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Translation abstract Effects of traffic‐induced vibrations on young concrete: part 2In the COUNT (COncreting UNder Traffic) research project, the effects of traffic vibrations on young concrete were extensively investigated. This issue has recently become more relevant. When bridges are being renewed or extended, traffic bans are often imposed for fear that the vibrations caused by traffic could damage the young (hardening) concrete. COUNT aimed to determine critical vibration values and underlying damage mechanisms on the basis of three systematically designed series of tests. The first two series, in which unreinforced concrete and the concrete‐steel composite were investigated, were reported on in the first part of the article, which has already been published. This second part of the article deals primarily with the third series, in which tests were carried out on a large, realistic scale. Concrete slabs were cast which were in direct contact with a vibrating prefabricated concrete slab. Possible damage was later analysed by means of crack measurements, bending tests and permeability tests. At the end, recommendations for practical application are given, also taking into account the findings of external research work. [ABSTRACT FROM AUTHOR]

AbstractThis study introduces a reinforced star-shaped auxetic honeycomb (RSSAH) sandwich beam, enhanced with hollow thin-walled tubes to improve bending resistance and energy absorption performance. The bending performance of the RSSAH is systematically investigated through quasi-static three-point bending tests and finite element numerical simulations. The findings suggest that when subjected to mid-span stress, the RSSAH displays both localized indentation and overall bending deformation, accompanied by notable negative Poisson’s ratio (NPR) impact under bending loads. Parametric studies are undertaken by numerical simulations to investigate the impact of compression position, auxetic angle, and face sheet thickness on the bending mode of the auxetic honeycomb sandwich beam. The analysis shows that the RSSAH can exhibit excellent bending performance and, at one of the compression positions, displays double-plateau stress characteristics. It is also found that altering key geometric parameters, such as the auxetic angle and panel thickness ratio, can greatly improve the bending capabilities of the RSSAH, achieving stable plastic deformation and high energy absorption. Finally, compared to star-triangle honeycomb (STH) sandwich beam, traditional reentrant honeycomb (RH) sandwich beam and star-shaped auxetic honeycomb (SSAH) sandwich beam, the RSSAH demonstrates superior bending performance and energy absorption capacity. This study offers insights and references for the development of innovative reinforced auxetic honeycomb sandwich beams. [ABSTRACT FROM AUTHOR]

A method for creating broadband ultrathin azo dye micropolarizers is introduced, utilizing photoalignment technology and liquid crystal polymers to organize azo dyes into a long-range ordered structure. Achievements include a 3.63 μm thick polarizer with an extinction ratio over 140 and polarization efficiency over 99.3% across 400–650 nm, 5 μm × 5 μm pixel pitch flexible ultrathin checkerboard arrays and 6 μm pixel pitch flexible ultrathin one-dimensional grating with a 0.45 duty ratio through mask exposure technology. After a substrate-transfer technique, the bending cycle test demonstrates the mechanical stability and durability of the broadband ultrathin flexible polarizers, highlighting their potential for widespread use in integrated flexible optoelectronic systems. [ABSTRACT FROM AUTHOR]

This study explores the 3D/4D printing of polylactic acid (PLA) composites reinforced with natural particles from mussels PLA (MPLA) and wheat PLA (WPLA) using fused filament fabrication (FFF). The study employs functionally graded (FG) and multi‐material (MM) printing processes emphasizing biodegradable and bio‐derived materials. Shape memory polymer composites (SMPCs) with various MM and FG combinations are printed and examined. The microstructure, mechanical properties, flammability, and shape memory characteristics of these SMPCs are evaluated. The findings demonstrate that incorporating mussel and wheat particles enhances the mechanical performance of PLA, with a reduced burning rate compared to pure PLA samples. A sandwich FG composite structure shows superior strength in compression, tensile, and three‐point bending tests, with WMWFG samples exhibiting a 106% increase in tensile strength compared to WPLA samples. The shape recovery and fixity of the 4D‐printed SMPCs are investigated and WPLA specimens reveal the highest shape recovery ratio of ≈ 93.3% ± 1%. These findings highlight the potential of 4D‐printed SMPCs for diverse applications, spanning shape morphing, human‐material interaction, and mechanical engineering. Additionally, the research contributes to sustainability by promoting reduced material consumption and waste generation, as demonstrated by creating reusable and lightweight objects such as miniature pots, cutlery, holders, grippers, and wrappers. [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]

In this study, the fatigue behavior of FDM‐3D printed polylactic acid (PLA) materials was investigated by rotary bending fatigue tests and finite element studies with varying printing speed and raster angle parameters. Fatigue test specimens were manufactured at five different raster angles (0°, 30°, 45°, 60°, and 90°) and two different printing speeds (20 and 80 mm/s). The effect of printing speed was evaluated at high print speed variation range (20 and 80 mm/s print speeds). It was noticed that the change in raster angle affects the fatigue life very significantly. The highest fatigue life was obtained at 30° raster angle, while the lowest fatigue life was found at 90° raster angle. Increasing the printing speed from 20 to 80 mm/s decreased the fatigue life of all specimens. The derived results from the finite element analyses were consistent with the experimental results. Highlights: The fatigue behavior of 3D printed polylactic acid (PLA) materials was examined by rotary bending fatigue tests and FEAs with different printing speed and raster angle parameters.Fatigue test specimens were manufactured at five different raster angles (0°, 30°, 45°, 60°, and 90°) and two different printing speeds (20 and 80 mm/s).The highest fatigue life was achieved at 30° raster angle, while the lowest fatigue life was found at 90° raster angle.Increasing the printing speed from 20 to 80 mm/s decreased the fatigue life of all specimens. [ABSTRACT FROM AUTHOR]

To investigate the effect of different thickness ratios of the upper and lower panels on the foam aluminum sandwich panels, this paper conducts three-point bending tests. And use micro-CT technology to perform phased scans of the bending process in the experiment. The results show that, the collapse, splitting, and lateral extrusion of each cell are simultaneously present in three different forms of damage. At a span of 100mm, cell collapse dominates the damage deformation. At spans of 80mm and 60mm, splitting becomes the dominant factor. When the intrusion depth of the loading roller significantly increases, lateral extrusion damage becomes dominant. [ABSTRACT FROM AUTHOR]

(1) Objectives: This study investigated and compared the wear and flexural strength of two highly filled (injectable), one flowable and one paste composite. (2) Methods: Two highly filled flowable composites (G-aenial Universal Injectable and Beautifil Plus F00), a paste composite (Empress Direct) and a conventional flowable (Tetric EvoFlow) were tested. A two-body wear test was carried out using 10 disc-shaped samples from each group, which were subjected to 200,000 wear machine cycles to simulate wear, followed by Scanning Electron Microscope analysis. Flexural strength was tested using a three-point bend test using 15 beam samples for each of the four groups. Values were statistically compared using one-way analysis of variance (ANOVA) for flexural strength and a Kruskal–Wallis test for wear. (3) Results: The median volume loss for G-aenial Universal Injectable and Beautifil Plus F00 was statistically lower than that of both Empress Direct and Tetric EvoFlow. For flexural strength the two highly filled flowable composites both exhibited statistically higher mean flexural strength values compared to Empress Direct (p < 0.004) and Tetric Evoflow (p < 0.001). There were no statistically significant differences in the values of wear and flexural strength between the two highly filled flowable composites. (4) Conclusions/significance: Highly filled flowable composite resins with nano filler particles outperformed a conventional flowable and a paste composite resin in terms of wear resistance and flexural strength, and may be suitable to use in occlusal, load-bearing areas. [ABSTRACT FROM AUTHOR]

