Search Results (2,087)

Tire-Derived Aggregate (TDA) is a recycled fill material made by cutting scrap tires into small pieces that satisfy the gradation requirements in ASTM D 6270. Since its introduction to civil engineering applications, TDA fill and TDA backfill have been successfully implemented in many projects. However, the dynamic behavior of the TDA backfill under significant earthquakes has not been substantially addressed. The present study used nonlinear time-history Finite Element Analysis (FEA) to analyze the dynamic behavior of a retaining wall with TDA backfill captured from the full-scale shake table test. Unlike typical soil failure observed in a similar retaining wall with conventional soil backfill, significant wall sliding occurred because lightweight TDA contributed to reducing the friction resistance of the wall footing. Therefore, the analysis required modeling capability of rigid body motion and impact loading from the separation between the wall stem and the backfill. With adequate friction models and softened contact models, the FEA generated the dynamic motion of the retaining wall that matched well with the measured responses, including the wall sliding. The friction model between the wall footing and soil was most critical in accurately reproducing wall sliding motion. It was determined to use different friction coefficients for the two different earthquakes used in the study in order to simplify the rate dependence of the coefficient. Also, the softened contact model generated more reasonable impact force by allowing overclosure and finite stiffness during impact. The FEA model and modeling technique in the present study can be used for the seismic design of various field-scale retaining walls with TDA backfill. Full article

The Taranto Landslide Complex (TLC) is a multi-episode submarine mass-failure system developed along the Apulian continental margin (Gulf of Taranto, northern Ionian Sea) between ~200 and ~900 m water depth. High-resolution multibeam bathymetry and chirp seismostratigraphy were integrated to map five partially overlapping Quaternary mass transport deposits (MTD1–MTD5) and quantify their geometry, conservative volumes, and first-order kinematics. Consistent morphometric parameters indicate mobilities (H/L) and angles of reach typical of continental-slope failures, whereas conservative volumes range between ~0.02–0.35 km³. A depth-averaged sliding-block approach yields bounds on peak velocity and travel time compatible with rapid emplacement. Cross-cutting relationships and post-failure sediment drapes constrain two principal phases of slope instability, expressed as time windows rather than fixed ages. This study develops a framework that integrates uniform morphometric, volumetric, and kinematic features with seismostratigraphy to reconstruct the evolution and relative mobility of multi-episode submarine landslide complexes. The proposed workflow provides a transferable framework for preliminary geohazard assessment on continental margins where repeated slope failure interacts with tectonic and sedimentary forcing. Full article

This preliminary study investigated the effects of ante-mortem Vitamin D₃ (VD₃) supplementation on blood parameters and meat quality in Yanbian yellow bulls. Twenty healthy Yanbian yellow bulls (intact male Yanbian yellow bulls, 30 ± 1 months of age; initial body weight 534 ± 15 kg) were allocated into five groups: a control (basal diet) and four treatment groups with varying VD₃ regimens (3 × 10⁶ or 6 × 10⁶ IU/d for 7 days, with or without a 7-day withdrawal). Results demonstrated that, compared to the control group, VD₃ supplementation elevated serum calcium (p < 0.01) and phosphorus levels (p < 0.05) while enhancing antioxidant capacity (p < 0.05) and immunoglobulin production (p < 0.01). Muscle calcium deposition increased (p < 0.01), accompanied by higher meat lightness (CIE L*) values (p < 0.01) and reduced drip loss rate (p < 0.01). Shear force decreased across cuts (p < 0.01), which was linked to calpain-mediated protein degradation and sarcomere elongation (p < 0.01). Under the conditions of this study, the protocol involving 3.0 × 10⁶ IU/d VD₃ supplementation for 7 days followed by a 7-day withdrawal yielded the most favorable outcomes. These findings suggest a potential strategy to improve beef quality by regulating calcium homeostasis and enhancing muscle proteolysis, warranting further validation in larger populations. Full article

