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Quantitative schlieren analysis is extended here to optically transparent solids in quasi-static and dynamic experiments to measure stress distributions. The quasi-static experiments in polymethyl methacrylate (PMMA) compared refraction angles and stress gradients calculated from schlieren images to the analytical Flamant solution of a line load on a half-space. The quantitative schlieren measurements of the stress field in the thin sample with a load compared well to the analytical solution. The analysis method was then extended to explosive induced shock waves in PMMA. The explosive induced response of PMMA was experimentally studied using high-speed schlieren to visualize the shock propagation in conjunction with Photon Doppler Velocimetry (PDV) to record surface velocity histories. The stress state estimated from the schlieren images was compared to the stress calculated from the PDV measurements. High-speed imaging limitations caused the shock wave to not be fully resolved in the images, but was resolved in the PDV measurement. The stress state behind the shock calculated from the high-speed images followed a similar trend to the stress calculated from the PDV measurements. [ABSTRACT FROM AUTHOR]

To meet commercialization requirements, the distributions of materials in hafnium-based ferroelectric devices—including their phase and orientation—need to be controlled. This article presents a method for improving the ferroelectric phase ratio and orientation by adjusting the stress distribution of the annealing structure in a three-dimensional capacitor. In such a structure, stress can be applied in three directions: tangential, axial, and radial; there are, thus, more ways to regulate stress in three-dimensional structures than in two-dimensional structures. This work sought to clarify the role of the stress direction on the proportions and orientations of ferroelectric phases. The results of stress simulations show that a structure with an internal TiN electrode, but no filling provides greater axial and tangential stresses in the hafnium-oxide layer. In comparison with the case of the hole being filled with tungsten, the proportion of the O phase is increased by approximately 20%, and in experiments, the projection of the polarization direction onto the normal was found to be increased by 5%. Axial and tangential stresses are regarded to be beneficial for the formation of the O phase and for improving the orientation of the polarization direction. This work provides a theoretical basis and guidance for the three-dimensional integration of hafnium-based ferroelectric materials. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the stress distribution along a premolar's root dentin, its post, and its post-luting agent when materials with different elastic moduli are used to fabricate one-piece post-and-cores in two different designs. Materials and Methods: Two 3D virtual models (for cylindrical and conical post designs) of a mandibular premolar restored with one-piece post-and-core restorations were obtained using a software. A total of eight post-and-core materials were tested: polyetheretherketone (PEEK), polyetherketoneketone (PEKK), glass fiber-reinforced polyetheretherketone (GFR-PEEK), carbon fiber-reinforced polyetheretherketone (CFR-PEEK), gold-palladium alloy (Au-Pd), titanium (Ti), zirconia (Zi), and chromium-nickel (Cr-Ni). Maximum principals stress (MPS) in the post, post-luting agent, and root dentin were determined. A load of 150 N was applied to the buccal cusp in the linguo-labial direction at an angle of 45 degrees oblique to the longitudinal axis of the crown. Results: The highest MPS value in post structure was observed with Cr-Ni material for both post designs. Similarly, the highest MPS value in the post-luting agent was observed for Cr-Ni, the material with the highest elastic modulus. However, in the root dentin, the highest value was observed in PEEK, the material with the lowest elastic modulus. Conclusions: Post material and design influenced the stress concentration in the post, post-luting agent, and root dentin. The stress at the root dentin was slightly higher for polymeric materials. Cylindrical post design revealed lower stresses than conical post design at root dentin for all post-and-core materials tested. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the effect of restora0on design on fracture resistance and stress distribu0on of veneered and monolithic three-unit zirconia fixed par0al dentures (FDPs) using finite element analysis (FEA). Materials and Methods: Iden0cal epoxy resin replicas of mandibular second premolars and second molars (to serve as abutments for the three-unit bridges) were divided into four groups (n = 10): monolithic zirconia (MZ) restora0ons; conven0onal layering veneering technique (ZL); heat pressed-on technique (ZP); or CAD/CAM lithium-disilicate glass-ceramics (CAD-on). Specimens were subjected to compressive cyclic loading on the mesio-buccal cusp of the pon0c (load range 50 to 600 N; aqueous environment; 500,000 cycles) in a universal tes0ng machine. Data were sta0s0cally analyzed at 5% significance level with Fisher exact test and Kaplan-Meier survival analysis. 3D models were constructed in accordance with experimental groups. The stress distribu0on in each model was analyzed and evaluated according to the loca0on and magnitude of the maximum principal stresses (MPSs) using ANSYS so\ware. Results: Specimens from ZL and ZP groups failed at different stages of the 500,000 cycles fa0gue, while CAD-on and MZ restora0ons survived the fa0gue test. Sta0s0cally, there was a significant difference between the groups (P < .001). The MPS were located under the mesial connector in both monolithic and bilayered three-unit zirconia FDPs. These stresses were found to be higher in monolithic geometries compared to bilayered zirconia FDPs. Conclusions: Monolithic threeunit zirconia and CAD-on zirconia frameworks resulted in superior fracture resistance. Restora0on design significantly affected the stress distribu0on of three-unit zirconia FDPs. [ABSTRACT FROM AUTHOR]

Scanning x-ray microbeam topography and fluorescence experiments were conducted in situ to study the electromigration behavior of a 0.5 μm thick, 10 μm wide, and 200 μm long Al(0.25 at. % Cu) conductor line with 1.5 μm-thick SiO2 passivation on a single crystal Si substrate. The strain sensitivity of x-ray topography measurement allowed detailed examination of the electromigration-induced stress distribution and evolution in the conductor line in response to the depletion of Cu solute early in the electromigration process. Upon electromigration at 0.4 MA/cm2 and 303 °C, a short-range stress gradient was quickly induced by Al migration in the Cu-depleted cathode region to counteract further Al flow. The stress gradient was fully developed during the 5.3 h incubation time, extending over the critical Blech length of about 66 μm from the cathode end. Plastic deformation then occurred at the downstream end of the Cu-depleted region. The preferential electromigration of Cu did not cause detectable stress change outside the Cu-depleted region, except for the significant stress development from the Al2Cu precipitation at the anode end which appeared to initiate the fracture in the passivation. Preliminary finite difference modeling was undertaken to simulate the experimental observations, from which important parameters dictating electromigration in Al(Cu) line were extracted: an apparent effective valence of −5.6 and −1.9 for Cu and Al in Al(Cu), respectively, and a critical Cu concentration of 0.16 at. % above which Al grain boundary diffusion is effectively blocked. [ABSTRACT FROM AUTHOR]

