Search Results (8,154)

Numerous studies have demonstrated that tooth-supported dental guides improve the accuracy of implant placement. However, current manufacturing procedures and available materials are not yet optimal and may still lead to deviations from the planned implant position. The influence of the surgeon’s manual force on the deformation of dental guides during implant placement has not yet been sufficiently investigated. Therefore, this study evaluates the mechanical behavior of dental guides using finite element analysis (FEA) in order to assess the influence of the surgeon’s hand force during clinical application. Finite element simulations of deformation and stress were performed for four types of tooth-supported dental guides, including cantilever dental guides with free ends and beam-type guides with a large span between the supporting teeth. The manual force applied by the surgeon was arbitrarily set to 30 N. Simulations were conducted for five commonly used biocompatible polymer materials: Stratasys MED610, VeroGlaze MED620, EOS PA2200, Formlabs FLSGAM01, and Stratasys ULTEM 1010. The numerical results quantified the deformation of dental guides caused by the applied manual force during surgical manipulation. For all analyzed guide designs, the deflection was primarily influenced by the arm length, i.e., the distance between the support and the point of force application. Based on the obtained results, design diagrams were developed to provide guidelines for the design of beam-type (A and A1) and cantilever-type (B and B1) tooth-supported dental guides. Full article

Poly(lactic acid) (PLA) films containing two different hemp-derived essential oils (EOs), Carmagnola CS (Carm) and Futura 75 (Fut), at 1, 5, and 10% wt were successfully produced via solvent casting for packaging applications. The influence of EO presence, type, and concentration on the chemical, morphological, and thermal properties of the PLA-based films was investigated. In addition, radical-scavenging activity, water transport properties, and antimicrobial performance were evaluated to assess the effect of EOs on the structural and functional characteristics of the resulting packaging materials. FTIR spectroscopy confirmed the successful incorporation of the hemp essential oils Carm and Fut into the polymer matrix, with a concentration-dependent effect that is more pronounced for Fut than for Carm. In the second heating run, evaluated by DSC measurements, both EOs lowered T_g from 60.3 °C (PLA) to 52.0 °C for PLA_10 Carm and 55.1 °C for PLA_10 Fut. The EOs act as plasticizers in the PLA matrix, improving the deformation at break. Gas barrier measurements showed that permeability decreased from 3027 ± 300 Barrer (PLA) to (2499 ± 44) Barrer in PLA_10 Carm and 2623 ± 130 Barrer in PLA_10 Fut, with a corresponding reduction in diffusivity. The barrier improvement factor reached 17% for Carm and 15% for Fut, confirming the enhanced barrier performance of PLA_EOs films. DPPH assays showed that PLA_EOs films retained most of the antioxidant activity of the free oils, with only a 10–15% reduction for PLA_Fut and no significant loss for PLA_Carm after one week. After one month, the activity of Carm in PLA film decreased by 18%, whereas the performance of its free form remained unchanged, confirming the superior and more stable radical scavenging capacity of Carm compared to Fut. Overall, the study demonstrates that hemp essential oils can be effectively integrated into PLA without compromising structural integrity, while preserving antioxidant performance and enhancing water barrier properties, supporting their potential as sustainable active packaging components. Full article

Ground subsidence and shaft lining deformation caused by compressed dewatered bottom aquifers in deep unconsolidated strata mining areas are critical engineering challenges, making the study of the seepage–soil deformation coupling mechanism during groundwater injection remediation vital. This study built a visual cylindrical model (1025 mm × 150 mm); formulated well-graded analogous materials based on the D₂₀ principle to simulate sandy gravel layers; embedded FBG sensors at 200/400/600 mm depths, combined with a dial indicator on the model top; and conducted two water injection–dewatering cycles. Results indicate: water injection generates excess pore water pressure, placing the entire model in a tensile stress state with top rebound; post-injection vertical stress redistributes (tension above the injection point, compression below, and an interlaced transitional band), validating the necessity of full-section injection; during the second injection–dewatering cycle, tensile strain at the upper monitoring point reaches 597.77 με, while compressive strain at lower depths reaches −253.90 με, internal deformation stabilizes within 6.5–10.0 days, injection improves the in situ stress state by reducing effective stress, and the deformation of the field strata remains in a stabilization period, with the stabilization time decreasing as the depth of the strata increases. This study clarifies the temporal evolution and representative spatial variation in internal strain at monitored depths during injection, providing theoretical and design references for optimizing water injection schemes to mitigate coal mine shaft damage. Full article

