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ABSTRACT A nonlinear variational auto‐encoder (NLVAE) is developed to reconstruct the plane strain stress field in a solid with embedded cracks subjected to uniaxial tension, uniaxial compression, and shear loading paths. Latent features are sampled from a skew‐normal distribution, which allows encoding marked variations of the features of the stress field across the load steps. The NLVAE is trained and tested based upon stress maps generated with the finite element method (FEM) with cohesive zone elements (CZEs). The NLVAE successfully captures stress concentrations that develop across the loading steps as a result of crack propagation, especially when enhanced disentanglement is emphasized during training. Some latent variables consistently emerge as significant across various microstructure descriptors and loading paths. Correlations observed between the evolution of fabric descriptors and that of their significant stress latent features indicate that the NLVAE can capture important microstructure transitions during the loading process. Crack connectivity, crack eccentricity, and the distribution of zones of highly connected opened cracks versus zones with no cracks are the fabric descriptors that best explain the sequences of latent features that are the most important for the reconstruction of the stress field. Notably, the distributional shape, tail behavior, and symmetry of microstructure descriptor distributions have more influence on the stress field than basic measures of central tendency and spread. [ABSTRACT FROM AUTHOR]

This paper presents an analytical solution for combined vertical and torsional shear loading of a cylindrical cavity in undrained modified Cam‐Clay. The governing partial differential equations for the cylindrical cavity are established in the polar coordinate. The problem is formulated as a set of first‐order differential equations by using the axisymmetric condition, equilibrium equations, and elastic‐plastic constitutive relationship. The influence of the second shear loading on the initial shear strain is considered in the plastic state. Then the stress‐strain distributions can be calculated by integrating within the elastic and plastic zones around the cavity. A finite element method simulation of the cavity under combined shear loading is established to verify the proposed approach, and the results are in good agreement with the proposed analytical solution. Parametric analyses are carried out on the effects of clay overconsolidation ratios and in situ stress coefficients under different loading paths and loading ratios. The results show that the combined shear loading on the cavity wall has a significant effect on the stress distribution of the surrounding soil, and the influence of the loading path cannot be neglected. [ABSTRACT FROM AUTHOR]

The unsatisfactory mechanical performance at high temperatures limits the broad application of 3D‐printed aluminum alloy structures in extreme environments. This study investigates the mechanical behavior of 4 different lattice cell structures in high‐temperature environments using AlSi12Fe2.5Ni3Mn4, a newly developed, heat‐resistant, high‐strength, and printable alloy. A novel Antisymmetric anti‐Buckling Lattice Cell (ASLC‐B) based on a unique rotation reflection multistage design is developed. Micro‐CT (Computed Tomography) and SEM (Scanning Electron Microscope) analyses revealed a smooth surface and dense interior with an average porosity of less than 0.454%. Quasi‐static compression tests at 25, 100, and 200 °C showed that ASLC‐B outperformed the other 3 lattice types in load‐bearing capacity, energy absorption, and heat transfer efficiency. Specifically, the ASLC‐B demonstrated a 51.56% and 44.14% increase in compression load‐bearing capacity at 100 and 200 °C compared to ASLC‐B(AlSi10Mg), highlighting its excellent high‐temperature mechanical properties. A numerical model based on the Johnson‐Cook constitutive relationship revealed the damage failure mechanisms, showing ASLC‐B's effectiveness in preventing buckling, enhancing load‐transfer efficiency, and reducing stress concentrations. This study emphasizes the importance of improving energy absorption and mechanical performance for structural optimization in extreme conditions. The ASLC‐B design offers significant advancements in maintaining structural integrity and performance under high temperatures. [ABSTRACT FROM AUTHOR]

A post‐installed rebar (PIR) is commonly used to establish structural connections between new components and existing structures, such as structural member extensions or concrete layer overlays in the construction/strengthening/retrofitting of buildings or bridges. In joint connections, the anchored PIR system always bears a non‐negligible compression in the component section, which is derived from the loads and self‐weight and has a confinement effect on the anchorage zone. However, excessive pressure can result in the fracture of the adhesive component, thereby leading to brittle failure in the PIR system. Owing to the important role of the adhesive component in the PIR system, this study is focused on the internal damage to the PIR system, and the effect of transverse pressure on the failure modes is investigated. This study comprises an experimental investigation of the failures of a PIR system under transverse pressure and a description of the internal damages based on the test results. Finally, an elastic analysis was established to explain the internal cracking and investigate the stress distribution in the PIR system. The tests on 34 pull‐out specimens showed two typical failures for the PIR system under transverse pressure (adhesive–rebar [A–R] interface failure and adhesive fracture failure). The A–R interface failure resulted from the shearing failure in the adhesive component, while the adhesive fracture failure resulted from the propagation of longitudinal and transverse cracks. The elastic analysis indicated that cracking in the concrete and adhesive component was dominated by circumferential stress, and the rebar rib direction and adhesive component thickness had a significant influence on the stress distribution. Based on this, some suggestions for anchorage design were made. [ABSTRACT FROM AUTHOR]

ABSTRACT The severe deformation of the surrounding rock of the coal floor in Shanghaimiao mining area is affecting the safe, efficient production of mine wells in this region. In this study, the heave mechanism and control of the roadway floor were investigated through laboratory experiments, field research, theoretical analysis, numerical simulation, and on‐site testing. The results showed that the main reason for the serious damage to the roadway floor was the low strength of the surrounding rock of the roadway floor, and floor damage was exacerbated by the low support strength, hydraulic effects, and mining impact. A mechanical model of the asymmetric floor heave was established, and it was found that the stability of the roadway floor was positively correlated with the floor rock type, the stress concentration coefficients on the two sides of the roadway, and the burial depth, whereas it was negatively correlated with the cohesive force and internal friction angle of the floor rock mass. Expressions for the upward resultant force R of the roadway floor and the stress concentration coefficients K and K′ on both sides of the roadway were derived. The results of a FLAC3D numerical simulation analysis showed that the stress peak in front of the working face was 36 MPa, with a stress concentration factor of 3.7. After the floor support was reinforced, the floor heave was remarkably reduced, with a maximum value of approximately 600 mm, and the floor deformation became somewhat asymmetric. Finally, a double‐seal floor‐reinforcing “inverted arch” control technique was proposed and tested on‐site. The new system could efficiently and stably support the surrounding rock of the roadway. [ABSTRACT FROM AUTHOR]

ABSTRACT This study aims to investigate the low cycle fatigue (LCF) behavior and fatigue life prediction method of an advanced solid solution–strengthened nickel‐based superalloy at various temperatures and stress concentrations. Cylindrical specimens as well as plates with three types of holes (including straight holes and inclined holes with different orientations) were designed and machined for fatigue tests. The test results revealed fatigue life decreases with the temperature increasing. Meanwhile, the fatigue lives of the plate specimens have decreased differently and are strongly dependent on the geometry and orientation of the holes. The key damage parameter related to the fatigue life was found on the strain gradient path. A criterion based on strain gradient is defined as the boundary of the damage process zone. The results show that the prediction was in good agreement with the experimental data, for the majority of the data are within a scatter band of ±2. [ABSTRACT FROM AUTHOR]

Flexible piezoelectric energy harvesters (FPEHs) have wide applications in mechanical energy harvesting, portable device driving, and piezoelectric sensors. However, the poor output performance of piezoelectric energy harvesters and the intrinsic shortcoming of piezoelectric sensors that can only detect dynamic pressure limit their further applications. BaTiO3 (BT) and PVDF are deposited on the glass fiber electronic cloth (GFEC) by impregnation and spin‐coating methods, respectively, to form BT‐GFEC/PVDF piezoelectric composite films. A mixed solution of mechanoluminescence (ML) particles ZnS:Cu and PDMS are used as the encapsulation layer to construct a high‐performance ML‐FPEH with self‐powered electrical and optical dual‐mode response characteristics. Due to the interconnection structure of the piezoelectric films, the prepared ML‐FPEH illustrates a high effective energy harvesting performance (≈58 V, ≈43.56 µW cm−2). It can also effectively harvest mechanical energy from human activities. More importantly, ML‐FPEH can sense stress distribution of hand‐writing via ML to achieve stress visualization, making up for the shortcomings of piezoelectric sensors. This work provides a new strategy for endowing FPEH with dual‐mode sensing and energy harvesting. [ABSTRACT FROM AUTHOR]

