Load Transfer Research Articles

Assessment of Fiber Loading Effects on Mechanical Properties and Prediction of Mechanical Properties via Artificial Neural Networks of Hybrid Jute /Sheep Wool Epoxy Composites

Abstract The primary purpose of this study is to realize the effect of fibre loading on mechanical properties like tensile, bending, impact, interlaminar shear strength and fracture toughness of hybrid composites made of alkaline treated jute and sheep wool hybrid fibres and epoxy. A series of composite laminates were prepared with varying fibre (30%, 40%, 50% and 60%) loadings using hand layup technique. The findings indicated that hybrid composite with equal amount of fiber and resin (JW50) showed a higher strength of 40 MPa against tensile load, maximum strength of 99 MPa against bending load, superior interlaminar shear strength (ILSS) of 3.09MPa, and a maximum fracture toughness of 72 MPa.m1/2 compared to other fibre loadings. In terms of impact test, JW50 displayed the highest impact strength of 85.98 J/m, underscoring its exceptional capacity to absorb energy compared to other composites. The mechanical strengths of these composites were also predicted using an Artificial Neural Network (ANN) model, which generated accuracy of 87.46% for tensile strength, 86.31% for flexural strength, and 83.52% for impact strength. The absolute percentage errors were found to be 12.53%, 13.68%, and 16.47%, respectively, demonstrating the model’s reliability in estimating composite properties based on fibre content and composition. SEM images of fractured samples under tensile load reveal that higher resin content reduces fibre-matrix bonding, while a balanced fibre-to-resin ratio improves load transfer, but too much fibre leads to debonding due to inadequate resin justifying the experimental results.

Haptiknit: Distributed stiffness knitting for wearable haptics.

Haptic devices typically rely on rigid actuators and bulky power supply systems, limiting wearability. Soft materials improve comfort, but careful distribution of stiffness is required to ground actuation forces and enable load transfer to the skin. We present Haptiknit, an approach in which soft, wearable, knit textiles with embedded pneumatic actuators enable programmable haptic display. By integrating pneumatic actuators within high- and low-stiffness machine-knit layers, each actuator can transmit 40 newtons in force with a bandwidth of 14.5 hertz. We demonstrate the concept with an adjustable sleeve for the forearm coupled to an untethered pneumatic control system that conveys a diverse array of social touch signals. We assessed the sleeve's performance for discriminative and affective touch in a three-part user study and compared our results with those of prior electromagnetically actuated approaches. Haptiknit improves touch localization compared with vibrotactile stimulation and communicates social touch cues with fewer actuators than pneumatic textiles that do not invoke distributed stiffness. The Haptiknit sleeve resulted in similar recognition of social touch gestures compared to a voice-coil array but represented a more portable and comfortable form factor.

Investigation of the Effects of Design Parameters on Tooth Profile Formation and Operating Performance in Cycloidal Reducers

Cycloidal reducers have a unique and complex tooth profile design compared to conventional gear systems. Unlike standardized gear profiles, cycloidal reducers provide significant flexibility in design parameters such as module, profile modification coefficient, and eccentricity. However, these parameters interact in a complex manner, affecting both tooth profile formation and the overall performance of the reducer. Inaccuracies in selecting parameters may lead to problems such as excessive contact stress, gear deformation or reduced load transfer efficiency. This study aims to investigate the effects of design parameters on the formation of cycloidal tooth profiles and the operating performance of reducers. By analyzing the relationships and interactions between these parameters, the research provides a deeper understanding that will improve design processes, enhance performance, and contribute to future standardization efforts. As a result, this study aims to contribute to the development of cycloidal reducers that are structurally robust, efficient and suitable for high-performance operation.