Background: Hallux valgus (HV) is a complex forefoot deformity influenced by interactions between osseous alignment, ligamentous restraint, and muscle–tendon forces. While the biomechanical role of ligament laxity and bone geometry has been extensively investigated, the contribution of tibialis anterior (TA) tendon insertion variability to medial column mechanics remains insufficiently understood. Materials and Methods: A patient-specific finite element model of the foot was developed from high-resolution computed tomography data. Five anatomically documented TA distal insertion configurations were modeled, representing different distributions of attachment to the medial cuneiform and first metatarsal base. All simulations were performed under identical boundary and loading conditions representative of the stance phase of gait. Global (full-foot) and local (first bone and first metatarsal) mechanical responses were quantified using total deformation, equivalent von Mises stress, and strain distributions. Results: Marked differences in mechanical behavior were observed across TA insertion types. The metatarsal-dominant configuration (Type 3) demonstrated the highest global and local deformation values (global deformation: 1.0928 mm; first bone deformation: 1.0928 mm) and elevated strain distributions, whereas the medial-dominant configuration (Type 2) showed minimal deformation (global: 0.0727 mm; first bone: 0.0350 mm) but the highest global equivalent von Mises stress (5.7698 MPa). The single-band insertion to the medial cuneiform (Type 5) produced the greatest localized stress in the first bone region (3.8634 MPa). Representative strain maps revealed distinct spatial redistribution patterns within the medial column associated with TA insertion geometry. Conclusions: This patient-specific finite element analysis indicated that distal TA insertion variability alone can substantially modify deformation, stress, and strain patterns within the medial column. These findings suggested that TA insertion anatomy may act as a biomechanical modulator of first-ray mechanics and should be considered in future studies investigating hallux valgus pathomechanics and personalized treatment strategies. Full article

Polydimethylsiloxane (PDMS) films doped with graphene nanoplatelets (GNP) with an embossed surface-relief grating were investigated as photothermal actuated sensors. The films were initially characterized using controlled environmental heating where the wavelength of a diffracted white-light probe beam measured at a fixed angle increased monotonically with temperature due to thermal expansion of the grating. An asymmetric double sigmoidal function tracked the shift in peak diffraction wavelength. The observed thermal response is consistent with the thermal expansion of a freestanding PDMS composite film. When a continuous-wave (CW) laser was incident on the film, intensity-dependent photothermal expansion caused a transient deformation in the grating. The photomechanical behavior of the grating, tracked by the diffracted probe beam with a miniature spectrometer, was then shown to act as a laser power meter. These results demonstrate that photomechanical materials can be used as add-ons to existing optical spectroscopy devices for power-sensing applications. Full article

