysis in the mantle transition zone (depths 410–670 km) with a focus on southern Tonga (south of latitude 22°S) where seismicity forms two subparallel bands of events in the east and west. We inverted publicly available data, focal mechanisms of earthquakes from the Global Centroid Moment Tensor catalog, and revealed two distinct stress regimes. While the stress orientation in the eastern segment matches the down‐dip compression of the subducting slab, the stress orientation of the western segment is different with the maximum compression in the vertical direction. This suggests that the western segment represents a stagnant slab with flattening and bending. Such findings are supported by the horizontal westward shift at 520 km depth and by substantially different fault orientations in both segments. Key Points: We performed stress analysis in southern Tonga mantle transition zone from focal mechanisms of earthquakes listed in Global Centroid Moment Tensor catalogWe revealed two distinct stress regimes: down‐dip compression matching subducting slab in the east and vertical compression in the westWestern segment suggests a stagnant slab with flattening and bending supported by horizontal shift and different fault orientations [ABSTRACT FROM AUTHOR]

The brittle‐ductile rheological behavior in subduction zones is commonly proposed to explain deep transient slips. Generally observed at large scales in tectonic "mélanges", here we show that it is also observed at the grain scale in exhumed blueschist metagabbros. In these rocks, petrologic and microstructural observations show a bi‐phase material constituted by strong microfractured magmatic pyroxene clasts located in a weak and ductile lawsonite‐rich metamorphic matrix. To constrain the mechanical conditions allowing the brittle deformation of a clast in a ductile matrix, we used two‐dimensional simple shear numerical experiments. Results show four behaviors: (a) entirely brittle; (b) brittle‐ductile with clast fracturing in a ductile matrix; (c) ductile‐dominant with limited plastic deformation at clast edges; and (d) entirely ductile. We propose that the conditions of the brittle‐ductile behavior, commonly associated with deep transient slips, are controlled by the strength ratio between the strong brittle phase and the weak ductile phase. Plain Language Summary: In subduction zones, brittle‐ductile behavior is commonly proposed to explain deep transient slips at the subduction interface. This particular behavior is generally characterized by the fracturing of strong pods located in a weak fluid‐like material. In this study, we observe this mixed rheological behavior at the mineral‐scale in oceanic rocks under deep transient slip conditions. We carry out petrological and microstructural observations that show micro‐fracturing of strong magmatic clasts and ductile deformation of a weak metamorphic hydrated matrix. Numerical experiments, inspired by these observations, are used to constrain the physical conditions for this brittle‐ductile behavior. Numerical results show four types of behavior: (a) both matrix and clast are brittle and fractured; (b) the clast is brittle and fractured and the matrix is ductilely deformed; (c) only the clast is brittle and fractures are localized at clast edges; and (d) both matrix and clast are ductile. This study demonstrates that the behavior of this bi‐phase material is controlled by the strength ratio between the brittle strong clast and the ductile weak matrix. These physical conditions significantly differ from the theoretical rheological prediction and may be the key to a better understanding of the mechanics of deep transient slips. Key Points: The modeled brittle‐ductile rheological behavior occurs in a more limited temperature range than theoretically predictedThe strength ratio between the brittle yield stress and the dislocation creep stress predicts conditions for the brittle‐ductile behaviorThe temperature, pressure and pore‐fluid pressure conditions for the brittle‐ductile behavior are those of the deep transient slips [ABSTRACT FROM AUTHOR]

The effect of damage on the brittle deformation of mafic and ultramafic rocks has been investigated by performing triaxial deformation experiments on thermally cracked and intact rock samples. The investigation was performed by recording the axial and lateral strains during deformation while simultaneously capturing the ultrasonic velocity, and electrical resistivity. While the peak strength is presumably controlled by the stiff intrinsic fractures, the crack opening mode also showed critical effects on the attained peak strength. The pore pressure distribution showed an apparent control over the dynamic Young's modulus as the ratio between the dynamic and static modulus of thermally cracked rocks is significantly higher than that of intact rocks. The compliant nature and the higher inelastic volumetric strain of the thermally cracked samples further indicated a possible explanation to the steep dipping plates and the taller topographic heights at the trench outer rise systems of old subduction zones. Plain Language Summary: The presence of fractures strongly influences the physical properties of rocks and not many experiments have been performed to understand the effect those fractures have on the deformation of mafic and ultramafic rocks. We find that, to address the deformation of the subduction zones, it is essential to perform experiments on such rocks under fully saturated conditions. As the incoming, relatively intact, oceanic plate sinks at the convergent boundaries, the plate bends significantly and creates a large number of faults. Therefore, the physical properties of the rock are subject to change and the way that rock deforms changes compared to an undamaged rock. However, so far, no research has been conducted to understand this change fully. Therefore, by performing experiments in the laboratory, we have attempted to understand how damage affects the physical properties and the deformation. By such experiments, we have identified that when fractures are present, the oceanic rocks show strong volume expansions before break by fracture and alter the physical properties. The results we have obtained here by gathering velocity, electrical resistivity, and strain, at the same time, can be related to the geophysical and topographic observations of the trench outer‐rise systems. Key Points: The effect of damage on brittle deformation of mafic and ultramafic rocks has been addressed via experimentsThe ultrasonic velocity, electrical resistivity, and strain are measured simultaneously during deformation of rocksPresence of cracks strongly influence deformation and physical properties which are comparable to outer rise geophysical observations [ABSTRACT FROM AUTHOR]

