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We have previously shown evidence that some individuals seem to consistently minimize low back loads when lifting. while others do not. However, it is unknown why. Individual differences in ability to perceive relevant sensory information may explain differences in minimization of low back loads during lifting, consistent with considering load reduction in one's movement objective in an optimal feedback control theory framework. The purpose of this study was to investigate whether individuals' ability to perceive proprioceptive information (both force- and posture-senses) at the low back was associated with peak low back loads when performing generic or occupation-specific lifts. Seventy-two participants were recruited to perform 10 barbell (generic) and backboard (occupation-specific) lifts, while whole-body kinematics and ground reaction forces were collected. Peak low back compression and anteroposterior shear forces normalized to body mass were calculated as dependent variables. Both posture matching ability and force matching ability at the heavier force targets were associated with lower means and variability of peak low-back loads in both lift types, albeit with small effect sizes (R² 5.17). These findings support the utility of an optimal feedback control theory framework to explore factors explaining interindividual differences in low back loads during lifting. Further, this evidence suggests improving proprioceptive ability may be a useful strategy in lift training programs designed for workplace injury prevention. [ABSTRACT FROM AUTHOR]

Purpose: To compare the fracture resistance of five different groups of chairside CAD/CAM molar crowns fabricated from various lithium disilicate ceramic materials (LDC): one conventional precrystallized CAD/CAM LDC, two novel precrystallized LDCs, and one fully crystallized LDC tested both with and without optional sintering. Materials and Methods: A total of 60 chairside CAD/CAM lithium disilicate molar crowns (n = 12 per group) with 1.5-mm occlusal thickness and a 1.0-mm chamfer finish were designed and fabricated with a chairside CAD/CAM system (CEREC, Dentsply Sirona). The restorations were divided into five groups: (1) IPS e.max CAD; (2) Amber Mill; (3) Straumann n!ce; (4) Straumann n!ce with optional sintering; and (5) Supreme CAD. Restorations were cemented using conventional resin luting cement and primer system to 3D-printed resin dies. Bonded restorations were loaded for 100,000 cycles with 275-N force, and the load at break (LB) and peak load (PL) until fracture were measured. SEM images of fracture surfaces on the printed dies were obtained. Results: Fracture resistance was significantly different depending on the material. Supreme CAD showed the highest fracture resistance (LB: 1,557.2 N; PL: 1,785.8 N), followed by Amber Mill (LB: 1,393.0 N; PL: 1,604.2 N) and IPS e.max CAD (LB: 1,315.7 N; PL: 1,461.9 N). Straumann n!ce without (LB: 862.4 N; PL: 942.9 N) and with the optional sintering (LB: 490.4 N; PL: 541.0 N) showed significantly lower fracture resistance than the others. Conclusion: The fracture resistance of chairside CAD/CAM lithium disilicate molar crowns varied depending on the material, and the novel materials did not perform as well as the conventional equivalents. Fully crystallized lithium disilicate ceramic block materials showed lower fracture resistance than precrystallized counterparts and should be used with caution in the clinic, especially with optional sintering. [ABSTRACT FROM AUTHOR]

In this study, we delved into innovative strategies to make neat E‐glass fabrics (NGFs) more impact‐ and tensile‐resistant by using shear‐thickening fluids (STFs). To achieve this goal, the polyethylene glycol (PEG) in STFs has been modified. Subsequently, the STF‐impregnated fabric composites were prepared from unmodified PEG and functionally modified PEGs using malonic and tartaric acids, V/S/GF, M/S/GF, and T/S/GF composites, respectively. Fourier‐transform infrared spectroscopy (FTIR) analysis was conducted to confirm the chemical modification of PEGs. The rheological tests showed a significant improvement in the peak viscosity of modified STFs compared with virgin STF. Dynamic rheological analysis also studied media‐particle interaction, revealing improved media‐particle interaction in STFs due to abundant H‐bonding. In addition, a series of experimental tests, namely compressive impact resistance and strip tensile strength tests, have been conducted to investigate the effect of STF modification on the NGF. The results revealed notable improvements in tensile strength and energy dissipation in the T/S/GF and M/S/GF composites compared with V/S/GF and NGF. Importantly, this improvement extended to the impact performance of single, triple, and quintuple layers. Notably, we found that the peak load of 5 T/S/GF was 37.71%, 18.57%, and 11.87% lower than that of 5NGF, 5 V/S/GF, and 5 M/S/GF, respectively. The idea that made these improvements possible came from PEG functionalization, which helps hydrogen bonds form between the dispersed phase and the dispersion medium, leading to higher viscosity. This, in turn, increases inter‐yarn friction, effectively enhancing the spring‐like properties of T/S/GF and M/S/GF compared with V/S/GF. A two‐step artificial intelligence regression analysis underpinned these findings, elucidating the interplay of molecular mechanisms in high‐performance fabric composites. [ABSTRACT FROM AUTHOR]

The performance of fly ash blended concrete is influenced by the pozzolanic and/or micro-aggregate effect of fly ash particles based on the replacement levels. Dominance of either of this effect greatly influences the mechanical and fracture properties of fly ash blended concrete. In view of this, in the present study, 0%, 20%, 30%, 35%, 40%, 50%, 60% and 70% of fly ash is replaced for cement to investigate the dominance of pozzolanic or micro aggregate effect. The results obtained from the study indicate the reduced strength with increased replacement of fly ash. Similarly, the peak load at fracture decreases with the increased replacement of fly ash. Further, it is concluded that with the increased curing age the compressive strength increases and the fracture strength decreases. Furthermore, the decreased content of calcium hydroxide (CH) with increased fly ash content as obtained from thermo gravimetric analysis (TGA) confirms the presence of excessive fly ash that can contribute as filler material demonstrating the micro-aggregate effect. [ABSTRACT FROM AUTHOR]

This paper presents the results of experimental testing of block masonry prisms and wallettes under uniaxial compression. The compressive load was applied in a direction perpendicular or parallel to the bed joints. Masonry prisms and wallettes were tested in the former direction, whereas only wallettes were tested in the latter direction. No influence of mortar strength or block thickness was observed on the cracking and failure patterns of specimens of similar type, although material crushing and spalling was marginally influenced by block strength. The cracking load for the assemblages tested normal to the bed joint was nearly 90% of the peak load capacity and higher as compared to 70% of the peak load capacity for the wallettes tested parallel to the bed joints. Similar load capacity and elastic modulus were observed for the prisms and wallettes tested normal to the bed joints. Whereas the strength for the wallettes tested parallel to the bed joints was 49%–83% less compared to those tested normal to the bed joints, their elastic modulus was nearly 25% higher. The experimental strength and strain values were compared with the existing analytical methods, which correlated well. [ABSTRACT FROM AUTHOR]

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Extreme wintertime cold in the central United States (US) can drive excessive electricity demand and grid failures, with substantial socioeconomic effects. Predicting cold-induced demand surges is relatively understudied, especially on the subseasonal-to-seasonal (S2S) timescale of 2 weeks to 2 months. North American winter weather regimes are atmospheric tools that are based on persistent atmospheric circulation patterns, and have been linked to potential S2S predictability of extreme cold in the central US. We study the relationship between winter weather regimes and daily peak load across 13 balancing authorities in the Southwest Power Pool. Anomalous ridging across Alaska, the West Coast, and Greenland drive increases in demand and extreme demand risk. Conversely, anomalous troughing across the Arctic and North Pacific reduces extreme demand risk. Thus, weather regimes may not only be an important long-lead predictor for North American electricity load, but potentially a useful tool for end users and stakeholders. [ABSTRACT FROM AUTHOR]