Water-based drill cuttings generated during onshore natural gas development are complex solid wastes that may pose environmental risks if improperly managed. This study evaluates the feasibility of reutilizing water-based drill cuttings as pavement base materials after stabilization using a novel composite stabilizer composed of cement, stabilizer liquid agent, and water-reducing powder (CLP stabilizer). Mix proportion optimization was conducted through compaction and 7-day unconfined compressive strength tests, followed by evaluation of road performance, including strength, compressive rebound modulus, water stability, and temperature shrinkage, with stabilized powder stabilized soil as a control. Microstructural characteristics were analyzed using X-ray diffraction and scanning electron microscopy, and environmental safety was assessed through heavy metal leaching tests and background soil investigation. The results show that the optimal mixture ratio of curing agent (5% cement + 2% liquid stabilizer + 8% superplasticizer powder) satisfies the strength requirement for pre-drilling road bases, exhibiting superior performance compared to the control group. When the stabilizer dosage reaches 9%, the 7-day unconfined compressive strength achieves a maximum of 3.38 MPa, representing a 51% increase over the control group. At a stabilizer dosage of 12%, the splitting tensile strength reaches a peak value of 0.901 MPa, showing a 60.3% improvement. These results indicate enhanced deformation resistance, water stability, and reduced temperature shrinkage rates. Microstructural analysis indicates that the formation of calcium silicate hydrate (C-S-H) gel and ettringite (AFt phase) leads to a denser structure and enhanced durability. Heavy metal concentrations comply with relevant standards, demonstrating controllable environmental risks and supporting sustainable pavement base application. Full article

Acoustic microactuation technology has emerged as an effective approach for fabrication of micro- and nanoscale objects, enabling precise processing and shaping control of microscale materials by efficiently transmitting ultrasonic vibration energy and focusing energy locally. In this work, the proposed platform is regarded as an acoustically driven micromachine, in which ultrasonic excitation acts as the primary microactuation mechanism. Micrometer-scale copper wires are widely used in microelectronics and precision manufacturing. However, their small dimensions and low rigidity make fixation and forming particularly challenging. To achieve controllable forming of fine copper wires, this study introduces an ultrasonic vibration energy-focusing principle and investigates an ultrasonic post-processing method tailored for such materials, with the aim of enhancing processing stability and forming accuracy. An ultrasonic processing experimental platform for copper wires was established, and multiple micro-tool designs—including glass fiber, 304 stainless steel wire with support, and elastic hard 304 stainless steel—were evaluated. Single-point and continuous processing experiments were conducted by varying micro-tool materials and support configurations, and the influence of feed speed on processing width and depth was systematically analyzed. The results indicate that a hard 304 stainless steel micro-tool supported by a hard plastic ring provides the best overall performance. Feed speed has a significant effect on processing depth, with a maximum average depth of approximately 0.95 μm achieved at a feed speed of 1 mm/min. These findings demonstrate the feasibility of ultrasonic processing for the effective forming of fine copper wires and confirm that appropriate micro-tool design and feed speed are critical for achieving stable and reliable processing results. The proposed system employs an ultrasonically actuated micro-tool to perform post-processing on micrometer-scale copper wires. The ultrasonic vibration serves as a microactuation mechanism that enhances local deformation and material response during micro-machining. Full article

Land subsidence and coseismic deformation can interact in groundwater-stressed sedimentary basins, yet basin-scale identification of event-timed vertical offsets in InSAR products requires explicit control of referencing and processing effects. This study evaluates whether the 27 September 2021 Arkalochori earthquake (Mw 6.0; central Crete) produced detectable coseismic vertical offsets within the Messara Basin by applying a reproducible screening workflow to Copernicus European Ground Motion Service (EGMS) Level-3 Vertical time series, from two processing generations (EGMS 2015–2021 and EGMS 2018–2022). An event-centered step metric (stepEQ), defined as the difference between post-event and pre-event mean displacements over a fixed acquisition window, is evaluated across three fixed spatial masks (MESSARA, R15060, R8750) together with a dispersion-based precision proxy (σstep) and a cross-generation sensitivity diagnostic (ΔstepEQ). A supplementary 2 + 2 subset sensitivity analysis indicates that the adopted fixed 3 + 3 estimator is stable at the basin scale, with sensitivity concentrated mainly in threshold-adjacent cases. Results indicate that Arkalochori-related offsets are not expressed as a basin-wide step across Messara; instead, non-background responses form a spatially limited and coherent subset concentrated where the basin intersects the near-source footprint. In EGMS 2018–2022, the higher vertical offset class (C2; |stepEQ| > 40 mm) is exclusively subsidence-direction and is enriched toward the screening center (up to ~19% within the radii mask R8750 m) but remains sparse at the basin scale mask (MESSARA mask) (~1%). Step-dominated points co-locate with strongly subsiding mean vertical velocity regimes and are hosted almost entirely by post-Alpine basin deposits, indicating strong material and background-deformation conditioning of step detectability. Cross-generation comparison shows basin-scale stability of background behavior but localized near-source sensitivity, supporting use of ΔstepEQ as a Quality Control (QC) lens for threshold-adjacent interpretations. The workflow provides a transparent, transferable approach for prioritizing candidate coseismic-step locations in EGMS time series. Results are interpreted as screening-level evidence in the derived vertical signal using event timing, spatial coherence, and QC diagnostics. Full article