Purpose: To compare the biomechanical responses of a normal mandible to an osteoporotic mandible with two-implant--supported magnetic attachments. Materials and Methods: A 3D finite-element model of a two-implant--supported mandibular overdenture with magnetic attachments was developed, and normal and osteoporotic bone samples were prepared. Four types of load were applied to the overdenture in each model: 100 N vertical and oblique loads on the right first molar, and a 100 N vertical load on the right canine and incisors. Biomechanical behaviors of the peri-implant bone, implant, and mucosa were recorded. Maximum equivalent stresses and elastic strains were analyzed. Results: Equivalent elastic strain in osteoporotic cortical and cancellous bone was 9% to 71% and was 142% and 207% greater than in normal cortical bone, respectively. Equivalent elastic strain in the first molar oblique loading condition was 101% to 190% greater than in the first molar vertical loading condition. Conclusions: Osteoporotic cancellous bone was weaker and less resistant to deformation than normal bone, and oblique loading was more harmful than vertical loading. [ABSTRACT FROM AUTHOR]

The discovery of graphene led to a burst in search for 2D materials originating from layered atomic crystals coupled by van der Waals force. While bulk bismuth crystals share this layered crystal structure, unlike other group V members of the periodic table, its interlayer bonds are stronger such that traditional mechanical cleavage and exfoliation techniques have shown to be inefficient. In this work, we present a novel mechanical cleavage method for exfoliating bismuth by utilizing the stress concentration effect induced by micro-trench SiO 2 structures. As a result, the exfoliated bismuth flakes can achieve thicknesses down to the sub-10 nm range, which are analyzed by atomic force microscopy and Raman spectroscopy. [ABSTRACT FROM AUTHOR]

Amorphous intergranular films (AIFs) have been proven in experiments to improve the damage tolerance of nanocrystalline materials. However, a quantitative study is still lacking. Molecular dynamics simulations were performed here to investigate the effect of CuNb AIFs on the fracture toughness of nanocrystalline Nb. In order to clarify the role of AIFs, a bicrystal Nb model with one straight symmetrical tilt grain boundary and a mode-I crack in one of the grains was constructed, in which the AIF effect was introduced by replacing the normal grain boundary with a CuNb AIF. Then, AIF thickness-dependent tensile deformation of the bicrystal Nb samples was simulated. The work-of-fracture, which is defined as the released strain energy due to the newly generated unit area in the crack during stretching, was employed to quantify the fracture toughness of the bicrystal systems. The results show that the fracture toughness of the AIF sample can be tripled due to the blunted crack tip and the relieved stress concentration at the crack tip as compared to the AIF-free one that exhibits a brittle crack propagation behavior. Also, the thicker the AIFs, the more pronounced this reinforcing effect. More importantly, it is found that there exists a critical AIF width of 1.7 nm, below which the crack will eventually break through the AIF, and above which the crack failed to do this. It is revealed that the enhanced fracture toughness originated from the transformation of brittle crack propagation to abundant dislocation emission from AIFs. [ABSTRACT FROM AUTHOR]

Properties of fragmentation from an explosively driven 316L stainless steel spherical shell section fabricated by a laser powder bed additive manufacturing process with minimal surface finishing are investigated. This shell is driven by an insensitive high explosive, resulting in high strain rate deformation (>8 × 103 s−1) and failure of the stainless steel. Photonic Doppler velocimetry measures the expansion rate; dynamic radiography and high-speed imaging capture the fracture behavior of the stainless steel. The fracture response of the additively manufactured stainless steel shell is compared to published experimental results on additively manufactured 316L stainless steel and conventionally manufactured wrought 316L and 304 stainless steel shell fragmentation. Despite preferred crack orientation, suggesting the influence of surface grooves on fracture time, fragment size is identical to that measured in a similar experiment on wrought 304 stainless steel. Further analysis indicates that the 316L additively manufactured stainless steel shell exhibits comparable spall strength and fragmentation toughness to conventionally manufactured stainless steel yet lower failure strain due to surface stress concentrations. [ABSTRACT FROM AUTHOR]

The pyrolysis process of waste printed circuit board (WPCB) with high economic benefit has been a black box problem, limiting the upgrading of pyrolysis processes. The resourcefulness and hazardous nature of WPCB will make it necessary for it to be treated properly. Multiphysics model was built to simulate the whole processes of WPCB pyrolysis and contaminants' release. The circuit board samples containing six components were selected for pyrolysis in a tube furnace at a rate of 10 ∘ C/min from room temperature to 600 ∘ C, and the residual rate of Br- was determined by the oxygen bomb method. The results showed that the difference in temperature distribution could be attributed to thermal conductivity and surface area. Heat distribution would be more even from the inner material in areas where holes existed. The assembly method would affect the stress distribution around the components. Thermal stress at the pins might cause the separation of components from the substrate. The concentration of brominated contaminants was influenced by the material and assembly method. The instantaneous concentration around the pin was 3–4 times compared to the bare substrate, which was beneficial for the release and control of brominated organics. This study provided the research method for the in-depth understanding of the pyrolysis process of complex materials; and provided a basis for the upgrading of related processes. [ABSTRACT FROM AUTHOR]

The formation and distribution of residual stress during the micro-milling process significantly affect the crack resistance and service life of alumina bioceramics. This study aims to optimize the surface residual stress distribution by adjusting machining parameters, thereby improving the machining quality of alumina ceramics. A three-dimensional finite element model of alumina bioceramics was developed, and numerical simulations were conducted to analyze the effects of feed per tooth, cutting depth, and spindle speed on temperature and residual stress. The study further explores the patterns of residual stress variation. The results show that both surface temperature and residual tensile stress exhibit systematic trends with parameter changes. Specifically, surface residual tensile stress increases with cutting depth initially but decreases sharply once the cutting depth exceeds 25 μm. Residual tensile stress increases with spindle speed, reaching its peak at 21,000 r/min before stabilizing. Additionally, the residual tensile stress rises with feed per tooth at first but gradually declines when the value exceeds 25 μm/z. This research reveals the mechanisms by which micro-milling parameters influence surface temperature and residual stress in alumina bioceramics, providing theoretical guidance for optimizing micro-milling processes. The findings can also be extended to the micro-milling of other hard-to-machine materials, offering broad engineering application potential. [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]