This research investigates the structural performance and failure mechanisms of beam‐column joints reinforced with aramid fiber‐reinforced polymer to bolster the durability and seismic resilience of concrete structures. It meticulously selects and proportions materials such as ordinary Portland cement Grade 53 cement, fine and coarse aggregates meeting IS: 383–1970 standards, and water conforming to IS: 456–2000 specifications. Tests confirm the high quality of ordinary Portland cement, crucial for optimal beam‐column joint performance, while carbon fiber‐reinforced polymer enhances structural integrity with its lightweight composition and substantial tensile strength (3800 MPa–4200 MPa). Failure analysis reveals that non‐aramid fiber reinforced polymer wrapped beam‐column joint specimens predominantly failed due to concrete crushing, whereas aramid fiber‐reinforced polymer‐wrapped specimens failed due to fracture in the aramid fiber‐reinforced polymer composite, emphasizing stress concentration areas. This study underscores the pivotal role of stress distribution in failure mechanisms and underscores the significance of robust reinforcement design in bolstering structural resilience. These insights advance retrofitting strategies and reinforce techniques aimed at enhancing the longevity and seismic resistance of concrete structures. [ABSTRACT FROM AUTHOR]

ABSTRACT This study investigates the stress–strain behavior of AISI H13 hot work die steel under thermomechanical fatigue (TMF) conditions. An electromagnetic‐thermal‐mechanical coupled finite element model was established to analyze the temperature and stress evolution during TMF cycles. Experimental results reveal that as TMF cycles increase, the hysteresis loop areas expand, and maximum tensile and compressive stress values decrease, indicating cyclic softening of AISI H13 steel. After undergoing TMF, observations show martensitic lath recovery and carbide coarsening along boundaries. Numerical results indicate thermal cycles cause temperature field inhomogeneity along the axial direction, which leads to a non‐uniform distribution of internal stresses along the longitudinal axis. Besides, the TMF lifetime under numerical simulation is comparable to that obtained through experiments. Based on experimental and simulation data, four life prediction models are employed, with the Ostergren model showing the highest consistency with a reliability factor of 1.2. [ABSTRACT FROM AUTHOR]

Highlights In this study, experiments combined with finite element analysis (FEA) were used to investigate the damage mechanism of transverse low‐velocity impacts on three‐dimensional woven tubular composites (3DWTC) with different structures. The damage morphology after impact was observed using three‐dimensional microscopy and scanning electron microscopy (SEM). Three mesoscale models were constructed based on the authentic structure of the 3DWTC. Additionally, the effects of the structure type on the impact resistance, stress distribution, and damage morphology of 3DWTC were studied. The impact resistance of the shallow cross‐linked (SCL) structure is the strongest, according to the data. The structure that resists impacts the least is the through orthogonal (TO) structure. The greater the straightness of the warps in the structure, the density of the weft, the volume fraction, the greater the cooperative load‐bearing capacity of the warps and wefts, and the greater the speed of stress propagation. The wefts and inner warps are subjected to tensile forces at the point of impact. The outer warps are subjected to compression. The stresses are distributed in a cross‐shaped pattern. The straightened warp and weft parts of the TO serve a key structural role in load‐bearing. The warps of the SCL and the shallow‐crossed curved joint (SCCJ) structure serve a key structural role in the load‐bearing capacity. The impact resistance of 3DWTCs was investigated. The tensile state, stress propagation rate of 3DWTC were analyzed using the mesoscale model. The main load‐bearing components are revealed. The differences in damage morphology of 3DWTCs are analyzed. [ABSTRACT FROM AUTHOR]

The development of lightweight and high‐performance composite pressure vessels have become a popular research objective. The purpose of this study is to the layup design and improve the mechanical properties of pressure vessel structure with optimal dome profile under an internal pressure of 70 MPa. First, the prediction equations of fiber thickness for the cylindrical and dome sections are provided. Second, the influence laws of linear parameters on fiber layer thickness distribution are analyzed. Third, the optimal dome profile is used as the pressure vessel structure for the layup design, and the variable polar hole process is applied to solve the fiber thickness accumulation problem near the polar holes. Finally, the composite pressure vessel is modeled using Abaqus finite element software, and the stress and strain distributions of the liner and the composite layer under different internal pressure loads are analyzed under self‐tightening pressure. Results show that the variable polar hole process reduces the maximum thickness value by nearly 50.16% at the maximum fiber thickness of the dome. Under working pressure, the maximum stress of the liner is reduced by 43.41% after applying self‐tightening pressure. In addition, the variable polar hole process can effectively realize the lightweighting of composite pressure vessels while self‐tightening pressure can effectively improve the mechanical properties of the liner. This research provides a valuable reference for the design of composite pressure vessels. Highlights: Fiber accumulation occurs in two bandwidth regions near the polar hole.The variable polar hole process can solve the fiber accumulation problem.The optimum dome profile geometric parameters are m = 0.8 and rc = 0.4R.The self‐tightening pressure improves liner loading capacity. [ABSTRACT FROM AUTHOR]

In this study, under the conformity of engineering reality, considering the influence of slip coefficient on the variation range of winding angle, 15 composite lay‐up schemes of hydrogen storage vessels were designed using grid theory, and the hydrogen storage vessels's structural strength was analyzed. The distribution of non‐geodesic fiber windings on the outer surface of the inner layer was solved using differential theory and the winding principle, and ABAQUS established the finite element model. The maximum stress value and stress distribution of the composite layer of the hydrogen storage vessel along the fiber direction were studied, the damage of the composite layer was analyzed, and the pressure and mode of the bursting were predicted. Results show that the structural strength of the hydrogen storage vessel designed by this method can be effectively guaranteed. The hoop winding layer bears the majority of the stress on the hydrogen storage vessel, while the helical winding layer's fiber strength is not entirely utilized. The hydrogen storage vessel gains greater structural strength when the circumferential winding layer is concentrated and situated at the outermost portion of the composite layer. The layup scheme has an impact of approximately 17.21% on burst pressure. Highlights: Effect of slip coefficient on the change of winding angle.Different forms of composite lay‐up schemes were designed.The stress distribution in the composite layer was studied.Analyzed structural strength and damage of the composite layer.Predicted the pressure and mode of bursting. [ABSTRACT FROM AUTHOR]

Stress concentration surrounding wounds drives fibroblasts into a state of high mechanical tension, leading to the delay of wound healing, exacerbating pathological fibrosis, and even causing tissue dysfunction. Here, an innovative skin stress‐shielding hydrogel wound dressing is reported that makes the wound sites shrink as a response to body temperature and then remolds the stress micro‐environment of wound sites to reduce the formation of skin scars. Composed of a modified natural temperature‐sensitive polymer cross‐linked with polyacrylic acid networks, this hydrogel wound dressing has demonstrated a substantial decrease in scar area for full‐thickness wounds in rat models. The physical forces exerted by the wound dressing are instrumental in attenuating the activation and transduction of fibroblasts within the wound sites, thereby mitigating the excessive deposition of the extracellular matrix (ECM). Notably, the wound dressing significantly down‐regulates the expression of transforming growth factor‐β1(TGF‐β1) and collagen I, while concurrently exerting a dramatic inhibitory effect on the integrin‐focal adhesion kinase (FAK)/phosphorylated‐FAK (p‐FAK) signaling pathway. Collectively, the fabrication of functional hydrogels with a stress‐shielding profile is a new route for achieving scar‐less wound healing, thus offering immense potential for improving clinical outcomes and restoring tissue integrity. [ABSTRACT FROM AUTHOR]