AbstractResearch on musculoskeletal disorders among tomato farmworkers is limited. This pilot study aims to generate insights and preliminary data on tasks performed by tomato farmworkers at a demonstration test plot, evaluating associated ergonomic risk factors. A demonstration test plot was constructed to simulate tasks performed by tomato farmworkers. Muscle activity in the anterior deltoid and upper trapezius was measured using surface electromyography (sEMG) and compared among tasks. The intensity of physical activity during stake pounding, bucket tossing, and tying tasks was monitored using a GT9X activity monitor. Non-parametric ANOVA revealed that the upper trapezius exhibited the highest muscle activity in all tasks (p < 0.05). Stake pounding showed the highest muscle activity, peak loads, and the most intense physical activity. Future studies will focus on assessing tomato farmworker activities over longer shifts and evaluating the impact of posture, fatigue, and energy expenditure on the risk for musculoskeletal disorders. [ABSTRACT FROM AUTHOR]

This study deals with the development of interlayer hybrid composites with improved low-velocity impact response. In the composites produced using the hand lay-up technique, glass, carbon, and Kevlar woven fabrics were used as reinforcement materials and epoxy resin was used as the matrix material. Shear thickening fluid (STF) was impregnated into the fabric for enhancing their performance. The effect of hybridization with different stacking sequences and the impregnation of STF on the peak load, deflection at peak load, energy absorption, impact strength, and damage degree were investigated. All samples were subjected to 3.12 m/s and 4.42 m/s impact velocities using a drop-weight impact tester applying 200J and 400J impact energy levels, respectively. The results revealed that in samples containing neat fabrics, the performances of the pure Kevlar samples were much better in comparison to hybrid samples, especially under high impact energy. However, STF significantly improved the impact strength and energy absorption (up to 30 times) of all samples, including hybrid ones. On the other hand, as the impact energy increased, the use of a Kevlar reinforced plate on the impact surface was crucial, providing higher energy absorption, and no perforation was observed since most of the energy was required to initiate the damage. In the samples with Kevlar in the intermediate layer, however, the majority of the impact energy caused propagation and expansion of the damage. According to the findings, up to 50% cost savings were achieved in STF-impregnated hybrid samples containing Kevlar. [ABSTRACT FROM AUTHOR]

In the Vehicle-to-Grid (V2G) scenario, a multitude of coordinated electric vehicles (EVs) equipped with high-capacity batteries actively participate in power grid dispatching as energy carriers, aiming to achieve a tripartite objective encompassing peak load reduction and valley filling, enhanced utilization of renewable energy sources, and added benefits for electric vehicle owners. To address the existing limitations in the charging–discharging decision-making process for electric vehicles based on V2G, such as the lack of consideration for charging pile constraints, EV profitability, EV transportation timeliness, and high costs associated with central servers, we proposed a reinforcement learning-based Multi-vehicle Joint Routing and Charging–Discharging Decision algorithm (MJRCDD). Firstly, the Markov decision process (MDP) was established to describe the problem, and the route selection and charging–discharging behavior of the vehicle were innovatively integrated in the vehicle action space. Secondly, the multi-vehicle joint route planning and charging–discharging decision problem was solved by multi-agent reinforcement learning. Finally, the effectiveness of MJRCDD was verified by simulation and comparison experiments based on PeMS. [ABSTRACT FROM AUTHOR]

This research aimed to understand how the incorporation of nanocarbon powder (NCP) influences the crashworthiness performance of glass fiber‐reinforced epoxy (GFRE) tubular components, potentially offering insights into improving the safety and resilience of structures or vehicles. Consequently, the crashworthiness behaviors of circular tubes made of GFRE with varying amounts of NCP was studied. Utilizing wet‐wrapping through hand lay‐up technique, GFRE tubes were fabricated with various weight percentages of NCP, that is, 0, 0.25, 0.50, 1, 2, 3, and 4 wt.%. Following that, the crashing load, total absorbed energy against displacement responses, and deformation histories of these tubes under quasi‐static axial loading conditions were calculated and tracked. As part of the crashworthiness analysis, critical indicators were evaluated, including initial peak load (Fip), total absorbed energy (U), mean crash force (Fm), crash force efficiency (CFE), and specific energy absorption (SEA). The findings reveal that the maximum Fip, U, Fm, and SEA were noted at 0.5 wt.% of NCP, with increasing percent's of 30.80, 12.17, 12.16, and 7.50, respectively, compared to the unfilled tube. While, the CFE was recorded by 3 wt.% of NCP with an enhancement of 16.67%. It is worth to note that, the findings reveal that the inclusion of NCP increases crashworthiness metrics up, that is, Fip, U, Fm, and SEA to a concentration of 0.50 wt.% NCP. However, beyond this point, there's a notable decline in performance. Highlights: The GFRE tubes were filled with various wt.% of NCP.The planned tubes were made using hand lay‐up methods.The tubes were subjected to axial compression loads to examine their crashing behavior.The crashing load and absorbed energy versus displacement responses for tubes were exposed.The experimental results were analyzed and discussed. [ABSTRACT FROM AUTHOR]

This study aims to investigate the bending performance and evaluation of aluminum‐carbon fiber reinforced plastic (Al‐CFRP) riveted laminates under varying parameters via self‐pierce riveting and three‐point bending tests. Through the self‐pierce riveting process test, a riveted joint meeting standard requirement was obtained. Based on this joint combination form, Al‐CFRP self‐pierce riveted laminates were prepared. The bending performance test showed the riveted laminate with a span of 80 mm had the greatest bending resistance at a thickness of 2 mm, and the overall strain of the Al‐CFRP self‐pierce riveted laminates was observed by digital image correlation (DIC) technology. Subsequently, validated numerical simulation modeling was conducted by correlating with the test results. On this numerical simulation model basis, further parametric studies and bending performance evaluations (including number of rivets, CFRP lay‐up angle, and laminates width) of the Al‐CFRP self‐pierce riveted laminates were systematically carried out. It was found that the peak load F and bending strength R improved by 1.32% and 26.66%, respectively, while the mass M reduced by 8.99%, for the design variables of var1 of 20 mm, var2 of 6, and var3 of [0/90°]2s. Highlight: An Al‐CFRP riveted laminate structure is proposed to improve the bending properties of riveted laminates by changing the rivet parameters and laminate parameters.The bending properties of riveted laminates with different spans were investigated under three‐point bending loading conditions.The DIC technique observed the changes in the strain field of riveted laminates during bending.The effects of different structural parameters on the bending performance of Al‐CFRP riveted laminates were investigated by numerical simulation.An evaluation method combining the gray correlation degree and the combination assignment method is proposed to obtain the optimum riveted laminate structure under bending load conditions. [ABSTRACT FROM AUTHOR]

A power system is a complex, nonlinear, and dynamic system, with operating parameters that change over time. Because of the complexity of big load lines and faults, high-voltage transmission power systems are usually vulnerable to transient instability concerns, resulting in power losses and increased voltage variation. This issue has the potential to cause catastrophic events such as cascade failure or widespread blackouts. This problem affects Ethiopia's high-voltage transmission power grid in the northwest area. Because of the increased demand for electrical energy, transmission lines' maximum carrying capacity should be enhanced to maintain a secure and uninterrupted power supply to consumers. To address the problem, ANFIS-based UPFC is used for high-voltage transmission lines. This device was chosen as the ideal alternative due to its capacity to rapidly correct reactive power on high-voltage transmission networks. The PSO algorithm was used to determine the best location for the UPFC. The ANFIS controller receives voltage error and rate of change of voltage error as inputs. Seventy percentage of the retrieved data are used for ANFIS training and 30% for ANFIS testing. To show the performance of the proposed controller, three-phase ground faults are used from a severity perspective. When a three-phase ground fault occurs at the midpoint of the Beles to Bahir Dar transmission line, for instance, the settling time of rotor angle deviation, rotor speed, rotor speed deviation, and output active power of synchronous generators using ANFIS-based UPFC is reduced by 70.58%, 37.75%, 37.75%, and 43.75%, respectively, compared to a system without UPFC. At peak load, PI-based UPFC and ANFIS-based UPFC reduce active power loss by 51.25% and 71.50%, respectively, compared to a system without UPFC on the Beles to Bahir Dar transmission line. In terms of percentage overshoot and settling time, ANFIS-based UPFC outperforms PI-based UPFC for transient stability enhancement. [ABSTRACT FROM AUTHOR]