This paper addresses the challenge of enhancing the bending capacity of beams through a cost‐effective and practical approach. Current methods are often expensive, brittle, time‐intensive, or massive. In response, an alternative method is proposed that involves the utilization of post‐tensioned heavy‐duty metal straps wrapped around steel plates anchored to the beams. To evaluate the effectiveness of the method, six large‐scale normal reinforced concrete beams were constructed with a width of 160 mm and a depth of 240 mm, and a clear span of 1900 mm. The testing parameters were the position of the steel plates along the length of the beam and the position of the metal straps along the height of the steel plates. Quantitative results demonstrate a significant enhancement in the load‐carrying capacity of the beams. Compared to the control specimen, the method led to a minimum increase of 40% of load carrying capacity and a maximum increase of 66%. Key influencing factors include the location of the metal straps on the steel plates (120 or 90 mm away from the bottom of the beam) and the position of the steel plates on the face of the beam (650 mm or 350 away from the edge of the beam). Notably, the load‐carrying capacity increases when the metal straps are positioned lower on the steel plates and the plates are placed further away from the center of the beam. Finally, analytical results obtained using VecTor2 software align well with experimental findings. [ABSTRACT FROM AUTHOR]

This study investigates the repair of damaged curved glass/epoxy composite laminates through various adhesive reinforcements and adhesively bonded external patches. The experimental procedures involve fabricating laminates, conducting four-point bending tests, quasi-static indentation tests, and optimizing damaged areas. Results demonstrate the influence of repairs on curved beam strength and interlaminar tensile strength. Adhesive repairs with chopped fiber reinforcement outperform plain epoxy and particle fiber-reinforced repairs, preserving 51.28% of curved beam strength. Adhesively bonded external patches, both single and double, with chopped fiber reinforcement exhibit significant strength recovery 72.08% and 80.78% compared to virgin samples. The study emphasizes the effectiveness of adhesively bonded external patches, particularly those with chopped glass fiber reinforcement, in enhancing curved beam strength and interlaminar tensile strength. This research provides valuable insights for repairing angled structures, such as those in airplane components, showcasing potential applications of these techniques for structural maintenance. HIGHLIGHTS: Investigated adhesive reinforcements and bonded external patches for curved composites. Laminates fabricated, tested for bending, indentation, and optimized in damaged region Chopped fiber adhesive repairs preserve significant 51.28% strength. Adhesively bonded patches exhibit 72.08% and 80.78% strength recovery. [ABSTRACT FROM AUTHOR]

Background: The aim of this study was to evaluate the chicken femur as a laboratory model for the human metacarpal by comparing the bone microarchitecture and mechanical properties of chicken femurs to human cadaveric metacarpals. Methods: Sixteen fresh chicken femora and 20 fresh frozen cadaveric human metacarpals were imaged using a micro computed tomography scanner. The bones were then mechanically tested using four-point-bending and torsional testing. Results: There were no significant differences in macroscopic features between chicken femora and human metacarpals, including overall length, external radius, internal radius, cortical width and cross-sectional area of the diaphyseal cortex (p > 0.05). There were no significant differences in the trabecular number and spacing in the distal metaphysis of both groups (p > 0.05). The diaphysis and proximal metaphysis did not share any microarchitectural similarities. Four-point bending tests resulted in significantly higher yield forces, ultimate force, failure points and stiffness in human metacarpals (p < 0.05). Torsion tests resulted in significant higher ultimate torque and torsional rigidity in human metacarpals (p < 0.05). Conclusions: The chicken femur has structural and biomechanical differences to the fresh frozen human metacarpal despite the similarity in their macroscopic features. [ABSTRACT FROM AUTHOR]

Auxetic structures possess negative Poisson's ratio (NPR). They exhibit enhanced indentation resistance, synclastic deformation, high fracture toughness and high energy absorption. Several sorts of auxetic structures exist, such as re-entrant, arrowhead, chiral, etc. The re-entrant structure is the most common sort of auxetic structures. This paper investigates the mechanical behavior of the re-entrant auxetic structure using experimental and numerical methods. Two modified re-entrant topologies are proposed based on the original (conventional) re-entrant topology. Using these modified topologies, two re-entrant auxetic sandwich structures are designed and 3D printed using fused deposition modeling (FDM) out of polylactic acid (PLA). Conducting compression, three and four-point bending tests, the compressive and flexural performance of the two new re-entrant auxetic sandwich structures is studied and compared with the original (conventional) re-entrant structure. More specifically, Poisson's ratio, compressive modulus, flexural stiffness and maximum loads of the structures are focused and studied. The mechanical properties of auxetic sandwich structures are improved using modified topologies. The new re-entrant auxetic sandwich structures show 11% higher normalized compressive modulus and 9% higher normalized flexural stiffness than the original re-entrant structure. [ABSTRACT FROM AUTHOR]

In this study, the harmful effects of a banded structure on the bending fracture of electroplated fasteners are investigated. The origins and ways to control these structures are also explored. The fracture surfaces of the fasteners exhibit stepwise cracks and numerous intergranular facets associated with ductile tearing, which is a characteristic of hydrogen embrittlement. The origin of these stepwise cracks can be traced to the internal banded structures. Therefore, the internal banded structures promote fracturing during the bending test. The internal banded structures in the fasteners can be traced back to the internal cracks in the bloom, and inappropriate soft‐reduction processes lead to internal cracks. Notably, the carbon segregation at the internal cracks is severe. This is attributed to the proximity of the internal cracks to the center of the bloom, causing the enriched liquid in the interdendritic region to be sucked into these internal cracks. The optimal reduction position and amount are determined by employing heat‐transfer and soft‐reduction models. Fluctuations in superheat and casting speed significantly influence this optimal position and reduction amount. [ABSTRACT FROM AUTHOR]

