Search Results (2,803)

The mechanical properties of dental implants are critical for their durability. The purpose of this study was to determine the maximum force required to induce full pull-out of a titanium implant from the bone and to characterize the mechanical behavior during this process. First, pull-out tests were performed on monolithic implants embedded in bovine ribs and foam blocks that mimic the mechanical parameters of human bone, allowing a quantitative evaluation of implant–bone interface strength and a comparison of geometric variants. Second, the extraction process was recreated in a three dimensional finite element model incorporating nonlinear interface contact and parameterization, enabling the reproduction of load–displacement curves; the results obtained showed good agreement with the experiment. Third, the fracture surfaces were observed macroscopically and by scanning electron microscopy/energy dispersive spectroscopy. The results demonstrated significant distinctions in the forces required to extract implants with varying thread geometries, clearly indicating the impact of implant design on their mechanical stability. The presented FEM-based methodology provides a reliable tool to study mechanical interactions at the implant–bone interface. The findings obtained can improve our understanding of implant behavior in biological systems and provide a basis for further optimization of their design. Full article

This study investigates the deterioration of corroded reinforced concrete pipes and their restoration using ultra-high performance concrete (UHPC), utilizing Three-Edge Bearing Tests and 3D finite element analysis under uniform corrosion-induced wall thinning. Unrepaired pipes exhibit elastic behavior, crack propagation, and yield stages, with failure driven by concrete cracking and rebar yielding. UHPC repair mitigates load drop during crack propagation, extends the yield phase, and enhances plastic deformation capacity. Pipe load-bearing capacity is negatively correlated with corrosion thickness and positively correlated with repair thickness (R² > 0.979) and repair compensation ratio. Interfacial performance analysis indicates natural bond degradation under sustained loading, transitioning the pipe to a unitized structure. Embedding steel nails significantly improves interfacial bond strength, increasing failure bearing capacity by 2.91 and 3.56 times compared to natural and PE film interfaces, respectively. Numerical simulations reveal that interface shear strength is five times more influential on bearing capacity decay than interface fracture energy, underscoring its critical role in durability design. An optimization strategy is proposed: reinforce stress-concentrated areas with nails to enhance shear strength and prioritize monitoring interfacial slip to ensure service safety. Full article

Hybrid woven composite materials and structures have important application value in modern engineering because of their high specific stiffness, specific strength and excellent impact resistance. The mechanical properties of carbon/aramid fiber hybrid woven composite laminates under repeated low-velocity impacts were studied in this paper. This study aims to understand the behavior of these materials under repeated impact conditions and to evaluate their damage resistance and failure mechanisms. The materials and methods used are introduced in detail, including the preparation of samples, the experimental apparatus for impact testing, and the methods of damage assessment and data analysis. The experimental setup simulated real impact scenarios and followed procedures to collect and analyze data. The low-velocity impact tests were carried out in accordance with ASTM D7136 test standard. The experimental results show that with the increase in impact energy, the damage of laminates includes delamination, matrix cracking and fiber fracture. The damage threshold and damage propagation rate are affected by the type of fiber used and its lay-up direction in the composite. Compared with (0,90)₁₂ laminates, [(0,90)]/(±45)]_3s laminates show more obvious damage expansion, which highlights the importance of fiber orientation in the impact durability design of laminates. The results can be used to design and optimize the structure of hybrid woven composite laminates. Full article