AbstractIn this study, the out-of-plane performance of ultra-high performance concrete (UHPC) thin panels reinforced with basalt fiber reinforced polymer (BFRP) bars was investigated. Eight panels were tested under four-point load, with the investigating parameters including panel thickness, reinforcement ratio, and the presence of steel fibers. The failure mode, crack pattern, load vs. mid-span displacement, and reinforcement strain relationships were studied. Test results revealed that panels with a higher thickness (70 mm) exhibited 178.6% higher initial stiffness, 34.5% higher cracking loads, and 88.7% higher peak loads compared to those with a lower thickness (50 mm). The effects of a larger reinforcement ratio and the presence of steel fibers became more pronounced after concrete cracking, leading to 21.2% and 22.1% higher post-cracking stiffness, respectively. Adding steel fibers helped control the development of diagonal cracks and shifted the panel failure mode from shear to flexural failure. Based on the comparison of test results with design codes, the expressions in CAN/CSA-S806-12 were recommended for predicting the load-carrying capacity of the specimens. Furthermore, a two-dimensional finite element (FE) model was developed to reproduce the test results, which validates the adopted CDP model for UHPC and the bond-slip behaviors between UHPC and BFRP bars. [ABSTRACT FROM AUTHOR]

Battery electric vehicles have been developing rapidly in recent years due to their advantages of energy saving and emission reduction. However, the development of battery electric vehicles is still in its infancy due to the relatively immature charging technology and the lack of infrastructure development. In many researches, there have been many solutions to adopt remote monitoring systems in battery electric vehicles to monitor and collect them in real time for statistical analysis and fault diagnosis. However, the current monitoring systems are carried out statistically and it is difficult to extract much valuable information from the data. In this paper, after analyzing the construction mode of battery electric vehicle charging facilities, the battery electric vehicle charging facility system platform using embedded system was analyzed. Several functions were simulated to meet the problems encountered by users in using it, studying the battery electric vehicle charging facility layout optimization model based on data mining algorithm. Focusing on the coverage problem in the siting problem, the State-of-Charge (SOC) of the battery charge state was analyzed. Taking residential areas as an example and 4 weeks as a cycle, it was found that during the first to fourth weeks, the negative power at 1:00, 20:00 and 24:00 was higher. At the same type of time point, different charging thresholds had a significant impact on the charging load demand of users. The larger the charging threshold of battery electric vehicles appeared, the earlier the peak moment and the higher the peak load. The battery state of the battery electric vehicle in the work area is 60 % at 1:00, and it reaches a relatively full state of 90 % at 8:00. In different regions, the allocation of charging thresholds for battery electric vehicles was different, and the Markov theory was derived from the analysis of the coverage problem to enable fast and effective siting of charging piles while satisfying charging convenience and high utilization of charging facilities to complement the research on the optimization model of battery electric vehicle charging facility layout. [ABSTRACT FROM AUTHOR]

The effectiveness of repair work relies on whether the interface substrate can achieve sufficient bond strength when subjected to numerous stresses. This study investigated the bond properties of repaired normal concrete (NC-to-NC) elements, including cube, beam, and U-shaped specimens, after undergoing natural fracture due to flexural and tensile stresses. The specimens were repaired using a polyurethane (PU) matrix by gluing the two parts and applying compression, splitting, and drop-weight impact (DWI) tests to evaluate the bond strength properties. The results revealed that the PU matrix effectively repairs NC substrate with adequate bond strength, which exceeds the minimum allowable bond strength specified in the ASTM ACI 546-06 to rehabilitate damage concrete structures. The reference beams exhibit a peak applied load capacity of 15.6 kN with less deflection than the repaired samples. The compressive strength of the NC-to-NC repaired specimens loaded along and parallel to the interface plane revealed a decrease in compressive strength of 47.3% and 31.5% compared to the NC-R samples, respectively. The mean number of blows at the cracking stages appeared nearly equal for reference and repaired NC-to-NC specimens. The reference specimens exhibited an average number of 24 and 31 blows at the initial and failure stages, respectively, which were higher by 9.1% and 5.2% than the NC-to-NC repaired specimens. The PU binder showed promising results in achieving adequate interfacial bond strength under static and impact loads. [ABSTRACT FROM AUTHOR]

A two-layer scheduling method of energy storage that considers the uncertainty of both source and load is proposed to coordinate thermal power with composite energy storage to participate in the peak regulation of power systems. Firstly, considering the characteristics of thermal power deep peak regulation, a cost model of thermal power deep peak regulation is constructed and fuzzy parameters are used to manage the uncertainty of wind, photovoltaics, and load. Secondly, based on the peaking characteristics and operating costs of composite energy storage, a two-layer optimal scheduling model of energy storage is constructed. The upper layer takes pumped storage as the optimization goal to improve net load fluctuation and the optimal peak load benefit; the lower layer takes the system's total peak load cost as the optimization goal and obtains a day-before scheduling plan for the energy storage system, using an improved gray wolf algorithm to process it. Finally, we verify the effectiveness of the proposed strategy based on an IEEE 39-node system. [ABSTRACT FROM AUTHOR]

The initial gap (IG) is frequently occurring in the process of resistance spot welding (RSW) for automotive body-in-white structures. It is an inevitable challenge that the RSW with IG can negatively impact the welding quality, subsequently reducing the structural integrity and safety of the vehicle. This research aims to study the influence of the IG on RSW mechanical behaviors based on the refined finite element model (FEM) of RSW with different IGs under tensile shear load. The influence of six types of IGs on the peak load and fracture modes of RSW of plates with similar thicknesses of 1.0 mm and 1.5 mm is investigated through FEM and experiments. To quantify the influence of the IG on the RSW's deformational behavior, a prediction model is introduced to predict the peak load of RSW with different IGs. The prediction model is locally optimized through the Limited memory Broyden Fletcher Goldfarb Shanno (L-BFGS-B) optimization algorithm. Based on the prediction model, the relationship among the peak load values of the tensile shear specimens, the IG, and the mechanical behavior of the RSW is revealed. The results show that the IG has an obvious influence on the peak load values of RSW under tensile shear load, and the fracture modes are both the pull-out fracture (PF) mode. The peak load values of the RSW's tensile shear specimens are decreased with the increment in the IG. Finally, the prediction model can accurately predict the peak load for various IGs, with errors of no more than 3%. [ABSTRACT FROM AUTHOR]

ABSTRACT The mechanical performance of joints for any engineering applications requires accurate characterization of joint interfaces. This paper presents a simplified experimental procedure to estimate the cohesive zone model (CZM) parameters for predicting the interface failure of adhesively bonded joints subjected to mode I (opening) and mode II (shear) loading. The novelty of this procedure lies in predicting all CZM parameters—cohesive stiffness, strength, and cohesive energy (fracture toughness), of the bonded interface using one common experimental setup. It is observed that the cohesive strength and cohesive energy in shear loading are approximately 3.8 and 11.6 times, respectively, compared to the opening loading condition. Employing a triangular cohesive law, the CZM parameters are combined with appropriate damage initiation (quadratic stress) and evolution (power law) criteria. The proposed methodology is verified against experimental load–displacement responses of the bonded interface under mixed‐mode I/II (opening/shear) loading across a wide range of mode mixity (α = 0°, 15°, 30°, 45°, 60°, 75°, and 90°). The maximum error between the experimental and the numerical peak load is 5.11%. The acceptable agreement between the numerical and experimental results confirms the effectiveness of this method in investigating interface fracture in adhesively bonded joints under different loading conditions. [ABSTRACT FROM AUTHOR]