To evaluate the effect of different ratios of Bis-EMA/Bis-GMA resin mixtures on the inherent viscosity and curing-related properties: including degree of cure (DC%), shrinkage strain, Knoop micro-hardness (KH) and flexural strength of resin-impregnated fiber-bundles. Bis-EMA/Bis-GMA monomers were mixed (by weight) in the following ratios: M1 = 30 %/70 %, M2 = 50 %/50 %, M3 = 70 %/30 %, and M4 = 100 %/0 %. Standard measurements were made of refractive index, viscosity, degree of conversion, shrinkage strain and Knoop hardness (KHN). For 60 % glass fiber-bundles impregnated with 40 % resin, three-point bending test for flexural strength and shrinkage strain were measured. Data were analyzed by One-way ANOVA and Bonferroni post-hoc tests (α = 0.05). For resin mixtures, increasing Bis-EMA proportion decreased refractive index (p < 0.05), and viscosity (p < 0.05), and increased monomer conversion (DC%), shrinkage strain and KHN (p < 0.05). DC% increased after 1 h for all resin mixtures. The shrinkage strain and flexural strength of resin-impregnated fiber-bundles reduced with increased Bis-EMA. Monomeric mixtures with highest amounts of Bis-EMA showed enhancement in several clinically-relevant properties and polymerization of respective resin-impregnated glass fibers. This makes them potential candidates for impregnating glass fibers in fiber-reinforced restorations. [ABSTRACT FROM AUTHOR]

This article experimentally and numerically investigates the bending response and failure mechanisms of FMLs under three-point bending tests. The in-situ microscope observation from step-by-step interrupted flexural tests is implemented to capture the failure mechanisms and damage evolution. Then, a numerical simulation is employed to characterize the damage initiation and progressive damage evolution process. Finally, the bending response and stiffness degradation of FMLs under incremental cyclic flexural loading tests are experimentally researched. The in-situ monitoring for FMLs-A shows that the appearance of fiber kink-band, fiber fracture, and metal cracking are identical with the moments of sudden loading decrease, respectively. [ABSTRACT FROM AUTHOR]

This study focuses on fabricating lattice structural Al 2 O 3 ceramics with lattice infill densities ranging from 25 % to 70 % using filament-based fused deposition modeling (FDM) technology. A specialized filament for FDM printing was developed, comprising 53 vol% Al 2 O 3 powder and ethylene vinyl acetate (EVA) as the primary binder component. The filament demonstrated excellent flexibility as assessed by a self-designed three-point bending test. The impact of lattice infill density and sintering temperature on dimensional changes, microstructure evolution, compressive strength, and strength-to-density ratio was explored. It was found that with increasing sintering temperature, the samples became more compact, resulting in higher levels of shrinkage, bulk density, and compressive strength. At a sintering temperature of 1600 °C, the sintered parts reached their maximum density through the solid-state sintering process. The sample sintered at 1600 °C with 70 % infill density exhibited the maximum compressive strength of 31.47 MPa, with a corresponding strength-to-density ratio of 20.84 MPa/g·cm−3. These findings highlight the successful fabrication of lattice structural Al 2 O 3 with low density and high compressive strength by FDM technology. • Lattice structural Al 2 O 3 ceramics were fabricated by FDM technique. • The filament for FDM with 53 vol% Al 2 O 3 was developed. • Filament demonstrated excellent flexibility. • Sintered lattice structural Al 2 O 3 ceramics at 1600 °C exhibited the maximum compressive strength of 31.47 MPa. [ABSTRACT FROM AUTHOR]

To investigate the flexural failure mode and behavior of wooden beams strengthened using aluminum (Al) plates, which were attached with self-tapping screws and structural adhesive, ten specimens were tested in bending. The experimental parameters were the thickness of the bottom Al plate, the longitudinal and transverse grain spacing of the self-tapping screws. The experimental results revealed that (1) compared with unreinforced beams, the reinforced beams exhibited ultimate load capacity and displacement ductility coefficients that were 18.4%–54.3% and 6.4%–43.1% higher, respectively; (2) for the same Al plate thickness in the tensioned area, the initial stiffness of the reinforced wooden beams increases as the longitudinal grain spacing of the screw grains decreases; (3) the plane-section assumption was satisfied by the strain in the middle section of the Al plate-reinforced wooden beam along the height; (4) the strains at the same position in the wooden beam and Al plate were similar, thus indicating that the wooden beam and Al plate behaved collectively. Furthermore, a formula was proposed for calculating the flexural capacity of an Al plate-reinforced wooden beam, thus providing a valuable reference when designing wooden beam reinforcements. [ABSTRACT FROM AUTHOR]

Multilayer reinforcement fabrics are increasingly used for manufacturing structural polymer composites. In liquid molding processes, dry reinforcement fabrics are draped on a mold first, and infused with a liquid resin such as an epoxy in a subsequent manufacturing step. This presents major advantages in terms of operational flexibility and costs. However, draping multilayer reinforcement fabrics on complex mold geometries is challenging. Small radius mold corners constitute a major manufacturing challenge as they lead to variability in dry fabric positioning and resin-rich corners in polymer composite parts. Spring-back of fabrics bent over or into single curvature mold corners is a widespread industrial concern. However, contrary to draping over double-curvature surfaces, bending spring-back from convex or concave single-curvature corners has received very limited attention. No testing method is available. This paper quantifies reinforcement fabric bending spring-back. Single and multiple layer stacks were bent along three directions over convex and into concave 90° corners with five radii spanning 1.59 mm to 12.70 mm. In all cases, five replicated tests enabled variability quantification. Fabric stacks were also quantified using cantilevered bending tests for comparison purposes. Mold radius was found to affect the behavior to a larger extent than testing direction, number of layers or use of a binder. [ABSTRACT FROM AUTHOR]

Additive technologies, also known as 3D printing technologies, are becoming more and more widely used in industrial conditions for the production of finished elements, especially for the production of parts that would be very difficult or even impossible to produce using existing technologies. Technologically difficult elements include parts with a thin-walled spatial structure. This work presents the research results and describes the problems of producing specimens of thin-walled profiles filled with an appropriate spatial structure, also thin-walled, using 3D printing technology. The results of a three-point bending test of specimens of various lengths and specimens filled with chemically cured resin are presented. Print simulations were discussed, paying attention to problems related to applying lines and layers in FDM/FFF technology and the impact of print technological parameters on the properties of the manufactured specimens. [ABSTRACT FROM AUTHOR]

Objective: To determine the effects of adding a quaternary ammonium methacryloxy silicate (K18) and K18-functionalized filler (K18-Filler) on the material and antimicrobial properties of a hard denture reline material. Materials and methods: 30% K18 in methyl methacrylate (K18-MMA; 0–20 wt% of reliner) and K18-Filler (0–30 wt% of reliner) were incorporated into KoolinerTM hard denture reliner. KoolinerTM served as the control. The cure (Shore A hardness), hydrophilicity (contact angles), mechanical (3-point bend test), water sorption, and antimicrobial properties against Streptococcus mutans, S. sanguinis, and Candida albicans were determined. Results: Most K18 groups cured well and had comparable Shore A hardness values (range ~52 to 70 DHN) to that of controls (67.2 ± 1.8 DHN; Bonferroni corrected p > 0.0003). Even the softest group had hardness values within the range of commercial products. Half of the K18 groups had comparable contact angles to that of controls (range ~75° to 80° vs 83.41° ± 2.66°; Bonferroni corrected p > 0.0003), and most were within the range of commercial liners. K18-MMA and K18-Filler increased modulus but decreased ultimate transverse strength (UTS). All experimental groups had comparable or higher moduli than controls (range ~966 to 2069 MPa vs 1340 ± 119 MPa; Bonferroni corrected p < 0.0003), but only half of the experimental groups had comparable UTS to that of controls (range ~41 to 49 MPa vs 55.8 ± 1.5 MPa; Bonferroni corrected p > 0.0003). The 15% and 20% K18-MMA with 30% K18-Filler groups had significant antimicrobial activity against all three microbes (p < 0.05). However, the 15% and 20% K18-MMA with 30% K18-Filler groups had significantly higher water sorption at early time points (p < 0.05). After 8 weeks, they were comparable to each other (p > 0.05). Conclusions: K18-MMA and K18-Filler are promising antimicrobial additives that produce hard denture liners with material properties within the range of commercial products and significant antimicrobial properties against S. mutans, S. sanguinis, and C. albicans. Further development is needed to reduce water sorption. [ABSTRACT FROM AUTHOR]