Effects of steel fibers and carbon nanotubes on the flexural behavior of hybrid GFRP/steel reinforced concrete beams

BackgroundGlass fiber-reinforced polymer (GFRP) bars offer a superior alternative to steel bars in concrete reinforcement but are associated with wider cracks and higher deformation rates. This study introduces a novel approach by combining steel fibers (SFs) and carbon nanotubes (CNTs) to address these drawbacks and enhance the performance of GFRP-reinforced concrete beams. The unique contribution of this study lies in the simultaneous use of SFs and CNTs, which has not been extensively investigated, particularly in the context of GFRP-reinforced concrete. The study involved testing three sets of nine specimens with different concrete mixtures and reinforcement forms.ResultsThe results showed that adding 0.04% CNTs by cement weight and 0.6% SFs by volume fraction significantly improved the mechanical performance of GFRP and steel reinforced beams. GFRP reinforced beams with CNTs and SFs exhibited a reduction in crack width, a 20% increase in load-carrying capacity, and a 25% reduction in deflection compared to reference specimens. Scanning electron microscope analysis further revealed that CNTs effectively enhanced tensile load transfer, improving flexural behavior of the beams. The finite element analysis using ANSYS confirmed the experimental findings, highlighting the improved stress distribution in the modified concrete mixtures.ConclusionsIncorporating SFs and CNTs in concrete significantly improves the mechanical performance of GFRP-reinforced beams, making them more durable and resilient. These findings suggest that the proposed approach can enhance the longevity and sustainability of concrete structures, particularly in dynamic load applications such as bridges and high-rise buildings. Further experimental and analytical studies are recommended to assess the practical implications and cost-effectiveness of these materials in large-scale construction projects.

Shaft-grouted bored pile – a practical engineering approach to the bearing capacity

ABSTRACT The paper investigates various static load test results on both shaft-grouted and non-shaft-grouted (plain) bored piles at eight project sites in Vietnam. A practical engineering model for shaft-grouted bored piles is proposed to determine the side friction of the shaft-grouted bored piles (drilled shafts), with consideration of shaft friction distribution on instrumented bored piles. The improved ratio of bored pile skin resistance after shaft grouting, compared to non-shaft grouting, ranges from 1.058 to 1.323. The application of shaft grouting is beneficial for the soils of gravel, sand, clayey sand, and silty sand, which have the permeability ranging from 1.00 × 10–5 to 8.60 × 10–5 m/s, while it is not sufficient for clayey soils. Moreover, the possibly mobilised side friction for these shaft-grouted bore piles can be up to 250 kPa. The results derived from the proposed model agree well with the static load test data of the shaft-grouted piles in term of side friction, bearing capacity, and load transfer mechanism.

Field test of geosynthetic-reinforced floating pile-supported embankments on soft soil

This study conducted field tests on geosynthetic-reinforced floating pile-supported embankments to evaluate the load transfer mechanism and embankment deformation during embankment construction. Vertical pressures on pile caps and subsoils between piles, geosynthetic strains, settlement of pile caps and subsoils between piles, and settlement of the embankment at different elevations were measured throughout the embankment construction. Test results showed that the maximum settlement of the pile cap was approximately 66% of subsoils between the piles. Due to the large settlement of the floating piles, the soil arching was not significantly mobilized. The geosynthetic reinforcement exhibited a maximum tensile strain of 0.2% at the end of embankment construction, indicating a mobilization of low tensioned membrane effect. The predicted equal settlement heights at adjacent piles center and the diagonal pile center were close with an average value of approximately 1.23 times the pile net spacing. The measured vertical pressures on subsoil between piles were compared with calculated results using available analytical models from the literature. The analytical models underestimated the vertical pressures on the subsoils between piles, while the modified Terzaghi's model showed better agreement with the measured results than other analytical models.

Transition Effects in Bridge Structures and Their Possible Reduction Using Recycled Materials

This article serves as a review of the current challenges in bridge engineering, specifically addressing the transition effect and the utilization of recycled materials. It aims to identify research gaps and propose innovative approaches, paving the way for future experimental studies. As a review article, the authors critically analyze the existing literature on the transition effects in bridge construction, their causes, and their negative impacts. Integral bridges are discussed as a solution designed to work in conjunction with road or rail embankments to transfer loads, minimizing maintenance and construction costs while increasing durability. Particular attention is given to the potential use of modified plastic composites as an alternative material in integral bridge structures. This concept not only addresses the issue of plastic waste but also promotes the long-term use of recycled materials, a key consideration given recycling limitations. This article highlights the importance of the connection between the embankment and the abutment and provides examples of polymer applications in bridge engineering. By outlining the state of the art, this review identifies future development paths in this niche, but promising, field. Almost 240 literature items were analyzed in detail, and works containing 475 different key words contained in about 3500 individual works were used for scientometric analysis. The results of the analysis clearly indicate the novelty of the presented subject matter.