Injection-molding purges are heterogeneous, bulky residues whose uncertain composition and irregular geometry hinder direct reinsertion, making cold shredding costly and maintenance-intensive. This work develops a low-infrastructure solar-assisted pre-processing route using a PMMA Fresnel lens to induce controlled sub-onset softening and enable clean shear cutting without destructive thermal histories. The sub-onset softening is here defined into a viscoelastically active range (at or above T_g for the amorphous phase) while remaining below the melting onset (T_m, onset) and below the onset of thermal degradation (T_d, onset). The station was engineered via QFD and risk-oriented design tools, while a weighted Pugh matrix selected shear cutting over saw-based alternatives. A screening factorial DOE showed that lens height, angle, and their interaction significantly govern focal-spot diameter and receiver temperature, yielding linear relations for conservative set-point selection. Receiver benchmarking further indicated that copper reaches substantially higher temperatures than graphite under identical exposure conditions, supporting copper as the simplest, rapid-heating receiver. Under DOE-calibrated operation, tear-free shear cutting was achieved across representative purge families (PP–ABS, PC–ABS–PP, PA66, PA66-filler, and POM) without forced convection. From a recycling and waste-management perspective, the approach converts bulky purge scrap into mill-compatible feedstock with reduced mechanical resistance, lowering tool wear and fines generation, accelerating downsizing, and limiting stockpiling that elevates combustible-inventory fire risk. Overall, the proposed DOE-calibrated, operator-friendly framework improves recycling feasibility by enabling safer handling, more stable preprocessing throughput, and reduced reliance on disposal or long-term storage for heterogeneous industrial purges. Full article

Barrel tools are relatively new tools that use atypical geometries to achieve shorter production times and improve surface quality. They have been increasingly used in the finishing operations industry, where they are gaining more and more popularity. For their optimal use, it is necessary to know how these tools behave during work in terms of how they load the machined product and what surface qualities they can achieve. For this reason, this study was conducted to compare two tools when machining a free surface. The obtained surface quality and the force load caused by the tool were evaluated. It was found that barrel tool machining results in a heterogeneous surface caused by different cutting speeds along the length of the tool and that the two obtained regions show differences in the obtained roughness. Even though the operation was classified as a finishing process, a difference of up to 30% was identified in the cutting forces acting on the tool and the workpiece. Full article

Accurate prediction of excavation forces is critical for the design reliability and operational safety of Mars surface sampling systems. This study establishes an analytical modeling framework to describe the excavation mechanics of Martian soil, focusing on the formation mechanism and evolution of resistance. Soil deformation and failure processes are qualitatively identified using particle image velocimetry (PIV) and discrete element method (DEM) simulations. Based on limit equilibrium theory, the passive earth pressure is derived, and the scoop is divided into seven force-bearing regions for three-dimensional force decomposition. The analytical model is validated against multibody dynamics–discrete element method (MBD–DEM) co-simulation. The results indicate that excavation resistance exhibits a distinct single-peak evolution, maximizing near the maximum excavation depth. Notably, the inner bottom surface and cutting edge dominate resistance during penetration, contributing approximately 56% and 30% of the total force, respectively. The resistance mechanism transitions after soil emergence due to the gravitational effect of retained soil. Consequently, this framework provides a physically interpretable and quantitatively validated approach for force prediction, offering theoretical support for sampling scoop design and optimization in future Mars missions. Full article

Excessive tool wear can compromise machining precision and increase costs, rendering accurate tool remaining useful life (RUL) prediction imperative in intelligent manufacturing. Traditional methods exhibit intrinsic limitations in cross-modal modeling accuracy and capturing temporal dependencies, failing to meet practical requirements. To transcend these bottlenecks, this study proposes a robust tool RUL prediction framework that combines a multi-channel CNN and a Cross-Modal Transformer. The CNN performs convolution operations to extract local features from wear signals, while the Transformer adaptively synchronizes heterogeneous features (cutting force, vibration, and acoustic emission) to capture long-term degradation trends. Empirical evaluations conducted on the PHM2010 dataset demonstrate the model’s robustness and generalization capability: under the random shuffle–split protocol, the proposed method achieves an R² of up to 0.99, with the RMSE and MAE reaching 2.51 and 1.98, respectively. To further evaluate the framework’s extrapolation ability under domain shifts, a cross-cutter validation protocol was implemented. Under this condition, the experimental results yield an R² of 0.961, an RMSE of 6.92, and an MAE of 6.09. Additionally, the correlation between modality-specific attention weights and their corresponding physical interpretations is systematically investigated. These results confirm the model’s potential for cross-cutter life cycle management in smart manufacturing, providing stable and physically consistent wear estimation and remaining useful life prediction in noise-intensive environments. Full article

