Three-dimensional simulation and experimental investigation of ultrasound propagation through pores in additively manufactured metals.

Pectoralis major tendon repair outcomes: comparison of transosseous tunnel and cortical button fixation techniques.

The mechanical response of Bi-2223 multi filamentary superconducting wires during cold drawing directly affects filament integrity and overall performance. A homogenized finite element model based on the mixture theory was established to describe the elastic–plastic behavior of Bi 2223/Ag composite wires. Drawing processes for 37, 55, and 121 filament architectures were analyzed under realistic die–wire contact conditions. The simulations show a pronounced radial stress gradient, with outer filaments carrying higher loads. As the filament number increases, load sharing becomes more uniform and the overall stress concentration decreases. Quantitative analysis of filament distortion indicates that increasing the filament count improves structural uniformity but also enhances the sensitivity to local imperfections. The proposed modeling framework provides a reliable basis for optimizing wire architecture and drawing parameters to improve the mechanical stability and superconducting performance of Bi-2223 wires.

To investigate the relationship between the contact site and fracture patterns under static loading using finite element analysis (FEA). Although temporal bone fractures often lead to critical otologic complications, such as hearing loss and facial palsy, their mechanisms are not well understood. Two types of cranial models were developed: a "Simplified model" (S-model) using geometric approximations, and a "Precise model" (P-model) reconstructed from head CT images of a 40-year-old male. Static structural analysis was performed, and static loads were applied to the vertex, left temporal, and occipital regions. First, fracture initiation was estimated from the first principal shear stress, and then fracture propagation paths were predicted from the distribution of the vectors for the first principal stress distribution. S and P-models showed similar stress distribution patterns with some differences; thus, we used the S-model for general mechanical analysis and P-model for anatomically detailed evaluation. Under some loadings, high-stress concentrations were observed at both the contact site and temporal squama. Temporal loading induced stress distributions roughly similar to longitudinal fractures along the petrous ridge. Occipital loading resulted in stress concentration around the foramen magnum, suggesting a correlation with transverse fracture patterns. As an initial simulation effort, the results partially reproduced the clinical correlation between contact site and fracture orientation (longitudinal vs. transverse) under static analysis conditions. This mechanical approach provides a theoretical basis for predicting internal injuries from external trauma. Future refinements incorporating dynamic loading and internal structures are necessary to enhance diagnostic accuracy in emergency situations.

Macroscopic-microscopic performance experiments of ceramic fiber modified cementitious grouting materials and study on the interaction mechanism between slurry particles

Stress concentration factors of circular tubular column-to-H-shaped beam cast steel connections: Tests and simulations

Cross-scale friction analysis of rocks: Influences of mineral properties and interactions

Erosion resistance of basalt fiber-aeolian sand concrete under wind-sand erosion: Experimental analysis and mechanisms

Face stability of shallow shield tunnels in inclined sand-clay strata: effects of dip angle and interface elevation

Tubular composite joints offer a non-welded alternative for offshore structures by bonding a composite wrap to steel Circular Hollow Section (CHS) members, eliminating weld-induced stress concentrations and significantly improving fatigue life. This enables steel weight and cost reductions and faster fabrication for jacket structures supporting large off-shore wind turbines. In service, these joints experience complex cyclic loads combining axial forces and bending moments, which can lead to interfacial debonding and delamination, necessitating damage-tolerant design. This paper presents one of the first experimental campaigns applying combined axial and bending loads on composite X-joints using a Hexapod system, enabling realistic offshore load simulation. Fatigue tests on 1/4-scale X90 specimens cover pure axial tension, out-of-plane bending, and combined cases. Two primary failure modes were observed: interfacial debonding under compressive strain and delamination under tensile in-plane strain. A numerical methodology based on the Virtual Crack Closure Technique (VCCT) and a stepwise crack-growth model incorporating non-linear crack retardation effects, rarely considered in composite joint fatigue modelling, was developed. Calibration of the Paris-law constant C revealed variations up to two orders of magnitude due to interface quality and manufacturing variability. Despite this, results demonstrate fatigue life extensions of up to 2000 times compared to welded joints. This work introduces a design philosophy leveraging crack retardation and interface friction effects to predict fatigue life, moving beyond conservative stress-based criteria towards damage-tolerant offshore design. • Hexapod tests of 1/4-scale tubular composite X-joints under multi-axial fatigue. • VCCT stepwise model with specimen-specific Paris-law calibration (C). • Two failure modes: interface debonding and delamination. • Optical-fibre sensing tracked crack fronts. • Fatigue life ⩾ 8 × ; projected 600–2000 × vs welded joints at design loads.