This study investigates date palm fiber (DPF) and sheep wool hybrid polyester composites with fiber loadings of 0%, 10%, 20%, and 30% by weight, fabricated by compression molding, to develop a sustainable and reliable material system. Experimental data from prior work were modeled using Weibull analysis for reliability evaluation and response surface methodology (RSM) for multi-objective optimization. Weibull statistics fitted a two-parameter distribution to tensile strength and fracture toughness, extracting shape (η) and scale ($\beta$) parameters to quantify variability and failure probability. The analysis showed that 20% hybrid content achieved the highest scale values ($\beta$ = 28.85 MPa for tensile strength and $\beta$ = 15.03 $\mathrm{M}\mathrm{P}\mathrm{a}\sqrt{\mathrm{m}}$ for fracture toughness) and comparatively low scatter (η = 10.39 and 9.2, respectively), indicating superior reliability. RSM quadratic models were developed for tensile strength, fracture toughness, thermal conductivity, acoustic attenuation, and water absorption, and were combined using desirability functions. The RSM optimization was found at 18.97% fiber content with a desirability index of 0.673, predicting 25.89 MPa tensile strength, 14.23 $\mathrm{M}\mathrm{P}\mathrm{a}\sqrt{\mathrm{m}}$ fracture toughness, 0.08 W/m·K thermal conductivity, 20.49 dB acoustic attenuation, and 5.11% water absorption. Overlaying Weibull cumulative distribution functions with RSM desirability surfaces linked probabilistic reliability zones (90–95% survival) to the deterministic optimization peak. This integration establishes a unified framework for designing natural fiber composites by embedding reliability into multi-property optimization. Full article

Tunnel construction in weak and fractured strata often faces risks such as tunnel face instability and large deformation of surrounding rock, which are difficult to effectively control using conventional support methods. Based on the engineering background of the No. 8# TA Tunnel in the F3 section of Georgia’s E60 Highway, this study employed ADECO-RS and developed a 3D numerical model with finite difference software to simulate full-face tunnel excavation process. The influence of advanced reinforcement measures on the stability of the surrounding rock was systematically investigated. The control effectiveness of different advanced reinforcement schemes was evaluated by comparing the displacement field, stress field, and plastic zone distribution of the surrounding rock under three conditions: no support, advanced pipe roof support, and a combination of pipe roof and glass fiber bolts. A comprehensive quantitative analysis of the synergistic effect of the combined reinforcement was also performed. The results indicated that significant extrusion deformation of the tunnel face and vault settlement occurred after excavation. The pressure arch developed within a range of 17.5 to 22 m above the tunnel vault. The surrounding rock of this tunnel was classified as type B (short-term stable). Deformation primarily occurred within one tunnel diameter ahead of the face, with the deformation rate significantly reduced after support. Advanced pipe roof support effectively restrained surrounding rock deformation, while the combination of advanced pipe roof and glass fiber bolts delivered better performance: reducing final convergence by 73.10%, pre-convergence by 82.69%, and face extrusion by 87.66%. The combined support also contracted the pressure arch boundaries from 17.5 to 22 m to 6–12.5 m, reduced the extent of major principal stress deflection, and significantly shrinks the plastic zone. Glass fiber bolts played a key role in controlling plastic zone expansion and ensuring stability. This study provides theoretical and numerical references for safe construction and advanced support design in tunnels under complex geological conditions. Full article

This study investigates the impact absorption performance of bamboo-inspired 3D-printed circular tubes in terms of infill type (grid, gyroid, honeycomb, Archimedean chords), infill ratio (10%, 20%, 30%, and 40%), wall thickness (0.8, 1.2, 1.6, and 2.0 mm), and inner diameter parameters. The structures designed using Taguchi L16 orthogonal design are printed with PLA material using FDM technology and evaluated by quasi-static compression tests. Peak crushing force (PCF), energy absorption (EA), and specific energy absorption (SEA) criteria are used to analyse crashworthiness performance. The experimental results showed that EA improves as the infill rate increases, but the gain decreases as the infill rate approaches 40% (SEA at 30% is better than that at 40%). By visualising the PCF and EA data relative to the utopia point (the lowest PCF and highest EA), GRID_T16F30D24, HCOMB_T08F30D22, and GRID_T12F20D22 are found to be the best-performing tubes. The grid and honeycomb infill types showed superiority at 20–30% infill rates and similar wall thicknesses. The Archimedean chords type performed poorly due to its tendency to fracture. Full article