Helical milling is widely used in aerospace as a key processing technology for Carbon fiber reinforced polymer (CFRP). However, the eccentric machining characteristics lead to an unusually complex pattern of cutting force and residual stress distribution on the work-piece during helical milling processing. Based on the Hashin failure criterion, a 3D FEM model of CFRP helical milling was built for analyzing the changing law of cutting force, then the three factors and three levels orthogonal tests were used to investigate the influence of machining parameters on the axial force, radial force, and minimum principal residual stress, finally, the multi-objective optimization based on grey correlation analysis was realized. The results showed that the errors of axial force and radial force obtained by simulation and experiment were 10.68% and 12.26%, respectively. The axial force and radial force were negatively correlated to the spindle speed, positively correlated to the axial cutting depth, and uncorrelated to the feed per tooth. The minimum principal residual stress was negatively correlated to the spindle speed, positively correlated to the feed per tooth, and uncorrelated to the axial cutting depth. The degree of influence on optimization of machining parameters was: spindle speed > axial cutting depth > feed per tooth. The corresponding average grey correlation degree differences were 0.280981, 0.216859, and 0.013422, respectively. The maximum value of grey correlation degree in the orthogonal test was 0.874372, and the corresponding optimal parameters combination was the spindle speed 8000 r/min, feed per tooth 0.03 mm/z, and axial cutting depth 0.2 mm/r. [ABSTRACT FROM AUTHOR]

Circular saw blades, a large diameter-to-thickness ratio tool, are widely used in the aerospace and transportation sectors. However, it is limited due to its thinning tendency and weak stiffness. In this study, a novel tool tensioning technique was developed using the ultrasonic surface rolling process (USRP) to improve the tool performance of circular saw blades by changing the microstructure and residual stress distribution. Archimedean spiral curve textures were successfully created on both sides of a circular saw blade using an ultrasonic rolling experimental platform. The results show that USRP induced a gradual change in the dislocation structure from a microstrip mixing pattern to a lamellar band structure, accompanied by an increase in high-angle boundaries and a decrease in dislocation cell size. These textures result in a "low–high-low" trend in the radial residual stress distribution along the radius of the circular saw blade, and this residual stress variation improves the tool dynamic performance of the circular saw blade by more than 10% based on real-time x-direction (feed direction) cutting vibrations. In addition, a rolling tensioning evolution mechanism is proposed to explain how the synergistic effect of ultrasonic vibration and rolling force generates the residual stress field. This study elucidates the evolutionary mechanism of USRP-induced tensioning of thin circular saw blades, paving the way for a high-quality, cost-effective tensioning process. [ABSTRACT FROM AUTHOR]

Various generations of scholars have proposed many material removal models for grinding processing. However, the stress conditions of the free surface and regular surface are different. The free-form models will encounter problems in practical application. To refine the stress distribution in the contact area during grinding, it is necessary to construct the elastic contact model for the workpiece profile. This paper uses dimensional reduction to introduce the double curvatures to approximate the varying curvatures of the free surface. So, the conclusions of classical elastic Hertz contacting theory can be applied to the model. We use differential thought to deduce the relation between the normal force and the maximum deformation depth of the contact region. Then, we obtain the boundary of the contact region. After dimensional reduction by Winkler theory, we propose the normal equivalent spring potential energy correction error terms. They compensate for the local stress based on the relationship between stress and deformation of continuous media. According to the boundary of the contact region obtained above, we carry out the differential stress distribution. This accounts for the dispersion effect of the convex surface on the force. Using stress-indicating film to show the local stress distribution, the results revealed that the stress distribution was consistent with that of the simulated contact stress distribution. The error was controlled within 0.078MPa. To verify the practicality of the contact model in grinding experiments, we derived the theoretical grinding depth by combining the Hammann linear grinding model. This paper compares the experimental results with the model results. It demonstrates the proposed algorithm's superior adaptability and practical application ability to the free surface. [ABSTRACT FROM AUTHOR]

Inspired by the cross-laminated hierarchical structure and flexible interface of high toughness Strombus gigas shell, the "fiber-metal-polymer" laminated composites with different laying modes including cross-laminated structure and interfacial properties were designed, and the corresponding damage and toughening mechanisms were investigated. It shows that the cross-laminated structure, accompanying soft interface modification by metal ultra-thin strip and polymer can optimize the full-field stress distribution and failure behavior, then achieve maximize energy absorption and ensure good strength (ultimate strain and toughness increased to 352% and 127.5%, respectively compared to unidirectional laminated material), which may provide optimization strategies for the design of lightweight composites. [ABSTRACT FROM AUTHOR]

In order to explore a new method and mode of gently inclined hard roof treatment, the hydraulic fracturing axial roof cutting technology based on abrasive jet is introduced, and the key technical parameters of abrasive jet axial cutting and fracturing are determined based on indoor experiments and field industrial experiments. Taking the mining of working face under the condition of hard roof in Kuangou Coal Mine as the background, the implementation process and the effect of mining process are tested by means of water pressure gauge, drilling peep and observation well water level observation, mi-croseismic monitoring, support fracture monitoring and coal stress monitoring. The research results show that the key technical parameters of slotting and fracturing are mastered in the axial cutting test of abrasive jet. Wherein the kerf depth is 200 m, the kerf length is 300 m, the kerf pressure is 40–50 mpa, the fracturing pressure is 50–55 mpa, and the fracturing time is 20–30 min. After grooving fracturing, the cracks in the roof strata are effectively generated and expanded, which destroys the integrity of the roof, and the fracturing radius is 10–20 m. During the mining period, compared with the tradi-tional blasting technology, the concentrated area of microseismic events was shifted from 80 m in front of the working face to 130 m after the combined treatment of abrasive jet axial roof cutting and blasting, and the microseismic energy release was mainly small energy events. After the application of abrasive jet axial roof cutting and scour prevention technology in hard roof, the periodic weighting step is obviously reduced, the influence range of mining stress and stress concentration coefficient are obviously reduced, the activity intensity and dynamic load effect of surrounding rock are obviously weakened. The research results provide a basis for effective prevention and control of rockburst disasters under the condition of hard roof. [ABSTRACT FROM AUTHOR]