To prevent the early breakage of anchor cables under shear loads in support engineering, a combined structure of Anchor Cable with C-shaped Tube (ACC) has been proposed. The shear resistance enhancement mechanism of this structure and the mechanisms of various influencing factors have yet to be fully revealed. A refined nonlinear finite element model of ACC was original established using ABAQUS software, taking into account the actual structure of the steel strands and the interactions, such as contact and failure between the various components. Various anchor cable pretension forces and block strengths were set to investigate their effects on the shear mechanical response of ACC. The results successfully demonstrated a high correlation between peak shear load and pretension force. The results demonstrate that an increase in pretension force reduces the ACC's peak shear load and break displacement. Additionally, the structure exhibited higher flexural stiffness, the block strength was mobilized earlier, and the block failed locally more quickly. Under high pretension forces, the system exhibited higher shear stiffness in the early stages of shearing due to the influence of the axial force component. With low pretension forces, the ACC exhibited a larger break displacement due to the minor tensile deformation at the shear plane position for the same shear displacement. At low pretension forces, the structure's bending angle increased more rapidly during the middle and later stages of shearing, accompanied by a larger break displacement. Both of these factors led to a greater bending angle at the shear plane position at the point of failure. The results reveal the characteristic of the peak shear load initially increasing and then decreasing with the increase in test block strength, along with its underlying mechanism. As the block strength increased, the bending angle of the structure at the shear plane position increased more rapidly, resulting in higher shear stiffness. With high block strength, the combination of smaller break displacement and greater shear stiffness led to an initial increase followed by a decrease in peak shear load. A comprehensive RSSB (Relative Stiffness between Structure and Test Block) that considers both structural and test block stiffness was proposed. The deformation pattern of the structure was controlled by the RSSB. The higher the RSSB, the wider the plastic hinge extension range for the same shear displacement, the smaller the bending angle at the shear plane position, and the smaller the maximum curvature of the structure. The contact force of the C-shaped tube generally exhibited a "single peak" distribution. As the shear displacement increased, the peak position of the contact force moved away from the shear plane, and the maximum contact force increased rapidly and remained relatively stable. At the end of the shearing process, the contact force of the C-shaped tube exhibited a "double peak" distribution. [ABSTRACT FROM AUTHOR]

Some studies have outlined the use of 3D-printed polyvinylidene fluoride (PVDF) composite-based solid intramedullary (IM) pins with tunable mechanical (tensile, compressive, flexural, and torsional) properties for orthopedic applications. But hitherto little has been reported on the effect of meta-structure induced in 3D-printed IM pins for canines from the mechanical properties' viewpoint. This study highlights the design, fabrication, and testing to mimic actual loading conditions in the canine femur bone on novel IM pin with meta-structure employed in different length zones (30%, 40%, and 50% of total gauge length) prepared by fused filament fabrication (FFF) of PVDF composite. The IM pin (of length 150 mm) has square threads (pitch 2 mm) at the distal end (ɸ7 mm, up to 60 mm in length), and V threads (pitch 1.5 mm) at the proximal end (ɸ6 mm, up to 30 mm in length). The IM pin was fabricated at the best setting (of the FFF process) suggested by the multifactor optimization (at nozzle temperature (Nt) 235°C, printing speed (Ps) 60 mm/s, and raster angle (RA) 45°). The result suggests that for the solid IM pins prepared at the optimized settings the observed elongation, peak load (PL), and break load (BL) during tensile and compressive loading were 4.83 mm, 968.40 N, 958.20 N, and 14.19 mm, 412.80 N, 371.52 N respectively. Whereas for 50% meta-structure the observed elongation, PL, and BL during tensile and compressive loading were 14.49 mm, 405.49 N, 90.20 N, and 13.23 mm, 243.20 N, 218.88 N respectively. For both tensile and compression loading (in this case study), better elongation was noticed for the FFF-based IM pin with 50% meta-structure and hence recommended for implantation in the canine femur bone. The results are also supported by scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) based surface characteristics of the fracture sites. [ABSTRACT FROM AUTHOR]

Highlights This study examines the effects of multilayering in sandwich panel composite structures with different corrugated core configurations under quasi‐static indentation loading. The panels were fabricated using woven glass fibers and epoxy resin via the Vacuum Infusion Process. Experiments were conducted using two hemispherical cylindrical indenters with a diameter of 20 mm (ID = 20 mm) and 10 mm (ID = 10 mm) and the behavior of the composite structure in terms of contact force and fracture mechanisms for different core corrugations (square and butterfly) were investigated in two ways with foam and without foam. The experimental results demonstrate that, among corrugated core geometries without foam, butterfly cores outperform square cores in terms of structural strength, maximum force, moment force, energy absorption, specific energy absorption, and displacement until full indentation. Moreover, the butterfly core shows a higher peak load and different failure mechanisms compared to the square core. Under loading with a 10 mm indenter, the butterfly core without foam only experienced perforation in the loading area, without fracture completely. Also, adding foam did not change failure mechanisms and mechanical behavior in the butterfly geometry. However, in the square geometry, foam filled gaps between the core, preventing fracture completely and leading to only perforation in the loading area, unlike the specimen without foam. The visual analysis during the quasi‐static indentation process revealed several significant damage mechanisms, including matrix cracking, fiber breakage, delamination, buckling and crushing of cell walls, damage to top sheets, core separation, and complete indentation of the samples. Delamination and indentation failure mechanisms were seen on the butterfly core. Skin indentation and rib fracture failure mechanisms were seen on the square core. Butterfly corrugated cores revealed the best performance without/with foam. The core shape was more effective on the strength than the foam addition. [ABSTRACT FROM AUTHOR]

Repair of reinforced concrete structures is required to preserve the adequate performance of these structures throughout their service life. One of the credible techniques is using fibrous concrete as a repair material. In this paper, the performance of steel fibre-reinforced geopolymer concrete (SFRGPC) in the repair of pre-damaged reinforced concrete T-beams (pre-loaded up to 50% of their shear capacity) failing in shear was investigated. Five T-beam series and a four-point loading test were adopted: one reference beam, three beams were repaired with different fibrous ratios of 1, 2, and 3%, and one was repaired with 2% steel fibre and additional U-steel stirrups. The key test results include crack propagation, crack width, initial stiffness, load deflection, peak loads, and strain associated with web stirrups. A clear enhancement was noticed in the performance of the repaired T-beams; their shear capacity was boosted by as much as 45% compared to the control beam. It was also deduced that the beam went from a brittle to a ductile failure mode at 3% SFRGPC and at 2% SFRGPC with U-stirrups. Finally, an analytical model prediction was proposed to predict the shear capacity of repaired T-beams with the SFRGPC. The model showed a satisfactory correlation with experimental results, with an average ratio of 0.995 and a standard deviation of 0.035. [ABSTRACT FROM AUTHOR]

Background: This paper investigates the mechanical properties and failure behaviours of rivet-bonded hybrid joints composed of aluminium adherends and steel rivets under quasi-static tensile loading. Objective: The damage law of hybrid joints is studied to provide a reference for the design and manufacture of hybrid joints. Methods: Tensile tests were conducted on aluminium and steel specimens at various triaxial stress levels. The corresponding finite element model (FEM) was developed to verify the Johnson–Cook damage parameters of the studied metals. The hybrid joint considering the rivet forming process was constructed through FE modelling using the Johnson–Cook failure criterion and Cohesive Zone Model (CZM), which was then validated with the experimental results. Results: Experimental results of the hybrid joint showed that a typical two-stage failure: 1) the adhesive layer bears the majority of the load during the initial loading stage, and 2) the adhesive layer completely fails after reaching the peak load and the rivet solely bears the load subsequently. Conclusions: The riveting process did not cause damage to the adhesive layer, which ensured the reliability of the manufacturing techniques of the hybrid joint. And the yielding of rivets may buffer the immediate failure of hybrid joints. [ABSTRACT FROM AUTHOR]