Gangue backfilling has become an important technique for promoting environmentally friendly and low-carbon coal mining. The long-term creep behavior of cemented backfill plays a critical role in maintaining stope stability and controlling surface subsidence during long-term service. Although considerable research has been conducted on cemented tailings backfill, systematic investigations on the triaxial creep evolution, long-term strength characteristics, confining pressure effects, and the applicability of the classical Burgers model for gangue–gypsum cemented backfill under engineering-relevant confining pressures remain limited. In this study, the experimental scheme was designed based on field monitoring data from practical backfill mining operations, which indicate that the in situ backfill generally remains stable without significant deformation or instability under normal working conditions. Multi-stage loading triaxial creep tests were conducted on gangue–gypsum cemented backfill under confining pressures of 1, 2, 3, and 4 MPa. The creep deformation characteristics were analyzed using Chen’s superposition method, while the long-term strength was computed via inflection point method of isochronous stress–strain curves. The parameters of the Burgers creep model were identified using the Levenberg–Marquardt optimization algorithm, and numerical verification was performed using FLAC3D. Our findings demonstrate that the creep deformation process of the backfill consists of three typical stages: instantaneous deformation, attenuated creep, and steady-state creep, and no accelerated creep was observed within the applied stress range. The absolute creep strain surges nonlinearly with increasing stress level (S_L), whereas higher confining pressure significantly suppresses the creep response of the material. Within the investigated stress range, the backfill exhibits mainly linear viscoelastic behavior, and its critical long-term strength is not less than 0.9 times the failure deviatoric stress (qf). Although confining pressure enhances the long-term strength, the strengthening effect weakens as the confining pressure increases. Model fitting outcomes imply that Burgers model precisely describes the creep behavior of gangue–gypsum cemented backfill under all test conditions, with correlation coefficients (R²) exceeding 0.97. The identified parameters show systematic variation with S_L, reflecting stiffness degradation and viscous evolution during loading. Numerical simulation results agree well with the experimental data, providing theoretical guidance for mixture proportion optimization, long-term stability evaluation, and stope support parameter design in gangue backfill mining engineering. Full article

Benefiting from their outstanding porosity, considerable specific surface area, and natural flexibility, cellulose nanofibers (CNFs)/MOF materials have emerged as competitive candidates for advanced flexible energy storage devices. However, conventional CNFs/MOFs aerogels or films often suffer from poor recoverability under compression, bending, and folding, accompanied by severe plastic deformation that compromises the cycling and structural stability of devices. To address this issue, we report a rationally designed flexible PU/CNFs/ZIF-8/PANI composite foam with an interconnected micro-mesoporous structure. Using polyurethane foam as a soft substrate and CNFs/ZIF-8 as building blocks, the composite was fabricated through a combined strategy of impregnation, in situ ZIF-8 growth, hot-pressing, and in situ aniline polymerization with simultaneous etching of the ZIF-8. The incorporation of carboxylated CNFs enhances the hydrophilicity of the PU skeleton. This, in combination with the hot-pressed framework, establishes an interconnected 3D network, thereby effectively preventing the agglomeration of active materials. Meanwhile, the hierarchical pores derived from the sacrificial ZIF-8 template provide abundant electroactive sites, accelerate ion transport, and facilitate high PANI loading. By virtue of this synergistic architectural effect, the resultant electrode achieves a high specific capacitance of 449 F/g at 0.2 A/g, with 97% capacitance retention after 2000 cycles at 5 A/g. Furthermore, the composite foam demonstrates excellent mechanical flexibility, with a tensile strength of 0.87 MPa and an elongation at break of 230%. This work offers a feasible approach for developing high-performance flexible supercapacitors and provides novel perspectives for the rational design of portable energy storage devices. Full article