Stagger-folding leaflet design for improved durability in transcatheter heart valves.

Soft collagenous tissues inspire material design because of their excellent fracture properties. Their fracture is integral to surgical procedures and unavoidable in many forms of trauma and disease, yet measuring it remains challenging. Sample size limitations and emergent, strain-induced anisotropy increase boundary condition effects within classic test geometries, prohibiting cross-study comparison. Further, classic tests can neither sense internal heterogeneities nor disentangle their energetic contributions to the apparent fracture energy. Leveraging in situ microstructural observations from second harmonic generation imaging, we demonstrate that Y-shaped cutting addresses these limitations in bovine Glisson's capsule (bGC). We show cutting's sensitivity to tissue heterogeneity through characterization of bGC's sawtooth cutting force. We also report a boundary-condition-independent, intrinsic cutting energy for bGC in phosphate buffered solution (PBS). At 276 ± 17 J m-2, it is surprisingly lower than expected. Contextualizing bGC response against commercial silicone, we show that its excellent failure behavior arises primarily from management of stress concentration near the crack tip over a characteristic microscale, rather than from an unusually high intrinsic fracture energy.

The choice of fixation technique following bilateral sagittal split osteotomy (BSSO) plays a critical role in postoperative stability and biomechanical performance. Despite extensive research, the influence of varying mandibular advancement magnitudes and physiologic muscle forces on stress distribution remains insufficiently explored. This study aimed to compare stress distribution patterns and mechanical behavior of two commonly used fixation systems-miniplates (MPs) and bicortical screws (BCSs)-under different mandibular advancement conditions using three-dimensional finite element analysis (FEA). This was a computational in vitro study using three-dimensional FEA based on a patient-specific mandibular model reconstructed from computed tomography data of a 30-year-old male. Simulations were performed to evaluate BSSO under two advancement conditions (3mm and 9mm) using different fixation techniques (MPs and BCSs). At 3mm advancement, MP fixation demonstrated lower stress concentrations in the bone adjacent to screws (242MPa vs. 270MPa) but higher stress in teeth and greater displacement compared to BCSs. Conversely, at 9mm advancement, BCS fixation resulted in higher stress values in teeth, bone, and screws. At the same time, MPs exhibited more favorable stress distribution but increased localized stress around screw-bone interfaces. In all models, stress concentration was predominantly observed in the proximal segment near the vertical osteotomy line. Increasing the advancement magnitude significantly elevated stress levels across all components. The fixation method and the magnitude of advancement significantly influence stress distribution following BSSO. Findings suggest that MPs may provide a favorable stress distribution with smaller advancements, whereas BCSs may offer biomechanical advantages with larger advancements. However, further experimental and clinical validation is required before definitive clinical recommendations can be made.

Buried rigid box culverts are widely used in transportation and water structures and are often constructed beneath high embankments. Due to the stiffness contrast between the rigid structure and surrounding backfill soil, the soil column directly above the culvert experiences smaller settlement than adjacent soil columns, which may result in stress concentration and increased vertical pressure on the culvert. The induced trench installation (ITI) method was introduced to mitigate this problem by adopting a compressible inclusion above the structure to initiate positive soil arching and redistribute the loads away from the culvert. This study investigates the influence of expanded polystyrene (EPS) geofoam inclusion parameters on the structural behavior of buried rigid box culverts through a series of experimental tests. Eleven reduced-scale laboratory model tests were conducted, including one reference test without EPS and ten tests incorporating EPS inclusions with varying densities, thicknesses, widths, and installation locations. Static surface loading ranging from 20 to 140kPa was applied using a rigid footing system, while vertical pressures within the backfill were monitored using miniature pressure sensors installed above and beside the culvert. The results show that EPS inclusion significantly alters the load transfer mechanism within the backfill and promotes the development of positive soil arching. Among the investigated parameters, EPS thickness had the most pronounced influence on stress reduction, increasing the pressure reduction efficiency from approximately 50% to about 70% as the thickness increased from 2.5cm to 10cm. A lower EPS density also slightly enhanced stress reduction due to its higher compressibility. The findings demonstrate that properly configured EPS geofoam inclusions can effectively reduce vertical stresses acting on buried rigid culverts and improve their structural performance under embankment loading conditions.