[Objective] Gabion is widely used in slope stabilization, revetment engineering, subgrade reinforcement, and other applications. However, its use in tunnel lining remains underexplored. Owing to its unique multiporosity, which provides excellent deformation capacity and notable bearing strength, gabion shows promising potential for managing the notable deformations and high ground stresses encountered in tunnel surrounding rock. Therefore, studying the static mechanical behavior of tunnel lining components made with gabion is of practical importance. [Methods] This paper presents a simplified molding technique for gabion components and a custom-designed test loading apparatus. Additionally, a numerical modeling methodology specifically tailored for gabion components in tunnel lining is introduced based on discrete element calculations. Next, a comparative analysis is conducted to examine the influence of two key parameters--the strength of the gabion mesh and the effective modulus of the stone filling--on the variation in static mechanical characteristics of tunnel lining components constructed with gabion. This study provides valuable insights into the performance of gabion-based tunnel linings. [Results] 1) The failure of the gabion component in tunnel lining mainly occurs through instability, with only minor cases of wire breakage and stone-filling fracture. Throughout the loading process, the load-displacement curve of the component exhibits notable fluctuations driven by the ongoing interaction between the internal stone filling and the gabion mesh. The overall load-displacement curve increases and then decreases. Despite considerable deformation, the component maintains a high bearing capacity at the end of loading. 2) The tensile strength of the gabion mesh has little effect on the deformation modulus during the initial deformation stage under static load but has more impact on the peak load. The higher the tensile strength of the gabion mesh, the greater the displacement and peak strength at peak load. Under varying tensile strength conditions, the differences in peak load displacement and peak strength reached 28.9% and 25.2%, respectively, because when the tensile strength of the gabion mesh is higher, the component is more resistant to failure, allowing a more effective interaction between the stone filling and the gabion mesh. 3) Compared with the tensile strength of the gabion mesh, the effective modulus of stone filling has a pronounced impact on the component performance. As the effective modulus of the stone filling increases, the postpeak decline in the load-displacement curve becomes more prominent. During the loading process, the energy consumption of the component, peak loading strength, and effective modulus of the stone filling exhibit a distinct piecewise relationship, characterized by an initial increase followed by stabilization. [Conclusions] This experiment provides clear guidance for students conducting static loading mechanical model tests on gabion-constructed tunnel lining components, enhancing the effectiveness of experimental teaching. [ABSTRACT FROM AUTHOR]

Underground geotechnical engineering encounters persistent challenges in ensuring the stability and safety of surrounding rock structures, particularly within rocky tunnels. Rock reinforcement techniques, including the use of steel mesh, are critical to achieving this goal. However, there exists a knowledge gap regarding the comprehensive understanding of the mechanical behavior and failure mechanisms exhibited by steel mesh under diverse loading conditions. This study thoroughly explored the steel mesh's performance throughout the entire loading-failure process, innovating with detailed analysis and modeling techniques. By integrating advanced numerical modeling with laboratory experiments, the study examines the influence of varying reinforcement levels and geometric parameters on the steel mesh strength and deformation characteristics. Sensitivity analysis, employing gray correlation theory, identifies the key factors affecting the mesh performance, while a BP (Backpropagation) neural network model predicts maximum vertical deformation with high accuracy. The findings underscore the critical role of steel diameter and mesh spacing in optimizing peak load capacity, displacement, and energy absorption, offering practical guidelines for design improvements. The use of a Bayesian Regularization (BR) algorithm further enhances the predictive accuracy compared to traditional methods. This research provides new insights into optimizing steel mesh design for underground applications, offering an innovative approach to enhancing structural safety in geotechnical projects. [ABSTRACT FROM AUTHOR]

Load balancing between required power demand and the available generation capacity is the main task of demand response for a smart grid. Matching between the objectives of users and utilities is the main gap that should be addressed in the demand response context. In this paper, a multi-user optimal load scheduling is proposed to benefit both utility companies and users. Different objectives are considered to form a multi-objective artificial hummingbird algorithm (MAHA). The cost of energy consumption, peak of load, and user inconvenience are the main objectives considered in this work. A hybrid multi-criteria decision making method is considered to select the dominance solutions. This approach is based on the removal effects of criteria (MERECs) and is utilized for deriving appropriate weights of various criteria. Next, the Vlse Kriterijumska Optimizacija Kompromisno Resenje (VIKOR) method is used to find the best solution of load scheduling from a set of Pareto front solutions produced by MAHA. Multiple pricing schemes are applied in this work, namely the time of use (ToU) and adaptive consumption level pricing scheme (ACLPS), to test the proposed system with regards to different pricing rates. Furthermore, non-cooperative and cooperative users' working schemes are considered to overcome the issue of making a new peak load time through shifting the user load from the peak to off-peak period to realize minimum energy cost. The results demonstrate 81% cost savings for the proposed method with the cooperative mode while using ACLPS and 40% savings regarding ToU. Furthermore, the peak saving for the same mode of operation provides about 68% and 64% for ACLPs and ToU, respectively. The finding of this work has been validated against other related contributions to examine the significance of the proposed technique. The analyses in this research have concluded that the presented approach has realized a remarkable saving for the peak power intervals and energy cost while maintaining an acceptable range of the customer inconvenience level. [ABSTRACT FROM AUTHOR]

Demand-side management of smart grid with electric vehicles (EVs) is overviewed in this review paper. The major objective of the work is to reduce the hourly peak load to obtain a steady load schedule, maximize user satisfaction and reduce cost. This review allows for the probability of leveling the everyday energy load arc and unstable demand response to hourly prices from one time period to another. To obtain a balanced everyday load schedule, increase user satisfaction, and cut costs, the main aim is to reduce peak hourly load. A management system for an EV connected to the national grid for a future household with controllable electric loads. The approach that has been presented enables the integration of EVs and renewable resources while also optimizing the demand and generation in hourly distribution. The agents are taken into account for managing load, storage, and generation; specifically, they are EV aggregators. The vehicle-to-grid (V2G) combination of electric vehicles is a key aspect of this study; with this capability, EVs may offer power grid-specific services like load shifting and congestion management. By maximizing the hourly distribution of demand as well as generation, accounting for technical limitations, and enabling the addition of EVs and RES. [ABSTRACT FROM AUTHOR]

Transitioning from petrol or gas vehicles to electric vehicles (EVs) poses significant challenges in reducing emissions, lowering operational costs, and improving energy storage. Wireless charging EVs offer promising solutions to wired charging limitations such as restricted travel range and lengthy charging times. This paper presents a comprehensive approach to address the challenges of wireless power transfer (WPT) for EVs by optimizing coupling frequency and coil design to enhance efficiency while minimizing electromagnetic interference (EMI) and heat generation. A novel coil design and adaptive hardware are proposed to improve power transfer efficiency (PTE) by defining the optimal magnetic resonant coupling WPT and mitigating coil misalignment, which is considered a significant barrier to the widespread adoption of WPT for EVs. A new methodology for designing and arranging roadside lanes and facilities for dynamic wireless charging (DWC) of EVs is introduced. This includes the optimization of transmitter coils (TCs), receiving coils (RCs), compensation circuits, and high-frequency inverters/converters using the partial differential equation toolbox (pdetool). The integration of wireless charging systems with smart grid technology is explored to enhance energy distribution and reduce peak load issues. The paper proposes a DWC system with multiple segmented transmitters integrated with adaptive renewable photovoltaic (PV) units and a battery system using the utility main grid as a backup. The design process includes the determination of the required PV array capacity, station battery sizing, and inverters/converters to ensure maximum power point tracking (MPPT). To validate the proposed system, it was tested in two scenarios: charging a single EV at different speeds and simultaneously charging two EVs over a 1 km stretch with a 50 kW system, achieving a total range of 500 km. Experimental validation was performed through real-time simulation and hardware tests using an OPAL-RT platform, demonstrating a power transfer efficiency of 90.7%, thus confirming the scalability and feasibility of the system for future EV infrastructure. [ABSTRACT FROM AUTHOR]