Polycrystalline diamond compact (PDC) bits often experience localized heating during impact rock breaking in complex formations, resulting in reduced service life and lower drilling efficiency. An optimized structural design of PDC cutters can significantly enhance bit performance, mitigate thermal concentration, and extend operational longevity. Inspired by previous work on PDC cutter surface topography, five saw-type tooth-shaped cutter designs—featuring one to five saw-type teeth were developed. To evaluate their rock-breaking effectiveness and identify the optimum design, the impact-induced rock fragmentation processes of these cutters were compared using the finite element method. Key indicators, including cutting force, mechanical specific energy (MSE), and cutter surface temperature, were analyzed to determine the superior tooth configuration. Among the five designs, the four-saw-tooth cutter induced the most pronounced stress concentration in the rock. Its optimized number of saw-type teeth ensured full participation of all teeth in rock cutting, enabling efficient rock removal and maximizing breakage performance. Compared with other designs, this cutter exhibited the smallest fluctuations and mean cutting force. The specific mechanical energy decreased initially and then increased with the number of saw-type teeth, reaching a minimum for the four saw-type tooth design. Moreover, it showed the lowest surface temperature and the mildest temperature variation, which helps alleviate localized heating and improve wear resistance. The cutting performance of the four saw-type tooth was further influenced by cutting depth and back rake angle, with optimal values identified as 1.5 mm and 20°, respectively. Compared with a conventional cutter, the four saw-type tooth design reduced the overall surface temperature by approximately 10.69%, with temperature rise confined mainly to the grooves between adjacent saw-type teeth and no widespread thermal concentration observed, confirming its design superiority. Full-scale rock-breaking simulations demonstrated that the bit equipped with four saw-type tooth achieved greater penetration depth and required lower torque than the conventional design, indicating enhanced rock-breaking ability and higher drilling efficiency. In conclusion, the four saw-type tooth PDC cutter design offers a promising approach for developing high-performance drill bits and reducing drilling costs. Full article

Soft–hard composite strata are widely distributed in the surrounding rock of deep tunnels, which severely reduces TBM excavation efficiency. To elucidate the rock-breaking mechanism of TBM disc cutters in composite strata and to address unresolved issues related to cutter force evolution, a self-developed rotary cutting test platform was employed, and three types of large-scale samples (red sandstone, granite, and red sandstone–granite composites) were prepared, on which systematic rotary rock-cutting experiments were conducted under varying confining pressures, rotational speeds, and penetration depths. The results indicate that rock failure in composite strata exhibits pronounced heterogeneity, with significant stress concentration occurring at soft–hard rock interfaces, leading to abrupt increases in normal force and torque. Penetration depth is the most sensitive factor influencing cutting force and specific energy, followed by confining pressure and rotational speed. The minimum specific energy and maximum rock-breaking efficiency are achieved at a penetration depth of 2.5 mm, a confining pressure of 7 MPa, and a rotational speed of 2.5–3 r/min. Furthermore, a dynamic model describing the evolution of disc cutter normal force and torque at soft–hard rock interfaces was derived based on the CSM theoretical framework, and its validity was verified using the experimental results. Integrating experimental observations with theoretical analysis reveals that rock fragmentation in composite strata is dominated by radial tensile cracking in hard rock and shear-dominated crushing in soft rock, while strong stress perturbations and coupled failure occur at the composite interface. This study clarifies the force evolution and fracture mechanisms of disc cutters operating in composite strata and establishes a reliable dynamic prediction model for cutter loads, providing theoretical support and engineering guidance for TBM parameter optimization and cutterhead design. Full article