Research on the Mechanism of Load Transfer Structures in the Construction Process of “Internal Support—Large Block” Prefabricated Subway Stations

In the context of rising global temperatures, countries around the world are increasingly tailoring their own “carbon neutrality” plans. China has also formulated its “dual-carbon” goals, and the construction industry is gradually transitioning towards prefabrication to reduce carbon emissions. This paper uses the Sha Pu Station of Shenzhen’s Metro Line 12 as a case study by which to explore the effects and mechanisms of the load transfer structure during the assembly process of prefabricated subway stations. A three-dimensional finite element model considering soil–structure interaction was established using MIDAS GTS NX finite element software, 2018 version. The internal forces, stresses, and deformations of the station structure were compared under two scenarios—with and without the load transfer structure—using a control variable method. The research results indicate that the load transfer structure effectively reduces shear forces, bending moments, and stresses in the station structure; limits lateral displacements during the assembly process; and effectively concentrates the maximum stresses during construction at the location of the load transfer structure, thereby preventing stress concentration phenomena and enhancing the overall stability of the station structure. This study elucidates the role and effectiveness of the load transfer structure during the assembly of prefabricated components in subway stations, providing a reference for the construction of similar prefabricated metro stations.

Multi-stage load partitioning in additively manufactured Al6061+TiC nanocomposite characterized by in-situ neutron diffraction

Metal matrix composites (MMCs), combining metal matrix and ceramic particles, exhibit high mechanical strength and stiffness compared to conventional metallic materials. During fusion-based additive manufacturing (AM), MMCs undergo a rapid heating and cooling thermal history, which affects the interfacial bonding, thermal misfit stress and mechanical load transfer behavior between the metal matrix and particles, thus impacting the bulk mechanical performance. Here, we investigate the deformation dynamics and phase-specific load transfer in fusion-based AMed Al6061+TiC MMCs through in-situ neutron diffraction. By calculating the phase-specific lattice strains, a multi-stage load transfer and deformation behavior during uniaxial compression is revealed: (1) elastic deformation in Stage I for both phases; (2) sudden stress rebalance between two phases in Stage II, evidenced by a sudden decrease in Al lattice strain and increase in TiC; (3) active load carrying by both phases in Stage III, with both phases experiencing an increase in lattice strains. The deformation mechanism of each stage is deducted by correlating the evolutions of the interphase stresses and peaks’ broadening and intensity of the Al matrix. The local plastic deformation of the Al matrix near the phase interface is triggered and leads to stress rebalancing in Stage II. The global plastic deformation subsequently propagates throughout the Al matrix in Stage III, and the composite is further hardened through both dislocation multiplication and load transfer. The findings offer valuable insights into deformation and load-sharing behavior in AMed MMCs.

Implications of compressive loading of the stomach wall: Interplay between mechanical deformation and microstructure.