Using traditional methods to fabricate geometrically complicated items was challenging, but Additive Manufacturing (AM) has made it possible. Although AM (3D printing) was first developed to produce prototypes, in recent years it has also been utilized for the fabrication of end-use products. As a result, the mechanical strength of AMed parts has gained considerable significance. Three-dimensional printing has proved its capabilities in the fabrication of customizable parts with complex geometries. In the current study, the effects of manufacturing parameters on the mechanical strength and the fracture behavior of 3D-printed components have been investigated. To this aim, we fabricated specimens using Polyethylene Terephthalate Glycol (PETG) and the Fused Deposition Modeling (FDM) process. Particularly, the dumbbell-shaped and Single Edge Notched Bend (SENB) specimens were fabricated and examined to determine their tensile and fracture behaviors. Particularly, the notches in SENB specimens were introduced by two different techniques to investigate the influence of the manufacturing process on the mechanical performance of 3D-printed PETG parts. Moreover, finite element simulations were conducted to investigate the fracture behavior of the parts. The results indicate that the fracture loads of 3D-printed and milled parts are 599.1 N and 417.2 N, respectively. In addition, experiments confirm brittle fracture with no plastic deformation in all specimens with 3D-printed and milled notches. The outcomes of this study can be used for the future designs of FDM 3D-printed parts with a better structural performance. Full article

In the shale oil reservoirs, sandstone and shale often overlie each other. This significantly affects the vertical propagation of hydraulic fractures (HFs); however, the underlying mechanisms still remain unclear. This study employs Xsite software to investigate the influence of rock fracture toughness, tensile strength, elastic modulus, Poisson’s ratio, interlayer stress contrast, and the flow rate and viscosity of fracturing fluid on the propagation behaviour of HFs in sandstone–shale interbeds. As the type-I fracture toughness of the shale layer increases, the area of the vertical HF decreases and the average HF width becomes smaller. As the tensile strength of the sandstone layer increases, the distribution range of fluid pressure at the interface expands. The HF prefers to propagate in the softer rock rather than the harder one. A relatively narrower HF width is created in the layer with a higher elastic modulus resulting in a higher flow resistance to fracturing fluid. A shale layer with a high Poisson’s ratio is more likely to undergo a lateral expansion, causing stress at the fracture tip to be dispersed. When the effect of lithological interfaces is considered, an increasing interlayer stress contrast causes HFs to gradually transition from penetrating the interfaces to becoming confined between the two interfaces. When the influence of the lithological interface is not considered, an increasing interlayer stress contrast causes the HF to gradually transition from a penny-shaped fracture to a blade-shaped fracture. The HF penetrates the interfaces more easily at a higher injection rate and fluid viscosity, because most of the injected energy is used to create new fractures rather than leakoff into the interfaces. Understanding the influence of these factors on the HF propagation behaviour is of great significance for optimising hydraulic fracturing design. Full article

This study presents an integrated geophysical and hydrogeological characterization of fault systems in the sandstone-hosted uranium deposit within the K₁b² Ore Horizon of the Bayin Gobi Basin. Employing 3D seismic exploration with 64-fold coverage and advanced attribute analysis techniques (including coherence volumes, ant-tracking algorithms, and LOW_FRQ spectral attenuation), the research identified 18 normal faults with vertical displacements up to 21 m, demonstrating a predominant NE-oriented structural pattern consistent with regional tectonic features. The fracture network analysis reveals anisotropic permeability distributions (31.6:1–41.4:1 ratios) with microfracture densities reaching 3.2 fractures/km² in the central and northwestern sectors, significantly influencing lixiviant flow paths as validated by tracer tests showing 22° NE flow deviations. Hydrogeological assessments indicate that fault zones such as F11 exhibit 3.1 times higher transmissivity (5.3 m²/d) compared to non-fault areas, directly impacting in situ leaching (ISL) efficiency through preferential fluid pathways. The study establishes a technical framework for fracture system monitoring and hydraulic performance evaluation, addressing critical challenges in ISL operations, including undetected fault extensions that caused lixiviant leakage incidents in field cases. These findings provide essential geological foundations for optimizing well placement and leaching zone design in structurally complex sandstone-hosted uranium deposits. The methodology combines seismic attribute analysis with hydrogeological validation, demonstrating how fault systems control fluid flow dynamics in ISL operations. The results highlight the importance of integrated geophysical approaches for accurate structural characterization and operational risk mitigation in uranium mining. Full article