Although numerous efforts are made to synthesize active electrocatalysts for green hydrogen production; catalyst stability, and facile synthesis to scale up the production are still challenging. Herein, the production of novel non‐PGM catalysts for the oxygen reduction reaction (OER) in an alkaline aqueous medium is reported, which is based on the synthesis of a trimetallic metal–organic framework (MOF) precursors. Fine‐tuning of the composition of the metal centers (Ni, Co, and Fe) shows a great effect on OER activity after the MOF undergoes dynamic chemical and structural transformations under OER conditions. In situ characterization reveals the origin of OER activity enhancement as metals' oxidation state increases, inducing compressive mechanical strain on metal centers, enhancing the electronic conductivity through the formation of oxygen vacancies, and stronger metal–oxygen covalency. Catalysts are used in membrane electrode assembly (MEA) setup within an industrial full‐cell anion exchange membrane electrolyzer (AEMEC), showing a stable performance for 550 h without noticeable decay at 750 and 1000 mA cm−2 industrial level current densities. [ABSTRACT FROM AUTHOR]

A mesoscopic representative volume element (RVE) model of carbon fiber reinforced polymers (CFRP) laminate with 15 plies was established based on the principle of fiber random disturbance. The RVE model was validated by comparing the elastic parameters calculated by the RVE model, Chamis model, and Bridge model. Wet stress and thermal stress were coupled using a sequential method. Macroscopic and microscopic subroutines were developed to calculate the stress–strain field of CFRP laminate and RVE model. A multiscale numerical simulation of three‐point bending of moisture‐saturated CFRP laminate was conducted. Failure process and failure modes of CFRP laminate were discussed based on the multiscale simulation and SEM observations. The results show that the RVE model and the multiscale simulation strategy presented in this work can predict the coupled hygrothermal stress and the strength degradation due to moisture absorption very well. The maximum error between the simulated and experimental averaged force of the moisture‐saturated CFRP laminate subjected to three‐point bending is about 3.4%. Multiscale simulation demonstrated that uneven distribution of fibers can result in the fiber/matrix interfaces bearing a larger transverse stress in the fiber's dense distribution area. It is the main reason that results in fiber/matrix interface failure of CFRP laminates working in hygrothermal environments. Highlights: A RVE model of CFRP laminate was presented using fibers random disturbance.Coupled hygrothermal stress of single fiber and surrounded matrix was obtained.A multiscale simulation of the strength change of the CFRP plate due to wet‐thermal stress was conducted.Failure modes of CFRP laminate are discussed based on the multiscale simulation. [ABSTRACT FROM AUTHOR]

Fatal issues in lithium metal anodes (LMA), such as detrimental lithium dendrites growth and fragile solid‐electrolyte interphase (SEI) during the Li plating/stripping process, often hinder the practical application of Li metal batteries (LMBs). Herein, cobalt‐coordinated sp‐carbon‐conjugated organic polymer (Co‐spc‐COP) is constructed as the protective layer for regulating the interface stability of LMA. The unique synergistic beneficial effect of organic functional groups (C≡C linkage, C=N units and aromatic rings) and Co sites not only regulate the Li+ coordination environment and rearrange Li+ concentration to facilitate its transport by optimizing the electronic density, enhancing the compatibility with electrolyte interface and supplying "external magnetic driving strategy", but also strengthens the interfacial stiffness with high Young's modulus to better withstand the mechanical stress. These beneficial effects and relative underlying working mode and mechanism of uniform Li plating and rapid Li+ migration on the Co‐spc‐COP are also revealed by various in situ/ex situ experimental technologies and theory calculation. The Co‐spc‐COP‐based cell delivers an extraordinary lifespan of 6600 h and ultrahigh capacity retention of 78.3 % (111.9 mAh g−1) after 1000 cycles at 1 C. This demonstrated synergistic strategy in Co‐coordinated organic polymer may gain new insights to regulate the uniform and non‐dendritic deposition/dissolution behaviors for highly stable LMBs. [ABSTRACT FROM AUTHOR]