With the advancement of high-end manufacturing, the application of difficult-to-machine materials such as titanium alloys and superalloys is becoming increasingly widespread. Their inherent material properties pose challenges during machining, including high cutting temperatures, rapid tool wear, and difficulty in controlling surface quality. Nanofluid minimum quantity lubrication (NFMQL) technology, as an advanced lubrication and cooling method, enhances the thermal conductivity and lubricating properties of fluids by uniformly dispersing nanoparticles in the base oil. This paper reviews the preparation methods, advanced atomization techniques, and core mechanisms of NFMQL technology. It focuses on analyzing the effectiveness of this technology in four major machining processes, turning, milling, grinding, and drilling, for typical materials such as titanium alloys, steel, and superalloys. Compared to dry cutting, conventional MQL, and poured cooling, NFMQL reduces cutting forces/torque, cutting temperatures, tool wear, and surface roughness while improving material removal rates, machining accuracy, and surface integrity. This paper concludes by summarizing the technology’s advantages, current challenges, and future research directions. Full article

Grinding wheel conditioning is critical for maintaining cutting efficiency and surface quality, yet conventional mechanical dressers struggle with metal-bonded superabrasive wheels. In this study, wire electrical discharge machining (WEDM) dressing was evaluated on metal-bond diamond wheels of two grit sizes (D54 and D91) and compared to standard mechanical dressing. Dressing was performed on a WEDM machine using varied discharge currents, open-circuit voltages, and duty factors; subsequently, each wheel ground twelve grooves in tungsten carbide under identical parameters. Performance was assessed via maximum spindle power, tangential and normal forces, surface roughness (Ra), radial wheel wear, and edge radius. WEDM-dressed wheels exhibited up to 56% lower peak spindle power and 40–50% lower forces than mechanically dressed wheels. Compared to mechanically dressed wheels, WEDM-conditioned wheels exhibited markedly lower radial wear and maintained substantially sharper, more stable edge radii throughout the grinding cycles. Surface roughness converged after an initial break-in, matching mechanical methods. By selectively eroding the bond without damaging grains, WEDM dressing extends dressing intervals by approximately fivefold and reduces maintenance. Full article

Interface interaction mechanics analysis is of great significance for robot-assisted insertion surgery in minimally invasive surgery and therapy. Previous work indicates that the accurate modeling of soft tissue puncture forces plays a crucial role in surgical planning, robotic needle insertion, and biomechanical simulation, which can give insights useful for physicians to guide and operate assisted robots. The objective of this study is to develop a dynamic multi-component force model that integrates cutting force, stiffness resistance, and frictional interaction to characterize needle–soft tissue interaction during puncture. A dynamic force model is proposed, and a lateral periodic disturbance mechanism is introduced into the simulation framework in order to enhance the robustness and realism of the model under micro-manipulation scenarios. The model has been validated using a series of controlled puncture experiments on porcine liver and renal tissues under varying insertion angles (15°, 30°, 45°) and speeds (0.5 mm/s, 1.5 mm/s, 2.5 mm/s). Corresponding finite element simulations were also conducted using ANSYS software. The agreement between simulation and experiment has been quantitatively evaluated by comparing force–depth and force–time curves, and the statistical significance of the impact of angle and speed on puncture forces has been assessed using ANOVA and Tukey’s HSD tests. Quantitative comparison demonstrated strong consistency, with the optimal case reaching a coefficient of determination (R²) value of 0.96 and Root Mean Square Error (RMSE) below 0.13 N after incorporating a 0.05 mm lateral perturbation. Statistical analysis confirmed the impact of angle and speed on puncture force responses (p < 0.05). Furthermore, comparative analysis revealed that porcine liver exhibits more consistent biomechanical behavior than renal tissue, particularly under perturbation-enhanced simulation. This study successfully establishes a dynamic multi-component force model for soft tissue puncture, validated with high fidelity against experimental data. The incorporated lateral disturbance mechanism enhanced the model’s realism. This work can provide a reliable foundation for the future design of intelligent robot-assisted puncture systems and high-fidelity simulation-based training platforms. Full article