ABSTRACT We present a double‐phase–field framework for tensile fracturing processes in transversely isotropic rocks. Two distinct phase‐field variables are introduced to represent smeared approximations of tensile fractures along the weak bedding planes and through the anisotropic rock matrix, respectively. Driving forces that control fracture propagation in the phase‐field framework are constructed as a stress‐based formula with a recently developed tensile failure criterion that distinguishes the two failure modes in transversely isotropic rocks. For numerical implementation, we adopt a staggered integration scheme and decouple the governing equations so that the displacement field and phase‐field variables can be updated in sequence for a given loading step. The finite element formulation of the proposed framework is introduced in detail in this paper and is implemented in an in‐house finite element code. The numerical implementation is then validated by reproducing the uniaxial tension test results of Lyons sandstone. After that, we conduct simulations on a pre‐notched square plate loaded in tension to demonstrate the features of the proposed framework. Finally, we conduct simulations of three‐point bending tests of Pengshui shale and show that the proposed model can reproduce the force–displacement curves and failure patterns of specimens with different bedding plane orientations observed in laboratory experiments. [ABSTRACT FROM AUTHOR]

Translation abstract Lightweight ceiling elements made of carbon‐reinforced concreteIn concrete components under bending, a large proportion of the material used is underutilized. More material efficiency can be achieved, e. g., by resolving the solid interior of such components. In the presented project, this is realized by load‐bearing filigree carbon‐reinforced concrete membranes. At first, in the article, the method of producing such filigree structures by casting under negative air pressure is briefly explained and the material properties achieved in standard tests are discussed. Then, the design of two 1.8 m × 1.8 m large slabs and their load‐bearing behavior in 9‐point bending tests are described and compared with numerical simulations. Finally, an outlook on future research is given. [ABSTRACT FROM AUTHOR]

Sandwich structures are often prone to catastrophic failure due to premature separation between the core and skin layers. Geometric parameters, such as the thickness of the skin and core, along with the materials used in their manufacturing, directly influence the resistance to separation between the skin and core. This study explores how variations in skin thickness affect both failure modes and maximum load capacity in sandwich structures, utilizing both experimental testing and numerical simulations. Specimens were categorized as intact and pre-debonded samples. Each specimen featured four different skin thicknesses (3, 6, 8, and 10 layers of composite laminated skins, with corresponding thicknesses of 0.68, 1.33, 1.73, and 2.1 mm respectively). The specimens incorporated a foam-filled square corrugated core and underwent 3-point bending tests. Results revealed a significant shift in the failure mode: initially observed as upper skin fracture (V-shaped failure), it transitioned to separation between skins and cores with increased skin thickness, particularly in the presence of pre-debonding. Notably, the predominant failure mode did not involve separation between the skin and core in specimens without a pre-existing crack. Furthermore, numerical simulations effectively demonstrated the accurate capture of failure modes and loads using the Hashin and cohesive zone model (CZM). [ABSTRACT FROM AUTHOR]

Fused filament fabrication, also known as fused deposition modeling and 3D printing, is the most common additive manufacturing technology due to its cost-effectiveness and customization flexibility compared to existing alternatives. It may revolutionize unmanned aerial vehicle (UAV) design and fabrication. Therefore, this study hypothesizes the 3D printing possibility of UAV using a simple desktop printer and polymeric material. The extensive literature analysis identified the acceptable prototyping object and polymeric material. Thus, the research focuses on applying polylactic acid (PLA) in manufacturing the flying wing-type UAV and develops a fabrication concept to replicate arial vehicles initially produced from a mixture of expanded polystyrene and polyethylene. The material choice stems from PLA's non-toxicity, ease of fabrication, and cost-effectiveness. Alongside ordinary PLA, this study includes lightweight PLA to investigate the mechanical performance of this advanced material, which changes its density depending on the printing temperature. This proof-of-concept study explores the mechanical properties of printed parts of the wing prototype. It also considers the possibility of fragmentation in fabricated objects because of the limitations of printing space. The simplified bending tests identified significant reserves in the mechanical performance regarding the theoretical resistance of the material in the wing prototype, which proves the raised hypothesis and delivers the object for further optimization. Focusing on the mechanical resistance, this study ignored rheology and durability issues, which require additional investigations. Fabricating the wing of the exact geometry reveals acceptable precision of the 3D printing processes but highlights the problematic technology issues requiring further resolution. [ABSTRACT FROM AUTHOR]

In recent years, there have been an increasing number of examples of using ultrahigh-performance concrete (UHPC) as a pavement layer to form an ultrahigh-performance concrete–normal concrete (UHPC–NC) composite structure to improve the bearing capacity of bridges. In order to study the flexural performance of this kind of structure, this research studied the flexural performance of UHPC–NC composite slabs, with UHPC in the compression zone, using experiments, numerical simulation, and theoretical analysis. The results showed the following. Firstly, after the UHPC–NC interface had been chiseled, there was no obvious slip between the two materials during the test, and the composite plate was always subjected to synergistic stress. Secondly, the composite slabs in the compression zone of the UHPC were all subjected to bending failure, and the cooperative working performance of each part under the bending load was good, indicating that the composite slab had a unique failure mode and a high bearing capacity. Thirdly, increasing the thickness of the UHPC significantly improved the flexural capacity of the composite plate, and the maximum increase was about 15%. Increasing the reinforcement ratio of the tensile steel rebars also had an increasing effect, with a maximum increase of about 181%. Finally, the proposed formula for calculating the flexural capacity of composite slabs with UHPC in the compression zone could accurately predict the bearing capacity of said slabs. The calculated results were in good agreement with the experimental values, and the error was small. [ABSTRACT FROM AUTHOR]