Fault slip induced by coal seam mining is a major hazard that can trigger dynamic disasters such as coal bursts. Understanding the evolution of shear and normal stress on the fault plane is essential for revealing the mechanical mechanism of mining-induced fault activation. Based on physical experiment and numerical simulation of the 21,221 mining face in Qianqiu coal mine, this study investigates the stress spatiotemporal response during mining face advancement. Results show that shear stress fluctuates in repeated cycles of abrupt drop followed by rapid rise, with cycles becoming less frequent and intense farther from the coal seam, indicating a distance-dependent disturbance effect. Mining activity also induces migrating stress relief and concentration zones, the relief zone expands toward the near coal seam side while the concentration zone shrinks and shifts away. A rise in normal stress accompanied by a drop in shear stress serves as a key slip precursor of fault, whereas a simultaneous sharp decline in both shear and normal stress marks fault instability and energy release. Therefore, coupled monitoring of normal and shear stress evolution law provides valuable early warning of fault slip risk.

High-entropy transition metal sulfides (HESs) exhibit great potential as anodes for sodium-ion batteries owing to their synergistic entropy stabilization, lattice distortion and cocktail effects. However, potential phase separation caused by multi-component incompatibility severely limits their performance. Herein, we propose a low-mixing-enthalpy strategy through regulation of element chemical compatibility to precisely design high-performance HES anodes. This strategy enables the successful synthesis of a single-phase Co-Fe-Ni-Mn-Cr HES solid solution (HES-Cr). In contrast, inferior compatibility among components in Co-Fe-Ni-Mn-Mo HES (HES-Mo) leads to its phase separation. The electron delocalization in HES-Cr enhances conductivity and metal-sulfur bond covalency, while moderate lattice distortion alleviates volume changes and stress concentration during Na+ insertion/extraction and lowers the Na+ migration barrier. Consequently, the HES-Cr delivers excellent Na+ storage performance, including a high reversible capacity of 845.2 mAh g-1 at 0.2 A g-1 and ultra-high rate property of 497.5 mAh g-1 even at 40.0 A g-1 along with long stability, outperforming HES-Mo and most HES-based anodes. Furthermore, we propose a three-parameter descriptor to predict single-phase high-entropy materials across a broader compositional range. This work provides a new approach for rational design of single-phase HESs and deepens understanding of their composition-phase-performance relationships.

The effect of polishing pads is generally incorporated as a coefficient in the conventional Preston equation and its modified forms during the past century, and macroscopic stress distribution and microscopic motion states are discussed separately. To solve this challenge, we propose a novel cross-scale model using a unified physical framework integrating the macroscopic and microscopic states. The proposed model decomposes the effect of polishing pads into stress transfer and abrasive constraint factors. It connects microstructure, stress transfer, abrasive constraint and material removal in sequence and establishes a relationship between the microstructure of pads and the evolution of a polished surface. Finite element simulations show that the maxima of von Mises stresses on fused silica are 0.171, 0.749 and 0.446 MPa for non-woven, polyurethane, and asphalt pads, respectively, corresponding to the support of discrete fibers, local stress concentration and continuous transfer of stress. Furthermore, single-abrasive scratching confirms that the maxima of equivalent stress exerted by the associated three pads are 2.059, 4.701 and 7.771 MPa, respectively, relevant to weak, unstable and strong constraints of abrasives. Polishing experiments were performed on fused silica with ceria slurry. They demonstrate that the peak-to-valley value obtained using an asphalt pad decreases from 385.976 to 115.237 nm and the attenuation of power spectral density is 88%. The surface roughness Sa achieved using a non-woven pad is reduced from 2.145 to 0.721 nm. The predictions of the proposed model are in good agreement with the simulation and experimental results. Our outcomes provide new insights into achieving error convergence of full bands on polished surfaces using different polishing pads.

Understanding the microscopic origin of impact sensitivity (IS) in energetic materials (EMs) requires a physically meaningful descriptor that links molecular-scale dynamic response to macroscopic behavior. In this work, molecular dynamics simulations based on a Deep potential (DeepMD) were employed to investigate the impact response of α-RDX nanocrystals under practical drop-weight-like loading conditions. An explicit atomic impactor was introduced to capture heterogeneous mechanical responses, including stress concentration, energy localization, and compression-shear coupled deformation. The simulations reveal that impact-induced reaction initiation proceeds through a sequence of impact energy deposition, mechanical compression, hotspot formation, and rapid decomposition. These processes collectively reflect the intrinsic resistance of material to impact-induced failure at the molecular scale. The decomposition fraction is used as an observable to identify the onset of irreversible reactions, from which the critical impact velocity (vc) is defined. vc serves as a molecular-level descriptor of impact sensitivity that quantifies the material resistance to impact-induced failure, providing a physically interpretable measure of impact resistance. Comparative simulations on eight energetic crystals (IS = 3.5-120 J) reproduce the experimental impact sensitivity ranking with a good correlation (R2 = 0.91) between the descriptor vc2 and IS. These results establish a direct link between atomistic failure processes and macroscopic impact sensitivity, providing a descriptor-based framework for the quantitative prediction and virtual screening of EMs with improved safety-performance balance.