The study focused on the development and optimization of plastic deformation of pure M1E copper using an unconventional hydrostatic extrusion (HE) process aimed at improving the performance of electrodes used in electrical discharge machining (EDM). The process was designed to refine the microstructure while maintaining the high electrical conductivity required for EDM applications. Optimization of a three-stage HE process (cumulative strain ε = 2.51) resulted in the formation of an ultrafine-grained structure (d₂ ≈ 370 nm), leading to a significant increase in mechanical strength (UTS ≈ 400 MPa) while preserving very high electrical conductivity (~99% IACS). This combination of properties is particularly important for EDM electrodes, as it allows improved wear resistance without compromising electrical performance. Due to the application-oriented nature of the study, the HE-processed copper was tested under industrial EDM conditions. Wear tests were conducted using seven electrodes of different geometries required for the production of a sample injection mold. The results demonstrated a substantial reduction in electroerosion wear of HE-processed electrodes (30–90%) compared with undeformed copper, together with up to 25% improvement in surface quality. These findings indicate that hydrostatic extrusion is an effective method for producing high performance EDM electrode materials with improved durability and machining quality. Full article

With Aligned Formable Fibre Technology (AFFT^™), fibers are reformatted into highly oriented epoxy prepreg tapes, enabling the structural reuse of recycled composite waste. The present study investigates whether discontinuous fiber laminates produced with AFFT^™ can be characterized and optimized with the same finite-element workflows long established for continuous fiber composites and whether the resulting structures meet demanding stiffness targets. Initially, various manufacturing methods were adopted, including vacuum bagging, compression molding at 7 bar to simulate autoclave conditions, and compression molding at 90 bar, comprising the three most reasonable manufacturing processes for AFFT^™ laminates. Experimentally measured orthotropic properties were introduced into a finite-element model representing an idealized bicycle top tube, which was chosen as a case study. A genetic algorithm screened candidate stacking sequences, minimizing the combined bending-and-torsion deflection. The best lay-ups reduced deformation by more than 30% compared to a quasi-isotropic baseline, showing that well-oriented short fibers can significantly contribute to the stiffness of composites. Tubes produced with the optimized lay-up were tested in three-point bending tests, and the measured stiffness matched simulations within 5%. These results confirm a key point for sustainable engineering: despite the absence of continuous fibers, conventional simulation strategies accurately predict the performance of AFFT^™ laminates and can be used as the basis for effective genetic optimization. This validation is significant: it enables the design of stiff, high-performance structures from recycled materials using established, cost-effective methods. By proving that optimization strategies developed for traditional continuous fiber composites apply to AFFT^™, this study offers a trusted and accessible pathway to scale circular economy solutions in next-generation composite products. Full article