In this work, composites made of polylactide (PLA) and filled with alkali-pretreated rice husk (RH) were investigated. Composites containing 20, 30, and 40 wt.% of RH were synthesized. It was shown that alkaline treatment, along with the change in crystal lattice, led to an increase in the content of non-crystalline parts and the volume of intercrystalline spaces, and the internal surface of the cellulose fiber increased, which resulted in improved adhesion of the fiber with the matrix. The addition of rice husk to the PLA matrix led to an increase in the flexural modulus, which increased to 2881 MPa for the PLA/RH (80/20 wt.%) and 3034 MPa for the PLA/RH (70/30 wt.%) composites and lowered the peak load stress by approximately 43% for the composite with 20 wt.% RH and 56% for the composite with 30 wt.% RH. The reduction in the degree of PLA crystallinity allows macromolecules to move more freely in amorphous regions, which has a positive effect on increasing the flexibility of materials in general. The optimal formulation is a composite consisting of 30% RH and 70% PLA matrix. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Textile-reinforced ultrahigh-toughness cementitious composite (UHTCC) jackets––herein referred to as TRU jackets––are an innovative strengthening system for reinforced concrete (RC) structures. The ductile UHTCC used for this jacket system exhibits better deformation compatibility with the textile than brittle mortar does. In this paper, we present an experimental study of the seismic performance of RC columns strengthened with TRU jackets using cyclic lateral loading tests. The results indicated that the TRU jacket could effectively restrain the development of cracks in the plastic hinge zone, delay stiffness deterioration, and significantly improve ductility and energy dissipation. Moreover, at a low stirrup ratio of 0.39%, the peak load of the jacketed columns was greatly enhanced compared to the peak load of the RC companion columns. With an increased number of textile layers, seismic performance was improved. When the ratio of axial force to axial capacity was increased from 0.15 to 0.30, ductility and energy dissipation did not drop for the TRU-jacketed columns. As the strengthening height decreased from 2.0 to 1.2 times the cross-sectional height of the columns, the seismic performance of the jacketed columns remained almost unchanged. A numerical model was developed for the seismic simulation of TRU-jacketed columns, and the predicted hysteresis curves agree well with the test data. [ABSTRACT FROM AUTHOR]

Sierra Leone struggles with electricity with a 38% electrification rate. The expanding distribution network with limited generation capacity leads to frequent power outages during peak hours. Demand response (DR), a widely recognized demand‐side management strategy, has effectively balanced the electricity supply and generation worldwide. The primary objective of this study is to assess the potential for DR in the residential electricity sector, focusing on drivers such as security, environmental concerns, and incentives. The case study was conducted in Freetown, Sierra Leone. This study employs diversified demand modeling with household energy audit data to estimate the potential reduction in peak load achievable through voluntary demand response (VDR). This study generated load profiles for 12 household appliances and an aggregated load profile for the Freetown distribution network. Notably, the study achieved a substantial peak load reduction of 4.19 and 3.54 MW during the morning and evening peak hours, respectively. Additionally, this research highlights the significant roles of power security, price incentives, and environmental factors in encouraging residential consumers in Sierra Leone to participate in DR programs. This study underscores the response's role in Sierra Leone's electricity challenges, providing insights into peak load reduction and the motivation for residential consumer participation in DR programs. [ABSTRACT FROM AUTHOR]

Lawsonia intracellularis is the etiological agent of proliferative enteropathy (PE) in pigs, horses and wide range of mammals. Little is known about the role of innate immune response during L. intracellularis infection. In this study, we investigated the nuclear factor-κB (NF-κB)-regulated immune response against infection of a clinical strain Dkp23 and a live-attenuated Enterisol vaccine strain in PK-15 cells. We found that expression of NF-κB target genes TNF-α, IFN-γ, IL-6 and IL-8 were modulated during the course of infection. At 5 dpi, there was a significant increase in p65 NF-κB activation, including protein nuclear translocation and phosphorylation, synchronous with the induction of IL-6, IFN-γ and IL-8 expression in L. intracellularis infected cells, especially for Enterisol vaccine strain-infected cells. This result suggests that NF-κB signalling level is induced when L. intracellularis bacterial load peaks at 5 dpi. The induction of pro-inflammatory cytokines expression is consistent with the decreased viability of L. intracellularis-infected cells especially that of the vaccine strain. There were no significant changes in NF-κB signalling between vaccine and Dkp23 infection in PK-15 cells, except for moderate levels of differences in NF-κB target genes expression which might be a reflection of differences in intracellular bacterial load. Overall, the data presented here indicate a correlation between the induction of NF-κB signalling and the L. intracellularis bacterial load in PK-15 cells. [ABSTRACT FROM AUTHOR]

Accurate load forecasting is essential for reliable and efficient operation of power systems. Traditional forecasting methods often struggle with capturing complex nonlinear patterns in load data. Artificial neural networks (ANNs) have emerged as a promising alternative due to their ability to learn complex relationships from historical data (Syed et al. in IEEEA 9:54992–55008, 2021. https://doi.org/10.1109/ACCESS.2021.3071654). This study investigates the potential of ANNs for short-term peak load forecasting in a 150 kV power system in Semarang, Indonesia. The study examines the impact of different input variables, including historical peak load, minimum load, population, and energy production, on forecasting accuracy. Several ANN architectures are trained and evaluated using mean absolute percentage error (MAPE) and mean squared error (MSE) metrics as reported by Demuth and De Jesús (neural network design). The results indicate that ANNs can achieve high accuracy in predicting peak load, with MAPE values below 10%. The study also demonstrates the importance of carefully selecting input variables and training parameters for optimal model performance. The findings highlight the potential of ANNs for improving load forecasting accuracy in power systems, contributing to enhanced grid reliability and operational efficiency. The findings of this study contribute to a deeper understanding of the application of ANNs in power system load forecasting. They demonstrate the potential of ANNs to achieve high accuracy and provide valuable insights into the factors influencing model performance. The findings are relevant for power system operators, researchers, and policymakers working to improve grid reliability and efficiency as reported by Prabha Kundur and Malik (Power System Stability and Control, McGraw-Hill Education, New York, 2022. https://www.accessengineeringlibrary.com/content/book/9781260473544). [ABSTRACT FROM AUTHOR]

Highlights The aim of this paper is to explore the effect of polyurethane foam filler on the out‐of‐plane compressive property and low‐velocity impact resistance of the orthogonal corrugated sandwich panel by experimental method. The results show that foam filling increases the energy absorption and specific energy absorption of the orthogonal corrugated sandwich panel by 64.75% and 38.22% under compressive load, respectively. Furthermore, during compression, the filled foam causes the core strut undergo pure buckling failure and gradually folds rather than brittle fracture. Under low‐velocity impact, the strengthening effect of foam filling on the first peak load of the load–displacement of the orthogonal corrugated sandwich panel decreases with the increase of impact energy, while the inhibition effect on the impactor drop increases with the increase of impact energy. The results can provide a reference for the design and optimization of foam‐filled hybrid sandwich structures. The compressive property and low‐velocity impact resistance of the foam‐filled orthogonal corrugated sandwich panel are tested. The effect of foam filling on the mechanical properties of the orthogonal corrugated sandwich panel is obtained by comparing the out‐of‐plane compressive response and low‐velocity impact response of the empty and foam‐filled orthogonal corrugated sandwich panel and foam sandwich panel. Foam filling can improve the load‐bearing property and energy‐absorbing capacity of the orthogonal corrugated sandwich panel and make it more stable progressive damage. [ABSTRACT FROM AUTHOR]