ABSTRACT Introduction Methods Results Conclusion Implantoplasty can be performed on implants diagnosed with peri‐implantitis to facilitate implant decontamination and improve access for oral home care. However, its effect on the mechanical strength of the implant is still uncertain. This study aimed to evaluate the effect of implantoplasty on the fracture resistance of dental implants with various degrees of bone loss, as well as its surface changes.Eighty 4.2 × 13 mm conical connection dental implants were allocated evenly into four groups based on the bone defect morphology: circumferential or semi‐circumferential, and 3 or 5 mm vertical height. Half of the implants underwent implantoplasty with tungsten carbide finishing burs. Weight, volume, and surface roughness of the implants were recorded prior to and after instrumentation. All implants were subjected to static loading to failure or fracture and the implant surfaces were then analyzed using optical microscopy. Finite element analysis was carried out to assess the stress pattern on dental implants after implantoplasty.Implantoplasty significantly reduced the fracture resistance of implants with all defect morphologies, aside from those with 3 mm of circumferential bone loss. Implants with 5 mm of peri‐implant bone loss also experienced significantly reduced fracture resistance compared to the 3 mm group. Significant decrease in fracture resistance was only observed between the circumferential and semi‐circumferential groups with 5 mm of bone loss. Surface roughness was also significantly reduced following implantoplasty. The results from finite element analysis revealed a change in pattern of stress concentration in the implant after implantoplasty.Implantoplasty negatively impacted the fracture resistance of standard diameter dental implants in most scenarios. The increase in exposed implant length resulted in a decrease in fracture resistance. This increase in fracture risk should be considered prior to implantoplasty, especially in implants with more advanced bone loss. [ABSTRACT FROM AUTHOR]

Reinforcing bars in structural concrete are typically designed to carry axial forces. Nevertheless, due to their bending stiffness, the bars can also carry transverse forces, that are associated with the localized bending mechanism (dowel action) resulting from the relative displacements (or slip) wherever a crack interface or a discontinuity interface (between two concrete parts cast at different times) intercept the bar. Such localized bending induces stress concentrations in both the bars and the concrete. The relative displacement can occur at interfaces either perpendicular to the bar or inclined with respect to its axis. Thanks to steel ductility, the bending stresses in the bars due to dowel action do not impair the sectional capacity at the ultimate limit state. Fatigue verifications, however, require an accurate evaluation of these stresses under imposed transverse displacements or shear forces. As well known, dowel action can be described by means of the traditional unidimensional Winkler's model (beam on an elastic foundation), where the bearing stiffness of the concrete embedment is typically introduced through a couple of parameters, namely the bar diameter and the concrete strength in compression. The actual behavior of a dowel, however, is definitely more complex and for such a reason, improvements are needed for the Winkler's model to introduce other parameters typical of actual structures. Hence, a new formulation is introduced in this study for the bearing stiffness, that is calibrated based on mechanical considerations and measurements with optical fibers. The proposed formulation also accounts for the following parameters: angle between the crack and the bar, concrete‐cover thickness, number of load cycles and the softening effect caused by the local secondary cracks radiating from bar ribs during the pull‐out process. The predictions of the model—implemented with the proposed bearing stiffness—fit fairly well the test results under both monotonic and cyclic loads, in terms of shear force–transverse displacement response and peak stress in the reinforcing bars. [ABSTRACT FROM AUTHOR]

Highlights This paper investigates how combining natural and synthetic fibers within yarns, altering the degree of hybridisation, and varying weave architectures affect the homogenized elastic properties and stress distributions in 2D woven composite laminae using a two‐scale homogenization scheme. The novelty lies in integrating a micro‐scale representative volume element model with a meso‐scale repeating unit cell model to capture intra‐yarn natural/synthetic fiber hybridisation. The study focuses on 2/2 twill and 5‐harness satin woven laminae with flax/E‐glass, hemp/E‐glass and basalt/E‐glass hybrid yarns, all with a total fiber volume fraction of 0.6. Fiber distributions are created through a random sequential expansion algorithm for hybrid RVEs, while periodic meso‐structures are used to define weave architectures for RUCs. Results show that yarn‐level fiber hybridisation significantly influences matrix stress distributions, with variations of up to 22%. In contrast, weave architecture has a minimal effect, with variations in homogenized properties below 2%. Varying fiber types, degrees of hybridisation and weave architectures allow for the tailoring of yarn and lamina properties and altering the stress distributions at micro‐ and meso‐scales and potentially influencing damage mechanisms. The modeling approach for analyzing the mechanical behavior of intra‐yarn hybrid natural/synthetic woven laminae could potentially be used to tailor their tolerance to damage. Two‐scale homogenization integrates RVE and RUC for 2D woven hybrid composites. Analyzed flax/E‐glass, hemp/E‐glass, basalt/E‐glass in twill and satin weaves. Intra‐yarn hybridisation significantly affects properties and stress fields. Hybridizing fibers offers tailored properties and may improve damage tolerance. [ABSTRACT FROM AUTHOR]

This work addresses the challenges in brazing thermohydraulic sealings involving dissimilar materials, specifically 316Ti stainless steel and alumina, which have significantly different coefficients of thermal expansion (CTEs) and elastic constants. Traditional brazing methods require complex interlayers or extensive metallization steps, leading to issues such as dimensional changes, braze voids, and inadequate corrosion resistance due to prolonged high‐temperature exposure. A novel laser‐based brazing technique utilizing a diode laser is introduced to create high‐quality, localized joints while preserving the integrity of the parent materials. The study systematically optimizes laser process parameters using finite‐element modeling and the Taguchi method to achieve the desired bead geometry and thermal stress distribution with minimal heat input. Comparative analysis between laser active brazing (LAB) and conventional furnace brazing was conducted through metallography, shear testing, and autoclave testing. Results indicate that LAB parameters significantly affect bead thickness and shear strength, with laser‐brazed joints demonstrating superior quality and stability post‐autoclave testing compared with furnace‐brazed joints. The thermodynamic and kinetic aspects of the brazing process were also analyzed. In conclusion, the LAB method for brazing 316Ti to alumina proves to be a successful and efficient alternative, with joint properties meeting or exceeding those of traditional furnace brazing. [ABSTRACT FROM AUTHOR]

ABSTRACT Background/Aim Materials and Methods Results Conclusion The fiber splint represents an advanced treatment for traumatized dental injuries. The complete understanding of the localization of a splint on traumatized teeth remains elusive. The aim of this study was to assess the impact of the incisal/cervical positions of the fiber splint on the stress distribution of traumatized dental roots in various occlusal relationships.Three‐dimensional finite element models were generated based on a cone beam computer tomogram of a patient. The incisal and cervical splints were simulated by strips that were bonded close to the incisal/cervical labial surface of traumatic teeth. Force was loaded on the incisal ridge, incisal and cervical positions on the palatal surface of each tooth to simulate the conditions of traumatized teeth during mastication. The equivalent stress (von Mises) on the traumatic teeth and abutment teeth was calculated by Ansys software (version 2021, R1).The incisal splint effectively transferred the stress from the traumatized tooth roots to the abutment teeth when force was loaded on the incisal ridge and incisal and cervical positions on the palatal surface. Nevertheless, the reduction effect was notably diminished when the cervical splint was used. Notably, in cases of cervical splints, with a loading force on the incisal ridge, there is an increase in stress on the roots of traumatized teeth, which poses a disadvantage in the management of traumatic dental injuries.The incisal splint demonstrated a more effective transfer of stress from the roots of the traumatic teeth to the abutment teeth than the cervical splint and the raw. [ABSTRACT FROM AUTHOR]