During gastric surgery, the stomach wall is compressed with clamps and sutures or staple lines. These short- and long-term deformations can severely compromise the integrity of the tissue and make it difficult for the stomach wall to respond and remodel to the new loading conditions. Consequently, serious intra- and postoperative complications such as the formation of leaks during bariatric surgeries, can be associated with these immense tissue deformations. Hence, the study aimed to investigate the effects of compressive loading of the stomach wall in the radial direction. This was done by macroscopic mechanical loading of the stomach wall in each region of the stomach and evaluating the microstructural changes inflicted in the tissue. For this purpose, several imaging techniques were used, i.e., a histological analysis, second-harmonic generation microscopy, and X-ray micro-computed tomography. The combination of these three methods allowed us to investigate the gradual compression of the different stomach layers as well as the local reorientation and deformation of the main microstructural components, e.g., collagen fibers and muscle bundles. Importantly, this study found that the collagen bundles in the stomach wall straighten and reorient toward the circumferential-longitudinal plane and partially fan out with increased radial compressive deformation. The 3D scans of the stomach wall indicated a deterioration of the blood vessels and buckling of the mucosal glands due to compression. Statement of significance Unfortunately, little is known about the load transfer in the stomach wall during gastric surgery and the associated deformations on the macro- and microscale. The present study investigates the structural changes of the stomach wall, its layers and the inherent biological building blocks using histology, multi-photon microscopy, and micro-computed tomography. For the first time, the layer-specific response to stepwise radial compression of the stomach wall was studied, the related collagen fiber parameters were estimated, and a 3D sample structure was visualized. This clinically-oriented study links the structural changes within the wall to the postoperative remodel- ing process and the irreversibly altered gastric motility, thereby underscoring its relevance to the field of biomedical engineering, e.g., the development and improvement of surgical instruments.

Performance of hinge joints in hollow-core slab bridges reinforced with iron-based shape memory alloy U-bars

The mechanical behavior of hinge joints has an important influence on the hollow-core slab bridges. However, hinge joints are prone to cracking. This study proposed a new hinge joint reinforced by locally prestressed iron-based shape memory alloy (Fe-SMA) U-bars for the new hollow-core slab bridge. To verify the effectiveness of this hinge joint, six test specimens were prepared, encompassing two spans (10 m and 20 m), and three working conditions (nonactivation, activation before cracking, and repair and activation after cracking). The load transfer mechanism under flexural-shear load was investigated, and the validity was verified using a proposed simplified analytical model. The results indicated that the failure mode of the new hinge joint under flexural-shear load can be divided into three stages. The new hinge joint can effectively apply local prestressing by heating activation of the Fe-SMA U-bars, thus increasing the crack penetration load. In addition, the damaged new hinge joints can be repaired and further reinforced by pressure injection of adhesive and heating activation of the Fe-SMA U-bars. Load transfer is affected by the development of cracks, and the ultimate load of the new hinge joint is controlled by the splitting tensile strength of the concrete in the hinge joint.

Investigation of Acid-Etching Evolution in Natural Fractures of Carbonate Reservoirs Under High Closure Stress

Summary The acid-etching evolution of local natural fractures in high-stress carbonate rocks is a complex, multifield coupled phenomenon, governed primarily by closure stress loading, acid flow, and mass transfer reaction. To unravel the characteristics of this evolution and the impact of closure stress and acid injection rate on acid-etching effectiveness, a set of numerical models that integrate fluid flow, chemical reaction, and mechanical deformation within local natural fractures is established, and numerical simulations of fracture deformation and fracture acid-etching are conducted. The results show that continuous closure stress loading fosters the emergence of dominant flow channels by means of acid flow and acid-rock reaction. These channels guide most of the acid flow, continuously dissolving and etching the fracture walls, ultimately forming channelized acid-etching fractures. When closure stress ranges between 10 MPa and 15 MPa, a coupling balance between high closure stress and flow reaction enables the acid-etching fractures to attain greater widths and flow channels, significantly enhancing their long-term conductivity and deformation resistance. As the acid injection rate increases, the dominant flow channels merge into a single channelized acid-etching fracture due to competitive propagation and preferential dissolution. The dominant flow channel expands both vertically and horizontally under the scouring effect of high injection rates, leading to an increase in both the width of the channelized acid-etching fracture channel and the overall acid-etching fracture width.