The fatigue performance of laser powder bed fusion-fabricated Ti-6Al-4V alloy was investigated using four-point bending testing. Specifically, the effects of keyhole and lack-of-fusion porosities along with various surface roughness parameters, were evaluated in the context of pore circularity and size using 2D optical metallography. Surface roughness of Sa = 15 to 7 microns was examined by SEM, and the corresponding fatigue performance was found to vary by 102 cycles to failure. The S–N curves for the various defects were also correlated with process window examination in laser beam power–velocity (P–V) space. Basquin's stress-life relation was well fitted to the experimental S–N curves for various process parameters except keyhole porosity, indicating reduced importance for LPBF-fabricated Ti-6Al-4V alloy components. [ABSTRACT FROM AUTHOR]

Tensile perpendicular to grain is an important mechanical property in the design of joints in timber structures. However, according to the standards, this strength can be determined using at least two different methods: uniaxial tensile and three-point static bending. In this context, the present paper aims to investigate the influence of these test methods on the determination of tensile strength perpendicular to grain of wood used in civil construction timber. Three wood species from Brazilian planted forests (Pinus spp., Eucalyptus saligna, and Corymbia citriodora) were used in this investigation. Twelve specimens of each species were used for each test method investigated. Moreover, a statistical analysis was performed to propose an adjustment to the equation of the Code of International Organization for Standardization 13910:2014 for the three-point bending test. Tensile strength values perpendicular to grain obtained from the uniaxial tensile test were significantly higher than those determined by the three-point bending test. It is proposed that the tensile strength perpendicular to grain can be determined more precisely with adoption of coefficient 5.233 in the term [(3.75·Fult)/b·Lh] of the equation specified by the Code of International Organization for Standardization 13910:2014 for the three-point bending test. [ABSTRACT FROM AUTHOR]

This paper was aimed to study the mechanical properties of Istle fibre composites. The process of fabrication was done by hand layup technique at three different fibre orientations i.e., unidirectional, bidirectional and 45 degrees inclined, and also its effect on tensile and flexural property that was studied in the Instron Testing Machine. The fibre volume ratio was kept uniform for the entire specimen as 50:50. The treatment of istle fibre was done with sodium hydroxide to increase the fibre matrix bonding. The effect of E-glass reinforcement has also been studied in both bending tests and flexural tests. The maximum tensile and bending modulus recorded were from unidirectional fibre specimen. [ABSTRACT FROM AUTHOR]

The characterization and modeling of the out-of-plane behavior of fiber-based materials is essential for understanding their mechanical properties and improving their performance in various applications, especially in the forming process. Despite this, research on paper and paperboard has mainly focused on its in-plane behavior rather than its out-of-plane behavior. However, for accurate material characterization and modeling, it is critical to consider the out-of-plane behavior. In particular, delamination occurs during forming processes such as creasing, folding, and deep drawing. In this study, three material models for paperboard are presented: a single all-material continuum model and two composite models using different cohesion methods. The two composite models decouple in-plane and out-of-plane behavior and consist of continuum models describing the behavior of individual layers and cohesive interface models connecting the layers. Material characterization experiments are performed to derive the model parameters and verify the models. The models are validated using three-point bending and bulge tests and show good agreement. A case study is also conducted on the application of the three models in the simulation of a deep drawing process with respect to wrinkle formation. By comparing the simulation results of wrinkle formation in the deep drawing process, the composite models, especially the cohesive interface composite model, show greater accuracy in replicating the experimental results, indicating that a single continuum model can also be used to represent wrinkles. [ABSTRACT FROM AUTHOR]

The hybridization of single-walled carbon nanotubes (SWCNTs) and Cu nanoparticles offers a promising strategy for creating highly conductive and mechanically stable fillers for flexible printed electronics. In this study, we report the ultrafast synthesis of SWCNT/Cu hybrid nanostructures and the fabrication of flexible electrodes under ambient conditions through a laser-induced photo-thermal reaction. Thermal energy generated from the nonradiative relaxation of the π-plasmon resonance of SWCNTs was utilized to reduce the Cu-complex (known as a metal–organic decomposition ink) into Cu nanoparticles. We systematically investigated the effects of SWCNT concentration and output laser power on the structural and electrical properties of the SWCNT/Cu hybrid electrodes. The SWCNT/Cu electrodes achieved a minimum electrical resistivity of 46 μohm·cm, comparable to that of the metal-based printed electrodes. Mechanical bending tests demonstrated that the SWCNT/Cu electrodes were highly stable and durable, with no significant deformation observed even after 1000 bending cycles. Additionally, the electrodes showed rapid temperature increases and stable Joule heating performance, reaching temperatures of nearly 80 °C at an applied voltage of less than 3.5 V. [ABSTRACT FROM AUTHOR]

Plant cells withstand mechanical stress originating from turgor pressure by robustly maintaining the mechanical properties of the cell wall. This applies at the organ scale as well; many plant stems act as pressurized cylinders, where the epidermis is under tension and inner tissues are under compression. The clavata3 de-etiolated3 (clv3-8 det3-1) double mutant of Arabidopsis thaliana displays cracks in its stems because of a conflict between the mechanical properties of the weak epidermis and over-proliferation of inner stem tissues. In this work, we conducted three-point bending tests on various Arabidopsis thaliana mutants, including those displaying the stem cracking phenotype, to examine the differences in their mechanical properties. The clv3-8 det3-1 double mutant exhibited reduced stem stiffness, consistent with reduced differentiation due to the clv3-8 mutation. Yet, in clv3-8, stem cross-sectional area was increased associating with the increase in vascular bundle number, and stem cross-sections displayed various shapes. To uncouple the contribution of geometry and cell-wall differentiation to the mechanical properties of the whole stems, we tested the contribution of lignified fibers to stem stiffness. In order to suppress lignin deposition in stems genetically, we generated multiple higher-order mutants by crossing clv3-8 and/or det3-1 with nst1-1 nst3-1, in which lignin deposition is suppressed. Stem stiffness was reduced markedly in all nst1-1 nst3-1 mutant backgrounds. Overall, our results suggest that stem stiffness relies on the presence of differentiated, lignified, fiber tissue as well as on the alignment or spatial distribution of vascular bundles within the stem organ. [ABSTRACT FROM AUTHOR]

The experimental and numerical studies of carbon composite sandwich panels with stiffened polyurethane (PU) foam core were carried out. A novel concept of stiffening the panels by co-bonding to skin was introduced. The stiffening of PU core was conceptualized using carbon composite by wrapping and skin/facesheet was co-bonded. Four different sandwich panel configurations such as plain, longitudinal stiffening, transverse stiffening, and stiffening in both directions were manufactured. To explore the suitability of this novel concept for structural applications, the bending behavior of panels were investigated under three-point bend tests. A three-dimensional finite element model incorporating stiffness degradation concept was developed in ANSYS to understand the fundamental behavior of configured panels. Experimental and numerical results showed failure patterns like shear in foam core, indentation in composite skin and bulge/lift-off of outer composite stiffener. Comparative study of results showed that oriented stiffened sandwich panels have superior mechanical characteristics with 75% increase in the load-bearing capacity and 29% reduction in displacement. The failure patterns were envisaged through microscopy and computer-based tomography techniques. [ABSTRACT FROM AUTHOR]