Under the condition of slicing mining in extra-thick coal seams, the presence of irregular coal pillars is likely to cause stress redistribution in the roadway region and induce rockburst. Taking the "3·22" rockburst event that occurred in the haulage roadway of the 250,101-2 working face in Huating Coal Mine as the engineering background, this paper investigated the occurrence mechanism of roadway rockburst under irregular coal pillar conditions by combining source mechanism inversion, numerical simulation, and theoretical analysis. The results show that the double-couple component is dominant in the moment tensor inversion results, indicating that the source type of this event was shear-type, and that the essence of the rockburst instability was the sudden shear slip of the coal-rock mass under high-stress conditions. The PFC simulation results show that, under the control of an L-shaped irregular coal pillar formed by a 20m residual section pillar and a 34m residual pillar, the overburden load developed a zonal load transfer pattern. Specifically, the 20m pillar constituted the main load transfer channel, while the compacted zone above the 34m pillar regained a certain bearing capacity after compaction of the caved rock mass and exerted an auxiliary reloading effect on the underlying surrounding rock, resulting in the haulage roadway not being in a fully destressed state. On this basis, a two-segment bearing model of the L-shaped irregular coal pillar was established, and the static stress distribution characteristics in the roadway region under the combined action of the two-segment loads were analyzed based on half-plane elasticity theory. Furthermore, by incorporating the attenuation law of vibration waves, a stress increment estimation model under dynamic loading disturbance was established, and the dynamic stress increment generated on the roadway surface by the "3·22" rockburst event was calculated to be about 4.06MPa. Finally, the stress concentration characteristics and stress deflection effect under the control of the L-shaped coal pillar structure were discussed. The results show that an increase in the right-wing thickness of the L-shaped coal pillar structure enlarges the stress deflection zone and enhances stress redistribution toward the roadway, thereby increasing the possibility of rockburst under the combined action of high static stress and dynamic disturbance. The research results reveal the occurrence mechanism of roadway rockburst under L-shaped irregular coal pillar conditions, and can provide a theoretical reference for identifying rockburst hazard zones and optimizing working face layout parameters under similar engineering conditions.

The lunar mare region is rich in basaltic minerals, and in situ resource utilization (ISRU) is a fundamental strategy for sustainable extraterrestrial construction. However, combining electroless plating with basalt fibers for such construction leads to a significant mismatch of coefficient of thermal expansion (CTE) between the fiber substrate and metal coating. Under extreme temperature alternations, this mismatch induces interfacial thermal stress concentration, causing coating peeling and performance failure. To address this issue, this study, using commercial terrestrial basalt fiber as an analogue for lunar basaltic materials, proposes an ISRU-inspired metallized fiber composite suitable for wide-temperature-range applications. By sequential electroless nickel plating and copper electroplating on basalt fibers, a nickel-copper-coated basalt fiber fabric (BF@Ni@Cu) was successfully fabricated, exhibiting high electrical conductivity, excellent electromagnetic interference shielding effectiveness (62.59 dB), and significant joule heating performance. The Ni interlayer forms a CTE gradient transition between the basalt substrate and the outer Cu layer, mitigating interfacial thermal stress. After annealing and PDMS encapsulation, the surface reflection characteristics are effectively regulated. To verify reliability under lunar diurnal temperature variations, cold-thermal shock cycle tests simulating the lunar range (from -196 to 130 °C) are conducted. After 30 cycles, the material maintained structural integrity without cracking or peeling, successfully overcoming interfacial thermal stress concentration. Consequently, the EMI shielding and joule heating performance showed only slight degradation, demonstrating excellent temperature shock resistance. This study not only provides a fiber metallization strategy that retains high performance under extreme temperature alternations but also offers a potential technical pathway inspired by ISRU for multifunctional protection and thermal management materials in future lunar base construction, through the design concept of thermal stress alleviation and failure-mode control via a gradient interlayer.