Search Results (217)

Prestressed concrete structures are facing serviceability challenges due to rising live loads, material degradation, and seismic demands. Retrofitting with carbon fiber-reinforced polymer (CFRP) offers a cost-effective alternative to full replacement. This study presents a finite element (FE) modeling framework to simulate the seismic performance of prestressed concrete T-beams retrofitted in the negative moment region using near-surface-mounted (NSM) CFRP rods and sheets. The model incorporates nonlinear material behavior and cohesive interaction at the CFRP–concrete interface and is validated against experimental benchmarks, with ultimate load prediction errors of 4.41% for RC T-beams, 0.49% for prestressed I-beams, and 1.30% for prestressed slabs. A parametric investigation was conducted to examine the influence of CFRP embedment depth and initial prestressing level under three seismic conditions. The results showed that fully embedded CFRP rods consistently improved the beams’ ultimate load capacity, with gains of up to 10.84%, 16.84%, and 14.91% under cyclic loading, near-fault ground motion, and far-field ground motion, respectively. Half-embedded CFRP rods also prove effective and offer comparable improvements where full-depth installation is impractical. The cyclic load–displacement histories, the time–load histories under near-fault and far-field excitations, stiffness degradation, and damage contour analysis further confirm that the synergy between full-depth CFRP retrofitting and optimized prestressing enhances structural resilience and energy dissipation under seismic excitation. Full article

This study aims to investigate the bond behavior at earthen mortar–brick interfaces in historic masonry structures. To that end, a series of combined compression–shear tests were conducted to systematically assess the influence of varying water–soil ratios and applied lateral compression on interfacial bond behavior. A fully decoupled microscopic finite element (FE) framework employing cohesive elements was developed to simulate the bond strength of earthen mortar–brick interfaces and validated using Spearman correlation analysis. The results indicate that increasing lateral compression markedly enhances both the peak displacement and shear strength, although it also reduces inter-specimen correlation by 18%. Notably, even under high lateral compression, the finite element predictions maintained a strong correlation with experimental data (R = 0.86), with a maximum deviation of less than 5%, demonstrating the model’s capability to accurately simulate the bond behavior of loess earthen mortar in masonry. These findings provide essential data and a robust computational framework for the preventive conservation of historic masonry structures. Full article

The purpose of this in silico study was to evaluate the main difference of the adhesion strength of direct and semi-direct composite resin restorations in dentin using micro-tensile testing (μTBS) and finite element analysis (FEA). This in silico study employed cohesive zone traction and shear laws to investigate interfacial damage in both restoration groups. Tridimensional finite element models of both restoration specimens were created. A 20 μm thick resin cement layer was created for the semi-direct case. The Clearfil SE Bond 2 adhesive system and the restorative material, Ceram X Spectra ST HV composite resin, were used on both restorations. The numerical bond strength of both restoration techniques was evaluated using two different analysis assumptions. In the first assumption, the numerical analysis procedure included only the non-linear behavior of dentin and the von Mises damage criterion, whereas cohesive zone models were included in the second analysis assumption. The influence of dentin-adhesive cohesive mechanical properties was studied using values reported in the literature, and a sensitivity study helped improve the correlation between experimental and numerical results. The mechanical properties of the composite cohesive zone were defined assuming that the interface strength of dentin and composite follows the values reported by the manufacturer of Spectra ST. Damage initiation and progression were analyzed, and strains and stresses of the cohesive zone models (CZM) were compared with the corresponding perfect bonded models. The experimental µTBS results for the direct restoration strategy showed an adhesive strength of 38.156 ± 10.750 MPa, while the CZM predicted a slightly higher value of 40.4 ± 10.8 MPa. For the indirect restoration strategy, the experimental adhesive strength was 25.449 ± 10.193 MPa, compared to a numerically predicted strength of 28.1 ± 9.3 MPa. Overall, the CZM tends to overestimate the adhesive strength relative to experimental values. The statistical analysis of dentin extension strains for direct (DR) and semi-direct (SR) group models reveals that the SR configuration yields higher strain levels. Hence, these results suggest that, assuming identical dentin properties across both restoration groups, the material configuration in the direct restoration offers better mechanical protection to the dentin. These findings highlight the critical role of incorporating damage mechanics to more accurately characterize stress distribution during tooth rehabilitation. Full article