Purpose: The paper's goal is to examine and illustrate the useful uses of submodeling in finite element modeling for topology optimization and stress analysis. The goal of the study is to demonstrate how submodeling – more especially, a 1D approach – can reliably and effectively produce ideal solutions for challenging structural issues. The paper aims to demonstrate the usefulness of submodeling in obtaining converged solutions for stress analysis and optimized geometry for improved fatigue life by studying a cantilever beam case and using beam formulations. In order to guarantee the precision and dependability of the optimization process, the developed approach will also be validated through experimental testing, such as 3-point bending tests and 3D printing. Using 3D finite element models, the 1D submodeling approach is further validated in the final step, showing a strong correlation with experimental data for deflection calculations. Design/methodology/approach: The authors conducted a literature review to understand the existing research on submodeling and its practical applications in finite element modeling. They selected a cantilever beam case as a test subject to demonstrate stress analysis and topology optimization through submodeling. They developed a 1D submodeling approach to streamline the optimization process and ensure result validity. The authors utilized beam formulations to optimize and validate the outcomes of the submodeling approach. They 3D-printed the optimized models and subjected them to a 3-point bending test to confirm the accuracy of the developed approach. They employed 3D finite element models for submodeling to validate the 1D approach, focusing on specific finite elements for deflection calculations and analyzed the results to demonstrate a strong correlation between the theoretical models and experimental data, showcasing the effectiveness of the submodeling methodology in achieving optimal solutions efficiently and accurately. Findings: The findings of the paper are as follows: 1. The use of submodeling, specifically a 1D submodeling approach, proved to be effective in achieving optimal solutions more efficiently and accurately in finite element modeling. 2. The study conducted on a cantilever beam case demonstrated successful stress analysis and topology optimization through submodeling, resulting in optimized geometry for enhanced fatigue life. 3. Beam formulations were utilized to optimize and validate the outcomes of the submodeling approach, leading to the successful 3D printing and testing of the optimized models through a 3-point bending test. 4. Experimental results confirmed the accuracy and validity of the developed submodeling approach in streamlining the optimization process. 5. The use of 3D finite element models for submodeling further validated the 1D approach, with specific finite elements showing a strong correlation with experimental data in deflection calculations. Overall, the findings highlight the effectiveness of submodeling techniques in achieving optimal solutions and validating results in finite element modeling, stress analysis and optimization processes. Originality/value: The originality and value of the paper lie in its innovative approach to utilizing submodeling techniques in finite element modeling for structural analysis and optimization. By focusing on the reduction of finite element models and the creation of smaller, more manageable models through submodeling, the paper offers designers a more efficient and accurate way to achieve optimal solutions for complex problems. The study's use of a cantilever beam case to demonstrate stress analysis and topology optimization showcases the practical applications of submodeling in real-world scenarios. The development of a 1D submodeling approach, along with the utilization of beam formulations and 3D printing for experimental validation, adds a novel dimension to the research. Furthermore, the paper's integration of 1D and 3D submodeling techniques for deflection calculations and validation highlights the thoroughness and rigor of the study. The strong correlation between the finite element models and experimental data underscores the reliability and accuracy of the developed approach. Overall, the originality and value of this paper lie in its comprehensive exploration of submodeling techniques, its practical applications in structural analysis and optimization and its successful validation through experimental testing. [ABSTRACT FROM AUTHOR]

In this paper, the suitability of digital image correlation (DIC) technology in evaluating the flexural behaviour of as-built and carbon-fiber-reinforced polymer (CFRP) strengthened reinforced concrete beams was verified by conducting a four-point bending test on four large-size beams. The DIC data obtained during the tests were compared to the results measured using traditional techniques such as displacement sensors and electrical strain gauges, as well as the findings derived from finite element (FE) numerical simulations. A good agreement was achieved between the local displacement and strain measurements and the data from DIC as a function of the applied load. Moreover, the crack patterns generated by the FE modelling were validated by the corresponding patterns derived from DIC. This suitability study is expected to contribute to the future field implementation of DIC technology to monitor the CFRP-strengthened members of critical structures such as bridges. [ABSTRACT FROM AUTHOR]

To accurately evaluate the fatigue performance of a full‐scale deep‐water steel catenary riser (SCR) using small‐size specimens, six fatigue testing strategies were explored, considering the effect of welding residual stress. Through a comparison with the full‐scale resonant bending fatigue testing results, the most equivalent strategy using small‐scale specimens was identified. The results indicate that the test strategies applying constant stress underestimated the fatigue life, compared with that of a full‐scale specimen; meanwhile, fatigue life values obtained from the low‐stress ratio testing strategy were higher, particularly in the low‐stress range region. Comparatively, the fatigue lives obtained for the 100 mm‐wide specimens without cutting were higher in the high‐stress range region. The variable‐applied mean stress strategy using the 25 mm‐wide welded joint specimen was the most suitable for equivalence with the full‐scale fatigue testing, with only a 9.7% difference in the fatigue life testing results. The difference between the applied mean stress and the actual transverse welding residual stress under various fatigue testing strategies is the key factor affecting the equivalence of the fatigue testing results. Highlights: Fatigue testing results between the full‐scale and small‐scale pipeline welded joint specimens were compared.Six types of fatigue testing strategies were systematically explored using small‐scale welded joints properly.The variable mean stress fatigue testing strategy was proposed, and its equivalency with the full‐scale pipeline joint was confirmed.Mechanisms on the difference of fatigue testing results between full‐scale and small‐scale pipeline joints were analyzed. [ABSTRACT FROM AUTHOR]

The bending strength of ultrafine-grained cemented carbides exceeds that of medium-grained cemented carbides. This was thought to be due to the smaller size of defects within the ultrafine-grained cemented carbides. However, this attribution had not been verified because the specimens broke into numerous small pieces during bending tests. In addition, previous studies on the bending strength of medium-grained cemented carbides reported that there is limiting strength which is a region of not increasing bending strength by reducing the defect size. Therefore, in this study, we conducted the tensile test, which is unlikely to produce many small pieces, and the bending test to determine the cause of the high strength in ultrafine-grained cemented carbides. The ratio of bending strength to tensile strength was comparable between the medium- and ultrafine-grained cemented carbides. The number of fragments produced by fractures were almost same between the medium- and ultrafinegrained cemented carbides in case of the almost same strength. It was clear that the tensile strength of both medium- and ultrafine-grained cemented carbides increased as the defect size decreased with no sign of limiting strength. These results suggest that further strength improvements can be achieved by controlling defect size in ultrafine-grained cemented carbides. [ABSTRACT FROM AUTHOR]

Acrylic resins are one of the most important thermoplastic resins used in various industries due to their significant properties. However, they are inherently brittle and the addition of plasticizers to them is very common. In this study, the role of both Polyethylene Glycol (PEG) and Triacetin on the mechanical properties of acrylic resin has been investigated. To do so, tensile test, bending, and wear tests have been performed. To achieve the optimal mixture of plasticizers, a tensile test has been carried out, and the best percentage of the mixture has been determined. Subsequently, bending and wear tests were conducted, which showed a significant increase in the bending strength of the acrylic resin after the addition of plasticizers. Furthermore, it was found that the abrasion mechanism of the resin was significantly altered compared to its pure state. [ABSTRACT FROM AUTHOR]