Highlights Carbon fiber reinforced resin matrix composites, when subjected to multi‐angle delamination during vacuum hot pressing, suffered from defects such as uneven fiber distribution, resin‐rich zones, and voids. These defects caused varied damage and failure behaviors in the composites, seriously affecting their mechanical properties. In this paper, the defect distribution, tensile and flexural properties, and damage behaviors of multi‐angle lay‐up specimens prepared in an autoclave were studied. The results indicated that irregularly shaped voids in laminates with a 0° angle difference primarily led to local stress concentration. Elliptical and elongated voids in laminates with a 90° angle difference were mainly susceptible to delamination. The [0/90]8 layer exhibited the best overall mechanical properties. The proportion of 0° laminates had a direct impact on the mechanical properties, with 0° contact laminates on the bending‐compression side capable of withstanding higher bending loads. The [+45/−45]8 plyer demonstrated pseudo‐delayed behavior, enabling the laminate to show better toughness under load. Variations in damage due to the proportions and positions of the laminates influenced the mechanical properties and damages behavior of multi‐angle laminates. Angular differences were observed to affect void and resin distribution. The best overall mechanical properties were attributed to [0/90]8 laminates. Pseudo‐delay behavior was exhibited by [+45/−45]8 laminates. Proportion of 0° layers impacted mechanical properties. Greater bending loads were withstood by the 0° contact layer. [ABSTRACT FROM AUTHOR]

In this paper, a crystal plasticity finite element method (CPFEM), considering the grain morphology and orientation, as well as the dislocation density, is used to research the tensile deformation behavior of GH4169 based on Electron Backscatter Diffraction (EBSD). The stress, plastic strain, and dislocation density distributions are obtained for different levels of deformation. Results show that the stress, plastic strain, and dislocation density exhibit obvious heterogeneous plastic deformation, and stress concentration and dislocation pileup mainly occurs near grain boundaries. The initial dislocation density mainly affects the stress–strain curve of the material, and it can obviously effect the yield strength but cannot influence the hardening ability of the material. The total dislocation density increases with plastic strain. However, the texture evolution has no evident change with increasing plastic strain, except for the increase of texture content in Cube (001)[100]. [ABSTRACT FROM AUTHOR]

This article is aimed at understanding of the complex design of metalorganic chemical vapour deposition ‐grown InGaN‐based red light‐emitting diode (LED) structure. The contribution of different elements of red LED structure to the stress distribution and threading dislocation density (TDD) evolution is theoretically investigated. For this purpose a self‐consistent modeling of the structure growth process is used, taking into account stress‐modulated indium incorporation, mismatch stress relaxation by threading dislocations and V‐pits, and nucleation of new threading dislocations. The simulation results, consisting of composition, stress, and TDD profiles, are then utilized for modeling of device operation, which allows to analyze contribution of different elements to the heterostructure operation. [ABSTRACT FROM AUTHOR]

Background: Although the specific relationship between the stress changes in the external fixator during tibial fracture treatment and the bone healing process remains unclear, it is believed that stress variations in the external fixator scaffold can, to a certain extent, reflect the progress of tibial healing. Objective: This study aims to propose a non‐invasive method for assessing the degree of fracture healing by monitoring the changes in stress transmission, the locations of stress‐sensitive points, and displacement in the external fixator‐tibia system during the healing process of tibial fractures. Methods: In this study, finite element models of tibial fractures at various healing stages were developed. Physiological conditions, including axial, torsional, and bending loads on the tibia, were simulated to evaluate stress and strain within the external scaffold‐tibia system under normal physiological loading conditions. Results: The results indicate variations in the stress distribution between the external fixator and the tibia during different stages of healing. In the early phase of fracture healing, the external fixator plays a crucial role as the primary load‐bearing unit under all three loading conditions. As the fracture healing progresses, the stress on the tibia gradually increases, concentrating on the medial part of the tibia under axial and torsional loading, and at the upper and lower ends, as well as the central part of the anterior and posterior tibia during bending loading. The stress at the callus gradually increases, while micro‐movements decrease. The stress within the external bracket gradually decreases, with a tendency for the connecting rod to transfer stress towards the screws. Throughout the fracture healing process, the location of maximum stress in the external fixator remains unchanged. Under axial and torsional loading, the maximum stress is located at the intersection of the lowest screw and the bone cortex, while under bending loading, it is at the intersection of the second screw and the connecting rod. Conclusion: During the bone healing process, stress is transferred between the external fixation frame and the bone. As bone healing advances, the stress on the connecting rods and screws of the external fixation frame decreases, and the amplitude of stress changes diminishes. When complete and robust fusion is achieved, stress variations stabilize, and the location of maximum stress on the external fixation frame remains unchanged. The intersections of the lowest screw and the bone cortex, as well as the second screw and the connecting rod, can serve as sensitive points for monitoring the degree of bone healing. [ABSTRACT FROM AUTHOR]

In this paper, the thickness debit and stress concentration effects of a nickel‐based directionally solidified superalloy were investigated through strain‐controlled low cycle fatigue (LCF) and creep–fatigue interaction (CFI) experiments. Compared to the fatigue lives of solid specimens provided in the existing literature, the results of this paper indicate that when the wall thickness of the specimen is reduced from 5 to 1.125 mm, the fatigue life with different strain amplitudes decreases by about 45%. When film‐cooling holes (FCHs) are introduced into the hollow specimens, the fatigue life is further reduced by about 25%. Based on the observation of the scanning electron microscope (SEM), the formation mechanisms of the thickness debit and stress concentration effects under LCF and CFI loads were revealed. Subsequently, two parameters, the "wall‐thickness coefficient" and "hole coefficient," were proposed to establish a new fatigue life prediction method. Highlights: LCF and CFI tests were investigated on hollow specimens with and without holes.The deformational behaviors of hollow specimens with holes were studied.Two parameters, the "wall‐thickness coefficient" and "hole coefficient," were proposed.A method for estimating the fatigue life of hollow specimens with holes was proposed. [ABSTRACT FROM AUTHOR]

Parts manufactured by wire arc additive manufacturing (WAAM) are characterized by a peculiar surface morphology, namely, surface waviness, that negatively affects the fatigue performance. To exploit the full potential of WAAM and minimize the need for postproduction work, it is crucial to utilize the components in the as‐built state. This is because conventional machining techniques, typically employed for postprocessing operations, severely curtail the freedom of geometry of the components. This study focuses on an experimental and numerical characterization of the notch effect of the surface waviness for an AISI 308 LSi stainless steel. This is done by quantifying the fatigue notch factor in a probabilistic fashion, considering the results of ad‐hoc designed fatigue tests. A finite element model is developed by considering a 3D scan of the geometry of WAAMed plates, allowing to determine the theoretical stress concentration factor. The fatigue notch factor is also estimated from the numerical model by making use of the gradient correction according to the FKM guidelines. To validate the numerical approach, test data produced for different testing conditions are correlated by using the local stress approach, showing that classical methods are also applicable to additive manufactured parts. Experimental determination of notch effect of as‐built surface in thick WAAMed plates. An FE model is formulated to estimate fatigue notch factor using FKM guidelines S‐N curves for WAAMed specimens of AISI308LSi steel at different load ratio. [ABSTRACT FROM AUTHOR]

The thermal shock resistance of ceramics is a key factor for determining the durability of ceramic components under transient thermal conditions and is also one of the key factors for evaluating the stability of ceramics under extreme thermal conditions. After rapid heating or cooling, the surface and internal thermal stress mismatches of ceramics can cause severe thermal damage. Two main types of ceramic thermal shock exist: rapid cooling and rapid heating thermal shock. This article presents a broad understanding and insight into fundamental theory and experimental methods for ceramic thermal shock testing. The experimental equipment and procedures, test result evaluation, and material characterization of ceramic thermal shock are summarized. Moreover, outlooks and perspectives are discussed for testing and characterizing ceramic thermal shock resistance. This review will be helpful to researchers performing studies in the relevant fields of ceramics. [ABSTRACT FROM AUTHOR]