This paper introduces the overall design plan, development timeline, and preliminary progress of the Autonomous Pit Exploration System project. This project aims to develop an advanced multi-robot system for the efficient inspection of nuclear waste-storage tank pits. The project is structured into three phases: Phase 1 involves data collection and interface definition in collaboration with Hanford Site experts and university partners, focusing on tank riser geometry and hardware solutions. Phase 2 includes the selection of sensors and robot components, detailed mechanical design, and prototyping. Phase 3 integrates all components into a cohesive system managed by a master control package which also incorporates digital twin and surrogate models, and culminates in comprehensive testing and validation at a simulated tank pit at the Idaho National Laboratory. Additionally, the system’s communication design ensures coordinated operation through shared data, power, and control signals. For transportation and deployment, an electric vehicle (EV) is chosen to support the system for a full 10 h shift with better regulatory compliance for field deployment. A telescopic arm design is selected for its simple configuration and superior reach capability and controllability. Preliminary testing utilizes an educational robot to demonstrate the feasibility of splitting computational tasks between edge and cloud computers. Successful simultaneous localization and mapping (SLAM) tasks validate our distributed computing approach. More design considerations are also discussed, including radiation hardness assurance, SLAM performance, software transferability, and digital twinning strategies. Full article

Compared to traditional connection joints, hybrid connection joints are more suitable for large-span frames, especially for prefabricated buildings. This study aims to investigate the seismic performance of novel hybrid connection joints using the proposed innovative finite element modeling method based on the cohesion zone model (referred to as the CZM method). The crack development mechanism of the beam–column interface and the bond–slip mechanism of mild steel were investigated in this work; the performances of self-centering and energy dissipation were also studied using the CZM method. It is demonstrated that the CZM method can be used to accurately and efficiently estimate the performance of hybrid connection joints. This study also shows that the damage of mild steel, post-tensioned steel (referred to as PT steel), and concrete of the innovative hybrid connection joint is slight, the residual deformation of the joint is small, and the equivalent viscous damping coefficient ${\xi }_{\mathrm{e}\mathrm{q}}$ is between 7.8% and 14.85%, which shows good self-resetting and energy dissipation performance. Full article

Deep coalbed methane (CBM) is challenging to develop due to considerable burial depth, high ground stress, and complex geological structures. However, modeling deep CBM in complex formations and setting reasonable simulation parameters to obtain reasonable results still needs exploration. This study presents a comprehensive equivalent finite element modeling method for deep CBM. The method is based on the cohesive element with pore pressure of the zero-thickness (CEPPZ) model to simulate hydraulic fracture propagation and characterize the effects of bedding interfaces and natural fractures. Taking Ordo’s deep CBM in China as an example, a comprehensive equivalent model for hydraulic fracturing was developed for the limestone layer–coal seam–mudstone layer. Then, the filtration parameters of the CEPPZ model and the permeability parameters of the deep CBM reservoir matrix were inverted and calibrated using on-site data from fracturing tests. Finally, the propagation path of hydraulic fractures was simulated under varying ground stress, construction parameters, and perforation positions. The results show that the hydraulic fractures are more likely to expand into layers with low minimum horizontal stress; the effect of a sizable fluid injection rate on the increase in hydraulic fracture length is noticeable; the improvement effect on fracture length and area gradually weakens with the increased fracturing fluid volume and viscosity; and when directional roof limestone/floor mudstone layer perforation is used, and the appropriate perforation location is selected, hydraulic fractures can communicate the coal seam to form a roof limestone/floor mudstone layer indirect fracturing. The results can guide the efficient development of deep CBM, improving the human society’s energy structure. Full article