Application of a combined arching model in the load transfer platform of rigid inclusion system with raft through FEM evaluation

Application of a combined arching model in the load transfer platform of rigid inclusion system with raft through FEM evaluation

Development and field test of Red mud-Fly Ash Geopolymer pile (RFP)

Red mud is an industrial solid waste obtained from the extraction of alumina from bauxite. In order to study the resource utilization of red mud and improve its comprehensive utilization rate, based on the principle of geological polymers, red mud based geological polymers are prepared using raw materials such as red mud, fly ash, blast furnace slag powder, sand, stone, and alkaline solution as pile materials. Through lab experiments, the ratio of red mud and fly ash geopolymer mixtures that can be used for underwater injection and pumping has been obtained; Through on-site experiments, the complete construction process and the bearing characteristics of red mud-fly ash geopolymer piles (RFP) was studied. Environmental impact assessments were conducted by monitoring the changes in water quality around the RFP. The research results laid the foundation for the engineering application of RFP piles. It was found that: (1) At a liquid-solid ratio of 0.55, the geopolymer mixture of red mud: fly ash: sand: crushed stone: GGBS=(1:2:2:4.94:0.1) has good workability. The geopolymer with this mix ratio can meet the performance requirements of pumping and underwater perfusion, the slump can be controlled between 220-225mm, and the strength after 28 days of room temperature curing is 13.9MPa. (2) Developed a complete set of construction techniques for RFP, including drying, grinding and sieving of red mud, preparation of alkaline activator solution, sequence of material mixing, and related processes for pile drilling, placement of conduits, and conduit method grouting. (3) The load test results show that in a silty clay foundation, the ultimate vertical compressive bearing capacity of a single RFP with a pile length of 10.0 meters and a pile diameter of 520mm is 753kN. When the pile spacing is 1.5m, the bearing capacity of single-pile composite foundation is 240kPa. The Q-S curve and the stress distribution curve of the pile indicate that its load transfer characteristics are consistent with those of ordinary concrete piles. The results of the core sampling test on the pile body show that the core sample taken from the 10m pile is relatively complete, the rate of core recovery reaches over 99%,it shows that the pile body is intact. The compressive strength experiment shows that the strength of core samples at different depths is above 10MPa,and up to 19.5MPa. (4) The continuous water quality monitoring results for 5 months indicate that the implementation of RFP has not cause significant adverse effects on the quality of surrounding water bodies.

Spring-Based Trapdoor Tests Evaluating Pile-Supported Load Transfer Platforms with Different Fill Materials

Spring-Based Trapdoor Tests Evaluating Pile-Supported Load Transfer Platforms with Different Fill Materials

Enhanced strength and ductility of boron nitride nanosheet reinforced cu composites through constructing an interfacial three-dimensional structure

To address the poor wettability and weak interface bonding between boron nitride nanosheet (BNNS) and Cu, BNNS/CuTi composites were prepared through matrix microalloying by adding 1 wt% Ti. Solid-state interfacial reactions resulted in the formation of TiN transition layers and TiB whiskers (TiBw), collectively constructed a BNNS-(TiN&TiB)-Cu interfacial three-dimensional structure (I-3DS). The coherent I-3DS significantly reduced the interfacial energy, improved the interfacial stability, and achieved a favorable combination of strength and ductility in BNNS/CuTi composites. The 0.1 wt% BNNS/CuTi composite achieved an ultimate tensile strength (UTS) of 485 MPa, representing increases of 114 % and 62 % over pure Cu and 0.1 wt% BNNS/Cu composite, respectively. The interlocking structure formed by I-3DS and Cu doubled the theoretical interface shear strength limit and improved load transfer efficiency. This study offered new insights into the innovative design of high-performance Cu matrix composites (CMCs) by constructing I-3DS.

Comparative study of failure mechanism of CFRP partially confined normal strength concrete (NSC) and UHPC cylinders under axial compression