The practical application of micropiles in landslide reinforcement and prevention advanced before theoretical research, significantly limiting their application and promotion. To determine the damage patterns and stress distribution of micropiles during sliding failure in reinforced shallow landslides, three sets of physical modeling tests were performed. These tests examined the stability of shallow soil slopes with and without micropiles, including single-row and three-row configurations. During the tests, the foot displacement of the landslide, the top displacement of the micropiles, and the strain within the micropiles were monitored throughout the loading process. Following the tests, the landslide was excavated to observe the damage patterns in the micropiles. The experimental results showed that the pile-soil composite structure formed by three rows of micropiles, together with the soil between them, significantly improved the stability of the landslide and demonstrated effective anti-sliding effects. The stress distribution curve of the micropile was inversely S-shaped, with the peak stress located near the sliding surface. Within the micropile group, the first row exhibited the highest stress, and the micropiles nearest to the free face experienced the greatest displacement. Through the micropile-reinforced landslide tests, we identified three stages in the slope's sliding damage process and the stress distribution pattern of the micropiles. The research findings offer valuable insights into the anti-sliding mechanism of micropiles, which can guide design and construction. [ABSTRACT FROM AUTHOR]

During coal mining operations, the activation of geological faults induced by mining activities, leading to sudden water inrush, presents a significant technical challenge to safe extraction. This study uses the Wugou Coal Mine as a case example to analyze the characteristics of fault activation under deep‐seated high stress and high confined water pressures, as well as to determine the optimal dimensions for the implementation of waterproof coal pillars. This study employs a combination of numerical simulation and indoor model experiments to establish a fracture–permeability coupled computational model. The dynamics of fault‐induced water inrush and the adequacy of waterproof coal pillar widths are evaluated through laboratory experiments. Results demonstrate that as the mining face progresses near the fault zone, fracture development within the fault increases, and the stresses in the coal seam's roof and floor escalate, reaching a peak before experiencing unloading. This intensification in fracture development, driven by the dual impacts of mining activity and subfloor hydrostatic pressures, leads to the formation of interconnected fractures through the fault zone. Numerical simulations provide insights into the changes in overburden stress, the characteristics of plastic deformation in the surrounding rock and fault zones, and the permeability traits of the faults at various coal pillar widths. The findings indicate that as the width of the waterproof coal pillars decreases, stress concentration at the interaction points between the fault and the mining layer becomes significantly pronounced. The plastic deformation in the roof shifts from an "elliptical arch" shape to a "saddleback" shape, while the floor displays extensive planar failure. Particularly when the width of the waterproof coal pillars is less than 20 m, there is a substantial increase in the pore water pressure within the fault zone, greatly increasing the probability of fault activation and subsequent water inrush. [ABSTRACT FROM AUTHOR]

This study investigates stress-deformation behavior in Himalayan tunnels, focusing on how geological features impact stability. The objective is to enhance the understanding of displacement phenomena, particularly in tunnels traversing jointed rocks. A modified support system, to specific rock mass classifications, is employed to address the unique challenges posed by geological discontinuities. Kinematic analysis reveals a 20% probability of wedge failure due to these discontinuities. Numerical analysis using Hoek–Brown parameters identifies significant stress concentrations at the tunnel crown, especially in jointed sections, where increased convergence and displacement (1.2 mm at the crown compared to 0.25 mm at the walls) highlight the susceptibility to deformation. The study indicates the critical need for specialized support in jointed regions to mitigate stability risks. Article highlights: This study contributes understanding of complex interactions between geological features and tunnel stability, regarding stress-deformation phenomena in Himalayan tunnels. The analysis identifies significant stability concerns, including a concerning 20% probability of wedge failure and increasing stress levels at the tunnel crown. It underscores the importance of support systems and proactive risk management strategies to mitigate instability risks, particularly in ultramafic sections characterized by higher stresses. The research highlights the importance of considering dynamic loading conditions, validation with field data, and long-term variations in stress and deformation for a comprehensive understanding of tunnel stability. Future investigations should explore the influence of groundwater flow and seismic information, to examining advanced support systems. [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]

This study aimed to investigate co-seismic stress and aftershock distribution along the Sumatra–Andaman subduction zone (SASZ). The fault parameters of six major earthquakes with an M ≥ 7 that occurred during 2010–2022 along the SASZ, were utilized to determine the Coulomb stress change using numerical modeling techniques calculated on the receiver faults with similar focal mechanisms of the mainshock, strike-slip, thrust, and normal faulting, respectively. The earthquake events were then classified to analyze the aftershocks of major earthquakes in the area. These aftershocks were mapped in order to determine the relationship between the aftershock distribution and the areas of increased or decreased stress. The relationship between the co-seismic stress and distribution of aftershocks in the SASZ was found to mainly depend on the focal mechanism of major earthquakes and the type of receiver fault used for calculation. After a major earthquake in the SASZ, there are two possible patterns that most aftershocks will be generated from in the areas of increased stress. First, a major earthquake is a type of thrust fault calculated on the receiver fault using the focal mechanism of the mainshock. Second, a major earthquake is a type of strike-slip fault calculated on the receiver fault with an optimum-oriented strike-slip fault. This relationship is likely to represent the specific pattern of the seismotectonic stress in the SASZ that can be used to evaluate the risk areas of aftershocks after a major earthquake has occurred. Furthermore, two earthquake events with large magnitudes were generated following the respective major earthquake in the SASZ that were located around the areas of increased stress, indicating that these two earthquake events were likely triggered in areas of increased stress following the respective major earthquake. Therefore, this study concluded that after a major earthquake occurrence in the SASZ, the areas of increased stress have a higher risk of generating both a large number of aftershocks and a new large-magnitude mainshock event. The investigation of co-seismic stress is very important to estimate areas of increased stress after a major earthquake, as this can be useful for monitoring both earthquake and tsunami hazards in the area. [ABSTRACT FROM AUTHOR]