Fatal issues in lithium metal anodes (LMA), such as detrimental lithium dendrites growth and fragile solid‐electrolyte interphase (SEI) during the Li plating/stripping process, often hinder the practical application of Li metal batteries (LMBs). Herein, cobalt‐coordinated sp‐carbon‐conjugated organic polymer (Co‐spc‐COP) is constructed as the protective layer for regulating the interface stability of LMA. The unique synergistic beneficial effect of organic functional groups (C≡C linkage, C=N units and aromatic rings) and Co sites not only regulate the Li+ coordination environment and rearrange Li+ concentration to facilitate its transport by optimizing the electronic density, enhancing the compatibility with electrolyte interface and supplying "external magnetic driving strategy", but also strengthens the interfacial stiffness with high Young's modulus to better withstand the mechanical stress. These beneficial effects and relative underlying working mode and mechanism of uniform Li plating and rapid Li+ migration on the Co‐spc‐COP are also revealed by various in situ/ex situ experimental technologies and theory calculation. The Co‐spc‐COP‐based cell delivers an extraordinary lifespan of 6600 h and ultrahigh capacity retention of 78.3 % (111.9 mAh g−1) after 1000 cycles at 1 C. This demonstrated synergistic strategy in Co‐coordinated organic polymer may gain new insights to regulate the uniform and non‐dendritic deposition/dissolution behaviors for highly stable LMBs. [ABSTRACT FROM AUTHOR]

This study aimed to pioneer a transformative approach in orthopedic implant design by developing and analyzing a groundbreaking carbon‐flax reinforced bioepoxy hybrid composite bone plate. The primary objectives of the present research were to enhance the bio‐mechanical performance of orthopedic implants and explore the potential applications of the novel material for orthopedic implants. Hybrid composite plate was fabricated mimicking the human bone with the soft inner core and a rigid outer coating. Mechanical properties for the hybrid composite were obtained through material characterization studies as per ASTM standards. The hybrid composite bone plates were tested as per bio‐mechanical test standard and the results were correlated with the finite element simulations. The maximum stress value in the experiments for the biomechanical four‐point bending tests was 331.74 MPa, and the corresponding strain value was 0.0337. The maximum equivalent stress and strain values obtained from simulation were in line with the findings of the experiments. The current research signifies a paradigm shift in orthopedic implant technology. The carbon‐flax bioepoxy hybrid composite offers remarkable potential for orthopedic applications, promising safer and more durable solutions for patients in need of bone repair or replacement. [ABSTRACT FROM AUTHOR]

As an important barrier for high‐level radioactive waste transportation and deep burial disposal, the welding quality of nuclear waste container is particularly important. At present, nuclear waste container is usually manufactured by plasma arc welding. Therefore, in order to manufacture nuclear waste container parts with high quality, based on the finite element simulation software simufact welding, this paper uses a combination of numerical simulation and experimental verification to simulate the temperature field, stress field and deformation of the longitudinal weld of 316L nuclear waste container cylinder body by selecting different welding groove angles. The test results show that the groove angle of the V‐groove increases, the residual stress distribution and size increase, and the deformation increases. The stress value of the I‐shaped groove is between the V‐shaped groove angle of 30° and 45°, but the deformation is the smallest. In practical engineering applications, residual stress and deformation need to be considered comprehensive. Reasonable groove angle plays an important role in controlling residual stress and deformation after welding. [ABSTRACT FROM AUTHOR]

The carbide gradation related to geometry size and local stress concentration sensitivity significantly impacts the performance of the carburized 16Cr3NiWMoVNbE steel. The conventional metallurgical graphic comparison method by manual comparison is not capable of grading the carbide gradation automatically. A novel method is thus introduced to automatically evaluate the carbide grade by using a new shape factor φsc with stress distribution analysis instead of using the circularity or roundness shape factor which only considers the geometry shape of carbide particles. The logarithm of the stress concentration factor ln(K) is linearly related to the logarithm of the shape factor ln(φsc). The gradient b of the fitted straight line shows sensitivity to the carbide grade. The gradients are b1 = 0.039, b3 = 0.049, and b5 = 0.055 for the three carbide classes from low to high. Furthermore, there is also a linear relationship between hardness in different grades of carbide microstructure and the gradient b. [ABSTRACT FROM AUTHOR]

Summary: Many trees exhibit masting – where reproduction is temporally variable and synchronous over large areas. Several dominant masting species occur in tropical cyclone (TC)‐prone regions, but it is unknown whether TCs correlate with mast seeding.We analyzed long‐term data (1958–2022) to test the hypothesis that TCs influence cone production in longleaf pine (Pinus palustris). We integrate field observations, weather data, satellite imagery, and hurricane models to test whether TCs influence cone production via: increased precipitation; canopy density reduction; and/or mechanical stress from wind.Cone production was 31% higher 1 yr after hurricanes and 71% higher after 2 yr, before returning to baseline levels. Cyclone‐associated precipitation was correlated with increased cone production in wet years and cone production increased after low‐intensity winds (≤ 25 m s−1) but not with high‐intensity winds (> 25 m s−1).Tropical cyclones may stimulate cone production via precipitation addition, but high‐intensity winds may offset any gains. Our study is the first to support the direct influence of TCs on reproduction, suggesting a previously unknown environmental correlate of masting, which may occur in hurricane‐prone forests world‐wide. See also the Commentary on this article by Pearse & Wion, 242: 8–9. [ABSTRACT FROM AUTHOR]