Safety in the operation of Unmanned Aerial Vehicles (UAVs) is emerging as an increasingly important requirement to avoid accidents or possible hazards, because of the growing number and variety of applications that make use of such systems. Consequently, the ability to detect and classify damages occurring on UAV components becomes critical, so that appropriate countermeasures can be applied on time. In this paper, a two-step methodology is proposed to detect damage to UAV propellers, and to classify its severity, so that the most appropriate response can be implemented. In fact, a first step is carried out onboard drone, in real-time, taking advantage of the acoustic emissions of the propeller and the potential of edge processing: a tiny Machine Learning (ML) classifier assesses the severity of the damage and, when deemed critical, the UAV is directed towards a ground station hosting a radar-based system, to discriminate the severity of the fault based on contactless vibration displacement and frequency measurements. The combination of both detection approaches realizes a diagnostic system that is time-responsive and accurate in defining the type, the amount, and the location of the damage. Damage classification performance values over 99% are provided by the embedded audio-based ML model; the radar-based step can further differentiate and measure the location of the propeller cut, which could eventually lead to forced landing of the UAV. Full article

This study investigates the machinability of Continuous Fiber-Reinforced Thermoplastic Composite (CFRTP) produced via Material Extrusion (MEX) additive manufacturing, focusing on drilling as a critical post-processing step in hybrid manufacturing. CFRTP components, fabricated from 3K carbon fibers and a PLA matrix, were subjected to systematic drilling tests under varying cutting speeds (50–110 m/min) and feed rates (0.06–0.24 mm/rev). Thrust force (Fz) and torque (Mz) were recorded using a high-precision dynamometer to evaluate the influence of cutting parameters on mechanical loads and damage mechanisms. Results indicate that increasing the feed rate significantly increases Fz and Mz, promoting fiber pull-out, delamination, and edge deformation, particularly at hole entry and exit regions. Conversely, higher cutting speeds reduce Fz and Mz due to thermal softening of the PLA matrix, enabling more controlled fiber–matrix interaction. Microscopic analyses revealed that damage severity correlates strongly with mechanical load levels. While high feed rates caused pronounced surface irregularities and matrix smearing, low feed rates combined with high cutting speeds yielded smoother hole morphology and preserved fiber–matrix integrity. The study concludes that optimal drilling conditions for CFRTP materials involve low feed rates and high cutting speeds, minimizing mechanical loads and suppressing damage formation. These findings provide a scientific basis for precision finishing strategies in hybrid manufacturing, enhancing dimensional accuracy and structural reliability of CFRTP components for advanced engineering applications. Full article

To address the high energy consumption and low efficiency in shredding film–stalk mixtures during the resource utilization of cotton-field residues in Xinjiang—issues arising from the large mechanical-property differences among the mixture components—a custom single-support shearing fixture was developed to investigate the effects of residual-film wrapping layers, blade rake angle, sliding-cutting angle, and shearing speed on the F_j^max. Based on a Box–Behnken response surface design combined with analysis of variance and microscopic observations of the shearing process, the results showed that all main-effect factors had extremely significant influences on the F_j^max (p < 0.0001). Their relative contributions followed the following order: number of film wrapping layers > blade rake angle > shearing speed > sliding-cutting angle. Residual-film wrapping markedly increased shear resistance; increasing the sliding-cutting angle effectively reduced the shearing force; and reducing the rake angle facilitated more energy-efficient shredding. Interaction analysis further revealed significant coupling between sliding-cutting angle and shearing speed, rake angle and sliding-cutting angle, and rake angle and shearing speed (p < 0.05). Comparative shearing tests indicated that pure cotton stalks exhibited continuous brittle fracture with relatively stable force–displacement profiles, whereas film–stalk composites showed a sequentially coupled failure mode characterized by “residual-film pre-shearing–primary stalk fracture–secondary film stretching,” leading to multi-peak fluctuations in the force–displacement curves. Based on response surface optimization and mechanistic analysis, a parameter combination of a 35° rake angle, a 4–8° sliding-cutting angle, and medium-to-low shearing speed is recommended for shredding operations. This study elucidates the shearing and fragmentation mechanisms of film–stalk mixtures, provides theoretical guidance for optimizing key structural and operational parameters of post-recovery equipment, and offers important engineering value for promoting farmland residual-film pollution control and agricultural waste resource utilization. Full article