The shape and extent of the plastic zone can effectively reflect the degree of deformation and failure of the surrounding rock. By applying complex variable functions and the theory of elasticity, a mechanical model for the surrounding rock of a rectangular roadway is established. The analytical solution for the stress in the surrounding rock of a rectangular roadway under a non-uniform stress field is derived, and the spatial stress distribution pattern in the surrounding rock of the rectangular roadway is obtained. Furthermore, using the Mohr-Coulomb criterion, the boundary equation of the plastic zone in the surrounding rock of a rectangular roadway is derived, and the morphological characteristics of the plastic zone are obtained. The results indicate that the plastic zones on both sides of the rectangular roadway are arc-shaped. The asymmetry of the stress environment has a significant impact on the plastic zones in the roof and floor of the rectangular roadway, causing the shape of the plastic zones to resemble a "petal" pattern. The lateral pressure coefficient and the height-to-width ratio have a significant impact on the stress distribution and the morphological characteristics of the plastic zone in the surrounding rock of the rectangular roadway. By validating the computational accuracy of the analytical solution through numerical simulations and conducting an engineering applicability analysis based on a coal mine roadway, it has been demonstrated that the analytical calculation method is both rational and possesses good engineering applicability. This provides reliable theoretical guidance for the design calculations and construction planning of similar roadway projects. [ABSTRACT FROM AUTHOR]

The present study pertains to the flexural behavior of RC beams with openings and non-metallic (GFRP) reinforcement. The main goal of preferring GFRP reinforcement over the conventional steel reinforcement was to safeguard the beams against the reinforcement corrosion. The presence of multiple regular transverse openings throughout the beam length increases the susceptibility of reinforcing bars to corrosion as the larger contact area in these beams with the outside environment increases the ingress of corrosive agents. Within the scope of the study, a total of 8 RC beams, including two reference beams without web openings, were tested under four-point bending. The test parameters were the flexural reinforcement ratio, the presence of short stirrups in the chords, and the presence of diagonal reinforcement spiraling around the openings. Since GFRP stirrups are difficult to bend, each stirrups was formed by connecting four individual FRP bars around the longitudinal bars. The opening circular geometry was adopted to avoid stress concentrations around the sharp corners of opening and to facilitate the placement and fixing of different schemes of reinforcement in the beams. The present tests depicted that the diagonal reinforcement around the openings have considerable contribution to the flexural behavior of RC beams with GFRP reinforcement and with multiple regular transverse openings. The RC beams with openings were able to approach their analytical flexural capacities in the presence of diagonal reinforcement for both moderately and heavily reinforced beam groups. The analytical deflection predictions of GFRP-RC beams with openings showed a good agreement with experimental data. [ABSTRACT FROM AUTHOR]

In recent years, the technology of the gob‐side entry retaining by roof cutting and pressure releasing (GERRC) has been widely used in coal mining. However, the stability of the roadway surrounding rock structure during GERRC in the coal seam with high dip angles is a major concern, limiting the widespread application of this technology. In this study, we analyzed the deformation and stress evolution of roadway surrounding rock during GERRC in the 011810‐working face of Jinfeng Coal Mine using theoretical analysis and numerical simulation. The results show that in coal seams with high dip angles, the gangue in the gob will slide down the lower trough, providing enough support for the upper rock layer and limiting rotation deformation along the gob‐side entry roof during GERRC. This weakens the impact of mining pressure on the roadway and promotes the stability of the surrounding rock structure. However, the stress in the coal of the lower roadway in the advanced influence area is the largest, reaching 16.3 MPa due to the influence of buried depth. The stress of the surrounding rock of the gob‐side entry tends to be stable at 110 m behind the working face in the lower roadways. There is also an obvious pressure relief zone in the coal in front of the working face, 10 m away from the cutting line, during GERRC. Its maximum stress is only 61.3% of the advanced coal and 10.0 MPa, indicating that the pressure relief effect of the roof cutting on the inclined coal seam is significant. [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]

In response to the problem of significant deformation and obvious strata pressure in tunnel caused by close‐distance repeated mining, along with difficult control of surrounding rocks, theoretical analysis, and numerical simulation methods were employed to study the asymmetric failure characteristics of tunnels under the influence of close‐distance repeated mining. The research provided insights into the mechanism of asymmetric failure of tunnels affected by close‐distance repeated mining, revealed the impact of residual coal pillars in the upper coal seam on the tunnel in the lower coal seam, analyzed the stress distribution of surrounding rocks before and after tunnel excavation under the influence of repeated mining, and proposed asymmetric surrounding rock control techniques for tunnels affected by close‐distance repeated mining. The study results indicate that the protection of coal pillars in the upper coal seam and the adjacent working face mining in the same coal seam are the main reasons for significant stress concentration on one side of the tunnel and the appearance of asymmetric failure characteristics. After tunnel excavation, the stress of surrounding rocks is released into the tunnel, resulting in a significant reduction in stress environment. However, the stress on the left side of the tunnel is significantly higher than that on the right side, showing an asymmetric distribution. The application of active support with anchor net cables and U‐shaped steel frames effectively reduces tunnel deformation, with good on‐site application results. [ABSTRACT FROM AUTHOR]

Intra-articular fractures of the distal radius require anatomical reduction and stable fixation. When the fracture encompasses the articular facet of the bone, maintaining the reduction is challenging due to the fragment's size and high instability. While specific implants have been developed to fix this fragment, their effectives have been limited. This study evaluates the mechanical performance of a novel hook plate conceived to stabilize the small fragment of the semilunar facet of the radius in non-osteoporotic bones. A simulated lunate facet fracture was created in an adult radius in a virtual model, and a modification of a hook plate was developed using computer-aided design (CAD). Two groups were established for the finite element method (FEM) simulation: a control group (standard plate Medartis™ (Switzerland, A-5500.23) and an angled plate with hooks set at 60º, 90º and 120º. In the FEM simulation, an axial load of 100 N was applied in the Z-axis direction on the fragment. Fracture displacement along the Z axis was more pronounced in the control model (0.32 mm) and less in the angled models, ranging from 0.22 to 0.28 mm. Notably, the plate with a 90° angle showed a more effective reduction in fragment displacement. The distribution of stresses in the system showed the highest levels of stress in the control group (59.31 MPa), followed by the subgroup with a 60° angle (55.78 MPa). In the side view, the control model showed a higher concentration of stresses (59.74 MPa), while the model with a 90° angle showed a lower value of stresses (18.87 MPa). Critical stress regions were identified in the bolts of the control and 120° models (59.47 MPa and 57.64 MPa, respectively). However, in the 90° model, no critical regions were observed in the bolts, which showed lower stress values, reaching 26.33 MPa. In the bone, the greatest concentration of stress occurred in the region where the plate was anchored. Our results showed that the 90° hook plate had a superior mechanical performance in fixing simulate lunate facet fractures at the distal radius. This angle led to minor displacements and minimized stress concentrations in the hardware, thus contributing to enhance the stability of this specific fracture. [ABSTRACT FROM AUTHOR]