Nondestructive methods are a fast and accurate way to obtain information about the mechanical properties of plywood panels. The objective was to determine the modulus of rupture and compare the modulus of elasticity (MOE) in plywood boards made with Pinus spp. and Eucalyptus urograndis using the destructive method of three-point static bending and the nondestructive method of ultrasound in parallel and perpendicular directions, as well as in complete board and test specimens, both with the ultrasound method and the correlation between the variables studied. The plywood boards evaluated were 18, 25 and 30 mm nominal thickness. Five structures were evaluated using pine and pine–eucalyptus veneers. Three boards were collected per structure, and 28 specimens were made from each board (14 in a parallel direction and 14 in a perpendicular direction). The elastic modulus was determined by the ultrasound method in complete plywood boards and in specimens obtained from them using the IML Micro Hammer® equipment and through the conventional bending test, carried out in an Instron® universal mechanical testing machine. The Tukey test of means (p < 0.05) shows that in the nominal thickness of 18 mm, the modulus of elasticity by ultrasound was lower compared to the result obtained by static bending in four of the five structures in the perpendicular direction and lower in all the structures evaluated in the parallel direction; while in the nominal thickness of 25 and 30 mm, it was greater in all structures and in both directions. The results of static bending by ultrasound, in complete boards and specimens, show that the only significant difference (p < 0.05) occurs in the nominal thickness of 30 mm in the treatment made with pine–eucalyptus with urea formaldehyde resin being lower in the parallel direction and in complete boards The correlation between the modulus of elasticity determined on specimens using the nondestructive method and the destructive method was r = 0.75 and Pr < 0.05; while comparing the nondestructive method on test specimens and complete plywood panels, r = 0.73 and Pr < 0.05 were obtained. It is concluded that the mechanical bending property of plywood boards can be characterized by the ultrasound method. [ABSTRACT FROM AUTHOR]

The phenolic‐type phthalonitrile (PN) was added to EP/DDM system in order to enhance the thermal and mechanical performance at high temperature. The influence of the added PN on the curing process of EP/DDM was studied via DSC and the activating energy (Eα) was calculated based on iso‐conversional method. The Eα values corresponding to EP/DDM crosslink reaction remained at about 60 kJ mol−1 while it dramatically increased to 68.2 kJ mol−1 when PN content reached 50 wt% (EP‐PN50). The Tg and char yield at 700°C in N2 increased from141°C, 25.7%, for the neat EP/DDM to 226°C, 68.7% for the EP‐PN50. The measured char yields of the cured blend were higher than the calculated values which implies the interaction between EP/DDM and polyphthalonitrile network. The tensile and bending tests were carried out at 413 K and the modulus of EP‐PN50 remains 2.3 Gpa. On the meantime, the cyano‐functionalized SiO2 (CNSiO2) was prepared to further promote the mechanical behaviors of this resin blend in high temperature. The contact angles of raw SiO2, KH560SiO2, CNSiO2 with EP‐PN50 are 59.3, 52.6, 49.7°, respectively, which confirms the better wettability of CNSiO2 to the EP/PN blend. Furthermore, the tensile and bending tests conducted at 413 K confirmed that the CNSiO2 was more efficient on enhancing the mechanical performance of this EP/DDM/PN system at high temperature. [ABSTRACT FROM AUTHOR]

This study explores the performance of asphalt mixtures modified with North American rock asphalt and desulfurized rubber particles at varying rubber-to-asphalt ratios ranging from 18% to 36% by weight. A comprehensive set of laboratory tests, including high-temperature rutting tests, low-temperature bending tests, indirect tensile tests, and freeze–thaw splitting tests, were conducted to evaluate the modified mixtures. The results indicate that both wet and dry blending methods produce mixtures that meet technical requirements, with the optimal asphalt-to-aggregate ratio determined to be 7.1%. At a rubber-to-asphalt ratio of 18%, the wet blending method slightly improves high-temperature rutting resistance compared to the dry method. However, an increase in rubber content generally enhances rutting resistance regardless of the blending technique. The wet blending method excels in low-temperature crack resistance, possibly due to better rubber dispersion, while an increase in rubber content diminishes crack resistance due to a thinning asphalt film. In terms of fatigue performance, the dry blending method results in significantly longer fatigue life, with a 27% rubber-to-asphalt ratio exhibiting optimal balance. The dry method consistently outperforms the wet method in water stability, and the resistance to water damage increases with rubber content. In conclusion, this study provides valuable insights into optimizing rubber-to-asphalt ratios and blending methods for various application needs, showcasing the benefits of rock asphalt and desulfurized rubber particles in asphalt modification. [ABSTRACT FROM AUTHOR]

Modeling the steel-concrete interface is a constant research topic in structural engineering. Several studies have explored advanced modeling methods, including cohesive models. This article fits into this context by investigating the bond strength at the steel-concrete interface based on a cohesive model. The numerical parameters considered in the software ABAQUS 2019 are investigated. The experimental and numerical results of pullout and beam tests were used as references for the parameters fitting process. With the Concrete Damaged Plasticity model (CDP), the physical non-linearity of the concrete was considered. The contact was described as a surface-to-surface interaction. The pullout tests' cohesive parameters were fitted with experimental tests. Regarding the beam models, an analysis was carried out verifying the use of pullout fitting parameters in the beam models, aiming to compensate for the eventual absence of these data. For the pullout models, the cohesive parameters fitting process yielded better results than those obtained with the recommended values. Improvements were especially significant regarding slippage at the maximum pullout force. The use of pullout test-fitted parameters in the beam models had a smaller influence on the ultimate load predictions. However, the slippage predictions and beam deflection were more affected by the change in cohesive parameters. The bond modeling using a surface-based technique performed well at a low computational cost, considering the materials' physical nonlinearities and 3D geometries. The results, also in general, did not significantly change the load predictions, which indicates a possibility of use in numerical simulations when the pullout data is available. [ABSTRACT FROM AUTHOR]

In order to solve the problems of low tensile strength of composite mortar prone to cracking when reinforced concrete beams are strengthened by traditional methods, this paper proposes a new polyurethane concrete–prestressing wire (PUC–PSW) reinforcement method using polyurethane concrete (PUC) as the wire embedding material. Twelve reinforced concrete T-beams were tested for PUC–PSW flexural reinforcement. These consisted of one unreinforced beam, four PSW-reinforced beams and seven PUC–PSW-reinforced beams. The wire embedding material, wire anchorage form, PUC material depth, amount of wire and loading type were used as variables. The test results show that PUC–PSW reinforcement can significantly increase the yield load and ultimate load of the reinforced beams by 24.1% and 44.6%, respectively, compared with PSW reinforcement. When the load reached 90 kN, the crack widths of PSW-reinforced beam A2 and PUC–PSW-reinforced beam A8 were 0.17 mm and 0.1 mm, respectively. The ability of PUC–PSW reinforcement to limit crack development is better than that of PSW reinforcement, especially after the main beam steel yield. The strength, stiffness and crack-limiting ability of the reinforced beam increase with the PUC thickness of the reinforced layer. [ABSTRACT FROM AUTHOR]