The construction sector’s environmental footprint is driving the adoption of sustainable modular timber systems. The WikiHouse Skylark is a promising open-source model whose structural reliability depends on the performance of its critical plywood TIE joints. This study presents an experimental investigation of full-scale TIE joints fabricated from 18 mm Pinus radiata plywood in three variants: Standard (STD), Weather-Resistant (HR), and Fire-Resistant (FR). Monotonic tensile and shear tests were conducted to evaluate load–displacement behavior and failure modes. While the mean ultimate strengths varied between panel types, with HR highest in tension (7.7 kN) and FR highest in shear (8.2 kN), the most critical finding was the effect of the treatments on failure mode. The FR treatment induced a brittle fracture with significantly reduced ductility, in contrast to the more ductile tearing observed in STD and HR panels. This highlights a clear strength–ductility trade-off introduced by the fire-retardant treatment, a key consideration for structural design in modular timber construction. This dataset provides an essential empirical foundation for the numerical modeling and design guidelines of WikiHouse TIE joints, advancing the development of resilient and sustainable prefabricated housing. Full article

Glass fiber reinforced polymer (GFRP) composite profiles produced by pultrusion method are widely used as an alternative to traditional building materials due to their lightness and corrosion resistance. However, these materials are susceptible to crushing type fractures known as “web crippling” especially under local loading due to their anisotropic structure and limited mechanical strength. Understanding web-crippling behavior is crucial for the safe and efficient structural application of pultruded GFRP profiles. This study report narrated the review of experimental, numerical, and analytical investigations of web-crippling behavior of pultruded GFRP profiles. Highlights of the major findings include profile geometry and detailing of the flange–web joint, loading types (end-two-flange (ETF), interior-two-flange (ITF), end bearing with ground (EG), interior bearing with ground (IG)), bearing plate dimensions, presence of web openings, and elevated temperatures. It also considers the limitations of current standards, along with new modeling techniques that incorporate finite element analysis as well as artificial intelligence. Damage types such as web–flange joint fractures, crushing, and buckling were comparatively analyzed; design approaches based on finite element modeling and artificial intelligence-supported prediction models were also included. These insights provide guidance for optimizing profile design and improving predictive models for structural engineering applications. Gaps in current design standards and modeling approaches are highlighted to guide future research. Full article

Natural rock materials, containing micro-cracks and pore defects, significantly alter their mechanical behavior. This study investigated fracture interactions of red sandstone containing double close-round holes (diameter: 10 mm; bridge angle: 30°, 45°, 60°, 90°) using acoustic emission (AE) monitoring and the discrete element simulations method (DEM), which was a novel methodology for revealing dynamic failure mechanisms. The uniaxial compression tests showed that hole geometry critically controlled failure modes: specimens with 0° bridge exhibited elastic–brittle failure with intense AE energy releases and large fractures, while 45° arrangements displayed elastic–plastic behaviors with stable AE signal responses until collapse. The quantitative AE analysis revealed that the fracture-type coefficient k had a distinct temporal clustering characteristic, demonstrating the spatiotemporal synchronization of tensile and shear crack initiation and propagation. Furthermore, numerical simulations identified a critical stress redistribution phenomenon, that axial compressive force chains concentrated along the loading axis, forming continuous longitudinal compression zones, while radial tensile dispersion dominated hole peripheries. Crucially, specimens with 45° and 90° bridges induced prominently symmetric tensile fractures (85° to horizontal direction) and shear-dominated failure near junctions. These findings can advance damage prediction in discontinuous geological media and offer direct insights for optimizing excavation sequences and support design in cavern engineering. Full article