The optimal treatment strategy for proximal humerus fractures (PHFs) is debatable owing to the relatively high failure rate of locking plates. Optimizing implants may enhance the fixation stability of PHFs and reduce the rate of mechanical failures. We developed a finite element (FE) model to simulate the treatment of PHFs with Proximal Humerus Internal Locking System (PHILOS) plates. The model evaluated the average bone strain around the screw tips under vertical loading (as an alternative to the risk of cyclic screw cutout failure verified through biomechanical testing) to minimize this strain and maximize predicted fixation stability. After determining the optimal screw configuration, further FE analysis and in vitro biomechanical testing were conducted on both standard and optimized PHILOS screw orientation to assess whether the optimized plates have biomechanical advantages over the standard plates. The FE-based optimized configuration exhibited significantly lower bone strain around the implant than the standard PHILOS screw orientation (− 17.24%, p < 0.001). In both FE analysis and in vitro biomechanical testing, the optimized PHILOS plates achieved significantly lower average bone strain around the screws (p < 0.05), more uniform stress distribution, and greater structural stiffness (p < 0.05) than the standard PHILOS screw orientation. Our results show that biomechanical performance of the PHILOS plates can be improved by altering the orientation of the locking screws. This approach may be useful for future patient-specific design optimization of implants for other fractures. [ABSTRACT FROM AUTHOR]

The first two years of the COVID-19 pandemic and subsequent health mandates resulted in significant disruptions to daily life, creating a period of heightened psychosocial stress in myriad aspects. Understanding the impact of this period on pregnant individuals' bacteriomes is crucial as pregnancy is a period of heightened vulnerability to stress and its sequelae, anxiety and mood disorders, which have been demonstrated to alter gut microbiome composition. In a prospective cohort study (N = 12–26) conducted from February 2019 to August 2021, we examined psychometric responses and rectal microbiome swabs from pregnant individuals. Full-length 16 S rRNA sequencing followed by calculation of diversity metrics and relative abundance values were used to interrogate fecal microbiome community composition across pandemic groups. Distinct shifts in bacterial diversity and composition were observed during early to late pregnancy in the pandemic group, including lower relative abundance of pathogenic and lesser-known taxa. However, distribution of stress and depressive symptoms did not significantly differ from the pre-pandemic period while the correlation between stress and depressive symptoms dissipated during the pandemic. Our findings suggest that living through the COVID-19 pandemic altered the gut microbiome of pregnant individuals, independent of perceived stress. [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]

Current treatment strategy for managing Weber B ankle fractures is mainly governed by mortise congruency, malleolar alignment, deltoid ligament competence and fracture stability. While nonoperative treatment has yielded good functional outcomes in satisfactorily aligned stable injuries, a biomechanical rationale is not firmly established. Furthermore, current radiographic analysis is obscured by observer inaccuracy and beam rotation. This study aimed to utilize weightbearing CT and computational biomechanics to analyse 3D mortise displacement and contact mechanics in Weber-B ankle fractures and compare them with the uninjured contralateral side. 32 patients were included who sustained a Weber-B ankle fracture and underwent bilateral weightbearing CT imaging at injury. Segmentation into 3D models of bone was performed semi-automatically, and individualized cartilage layers were modeled based on a previously validated methodology. The 3D mortise congruency was evaluated by use of following parameters: alpha angle, fibular length, talocrural angle, medial gutter- and tibiofibular clear space- distance mapping. Contact mechanics were evaluated by the mean and maximum contact stress of the tibiotalar articulation. Statistical analysis revealed that there were no significant differences for all anatomical parameters. There was also no significant difference between the mean contact stress of the injured (2.10 ± 0.42 MPa) and uninjured side (2.10 ± 0.41 MPa), nor the maximum contact stress of the injured (7.67 ± 1.55 MPa) and uninjured (7.47 ± 1.67), respectively. Contact mechanics were unaffected in congruent Weber-B fractures. These findings support consideration of nonoperative management in such cases, given their presumably low risk for posttraumatic arthritic development in the long term. Level of Evidence: Level III; retrospective case-control study. [ABSTRACT FROM AUTHOR]

Based on the shear flow theory for thin‐walled sections, a method for calculating the shear stress nonuniformity coefficient (µ) of a thin‐walled section is proposed according to the energy principle, and the formulas for calculating the µ values of several common sections are derived. The obtained µ value of a box section increases as the aspect ratio increases. Compared with commonly used calculation methods, the proposed method gives more reasonable results and shows that the effect of shear stress in the flange of the flat box section should not be ignored. The effects of the web and flange thicknesses on µ are analyzed and discussed. Based on these effects, a simplified method for calculating the µ value of complex box sections is presented, and this method is demonstrated to considerably reduce the calculation error and meet engineering needs. [ABSTRACT FROM AUTHOR]

The stability of coal pillars in fault areas is crucial for ensuring the safe passage of working faces. Based on field observations, frequent coal pillar spalling and substantial tectonic coal crumbs leakage, as well as tilting of hydraulic supports, are observed when working faces transition from primary coal to tectonic coal. To analyze the instability mechanisms behind these phenomena, this paper establishes a mechanical model of coal pillars in fault areas and analyzes the distribution of tectonic stresses and factors affecting the stability of coal pillars. The results indicate that horizontal tectonic stress adheres to an exponential function dependent on the angle factor, where (k0) is a parameter associated with the friction angle of the coal body, the dip angle of the fault, and the friction angle of the fault plane. The stability of coal pillars is influenced by factors such as roof and floor pressures, coal pillar integrity, mining height, and shield support force, with coal pillar integrity being the most critical. To ensure the smooth passage of working faces through faults, this study proposes a combined control technique of "inclined mining" and "grouting," including reducing mining heights, adjusting the slope of working face advancement, and pre-grouting of coal pillars. Industrial experiments conducted on-site have shown improved integrity of tectonic coal, enabling the working face to pass through faults smoothly and significantly increasing production efficiency. [ABSTRACT FROM AUTHOR]