Copyright of Zhejiang Electric Power is the property of Zhejiang Electric Power Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Highlights 3D printing of continuous fiber reinforced thermoplastic composites (CFRTPCs) has been applied for the molding of composite complex structures due to the advantages of flexibility and one‐step forming. In this study, feature points simplification, merging and rearrangement were accomplished for Messerschmitt‐Bölkow‐Blohm (MBB) beam and cantilever beam to generate single‐stroke print paths for the specimens. For the significant stress areas in the finite element analysis results of these structures, a local reinforcement method using orthogonal layups was proposed, which was achieved by raising and lowering the print head and adjusting the fiber volume fraction during the printing. After experimental validation and failure modes analysis, the path planning significantly improved the peak load and structural stiffness of the specimens, and the local reinforcement further enhanced the equivalent specific strength and specific stiffness. This study provides a single‐stroke 3D printing strategy for complex structure molding in conjunction with parameter adjustments. A single‐stroke path planning was developed for MBB beams and cantilever beams, including simplification, merging and rearrangement methods for feature points. A local reinforcement method was proposed, which was achieved by raising and lowering the print head and adjusting the fiber volume fraction during the printing process. The effect of different print paths on specimen properties was investigated. [ABSTRACT FROM AUTHOR]

This paper addresses the potential of integrating a concentrating photovoltaic thermal (CPV/T) system with an absorption chiller for the purpose of space cooling in residential buildings in the United Arab Emirates (UAE). The proposed system consists of a low concentrating photovoltaic thermal (CPV/T) collector that utilizes mono-crystalline silicon photovoltaic (PV) cells integrated with a single-effect absorption chiller. The integrated system was modeled using the Transient System Simulation (TRNSYS v17) software. The obtained model was implemented in a case study represented by a villa situated in Abu Dhabi having a peak cooling load of 366 kW. The hybrid system was proposed to have a contribution of 60% renewable energy and 40% conventional nonrenewable energy. A feasibility study was carried out that demonstrated that the system could save approximately 670,700 kWh annually and reduce carbon dioxide emissions by 461 tons per year. The reduction in carbon dioxide emissions is equivalent of removing approximately 98 cars off the road. The payback period for the system was estimated to be 3.12 years. [ABSTRACT FROM AUTHOR]

Highlights Interpenetrating phase composites (IPCs) can combine the advantages of each component and have a good application prospect. IPCs were prepared by combining open‐cell aluminum foam (AF) and epoxy resin (EP) in three‐dimensional space in this study. Different contents of silica powder (SP, 80, 100, 120, and 140 wt%) were added to EP to improve the compressive and three‐point bending properties of IPCs. In the bending test, acoustic emission (AE) was applied to track the bending deformation of the samples, and k‐means clustering algorithm was applied to identify the damage modes. The compressive and bending properties of IPCs increased first and then decreased with the increase of SP content, and reached the maximum when the SP content was 100 wt%, with a compressive yield strength of 74.6 MPa and a bending peak load of 1.96 kN. The performance degradation was mainly attributed to the AF/EP debonding due to SP distribution at the interface. The X‐type shear band and EP/AF debonding appeared in compression failures of AF and IPCs, respectively. The AE clustering results showed that under bending load, plastic deformation of matrix (60–200 kHz) and fracture failure (230–340 kHz) modes appeared in AF, while EP/AF debonding (60–120 kHz), EP failure (120–230 kHz) and plastic deformation of foam matrix (230–250 kHz) modes appeared in IPCs. Silica powder was added to improve compressive and bending properties of IPCs. Acoustic emission was used to monitor bending of foam and IPCs firstly. k‐means clustering was used to identify and classify bending damage patterns. [ABSTRACT FROM AUTHOR]

Layered rocks were prepared to conduct Brazilian splitting tests with different laminar inclinations. Cracks on the surface are identified and quantitatively characterized based on digital images. The discrete element numerical software PFC3D was utilized to model the Brazilian splitting of laminated rocks with different inclinations. The effect of cohesion strength, tensile strength, and joint roughness coefficient (JRC) of smooth joints on tensile strength was investigated. The findings reveal that with increasing the inclination angle (β), the properties of the laminar surface gradually play a dominant role in the specimen damage, demonstrating that the peak load decreases continuously. The variation in the fractal dimension of the cracks primarily undergoes three stages: continuous increase, sharp decrease, and increase again. The tensile strength and failure patterns of the numerical simulations correlate well with the test. When β = 0°, the tensile strength of the specimen is independent of the joint properties; As β increases, the influence becomes apparent. Specifically, the tensile strength gradually increases with the increase in joint cohesion. Except when β = 90°, the tensile strength shows initially increasing and then leveling off with increasing the tensile strength of joints. Whereas, under the influence of the bedding plane roughness, it exhibits a continuous decrease at low inclination and an increase at high inclination with increasing JRC. [ABSTRACT FROM AUTHOR]

To solve the problem of a large amount of fly ash accumulation and study the axial compression and bearing capacity prediction of the self-compacting fly ash concrete filled circle steel tube (SCCFST) columns, eight specimens are designed to explore the impact of concrete strength grade, internal structural measures, and additional parameters. The stress, progression of deformation, and failure mode of each specimen are observed during the loading process. The load–displacement curves, load-strain curves, characteristic load and displacement, ductility, and stiffness degradation are analyzed. The findings revealed that shear deformation occurred predominantly in the middle and upper portions of the steel tubes. Enhancing the strength of the concrete or adopting internal structural measures could increase the bearing capacity and ductility of the specimens. The peak load and ductility could be increased by up to 17.6 and 53.6%, respectively. The proposed unified calculation equation for the axial compression bearing capacity of SCCFST columns demonstrates notable reliability and precision. Furthermore, these tests offer valuable references for the engineering application of various forms of SCCFST columns, which are of significant importance in practical engineering. [ABSTRACT FROM AUTHOR]

Crash boxes are safety elements generally made of metallic materials and mounted on the chassis of vehicles to prevent possible injuries to driver and passengers by absorbing the energy generated during a collision and ensuring integrity of vehicle. In order to save fuel and reduce harmful gases released into the environment, the proportion of metallic materials used in vehicles is decreasing and being replaced by composite materials. While composite materials are as durable as metallic materials, they are preferred because they are lighter. In this study, circular composites consisting of glass (S1), aramid (S2), carbon (S3), and hybrid combinations of aramid‐carbon‐glass (S4), carbon‐glass‐aramid (S5), and glass‐aramid‐carbon (S6), all with epoxy resin matrices, were produced using the vacuum infusion method and investigated. Crush parameters, maximum peak loads and specific energy absorption of hybrid tubes with different fiber types and winding order were compared. S3 tube had the best energy absorption performance among all samples of 257.288 Joules, while the worst energy absorption performance was obtained for S2 tube with 30.944 Joules. Among the hybrid samples, the best result was determined as 166.50 Joule with hybrid S5. Although the energy absorption capacities of hybrid composite tubes were close to each other, they had lower results for energy absorption and specific energy absorption than S1 and S3. For specific energy absorption, as with energy absorption, the best result was obtained with S3, while the lowest result was obtained with S2. Highlights: The aim of this study is to evaluate the performance of composite crash boxes.The effect of fiber type and hybridization was examined.Specific energy absorptions and maximum contact forces were compared.Cylindrical samples were produced by vacuum infusion.The variation of damage depending on fiber type was investigated. [ABSTRACT FROM AUTHOR]

The load‐bearing capacity and failure characteristics of composite structures are closely related to their dimensions. In this study, low‐velocity impact, ultrasonic non‐destructive testing, and compression after impact tests were conducted on composite laminates of varying widths to investigate the influence of size effects. Distinct impact response profiles and compression failure modes were characterized. The results indicate that under impact loading, the delamination threshold load (6700 N ~ 7200 N) and the knee‐point energy (40 J) are not affected by width. However, variations in width lead to differences in indentation depth, impact duration, peak load, delamination characteristics, and energy absorption. Furthermore, increasing impact energy further magnifies these differences. Under compression loading, wider laminates exhibit lower residual strength, with the influence of impact energy on residual strength decreasing as width increases. Importantly, the observed compression failure deformation mode transitions from localized buckling to widespread sub‐layer delamination‐induced compression failure. This suggests that changes in width alter the governing mechanical mechanisms of CAI failure. Consequently, the use of a single‐size laminate to represent both LVI and CAI processes is not recommended. Based on experimental results, the reliability of the equivalent damage method in predicting the residual compression strength of laminates of different widths was confirmed, providing valuable insights for practical engineering applications. Highlights: Assess the variations in the low‐velocity impact process of laminates with different widths.Evaluate the delamination damage of laminates after impacts by ultrasonic C‐scan techniques.Investigate the effect of variation in widths on the compression behavior of laminates after impact.Validate the feasibility of equivalent damage modeling for calculating residual strength. [ABSTRACT FROM AUTHOR]