As oil and gas exploration advances, the development of deep, low-permeability, high-temperature, and high-salinity reservoirs poses increasing challenges. To address this, a novel amphoteric surfactant (TASS) was synthesized via free radical polymerization, and a high-performance water-based fracturing fluid system was developed. The system exhibited excellent thermal and salt resistance, with viscosity decreasing by less than 3.3% after 72 h at 150 °C and 20 wt% NaCl. It demonstrated clear shear-thinning behavior and strong elasticity. Interfacial activity tests showed that increasing NaCl concentrations reduced interfacial tension from 28.5 to 24.3 mN/m, while the contact angle on sandstone surfaces decreased significantly, indicating enhanced wettability and oil flow. Field applications further confirmed its effectiveness, with oil and gas production increasing by 81% and 133%, respectively, and a payback period of around 10 days. These results highlight the TASS fracturing fluid as a promising solution for stimulation in complex reservoirs. Unlike conventional betaine-type VES, the silane-grafted amphoteric design of TASS ensures viscosity retention at 220 °C and 25 wt% salinity. Full article

Proximal humerus fractures are frequent injuries that often require internal fixation. Conventional metallic plates, however, present significant drawbacks such as corrosion, secondary removal surgeries, and adverse reactions in patients with metal hypersensitivity. This study evaluates biocomposite plates fabricated from polylactic acid (PLA) and polyvinyl alcohol (PVA), reinforced with hydroxyapatite (HA) derived from sugar industry by-products (BCF) at 10% and 20% concentrations. These composites are compatible with both injection molding and 3D printing, enabling the design of patient-specific implants. Characterization by SEM, FTIR, XRD, and DSC confirmed that BCF incorporation enhances strength, stiffness, osteoconductivity, and biocompatibility. Mechanical testing showed that PVA/BCF exhibited greater tensile strength and stiffness, suggesting suitability for load-bearing applications, though their water solubility restricts use in humid environments and prevents filament-based 3D printing. PLA/BCF composites demonstrated better processability, favorable mechanical performance, and compatibility with both manufacturing routes. Finite element analysis highlighted the importance of plate–humerus contact in stress distribution and fixation stability. Compared with non-biodegradable thermoplastics such as PEI and PEEK, PLA/BCF and PVA/BCF offer the additional advantage of controlled biodegradation, reducing the need for secondary surgeries. Cell viability assays confirmed cytocompatibility, with optimal outcomes at 10% BCF in PVA and 20% in PLA. These results position PLA/BCF and PVA/BCF as sustainable, patient-tailored alternatives to metallic implants, combining adequate mechanical support with bone regeneration potential. Full article

This study investigates the effect of hydrogen embrittlement on the fracture toughness of 9% Ni steel and STS 316L stainless steel under cryogenic conditions ranging from −80 °C to −253 °C. Hydrogen charging was performed using electrochemical methods, and hydrogen uptake was quantitatively analyzed using thermal desorption spectroscopy (TDS). Fracture toughness was evaluated using crack tip opening displacement (CTOD) testing per ISO 12135, both without hydrogen (WO-H) and with hydrogen (W-H). The results showed a gradual decrease in CTOD values with decreasing temperature in both steels under hydrogen-free conditions, with ductile fracture maintained even at −253 °C. In contrast, hydrogen-charged specimens exhibited significant toughness degradation at intermediate subzero temperatures (−80 °C to −130 °C), particularly in 9% Ni steel due to its BCC crystal structure. However, at −160 °C and below, the effect of hydrogen embrittlement was suppressed mainly owing to the reduced hydrogen diffusivity. Scanning electron microscopy (SEM) analysis confirmed the transition from ductile to brittle fracture with decreasing temperature and hydrogen influences. At −253 °C, fully brittle fracture surfaces were observed in all specimens, confirming that at ultra-low temperatures, fracture behavior is dominated by temperature effects rather than hydrogen. These findings identify a practical temperature limit (approximately −160 °C) below which hydrogen embrittlement becomes negligible, providing critical insights for the design and application of structural materials in hydrogen cryogenic environments. Full article