A combination of experimental and simulation methods is adopted to study the relationship between micro‐stress and micro‐strain of a single spherulite upon uniaxial tensile deformation. To verify the simulation results and establish a suitable spherulite model, large‐sized isotactic polypropylene spherulite is first cultured with isothermal crystallization, whose structural deformation upon application of uniaxial tension is recorded using a polarizing optical microscope. A nanoindenter is used to measure the elastic modulus of the spherulite and amorphous region, preparing the property parameters for numerical simulation. Modeling and meshing of the single spherulite are conducted with the finite element software ABAQUS. The entire deformation of the spherulite is analyzed with fixed strain as the boundary condition, and the microscopic stress and strain distribution inside and outside of the spherulite is obtained. The higher micro‐stress region mainly locates at two poles in the equatorial direction, where might be the origin of craze. Generally, the simulation result is basically consistent with the experimental deformation process, which provides a new idea for the study of microscale structure and performance. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The seismic performance and construction speed of the prefabricated steel structures are greatly influenced by the configuration of the beam–column joints. The stepped beam–column joint proposed in this paper, featuring with flush surfaces on both the upper and lower beam flanges, was designed to satisfy the requirements of favorable seismic resistance and high installation efficiency. Notably, the junction between the stepped cantilever segment and the stepped beam segment is crucial in the stepped joint. Therefore, cyclic loading tests were conducted on two cantilever specimens with different connection forms to determine their seismic behavior and failure modes. The experimental results indicated that the connection forms have a minor effect on the elastic phase behavior. However, a significant influence was observed on the ultimate load‐bearing capacity and energy dissipation. The result also indicated that the specimen with a thicker end plate exhibited excellent seismic performance, with favorable load‐bearing and plastic deformation capacity. The seismic performance of the joint specimen with U‐shaped latch was inferior, with the welding seam on the flange connected to the end plate tearing prematurely due to the stress concentration. Besides, elaborate finite element models were established, which were confirmed by the test results. Finally, parametric analysis considering the effect of end plate thickness was conducted, and the bolts' forces during the loading progress on the connection surfaces were analyzed. The result indicated that the joint's load‐bearing capacity and stiffness would decrease with the reduction of end plate thickness. [ABSTRACT FROM AUTHOR]

The increasing application of TA2 titanium profiles in marine and petrochemical industries has spurred in a growing demand for diverse forms, including U‐shaped, rectangular, and tubular thin‐walled profiles. Traditional methods like mechanical subtractive processing and extrusion, despite their prevalence, suffer from high production costs and low efficiency. As a metal sheet forming technology, roll forming stands out for its efficiency, accuracy, and capability of producing complex shapes continuously. Nevertheless, the application of cold rolling to TA2 profiles is challenging primarily due to its low elastic modulus and high yield strength. In view of this, this study employed finite element simulation to analyze the stress and strain distribution during the TA2 roll forming process, aiming to have a better understanding of edge wave defect formation mechanism. Orthogonal experiments were performed to assess the influence of frame spacing, forming speed, roll gap, and downhill amount, on edge wave defects. The findings revealed a predominant influence of the downhill amount. Maintaining the downhill volume at 0.6 times the tube diameter kept the longitudinal strain below 0.9%, effectively mitigating edge wave defects. Implementation of these optimized parameters in an actual TA2 roll forming process confirmed the reliability of the simulations. This study establishes a solid foundation for advancing the TA2 tube cold roll forming process, enhancing the production efficiency of titanium profiles, and shedding some light on current energy conservation and emission reduction. [ABSTRACT FROM AUTHOR]

Highlights Fatigue damages of Carbon Fiber Reinforced Polymer (CFRP) laminates are not obvious. Obtaining the evolution of the internal fatigue damage in CFRP laminates before visible cracks occur is of vital importance for ensuring structural reliability. Micro X‐ray computed tomography (Micro‐CT) can provide micron scale nondestructive imaging of internal structure of materials. In this paper, a preliminary study was conducted on the early fatigue damage evolution of 0° UD laminates. Axial tension‐tension fatigue tests of [0]16 CFRP laminates were carried out, and the evolutionary behavior of damages was confirmed by fatigue dissipated energy. Then, the internal damages of fatigued specimens were observed and reconstructed using Micro‐CT, and statistical parameters such as damage sphericity, length and angle were calculated. The spatial distribution characteristics of cracks were further acquired by surface porosity and frequency distribution of damage positions in ROI. Early damages from tensile‐tensile fatigue in 0° UD laminates extend along the fiber direction with original defects in the interlayer resin enrichment areas as the nucleus, and tend to concentrate near the width edge of the specimens. Finally, a “sandwich” structural model was developed to analyze the internal stresses of laminates under the influence of interlayer resin enrichment. The FEA results revealed that the internal stresses σy and σz concentrate near the width edges of the specimen, resulting in cracks tend to evolve more in the regions close to edges. Imaging matrix cracks of specimens by Micro‐CT at 12.91 μm voxel size. Demonstrating evolution patterns of cracks with its morphology statistics. Revealing crack distributions in ROIs with variations of surface porosity. Analyzing internal stress distribution by “sandwich” model created from reality. [ABSTRACT FROM AUTHOR]

The commercialization of high‐capacity silicon materials in lithium‐ion batteries is hindered by significant volume changes. Composite anodes made from silicon and graphite, which increase battery capacity and maintain electrode structural stability, are receiving considerable attention. However, the spatial configuration of the active particles in the electrode is few investigated due to the complexity of experiments at the microscopic scale. Herein, this work focuses on electrochemical, mass transport, and stress coupling mechanisms by considering different spatial configurations of silicon and graphite. In situ electrochemical and stress measurements are first conducted to demonstrate the impact of the active material arrangement. Then, a 2D electrochemical‐mechanical model is developed considering the heterogeneity of electrochemical processes at the particle‐electrolyte interface. The results show that placing silicon in the upper active layer significantly reduces the ion transport resistance, while the graphite layer near the current collector provides a good conductive network for electron transport in the silicon layer, enhancing the performance of the composite electrode structure. By combining electrochemical and mechanical field models with experimental verification, this study deepens the understanding of composite electrode structure design, offering practical guidance for optimizing the spatial configuration of electrode materials to significantly improve battery performance. [ABSTRACT FROM AUTHOR]

Flexible pressure sensor (FPS) has promising applications in fields like health monitoring and human–machine interactions. The achieving of both high sensitivity and wide detection range in FPS remains highly challenging. Here, inspired by the filiform papillae on cat tongue, a FPS (noted as FPSp) with a sensitivity up to 504.5 kPa−1, a detection range from 30 Pa to 350 kPa, a fast response time of 83 ms, and a high stability over 8000 cycles is developed. The papilla‐like structure continuously shifts the location of stress concentration under increasing pressure, which avoids the accumulation of stress at papillae tips, resulting in a high sensitivity and wide detection range. Moreover, FPSp demonstrates capabilities in monitoring human physiological signals and movement status and can serve as the human‐machine interaction interface. The work not only presents a promising wearable pressure sensor but also establishes a design strategy for high‐performance wearable bioelectronics. [ABSTRACT FROM AUTHOR]

ABSTRACT In this paper, a new type of composite infiltration process was adopted for 20CrNi2Mo steel. Rolling contact fatigue (RCF) tests were carried out on the specimens treated with carburizing (C) and composite infiltration with carburizing and nitriding (C‐N). The results showed that after C and C‐N treatments were performed, the surface microhardness was increased by 78% and 114%, respectively, and the maximum CRS were −220 and −530 MPa. Moreover, the residual austenite volume fraction was controlled to approximately 10% for each treated sample. The fatigue limit of the C‐N sample was 11.3% higher than that of the C sample. The fatigue failure mechanisms are caused by the maximum shear stress distribution and surface roughness. The surface layer of the C‐N sample with higher hardness and more compressive residual stress inhibited the initiation of fatigue cracks, and the appropriate residual austenite in the carbon‐nitrogen infiltrated layer inhibited the propagation of fatigue cracks. [ABSTRACT FROM AUTHOR]