Ionic polymer–metal composites consist of an ion-conducting polymer–gel membrane sandwiched between two flexible electrodes, representing a class of soft electroactive materials capable of large deformation under low voltage. The gel membrane, swollen with solvent, facilitates ion migration under an electric field, enabling actuation. Tailoring the interfacial architecture between the electrode and the polymer–gel membrane is pivotal for advancing high-performance IPMC actuators. This study presents a comparative investigation of three core–shell nanocomposite electrodes, fabricated via in situ polymerization, for IPMC applications. Among these, the polyaniline-coated multi-walled carbon nanotube composite exhibits a deliberately designed hierarchical structure, with a specific surface area of 32.345 m²·g⁻¹ and a conductive doped polyaniline shell, as confirmed through XPS analysis. This optimized interface enables superior charge storage and transport, endowing the corresponding electrode with a specific capacitance of 40.28 mF·cm⁻² at 100 mV·s⁻¹—3.2 times greater than that of conventional silver-based electrodes—along with a reduced sheet resistance. When integrated with a Nafion ion–gel membrane, the PANI@MWCNT electrode achieves a 67% increase in force density and a larger displacement output compared to standard devices, directly correlated with its enhanced electrical and electrochemical properties. This work highlights the critical role of core–shell interfacial engineering in governing electromechanical performance at the electrode–gel interface and offers a practical design strategy for developing high-performance, cost-effective IPMC actuators for soft robotics, flexible electronics, and related applications. Full article

High nitrogen austenitic stainless steels are an important engineering structural material. Under annealing conditions, the addition of interstitial solid solution element nitrogen can improve the yield strength and tensile strength of the alloy without reducing its plasticity. In addition, nitrogen can partly or completely replace the more expensive nickel element at a relatively cheap element cost to improve economic benefits, while maintaining or even enhancing the excellent corrosion resistance of stainless steels. However, the cracks and defects caused by high nitrogen austenitic stainless steels during hot working in high temperature ranges have always been the pain points in the engineering field. High nitrogen elements bring high temperature strength, but also narrow the hot working temperature range, the possibility of nitride precipitation and the tendency of heat induced cracking, which limit the further engineering application of high nitrogen austenitic stainless steels. It is urgent to analyze and study the hot deformation law of high nitrogen austenitic stainless steels in engineering. This article commences with an examination of the developmental trajectory of high nitrogen austenitic stainless steel, elucidates the role and strengthening mechanism of nitrogen, and delineates the factors influencing the mechanical behavior of high nitrogen austenitic stainless steel during hot working. These factors include the impact of nitrogen content and manufacturing processes, hot-working parameters, grain size distribution, and the presence of precipitated phases. This article synthesizes various studies, analyzes the causes of thermal cracking, and proposes potential solutions. Ultimately, it summarizes the practical applications and future prospects of high nitrogen austenitic stainless steel, highlighting its substantial potential. Full article

Background and Objectives: Determining the mechanical stability of osteosynthesis in pertrochanteric fractures remains a critical challenge in orthopedic biomechanics. The aim of this study was to develop a mathematical model for quantifying the stability of osteosynthesis and to establish criteria for its evaluation under physiological loading conditions. Materials and Methods: A mathematical model describing the biomechanical behavior of a proximal femur with a pertrochanteric fracture stabilized using a cephalomedullary nail (CMN) was developed. The model integrates force equilibrium, stress–strain relationships, and loading conditions representative of early functional rehabilitation. The theoretical framework was implemented in MATLAB/Simulink R2025b and complemented by finite element analysis to determine stress distribution, deformation patterns, and stability-related parameters of the bone–implant system. Results: The developed mathematical model enabled a quantitative assessment of osteosynthesis stability through the evaluation of key mechanical indicators, including displacement, stress distribution, and safety factor within the fixation system. Critical stress zones in the implant and surrounding bone were identified, allowing analysis of load transfer mechanisms. Finite element simulations showed that improved fixation mechanics reduced peak implant stresses, limited displacement at the fracture site, and increased the safety factor of the fixation construct, resulting in a more uniform load distribution in the surrounding bone and enhanced overall stability of the osteosynthesis system. Conclusions: The proposed mathematical model provides a systematic approach for determining the stability of osteosynthesis in pertrochanteric fractures. It offers a theoretical basis for optimizing implant design and fixation strategies, with potential applications in preclinical evaluation and surgical planning. Full article