This study aligns with the development trend of glass substrate packaging. The research aims to analyze the delamination of the substrate–adhesive layer-chip trilayer structure in packaging through experimental testing to obtain interface strength parameters. Subsequently, an iterative process combining experiments and simulations was applied to establish a cohesive zone model characterizing crack initiation and propagation. Finally, reliability analysis of the packaging structure was conducted. The results indicate that the load–displacement curves during sample loading can be experimentally acquired, enabling the determination of critical load values triggering interface delamination. The specific locations of delamination within the packaging structure are also clearly observed. Through simulation fitting, cohesive parameters reflecting interface strength are obtained, which serve as the basis for evaluating interface delamination fractures. Furthermore, applying the calibrated cohesive parameters to the established glass substrate model, simulation analysis evaluates delamination risks under thermal conditions. Full article

Icing represents a significant hazard to the flight safety of unmanned aerial vehicles (UAVs), particularly affecting critical aerodynamic surfaces such as air intakes, wings, and empennages. While conventional adhesive electrothermal de-icing systems are straightforward to operate, they present safety concerns, including a 15–25% increase in system weight, elevated anti-/de-icing power consumption, and the risk of interlayer interface delamination. To address the objectives of reducing weight and power consumption, this study introduces an innovative electrothermal–structural–durability co-design strategy. This approach successfully led to the development of a glass fiber-reinforced polymer (GFRP) component that integrates anti-icing functionality with structural load-bearing capacity, achieved through an embedded hot-pressing process. A stress-damage cohesive zone model was utilized to accurately quantify the threshold of mechanical performance degradation under electrothermal cycling conditions, elucidating the evolution of interfacial stress and the mechanism underlying interlayer failure. Experimental data indicate that this novel component significantly enhances heating performance compared to traditional designs. Specifically, the heating rate increased by approximately 202%, electrothermal efficiency improved by about 13.8% at −30 °C, and interlayer shear strength was enhanced by approximately 30.5%. This research offers essential technical support for the structural optimization, strength assessment, and service life prediction of UAV anti-icing and de-icing systems in the aerospace field. Full article

Nomadic heritage villages constitute significant material cultural heritage. Under China’s cultural revitalization and rural development strategies, these villages face spatial degradation driven by tourism and urbanization. Current research predominantly employs isolated analytical approaches—space syntax often overlooks social dynamics while social network analysis (SNA) overlooks physical interfaces—hindering the development of holistic solutions for socio-spatial resilience. This study proposes a multi-scale integrated assessment framework combining social network analysis (SNA) and space syntax to systematically evaluate public space structures in traditional nomadic villages of Xinjiang. The framework provides scientific evidence for optimizing public space design in these villages, facilitating harmonious coexistence between spatial functionality and cultural values. Focusing on three heritage villages—representing compact, linear, and dispersed morphologies—the research employs a hierarchical “village-street-node” analytical model to dissect spatial configurations and their socio-functional dynamics. Key findings include the following: Compact villages exhibit high central clustering but excessive concentration, necessitating strategies to enhance network resilience and peripheral connectivity. Linear villages demonstrate weak systemic linkages, requiring “segment-connection point supplementation” interventions to mitigate structural elongation. Dispersed villages maintain moderate network density but face challenges in visual integration and centrality, demanding targeted activation of key intersections to improve regional cohesion. By merging SNA’s social attributes with space syntax’s geometric precision, this framework bridges a methodological gap, offering comprehensive spatial optimization solutions. Practical recommendations include culturally embedded placemaking, adaptive reuse of transitional spaces, and thematic zoning to balance heritage conservation with tourism needs. Analyzing Xinjiang’s unique spatial–social interactions provides innovative insights for sustainable heritage village planning and replicable solutions for comparable global cases. Full article