ABSTRACT Components in aero‐engine are likely excited in multiple resonance models in dynamic loads. This paper proposes an accelerated fatigue testing method that combines the vibration test with ultrasonic loading to develop a feasible experimental system for combined cycle fatigue (CCF) and explore the CCF characteristics in the high cycle fatigue (HCF) associated with very high cycle fatigue (VHCF) conditions. A thin plate specimen of 7075‐T6 aluminum alloy with two natural frequencies of 2 and 20 kHz is designed for the experiment. The stress waveform and distribution during real‐time monitoring provide validation for the method. Finally, the influences of composite loads are demonstrated by exploring the characteristics of the S–N curves and fracture morphology. The results suggest that the increase in both axial and bending stress markedly diminishes fatigue life, while the difference in stress levels under combined loading is revealed through variations in fatigue striation morphology. [ABSTRACT FROM AUTHOR]

In this study, a three‐dimensional large‐scale numerical model is established to investigate the failure characteristics of overlying strata and mechanism of strong ground pressure induced by excavation disturbance from multiple working faces. The characteristics of overlying strata fractures, heights of the caving zone and the fracture zone, and evolution of the stress field are systematically analyzed. The numerical simulation results reveal that the height of the caving zone after mining is 8.1 m, and that of the fracture zone is 27.3 m under the conditions of gently inclined thin coal seams. These findings are consistent with the theoretical results. The fracture development process can be divided into three stages: extensive development of new fractures, partial compaction of fractures, and closure of numerous fractures. In the structure of the post‐mining overlying rock, four stress zones are identified as follows: two zones of stress concentration at both ends of the working face, respectively, a zone of relatively high stress at the middle of the working face with low overlying strata, and a zone of stress fully released at the middle of the working face with high overlying strata. Comprehensive analysis of the maximum vertical stress of the cross section and the stress of the working face indicates that the stress increases significantly when mining enters the gob square stage and the roof does not collapse timely. [ABSTRACT FROM AUTHOR]

Highlights Additive manufacturing (AM) of continuous fiber reinforced polymer composites (cFRPCs) requires innovative tool‐pathing strategies that account for the anisotropic properties of the continuous fibers and ensure their continuous deposition as reinforcement along the designed structure, reducing fibers bending and cutting. Existing 3D printing slicing software, designed for isotropic materials like neat polymers, has been adapted for 3D printing of continuous fiber composites, resulting in a layer‐by‐layer approach that necessitates filament cutting after each layer deposition. This method introduces discontinuities, weakening the material and underutilizing continuous fibers strength. In this research, we propose a novel tool‐pathing strategy designed to address these challenges through (1) Ensuring fiber continuity across layers by allowing overlapping filaments and (2) Strategically positioning fiber cut points based on stress distribution, modeled using finite element analysis. A Multi‐Layer Continuous Fiber Path (ML‐CFP) approach was introduced and validated on a simple bracket structure featuring two load‐application inserts. 3D printed brackets using different tool paths were tested to failure under tension and compression after compression molding to improve interlayer adhesion. Mechanical investigations confirmed that the ML‐CFP approach enhances fiber utilization, improving tensile strength and work to fracture by up to 46% and 100% through promoting failure in fibers rather than at cut points. Introduced the multi‐layer continuous fiber path method (ML‐CFP) in AM of cFRPCs. Introduced the strategic cut point placement (SCPP) based on stress distribution. Maintaining fiber continuity and reduce fiber bending by allowing filament overlap. Mechanical testing to compare the ML‐CFP with conventional slicing methods. Enhanced tensile strength by up to 46% and work to fracture by 100%. [ABSTRACT FROM AUTHOR]

A computational model of ternary ion exchange (IOX) for strengthening glass is proposed to predict the cation concentration and residual stress distributions in glass after ternary IOX. The comparison between theoretical predictions and experimental results indicated the validates the model. Additionally, it provides a method to determine ion diffusivity and volume expansion through ternary IOX experiments. Simulations of K–Na–Li ternary IOX were conducted using the parameters calibrated based on experimental results from a thick silicate glass. Then the process parameters were changed to clarify their influences. Key findings reveal that for thick glass (where lateral expansion is negligible), the optimum ratio of K+ and Na+ concentrations in a molten salt is 2:1. We further consolidate the effects of process parameters by training a neural network (NN) and demonstrate that the NN can be a surrogate model to replace the time‐consuming simulations, which could be more adaptable by the glass industry. [ABSTRACT FROM AUTHOR]

Oxide‐bonded SiC porous ceramics (SCPCs), synthesized via reaction bonding, exhibit significant potential for high‐temperature applications. However, incorporating sintering aids inevitably results in a considerable quantity of amorphous glass phase within SCPCs, thereby introducing risks to their high‐temperature mechanical performance. In this study, we employ in‐situ characterization techniques to investigate the high‐temperature behavior of SCPCs. Our findings reveal that SCPCs demonstrate remarkable high‐temperature self‐enhancing properties, with a critical bending strength at 800°C. Beyond this temperature, the strength declines sharply. Intriguingly, the critical bending strength is 36.6% greater than at ambient temperature. Moreover, elevated temperatures enhance the elastic modulus and promote the transition of SCPCs from multilinear to nonelastic fracture. The neck phase, which imparts strength to the SCPCs, is composed of four distinct layers along the depth direction: silicate glass, oxygen‐containing, silicon‐rich, and SiC region, as revealed by FIB‐TEM. The transformation from α to β‐cristobalite in the oxygen‐containing region improves the thermal expansion match with SiC, thereby mitigating local stress concentration. Furthermore, the compressive stress within the neck region intensifies with increasing temperatures, thereby inhibiting crack propagation. This work provides a basis for the high‐temperature applications of SCPCs. [ABSTRACT FROM AUTHOR]

Highlights The CFRP/Ti multi‐bolt joints are commonly used in important structural parts of aircraft. These structure often adopts an integrated drilling method to improve manufacturing efficiency and avoid assembly problems. However, significant differences in material properties between CFRP and titanium alloy can affect hole accuracy, leading to deviations in hole‐size that impact joint performance. In response to these challenges, this study conducted experiments on the hole‐making process for CFRP/Ti laminated multi‐bolt joints and analyzed hole‐size characteristics and precision. The research investigated the effect of hole‐making processes on the static tensile and fatigue performance of CFRP/Ti three‐bolt single‐lap joints specimens and revealed the influence of hole‐size characteristics on load distribution among bolts. Results indicated that titanium alloy chip formation during CFRP hole drilling induced a microcutting effect on CFRP hole walls, resulting in stepped holes. The use of low‐frequency vibration‐assisted drilling improved chip removal and enhanced hole‐making precision. The use of the LDR‐LDR‐CD combined hole‐making process can mitigate the secondary bending phenomenon of critical bolt in CFRP/Ti three‐bolt, single‐lap joints specimens, thereby reducing local stress concentrations. This process combination effectively distributes bolt loads evenly, resulting in a reduction of the bolt load ratio in critical holes by 6.2%, and increases ultimate load and fatigue life by 6.7% and 47.7%, respectively. Therefore, in the hole‐making process of CFRP/Ti multi‐bolt joints, it is crucial to ensure that the precision of critical holes is lower than that of auxiliary holes to decrease the bolt load ratio in critical holes and enhance structural joint performance. Novel method for uniformly distributing load based on controlling drilling precision. The formation process of CFRP/Ti hole diameter characteristics in different processes. The LDR‐LDR‐CD can optimize load distribution, improve ultimate load and fatigue life. [ABSTRACT FROM AUTHOR]