Ultra-high performance concrete (UHPC) holds significant potential in marine structures due to its superior compressive strength and enhanced durability in comparison to normal strength concrete (NSC). Carbon fiber-reinforced polymer (CFRP) confinement has been proven to improve these properties further. However, the compressive behavior of CFRP-confined UHPC, especially for partial confinement, presents complexities arising from the intricate interaction mechanism between UHPC and wrapped CFRP strips. To address this issue, the present study conducted axial compression tests accompanied by digital image correlation (DIC) analyses. Failure modes, stress-strain behavior, hoop strain distribution, and cracking evolution of CFRP partially confined NSC/UHPC were elucidated, thereby uncovering the underlying load transfer mechanism between NSC/UHPC and wrapped CFRP strips. Research outcomes show that the enhancement in compressive strength fcc/fco (0.99 ∼ 1.43) and strain εcu/εco (1.51 ∼ 2.59) of CFRP partially confined UHPC is relatively lower than the NSC counterparts (1.28 ∼ 2.98 and 3.82 ∼ 15.14, respectively). Moreover, lower hoop strain efficiency εh,rup/εfrp can be found for CFRP partially confined UHPC compared to NSC (0.61 vs. 0.86). These phenomena were primarily attributed to the localized shear-cracking pattern and low dilation behavior of confined UHPC. Based on the experimental results, the elucidation of the underlying load transfer mechanism between UHPC/NSC and wrapped CFRP strips provides valuable insights into comprehending the compressive behavior of CFRP partially confined UHPC. Finally, the “arching effect” is found to exhibit limited effect on the ultimate condition’s prediction of partially confined UHPC according to the failure mechanism and Li et al.’s model can reliably predict the ultimate conditions among the existing models.

Evaluation of Load Response in Elastomeric Bearings Through Link Element and Finite Element Modelling

Abstract: The Finite element modeling (FEM) and link element analysis of elastomeric bearings were conducted in this study to evaluate load behaviour and ensure compliance with design standards. A detailed FEM was developed, where material properties and boundary conditions were incorporated to simulate load transfer mechanisms, which were enhanced through link element analysis. Validation of results was performed against design codes and analysis software data, confirming the model's accuracy. A reliable method for optimizing elastomeric bearing design, improving structural safety, and meeting essential design checks was presented. Ten models in total were analyzed with variations, firstly the models were selected as per the design checks criteria. Then selected parameter’s output values are compared with each passed model case and then to finalize the research conducted, the data validation table has created with providing recommendations to show the suitability, aiming to improve design practices and address challenges in modern bridge engineering

Time dependent thermal behavior of geothermal energy pile (GEP) for summer and winter periods using CFD analysis

This study investigates the thermomechanical behavior of geothermal energy piles, which serve the dual function of providing structural support and facilitating heat exchange with the surrounding ground. The thermal energy transfer is achieved by circulating a working fluid through U-shaped heat exchanger pipes embedded in the pile, enabling cooling during summer and heating in winter. Unlike conventional piles, the thermomechanical coupling in energy piles alters their load transfer mechanisms, with distinct responses during summer (cooling) and winter (heating) periods that require separate evaluation. While energy pile modeling is relatively new compared to borehole systems, both share operational similarities. To explore this, a numerical simulation was conducted using ANSYS Fluent, incorporating a polyethylene tube, concrete, and surrounding soil. The analysis was performed under various Reynolds numbers (500, 1000, 1500, and 2000) and time intervals (60 min, 360 min, and 720 min) to capture the time-dependent thermal behavior for both cooling and heating periods. The simulations demonstrated satisfactory outcomes, suggesting promising potential for geothermal energy applications in Algerian residential buildings.

Multiscale concurrent topology optimization of transient thermoelastic structures

Previous multiscale concurrent topology optimization methods for thermoelastic structures were primarily based on static loading and steady-state heat transfer conditions, which do not account for transient effects associated with time-dependent loads. To address this limitation, this paper establishes a novel generic multiscale concurrent topology optimization method that incorporates transient thermoelastic coupling based on transient heat conduction and structural dynamics. In this study, first, a transient multiscale thermoelastic sensitivity equation is innovatively derived through adjoint sensitivity analysis. The effectiveness of this equation is then demonstrated through comparative cases involving transient heat conduction, structural dynamics, and transient thermoelastic (including multimaterial and 3D problems) optimization. Furthermore, the research finds that the topology optimization of transient thermoelastic structures also presents transient effects at microscale. This method demonstrates good versatility and applicability across various optimization cases. The method has great potential in the integrated design of materials and structures involving coupling between time-dependent thermal loads and time-dependent mechanical loads.