In shield tunneling, ensuring bonding performance at new-to-old concrete interfaces between segments and linings is crucial for composite lining stability. While extensive research exists on the mechanical bonding behavior of such interfaces, comparative studies on two prevalent treatment methods—scabbling and grooving—remain limited. This study systematically evaluates these techniques’ effects on interfacial bonding via direct shear tests, benchmarking against smooth-interface specimens. Complementary cohesive zone modeling simulations further analyze stress distribution and damage evolution during shear failure. The results demonstrate that scabbled specimens exhibit 10.5%~18.2% higher shear strength than grooved counterparts under increasing normal stress, with both treatments significantly enhancing load–transfer synergy through mechanical interlocking. Furthermore, the energy-based bilinear cohesive model accurately predicts full-interface behavior, providing practical guidance for interface treatment selection in tunneling engineering. Full article

This study presents a robust numerical framework for evaluating the upper-bound ultimate bearing capacity of shallow foundations in cohesive and C-phi soils using a self-developed finite element method. The model incorporates multi-segment zero-thickness interface elements to accurately simulate soil discontinuities and progressive failure mechanisms, based on the Mohr–Coulomb failure criterion. In contrast to optimization-based methods such as discontinuity layout optimization (DLO) or traditional finite element limit analysis (FELA), the proposed approach uses predefined failure mechanisms to improve computational transparency and efficiency. A variety of geometric failure mechanisms are analyzed, including configurations with triangular, circular, and logarithmic spiral slip surfaces. Particular focus is given to the transition zone, which is discretized into multiple blocks to enhance accuracy and convergence. The method is developed for two-dimensional problems under the assumption of elastic deformable-plastic behavior and homogeneous isotropic soil, with limitations in automatically detecting failure mechanisms. The proposed approach is validated against classical theoretical solutions, demonstrating excellent agreement. For friction angles ranging from 0° to 40°, the computed bearing capacity factors N_c and N_q show minimal deviation from the analytical results, with errors as low as 0.04–0.19% and 0.12–2.43%, respectively. The findings confirm the method’s effectiveness in capturing complex failure behavior, providing a practical and accurate tool for geotechnical stability assessment and foundation design. Full article

Manufacturing enterprises implementing Industry 4.0 technologies face significant challenges in integrating heterogeneous maintenance data sources and deploying AI solutions effectively. While various AI methods exist for predictive maintenance, the fundamental challenge lies in creating a cohesive architecture that enables seamless data flow and AI deployment. This paper presents a standardized architecture framework with initial implementation steps at Toyota Motor Manufacturing France. The proposed architecture introduces a four-layer approach: (1) a unified data acquisition layer integrating IoT sensors, CMMS, and legacy systems through standardized interfaces (OPC UA/MQTT), (2) a data quality and standardization layer ensuring consistent formats and automated validation, (3) a modular AI deployment layer supporting anomaly detection (Wavelet-based analysis and Deep Learning) and remaining useful life prediction (LSTM networks), and (4) a maintenance workflow integration layer with bi-directional feedback. Key innovations include a unified maintenance data model, configurable data quality pipelines, and human-in-the-loop decision support. A conceptual validation suggests this architecture can improve integration efficiency and reduce equipment downtime. This research contributes to smart maintenance by providing a scalable architecture that balances interoperability, data quality, and practical deployment in brownfield environments. Full article