A nonexplosive expansion method is proposed to apply in the field of rock burst prevention and control in coal mine. The principle of the expansive agent reaction was analysed and specimens with one hole and two holes were tested with and without axial stress or an expansive agent. The results showed that the reaction products of the expansive agent exhibited excellent fluidity and did not induce secondary stress concentration within the specimens. The specimens with two holes exhibited more severe and intricate fractures upon introduction of the expansive agent, and the formation of crisscross networks of cracks occurred in both the horizontal and vertical directions. Stress concentration became more pronounced as the distance between the two holes decreased, making the specimen more vulnerable to cracking. A field test was conducted to evaluate the effectiveness of pressure relief through expansion‐induced fracturing in the roadway of 1318 working face. The results from the field test demonstrated that the quantity of coal powder in the deep area significantly decreased after expansion‐induced fracturing and fell well below the early warning index of the drilling cutting method. [ABSTRACT FROM AUTHOR]

Objective Methods Results Conclusions Based on the varying number and relative positions of cervical disc replacement (CDR) and anterior cervical discectomy and fusion (ACDF) procedures, three‐segment hybrid surgery (HS) presents a diverse structural approach. Currently, the potential differential effects of HS with different segment combinations and surgical procedures on overloaded vertebral body (OVB) occurrence remain unexplored. The purpose of this retrospective study is to compare the clinical and radiological outcomes of HS and ACDF in treating cervical degenerative disc disease (CDDD), aiming to provide further insights into OVB.This study included patients with three‐level CDDD who underwent ACDF or HS at our institution. Eligible patients were divided into three groups: Type I (one‐level CDR and two‐level ACDF), Type II (two‐level CDR and one‐level ACDF), and ACDF (three‐level ACDF). For radiographic analysis, patients were further divided into the Replacement Segment Group and the Nonreplacement Segment Group based on the presence of replacement segments above and below the OVB. Clinical outcomes were evaluated using visual analog scale (VAS) scores for neck and arm pain, Japanese Orthopedic Association (JOA) scores, and neck disability index (NDI) scores. The cervical radiological parameters assessed included (1) vertebral cross‐sectional area (CSA), (2) wedge angle (WA), (3) anterior vertebral height (AH), (4) posterior vertebral height (PH), and (5) Hounsfield unit (HU) values. Statistical methods included paired t‐test, ANOVA test, and chi‐square test. Independent samples t‐test, Mann–Whitney U test, and Wilcoxon signed‐rank test were used to compare the differences between two groups according to the results of normal distribution test.A total of 123 patients, evenly distributed among three groups, were included and were well matched in terms of demographic characteristics. The likelihood of vertebral body collapse (VBC) was notably higher in the ACDF group (41.5%) compared with the Type I (17.9%) and Type II (8.9%) groups (p < 0.01). Following surgery, both at 3 and 6 months, the ACDF group demonstrated higher VAS neck scores and NDI scores compared with the Type I and Type II groups (p < 0.01). Additionally, the WA and AH values of the upper and lower adjacent OVB were consistently lower in the ACDF group than in the Type I and Type II groups at 6 and 12 months and at the final follow‐up (p < 0.01). Notably, in the Nonreplacement Segment Group, WA significantly decreased at 12 months postoperatively and at the final follow‐up compared with the Replacement Segment Group (p < 0.01).Three levels of HS appear to reduce stress concentrations and alleviate morphological changes in OVB. The occurrence of more VBC patients with OVB was associated with the use of Zero‐P or Zero‐P VA implants. [ABSTRACT FROM AUTHOR]

Inspired by stimuli‐responsive creatures in nature, developing devices with synergistic color change and deformation will be of great value for realizing the adaptive variants. Yet, integrating adaptive color variation and deformation into a single device remains elusive. Herein, an intriguing electrochromic actuator based on MXene/WO3 bilayer film is developed with Fabry−Pérot (F–P) microcavity, which successfully integrates both functions of reversible deformation and vivid color variations into the same device. Upon applying a small electric field, the ion intercalation/de‐intercalation can synchronously alter the stress distribution and optical absorption of MXene/WO3, resulting in the dual response of electrochromic phenomenon and ultra‐fast deformation with a maximum angle of 95° within 10 s. Moreover, the F–P microcavity architecture with the physical light interaction additionally endows the bilayer film with a bright color gamut and high color tunability (yellow–green, purple, pink, blue, etc.). Furthermore, an asymmetric soft actuator based on MXene/WO3 bilayer film is assembled, which displays robust grasping ability and excellent cycling stability up to 1000 cycles. These findings may open new opportunities for somatosensory soft robots and next‐generation intelligent robots. [ABSTRACT FROM AUTHOR]

Highlights Investigating the macro‐mechanical properties of polymer composites at the nanoscale is a challenging topic. Here we report the compressive performances of carbon fiber‐reinforced epoxy composites using molecular dynamics (MD) simulations. The evolution of microstructure and microscopic energy, including free volume, radius of gyration, dihedral angle, potential energy, and interaction energy, has been investigated to characterize compressive behaviors at the nanoscale. Molecular chains gradually bend, and the movement space of the molecular chains decreases during compression loading. The radius of gyration and dihedral angle are deformed into a state of irreversible plasticity to accommodate the microstructural transformation. The interaction energy increases and subsequently declines as the carbon fiber/epoxy interface gets closer, reflecting the transition of the internal structure. The inhomogeneity and interfacial concentration distribution of stress, and local molecular stiffness under various strains have been obtained to reveal the nanoscopic mechanism of epoxy failure and interface delamination during compression. This study reveals the compression behaviors and deformation mechanism of carbon fiber‐reinforced epoxy composites at the molecular level, providing directions and possibilities for molecular design and structural optimization of composites. The nanoscopic compression deformation of CFRP composites is studied. Microstructural evolution and conformation transformation are revealed. The evolution and transition of microscopic energy are analyzed. Micro‐mechanism of epoxy deformation and interface delamination is elucidated. [ABSTRACT FROM AUTHOR]

Mechanoluminescent (ML) materials convert mechanical stimuli into light emission, enabling applications in stress distribution visualization, structural health monitoring, biomechanical imaging, and sono‐optogenetics. Achieving efficient and full‐spectrum ML materials represents a long‐standing challenge. Zinc alkaline earth metal oxysulfides, namely CaZnOS, SrZnOS, BaZnOS, and SrZn2S2O, have emerged as prominent contenders in this field due to their exceptional ML properties. These materials feature low‐stress thresholds for emission activation, high ML intensity without the need for irradiation charging, and tunable spectra ranging from visible to near‐infrared, thus advancing ML research and broadening application possibilities. Here, a comprehensive review of the significant advancements made in ML research on zinc alkaline earth metal oxysulfides over the past decade, encompassing synthesis, characterization, mechanisms, and promising applications is presented. Special attention is focused on addressing conflicting reports on ML generation conditions, recent progress in accurately characterizing ML performance, and understanding mechanical‐to‐optical conversion processes. Future directions in fundamental ML research and the challenges in translating these advancements into practical applications are also discussed. [ABSTRACT FROM AUTHOR]