Carbon fiber reinforced plastic (CFRP) composites have been widely used in engineering. This paper investigates the effect of composite z-pin (polyimide fiber/epoxy resin) on flexural properties of skin/stringer composite structure with different z-pin densities and diameters. Compared with unpinned specimens, the peak loading and energy absorption of z-pinned specimens are increased by 98% and 9 times, respectively. Parameterized research indicates that the optimal z-pin density is 1.35%. And thin z-pins are beneficial to improve the peak loading and energy absorption, which attributes to more total contact area of z-pins. The statistical results present that z-pin pre-hole inserted (ZPI) process can significantly reduce initial damages of z-pinned specimens compared with Ultrasonically Assisted Z-fiber (UAZ) process. Specifically, the z-pin inclination angle is decreased by 60%, and the initial damages in eye-like zone are prominently reduced. The z-pin makes the specimen exhibit the quasi-brittle behavior under flexural loading by playing a bridging role, which makes the flexural properties of specimens prominently increased. In addition, the "snubbing effect" will enhance the bridging effect of z-pins, but it will lead to inter-fibers debonding, splitting, and shear failure of z-pins. [ABSTRACT FROM AUTHOR]

Highlights This work proposes three Bouligand‐inspired layups to enhance low velocity impact (LVI) damage resistance and tolerance of convectional aircraft composite laminates. Two Bouligand‐like (HL and HL_S) and one hybrid design layup, merging conventional and Bouligand architecture (HYB), were produced by vacuum bag infusion. Their performance under LVI, at 13.5, 25 and 40 (J), and compression after impact (CAI) tests were evaluated and compared with a conventional aircraft multidirectional layup (LS) produced under identical conditions. Results demonstrated that, especially for the higher impact energy levels, both Bouligand‐like laminates consistently outperformed all the other configurations, exhibiting higher load bearing capacity (peak load) and energy absorption. Additionally, the rough and poorly defined interlaminar region of Bouligand‐like layups have showed to delay severe damage for higher loads and energies, dissipating all (at 13.5 J) or most of the impact energy (more than 50%) through subcritical damage mechanisms. Compared with LS laminate, Bouligand‐inspired layups postponed the onset of severe damage thresholds by up to 120% in load and 66% in energy (HL laminate) while developing smaller and more localized damages. The high number of fibers aligned in the loading direction of LS laminate led to better damage tolerance. Vacuum bag infused Bouligand‐like laminates consistently demonstrated superior performance than the conventional aircraft multidirectional layup, exhibiting higher load bearing capacity and energy absorption, particularly at higher impact energy levels; The rough and poorly defined interlaminar region observed in both Bouligand‐like layups demonstrated to play an essential role in the efficiency of damage mechanisms, dissipating all (at low impact energy levels) or more than 50% of impact energy on subcritical damages, such as translaminar matrix cracking; Compared with the conventional layup, HL Bouligand‐like laminate postponed 120% and 66% load and energy severe damage onset thresholds; The high number of fibers aligned in the loading direction of LS laminate led to better damage tolerance, despite the larger damaged areas observed. [ABSTRACT FROM AUTHOR]

In this paper, the potential of the five latest artificial intelligence (AI) predictive techniques, namely multiple linear regression (MLR), multi-layer perceptron neural network (MLPNN), Bayesian regularized neural network (BRNN), generalized feed-forward neural networks (GFFNN), extreme gradient boosting (XGBoost), and their ensemble soft computing models were evaluated to predict of the maximum peak load (PL) and displacement (DP) values resulting from pull-out tests. For this, 34 samples of the fully cementitious grouted rock bolts were prepared and cast. After conducting pull-out tests and building a dataset, twenty-four tests were randomly considered as a training dataset, and the remaining measurements were chosen to test the models' performance. The input parameters were water-to-grout ratio (%) and curing time (day), while peak loads and displacement values were the outputs. The results revealed that the ensemble XGBoost model was superior to the other models. It was because having higher values of R2 (0.989, 0.979) and VAF (99.473, 98.658) and lower values of RMSE (0.0201, 0.0435) were achieved for testing the dataset of PL and DP' values, respectively. Besides, sensitivity analysis proved that curing time was the most influential parameter in estimating values of peak loads and displacements. Also, the results confirmed that the ensemble XGBoost method was positioned to predict the axial-bearing capacity of the fully cementitious grouted rock bolting system with extreme performance and accuracy. Eventually, the results of the ensemble XGBoost modeling technique suggested that this novel model was more economical, less time-consuming, and less complicated than laboratory activities. [ABSTRACT FROM AUTHOR]

This paper aims to evaluate the impact response of the multi-core composite sandwich panels from low-velocity experiments. Geometrical parameters of sandwich panels like cell size, cell height, and facesheet thickness are varied and their effect on peak load, energy absorption, and efficiency is reported in this article. The effect of impact energy variation ongraded and non-graded types of sandwich panels is also studied. Based on these experiments suitable recommendations are given for impact energy absorber applications. From a crashworthiness point of view, graded multi-core composite sandwich panels are found to be more effective than non-graded ones. [ABSTRACT FROM AUTHOR]

The impact of heterogeneity on the failure of rocks has prompted researchers to perform numerical investigations. Heterogeneity can be incorporated into simulations through the implicit heterogeneity approach via cohesive zone modeling or the explicit heterogeneity approach by employing either grain-based modeling or the random distribution of properties technique. In this study, implicit and explicit heterogeneity schemes are thoroughly compared. Accordingly, bonded block models are developed using the Hybrid Lattice/Discrete Element Method and applied to laboratory test simulations and a microtunnel excavation of Opalinus Clay, an anisotropic shale. The laboratory models were used to simulate unconfined compression and direct tension tests, from which stress and strain behavior, failure modes, and acoustic emission (AE) activity were observed. The microtunnel model was based on the HG-A gallery in Mont Terri laboratory, and the simulations included the manifestation of the highly damaged and excavation damage zones as well as AE activity during the excavation phase. In conclusion, the implicit heterogeneity approach yielded easy-to-calibrate laboratory models that accurately captured anisotropy in deformability and peak strength properties. However, they exhibited linear-elastic behavior and lacked AE activity prior to peak load. In contrast, the explicit heterogeneity approach resulted in models with realistic anisotropic nonlinear behavior, but they were challenging to calibrate. The highly damaged zone in the implicit HG-A microtunnel model corresponded well with breakouts observed in situ. Nevertheless, it underestimated the excavation damage zone. Conversely, the explicit model presented a realistic excavation damage zone but lacked a well-defined highly damaged one. Highlights: Bonded block models with implicit and explicit heterogeneity were compared in simulations of laboratory and in-situ tests on Opalinus Clay. Implicit heterogeneity is introduced via Cohesive Zone Modeling (CZM) and explicit heterogeneity via Random Distribution of Properties (RDP) approach. Both CZM and RDP models presented anisotropy in strength and deformability, but the RDP ones showed non-linear features observed in laboratory tests. The CZM model for a microtunnel excavation presented an accurate highly damaged zone, whereas the RDP model gave a realistic excavation damage one. It is recommended that CZM and RDP models be analyzed and interpreted together for better insights into the behavior of rockmasses after excavations. [ABSTRACT FROM AUTHOR]