This study analyzed the enhancement effects and mechanisms of steel, glass, and polypropylene fibers on the mechanical properties of concrete, aiming to guide the selection of suitable fiber types and dosages for shotcrete projects. Through laboratory tests, numerical simulations, and field experiments, it investigated the enhancement laws of flexural and compressive strengths of concrete with different dosages of these three fibers. Results showed: (1) After 28 days of curing, flexural strength peaked with 2.0% steel, 1.5% glass, and 2.0% polypropylene fibers, increasing by 118.6%, 42.86%, and 138.6%, respectively, over plain concrete. Compressive strength increased by 2.13%, 10%, and 18.3% at optimal dosages of 0.5%, 1.0%, and 2.0% for steel, glass, and polypropylene fibers. Fiber effects on compressive strength were less significant than on flexural strength, with polypropylene fibers outperforming the others. (2) Based on ABAQUS numerical simulations, microscopic analysis indicates that fibers, due to their high yield capacity, enhance the connections between concrete elements, reduce stress concentration, and improve the mechanical properties of concrete. (3) For shotcrete, 2.0% polypropylene fibers were preferred due to high flexural strength and reduced agglomeration. (4) The optimal dosage was applied to a mine's wet shotcrete support, effectively controlling tunnel deformation. These findings provide practical guidance for shotcrete applications. [ABSTRACT FROM AUTHOR]

Evaluating complicated stress across the elbow under joint motion remains difficult. Here, we aimed to evaluate the distribution of the subchondral bone density in the normal elbow bones and further characterize their spatial relationships during elbow motion to estimate the loading stress across the articular surface using three-dimensional computed tomography bone models. The normal elbow joint exhibited a consistent distribution pattern of subchondral bone density. High-density regions were distributed in the capitellum and posterior humeral trochlea, sagittal ridge of the ulnar trochlear notch and ulnar-volar side of the radial head. Motion analyses revealed that the high-density regions proximate with elbow flexion with forearm pronation in the radiocapitellar joint and in the fully extended position in the ulnohumeral joint. This reasonably reflects the stress acting on the joint surface under actual loading conditions. These findings suggest that daily activities involving lifting or carrying objects in these positions are stress-prone activities. [ABSTRACT FROM AUTHOR]

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The phenolic antioxidant 2,6-Di-tert-butyl-p-cresol (BHT) has been detected in various environments and is considered a potential threat to aquatic organisms. Algal-bacterial interactions are crucial for maintaining ecosystem balance and elemental cycling, but their response to BHT remains to be investigated. This study analyzed the physiological and biochemical responses of the microalga Isochrysis galbana and the changes of associated bacterial communities under different concentrations of BHT stress. Results showed that the biomass of I. galbana exhibited a decreasing trend with increasing BHT concentrations up to 40 mg/L. The reduction in chlorophyll, carotenoid, and soluble protein content of microalgal cells was also observed under BHT stress. The production of malondialdehyde and the activities of superoxide dismutase, peroxidase, and catalase were further determined. Scanning electron microscopy analysis revealed that BHT caused surface rupture of the algal cells and loss of intracellular nutrients. Proteomic analysis demonstrated the upregulation of photosynthesis and citric acid cycle pathways as a response to BHT stress. Additionally, BHT significantly increased the relative abundance of specific bacteria in the phycosphere, including Marivita, Halomonas, Marinobacter, and Alteromonas. Further experiments confirmed that these bacteria had the ability to utilize BHT as the sole carbon resource for growth, and genes related to the degradation of phenolic compounds were detected through pangenome analysis. [ABSTRACT FROM AUTHOR]

Context: Among two-dimensional (2D) materials, transition metal dichalcogenides (TMDs) stand out for their remarkable electronic, optical, and chemical properties. Their atomic thinness also imparts flexibility, making them ideal for flexible and wearable devices. However, our understanding of the mechanical characteristics of molybdenum ditelluride (MoTe2), particularly with defects such as pits, remains limited. Such defects, common in grown TMDs, degrade the mechanical properties and affect electronic and magnetic behaviors. This study uses molecular dynamics (MD) simulations of uniaxial and biaxial tensile loading performed on monolayer molybdenum ditelluride sheets of 2H phase containing triangular pits of varying vertex angles to investigate their fracture properties and visualize their crack propagation. From the stress–strain relationship, Young's modulus, fracture strain, ultimate tensile strength, and toughness for comparative analysis were calculated. Method: Tensile loading simulations were performed in molecular dynamics (MD) software LAMMPS, using the Stillinger–Weber (SW) interatomic potential, under strain rate 108 s−1 at room temperature (300 K). From the stress–strain relationship obtained, we calculated Young's modulus, fracture strain, ultimate tensile strength, and toughness. Results showed that variations in pit edge length, angle, and perimeter significantly affected these properties in monolayer MoTe2. Regulated alteration of pit angle under constant simulation conditions resulted in improved uniaxial mechanical properties, while altering pit perimeters improved biaxial mechanical properties. Stress distribution was visualized using OVITO software. MoTe2 with pit defects was found to be more brittle than its pristine counterpart. This study provides foundational knowledge for advanced design strategies involving strain engineering in MoTe2 and similar TMDs. [ABSTRACT FROM AUTHOR]

Auxetic metamaterials, characterized by their negative Poisson's ratio, have garnered significant interest in various fields due to their unique mechanical properties. This article presents a pioneering approach to the development of auxetic smart metamaterials using shape memory alloy (SMA) as the core material. As SMAs can be Joule heated to change between their low‐ and high‐temperature phases to trigger the actuation of the structure, the auxetic smart metamaterial can actively modify its shape and stiffness to produce bidirectional actuation with a single power input and using a single bias mechanical element. The proposed active auxetic metamaterial consists of an SMA plate patterned with auxetic cuts, creating hinges that modulate the deformation of the structure to produce an auxetic behavior. This work looks at the impact of different geometric parameters on the behavior of the structure, including its generated force, its maximum strain, and its Poisson's ratio. The study also investigates the effect of the number of segmented units, revealing that designs with more segmented units suffer from stress concentrations near attachment points, limiting their advantages. This article shows that smart materials can help imbue metamaterials such as auxetic metamaterials with active properties to facilitate their implementation in future robotic applications. [ABSTRACT FROM AUTHOR]