This paper presents an enhanced hub location model tailored to port–hinterland logistics planning, grounded in the Capacitated Multiple-Allocation Hub Location Problem (CMAHLP). The formulation incorporates nonlinear cost structures, hub-specific operating costs, adaptive capacity constraints, and a feasibility condition based on the Social Net Present Value (NPVsocial) to support the design of intermodal freight networks under asymmetric spatial and socio-environmental conditions. The empirical case focuses on Spain, leveraging its strategic position between Asia, North Africa, and Europe. The model includes four major ports—Barcelona, Valencia, Málaga, and Algeciras—as intermodal gateways connected to the 47 provinces of peninsular Spain through calibrated cost matrices based on real distances and mode-specific road and rail costs. A Genetic Algorithm is applied to evaluate 120 scenarios, varying the number of active hubs (4, 6, 8, 10, 12), transshipment discounts (α = 0.2 and 1.0), and internal parameters. The most efficient configuration involved 300 generations, 150 individuals, a crossover rate of 0.85, and a mutation rate of 0.40. The algorithm integrates guided mutation, elitist reinsertion, and local search on the top 15% of individuals. Results confirm the central role of Madrid, Valencia, and Barcelona, frequently accompanied by high-performance inland hubs such as Málaga, Córdoba, Jaén, Palencia, León, and Zaragoza. Cities with active ports such as Cartagena, Seville, and Alicante appear in several of the most efficient network configurations. Their recurring presence underscores the strategic role of inland hubs located near seaports in supporting logistical cohesion and operational resilience across the system. The COVID-19 crisis, the Suez Canal incident, and the persistent tensions in the Red Sea have made clear the fragility of traditional freight corridors linking Asia and Europe. These shocks have brought renewed strategic attention to southern Spain—particularly the Mediterranean and Andalusian axes—as viable alternatives that offer both geographic and intermodal advantages. In this evolving context, the contribution of southern hubs gains further support through strong system-wide performance indicators such as entropy, cluster diversity, and Pareto efficiency, which allow for the assessment of spatial balance, structural robustness, and optimal trade-offs in intermodal freight planning. Southern hubs, particularly in coordination with North African partners, are poised to gain prominence in an emerging Euro–Maghreb logistics interface that demands a territorial balance and resilient port–hinterland integration. Full article

Aiming at the problem of the insufficient sealing performance of the solenoid valve poppet under a high working load and inspired by the multilevel groove structure of the octopus sucker and the adaptive sealing mechanism, a bionics-based design scheme for an annular groove sealing structure is proposed. By extracting the microscopic groove morphology features of the octopus sucker, we designed a multilayer rectangular cross-section groove structure at the annular interface, combined the designed structure with the Abaqus cohesive model to simulate the interface stripping behavior, and verified its mechanical properties by the pull-out test. The results show that the bionic groove structure significantly improves the bearing capacity of the sealing ring by enhancing the interface contact stress distribution and delaying the crack extension. Under the same working condition, the bionic structure increases the pull-out force by 46.1% compared with the traditional planar sealing ring. This study provides bionic theoretical support and an engineering practice reference for the design of sealing structures in complex working conditions, such as the solenoid valve poppet. Full article

In today’s aviation industry, research and studies are carried out to manufacture and design lightweight, high-performance materials. One of the materials developed in line with this goal is glass laminate aluminum-reinforced epoxy (GLARE), which consists of thin aluminum sheets and S2-glass/epoxy layers. Because of its high impact resistance and excellent fatigue and damage tolerance properties, GLARE is used in different aircraft parts, such as the wing, fuselage, empennage skins, and cargo floors. In this study, a survey was carried out and a low-velocity impact model for GLARE materials was developed using the ABAQUS (2014) version V6.14 software and compared with the results of low-velocity impact tests performed according to the American Society for Testing and Materials (ASTM) D7136 standard. This article introduces a novel integrated approach that combines detailed numerical modeling with experimental validation of GLARE 4A FMLs under low-velocity impact. Leveraging ABAQUS, a robust FEM featuring explicit analysis, cohesive resin interfaces, and custom VUMAT subroutines was developed to accurately simulate energy absorption, dent depth, and delamination. The precise model’s predictions align well with test results performed according to ASTM D7136 standards, exhibiting less than a 0.1% deviation in the displacement (dent depth)–time response, along with deviations of 4.3% in impact energy–time and 5.2% in velocity–time trends at 5.5 ms. Full article