This article investigates the seismic stability of E‐BRBF and E‐FBF systems previously proposed as stability‐enhanced alternatives to conventional BRBF and FBF systems. The E‐BRBF system is a buckling restrained braced frame with an inverted‐V brace configuration in which one of the two braces is a conventional brace designed to remain elastic during a strong earthquake. When the buckling restrained brace (BRB) yields, an unbalanced vertical force develops at the brace‐to‐beam connection, which imposes flexural demand on the beam and creates a positive post‐elastic storey shear stiffness. The E‐FBF system is identical except that the buckling restrained braces are replaced by conventional bracing members constructed with an end friction connection designed and detailed to slip at a predetermined load. At every storey, the beam and the elastic braces are designed such that this post‐elastic stiffness is sufficient to cancel the negative storey shear stiffness resulting from P‐delta effects and introduce a re‐centring mechanism to achieve an enhanced performance in steel buildings subjected to interface subduction earthquakes. Using distributed plasticity numerical models, past studies demonstrated the effectiveness of E‐BRBF and E‐FBF systems in mitigating P‐delta effects, emphasizing the importance of a stable and predictable response of the beam, which is a critical element in the scheme that provides the post‐elastic stiffness of the system. This beam is subjected to axial and flexural demands and must remain near elastic to ensure the global seismic stability of the structure. The response of the beam can be affected by localized yielding and local instability effects resulting from residual stresses, stress concentration near gusset plate connections and geometric imperfections. Employing a refined nonlinear finite element model of the beam element, this article assesses the performance of 10‐storey E‐BRBF and E‐FBF systems utilizing multi‐platform numerical hybrid simulations. The evaluation involves static‐monotonic and dynamic response history analyses, incorporating seismic excitations representing Vancouver, BC's seismic hazard (Crustal, In Slab, and Subduction Interface). In the hybrid simulation model, the most critical member for the proposed system (i.e., first‐storey beam) is sub‐structured in ABAQUS using solid elements, while the remaining frames are integrated using OpenSees using fiber‐based sections. Numerical hybrid simulation dynamic nonlinear response history analyses demonstrate the adequacy of the E‐BRBF and E‐FBF systems in mitigating P‐delta effects with residual drifts within repair limits, unlike conventional systems where instability or excessive drifting occurred. Monotonic Pushover hybrid simulations reveal a more ductile beam behavior compared to standalone models, in which frame members are entirely modeled in OpenSees. The analysis also indicates a ductile plastic hinging beam failure mechanism with no instability failure modes at extreme drifts. [ABSTRACT FROM AUTHOR]

Highlights The 3D woven spacer fabric lightweight composites (WSFC) show promising applications in construction, transportation and aerospace. In this study, the 3D WSFC with different structural variations (e.g., layer thicknesses, stacking and face layer thickening) were designed and fabricated. The fracture strengths of single‐layer WSFC in the weft direction with layer thicknesses of 5, 10 and 15 mm were 54.4, 14.3, and 5.4 MPa. In the weft direction, the fracture strengths of double‐ and triple‐stacked 3D WSFCs were 30.6 and 21.7 MPa, which improved 1.1 times and 3.0 times as compared with those of original single‐layer 3D WSFCs, respectively. The double‐ and triple‐stacked WSFC also had large flexural deformation. The 3D WSFC with double‐layer misaligned stacking had the similar flexural strengths in both directions, which obviously reduced the performance differentiation of 3D WSFC in different directions. With the addition of face layer fabric, the mechanical performances of 3D WSFC were notably enhanced, and the damage modes were changed from brittle failure to ductile failure. Furthermore, a multi‐scale model of 3D WSFC with different structural variations was developed for numerical simulation to analyze the stress distribution and damage mechanism. Stacking design obviously improves mechanical properties of 3D WSFC. WSFC with misaligned stacking has similar flexural strengths. A multi‐scale elastic–plastic damage model for 3D WSFC is established. Damage modes of WSFC are changed with the stacking method. [ABSTRACT FROM AUTHOR]

Nowadays, the seismological monitoring system in China is a valuable tool in the rockburst risk evaluation for deep coal mines. In the past, only parameters, like source location and energy, are widely used to estimate the risk level of rockburst. Sometimes, it is effective; however, some other important physical parameters, such as apparent stress drop, static stress drop, P‐wave velocity, and moment tensor, should also be included in order to improve the accuracy of risk assessment. In this study, these parameters are calculated using mine tremor signals recorded in the LW35001 workface of Liangbaosi Coal Mine. These calculations provide an overall identification of periodical stress distribution and rock mass energy‐releasing type under high concentrated stress. Via linear moment tensor inversion procedure, the source mechanism of mine tremors and stress state of the rock mass is determined whether it is risk or not to underground roadway. This comprehensive analysis provides a specific guidance for rockburst prevention for coal mine management, that is, knowing when and where measures must be taken to decrease the risk level or induce the occurrence of rockburst under control. [ABSTRACT FROM AUTHOR]

Components created with five‐axis machining show a multi‐scale surface character due to cusps created on the surface and feed and tool marks within the cusps. Therefore, it becomes difficult to incorporate the effects of surface character on fatigue life for such components. In this work, an Forschungskuratorium Maschinenbau (FKM) guideline is adapted to develop a fatigue prediction model which considers cusps as notches and marks within the cusps as surface roughness (characterized by parameter R10z). The assessment uses stresses obtained from an finite element analysis model to predict the fatigue life of components whilst considering stress concentration, stress gradient, mean stress, and surface roughness effects. When cusps are regarded as surface roughness within the conventional FKM approach, fatigue life is considerably underestimated. In comparison, fatigue life predictions that take into consideration the roughness within cusps and treat cusps as stress‐raising notches are closer to experimental life. [ABSTRACT FROM AUTHOR]

This study proposes a novel method to prevent fatigue cracks at the root of fillet welds in steel bridge supports by inserting epoxy resin as an adhesive material. A total of 36 specimens, categorized into welded‐only and bonding‐assisted types, were subjected to a series of four‐point bending fatigue tests to simulate cyclic tensile stress conditions. Additionally, finite element analysis was employed to investigate the impact of epoxy insertion on stress distribution near the weld root. The results demonstrated that bonding‐assisted specimens exhibited significantly improved fatigue life compared to welded‐only specimens, with a notable reduction in tensile stress at the weld root. Furthermore, a displacement‐based method was employed to evaluate weld root fatigue performance, yielding consistent results. These findings highlight the potential of integrating adhesive bonding in fillet welds to improve the durability and service life of steel bridge structures by effectively mitigating fatigue‐related issues. Highlights: Preventing fatigue cracks in fillet weld root through epoxy insertion.Inserted rubber prevents welding defects caused by epoxy burning during welding.The combination of welding and bonding reduces the opening displacement of the weld root.Displacement‐based method can effectively evaluate weld root fatigue life. [ABSTRACT FROM AUTHOR]

Welded components are highly vulnerable to fatigue failures due to stress concentrations and material imperfections. This study develops an analytical framework that predicts both high‐cycle (HCF) and low‐cycle (LCF) fatigue lives of welded joints using a structural strain parameter. By employing a linear hardening model, the method effectively translates structural stress into structural strain, providing a reliable metric for assessing fatigue life, especially in LCF conditions. Validated against experimental data from 62 longitudinal gusset joints, the approach proves both reliable and practical. This simplified method facilitates easier fatigue assessments, encouraging its wider use and potential standardization in engineering, thus improving the predictability of welded structures' performance. Highlights: An analytical framework is presented to assess the fatigue behavior of welded structures.The linear hardening law is introduced to capture the material hardening behavior.The analytical solutions for plane stress and plane strain conditions are provided.The method is applied to analyze 62 weldment fatigue data in both HCF and LCF regime. [ABSTRACT FROM AUTHOR]

The study investigated the fretting fatigue behavior of a bridge‐flat component, utilizing a flat specimen with two bridge‐type pads tested under cyclic loading. Numerical simulations were also carried out using the finite element method. Firstly, precise calculations of contact stress were performed with the material's elastoplastic model. Secondly, the stress distribution on the maximum stress cross‐section was extracted, and the stress gradient was computed. Finally, a stress fatigue life prediction model considering the stress gradient was proposed, and the predicted life was compared with the test life. The results of the study revealed that the specimens exhibited high stress gradients at the edges of the contact region during the bridge‐flat tests. In comparison with plain fatigue, fretting fatigue life was significantly reduced. The life prediction model proposed in this paper demonstrated good accuracy for predicting fretting fatigue. Highlights: A novel stress‐fatigue life prediction model for fretting fatigue was proposed.Parameters in the new model are easy to obtain with FEM and have good physical significance.A new stress gradient and critical distance calculation method was proposed.The performance of the new model shows good accuracy. [ABSTRACT FROM AUTHOR]