The ultrasonic surface rolling process (USRP) can effectively reduce surface roughness, reduce the stress concentration and extend the service life of a workpiece. Surface roughness prediction by finite element simulation has been a hot research topic of late. Most of the previous studies are based on plane models, but the influence of initial surface roughness on the prediction results of shaft parts has not been considered. In this paper, wavelet transform is used to reconstruct the measured cylindrical sample surface data, and the shaft model with initial surface roughness is established. Then the finite element simulation model of USRP is established to predict the surface roughness. The results show that compared with the experimental results, the maximum error of the proposed method is 9 %, which is better than that of the finite element simulation model without considering the initial surface roughness, which verifies the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Ultrasonic vibration as a novel and advanced auxiliary lithotripsy technology possesses great potential in the fields of deep mine drilling. This paper carries out a finite element (FE) analysis to investigate the coupling effects of weight on bit (WOB) and ultrasonic vibration amplitude on the ultrasonic vibration assisted drilling (UVAD) of hard rock. The critical model of WOB and amplitude for hard rock breaking is established to explore the coupling effects quantitatively. The results show that the ultrasonic-frequency axial percussive motion significantly enhances the drilling rate. During the UVAD process, the principle stress undergoes severe fluctuation, constituting more than 50 % of the maximum principal stress, and larger ultrasonic amplitudes correspond to more pronounced stress fluctuations. There are critical coupling values of WOB and ultrasonic amplitude for the rock breaking, with the amplitude increases from 0 µm to 15 µm, the critical WOB for rock breaking reduces by 25 %. [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]

In recent years, tunnel-boring machines (TBMs) have been widely applied in deep coal mining. Turning is an inevitable challenge in TBM tunneling, and a TBM turning roadway exhibits greater instability than a straight roadway, as engineering experience has indicated. This study aimed to explore the failure mechanism and evaluate the support performance of a deep-turning roadway. Several numerical models were established to investigate the deformation of the roadway, the stress distribution, and the failure zone of the surrounding rocks under different tunneling conditions. The results show that the tunneling depth influences the failure pattern of the turning roadway: deep tunneling with high in situ stress can cause asymmetric failure of the turning roadway, while shallow tunneling with low in situ stress does not. Moreover, the change in turning radius, namely the change in roadway geometry, does not influence the stability of the turning roadway. In addition, the support actions for both the straight and turning roadways do not differ significantly, and the amount of controlled deformation of the surrounding rocks is proportional to their natural deformation. [ABSTRACT FROM AUTHOR]

Owing to its enhanced production efficiency, roller hemming has become the mainstream process for forming and joining metal sheets in the automotive industry. This study investigates the roller hemming process of a specific car door panel through a combination of experimental analysis and finite element analysis (FEA) on both straight-edge and curved-edge flat surfaces. Consequently, the mechanical properties of the door panel, including tensile strength, yield strength, modulus of elasticity, and Poisson's ratio, were estimated through tensile testing and then underwent finite element modeling. The simulation results demonstrated the varying distribution of stress during the rolling hemming process, with the highest stress concentration observed in the bending area. Additionally, creepage and growing results were acquired from both simulation and experimental data to validate the precision of the numerical model. A comparison was made between the experimental and simulation results of the external forces exerted by the roller on the panel. In both straight- and curved-edge sections, the external force during final hemming exceeded that during pre-hemming, as revealed by experimental measurements of both normal and tangential external forces, surpassing their corresponding simulated values. [ABSTRACT FROM AUTHOR]

In the field of aeronautics, aircraft, as a critical aviation tool, exert a decisive influence on the structural integrity and safety of the entire system. Accurate prediction of the stress field distribution and variations within the aircraft structure is of great importance to ensuring its safety performance. To facilitate such predictions, a rapid assessment method for stress fields based on a multilayer perceptron (MLP) neural network is proposed. Compared to the traditional machine learning algorithm, the random forest algorithm, MLP demonstrates superior accuracy and computational efficiency in stress field prediction, particularly exhibiting enhanced adaptability when handling high-dimensional input data. This method is applied to predict stresses in the wing rib structure. By performing finite element meshing on the wing ribs, the angle of attack, inflow velocity, and node coordinates are utilized as input tensors for the model, enabling it to learn the stress distribution in the wing ribs. Additionally, a peak stress prediction model is separately established for regions experiencing peak stresses. The results indicate that the MAPE of the stress field prediction model is within 5%, with a coefficient of determination R2 exceeding 0.994. For the peak stress model, the MAPE is within 2%, with an R2 exceeding 0.995. This method offers faster computation and greater flexibility, presenting a novel approach for structural strength assessment. [ABSTRACT FROM AUTHOR]

The mechanical properties of fully-grouted bolt support are critical for the safety of support engineering works. To study the influences of factors including the bolt length and diameter, strength of the rock, and fracture angle on the mechanical properties of fully-grouted bolt support, compression tests were conducted on an anchored rock mass, considering the shortcomings of pullout tests on bolts. The discrete element software PFC2D (4.0) was adopted for numerical simulation and analysis from two aspects, namely, the stress distribution and anchorage force supplied by such bolts. The research found that by increasing the bolt diameter and length as well as the strength of the rock, the maximum anchorage force of bolts increases. Whereas the stress distribution of all bolts increases at first and then decreases along the bolts, and there is only one peak on the stress distribution curves, which also gradually shifts to a greater depth. In a fractured rock mass, the maximum anchorage force of bolts decreases, then increases (and is minimized at a fracture angle of 45°) with the decrease in fracture angle. The influence of fractures with different angles on the stress distribution of bolts is mainly reflected in the fracture zone. The bolt stress decreases abruptly in the zone with a fracture angle of 90°, forming a valley. The bolt stress increases suddenly in the zones with fracture angles of 60° and 45°, thus forming peaks. The bolt stress does not increase or decrease suddenly in the zone with a fracture angle of 30°. Therefore, it necessitates consideration of the influences of fractures on the anchorage force and the selection of bolts of appropriate size during anchorage design. After installation, the bolt stress should be monitored for stability and early warning of anchored rock mass according to changes in the stress provided. [ABSTRACT FROM AUTHOR]