This research paper offers an in‐depth comparative analysis focused on the long‐term durability of shear connectors fabricated from composite materials within a composite and concrete beam structure, extending over a length of six meters. To carry out this evaluation, the experiment employs a four‐point bending test designed to rigorously assess the performance and efficacy of two distinct types of tie straps utilized within the structure. The central element of this investigation, a composite beam integrated within a concrete deck, serves as the primary test specimen, providing a realistic and applicable context for the assessment. The overarching goal of this study is to meticulously examine and compare the resilience and resistance of these shear connectors when subjected to realistic, practical loading conditions. By doing so, the research aims to shed light on the critical performance characteristics of composite shear connectors, especially their role and effectiveness in enhancing the structural integrity and durability of composite and concrete beams in various structural applications. The outcomes of this study are expected to offer significant insights and contribute valuable knowledge to the field of structural engineering, particularly in understanding and improving the performance of composite shear connectors in structural frameworks. [ABSTRACT FROM AUTHOR]

The strain-rate dependence of slip persistence in TiZrNbHfTa was investigated using microcantilever bending tests instead of conventional single-crystal tensile tests. These tests were performed using micrometre-sized cantilevers fabricated within a grain of the polycrystalline material, and the ψ--Χ relationship was obtained in detail. Bending tests were conducted in two strain rates to determine the ψ--Χ relationship. The results showed that the slip plane macroscopically persisted on the {112} plane in the high-strain-rate test, while in the low-strain-rate test, the apparent slip plane roughly coincided with the plane where the maximum shear stress was applied. Detailed tracing of the slip bands, using atomic force microscopy, on the specimen surface showed that the slip plane was microscopically persisted on the {112} plane in high-strain-rate tests, while in low-strain-rate tests, the slip plane often cross-slipped between the {112} and {110} planes. [ABSTRACT FROM AUTHOR]

In this paper, we describe the mechanical characteristics of Al2O3 and TiCN thin films formed by chemical vapor deposition (CVD) and a TiAlN thin film formed by physical vapor deposition (PVD), which are used as hard coating films. A focused ion beam (FIB) was used to fabricate a microcantilever beam for strength tests and fracture toughness tests under bending. A nanoindentation system was used to apply normal force to cantilever beams. All the films showed a linear force–deflection relationship, indicating brittle fracture during elastic deformation. The Young’s modulus ranged from 340 to 379 GPa, with no significant difference among the films, whereas the fracture strength of the Al2O3 films was 5.5 GPa, which was almost twice those of the other two films. For the fracture toughness test, a precrack with various depths was made using FIB at 2 μm from the fixed end of the cantilever beam. The Al2O3 film toughness values ranged from 4.1 to 5.5 MPa√m, which were almost twice that of the TiCN film at each precrack depth. Both CVD films showed a similar trend, i.e., an increase in fracture toughness with decreasing precrack depth, However, the fracture toughness of the TiAlN film showed no precrack depth dependence. The difference in fracture toughness between the CVD and PVD films is discussed on the basis of fracture surface observation results and information on the crystal grain size and orientation. [ABSTRACT FROM AUTHOR]

Marine energy structures are typically made of advanced composite materials and are subjected to extreme ocean environments in service. In extreme ocean environments, seawater currents and waves load structures repeatedly, which cause two environmental conditions: water intrusion and mechanical fatigue. In prior research, the two environmental conditions were applied sequentially, where composite specimens were aged and then mechanically tested. To understand the combined effects of dynamic loading and water intrusion on composite materials, the present study involves the static and fatigue four-point bend testing of composite coupons in a water tank. The water tank was designed and built to fit either a 100 kN or a 250 kN load frame. Flexural strength value, cycles to failure, and failure mode results from submerged fatigue testing will be used to inform marine energy structure designs. The coupon-scale test method will be used to scale up to and inform methods for subsequent subcomponent testing and standards development. The benefits of designing marine energy structures to informed standards are decreased lifetime costs and increased reliability and energy production, ultimately leading to a sustainable and low-carbon energy system. [ABSTRACT FROM AUTHOR]

Highlights In this study, interleaving electrospun Nylon 6.6 nanofibers in the laminate was utilized to improve interlaminar properties of glass/epoxy composite during punching and as a solution to this issue. In order to do so, virgin and nano modified samples are produced and punched and the results are compared to determine the effect of nanofibers on the damaged area as well as the three‐point bending residual strength (carried out on both penetration and exit sides) of the punched laminate. Furthermore, punch—die clearance was also varied to investigate the range in which the nano modification improves the outcome of the process on the laminated composite. According to results of this study, using of Nylon 6.6 nanofibers between composite layers causes significant decrease in the damaged area up to 50%. Also, in both virgin and nano modified laminates, increasing the punch—die clearance increases the damaged area up to 50% and reduces the residual strength of the laminates up to 17%. In addition, nano modified laminates, the residual strength increased up to 28% and 22% for three‐point bending tests carried out on both punch penetration‐ and exit‐side samples, respectively. This is due to the fact that the punch exit‐side contains more damage compared to the penetration‐side. Toughening glass/epoxy laminates using electrospoon Nylon 6.6 nanofibers. Decreasing the damage area occur in the punching of composite laminates. Decreasing the damage area in punching by decreasing the punch‐die clearance. Increasing the strength of punched laminates by applying nanofibers. [ABSTRACT FROM AUTHOR]

Highlights The main limitations of using natural fibers reinforced unsaturated polyester (UPE) composites is poor impact damage behaviors. This work focuses to improve impact damage resistance and residual strength of needle punched banana and pineapple fibers UPE composites by hybridization and incorporating stainless steel (SS) mesh. Different configurations such as banana/UPE (PB), pineapple/UPE (PP) and banana/pineapple/UPE (H) composites were fabricated. Later, SS mesh was incorporated in PB, PP and H composites which are denoted as BS, PS and HS respectively. All specimens were impacted with incident energy of 3.5 and 15 J using Fractovis instrumental low velocity impact tester at 2 and 4 m/s respectively. Subsequently, residual strength of impacted specimens was estimated using three point bending test. Results reveal that the HS composites have least residual dent of 0.89 and 3.9 mm and maximum contact force of 1507 and 1959 N were obtained under the impacted velocity of 2 and 4 m/s respectively, which indicated better damage resistance followed by PS, PP, BS, H and PB specimens. Similarly, the least absorbed energy of 1.9 and 12 J observed in HS composites showed better impact damage tolerance. Moreover, the damage degree and performance index were computed and validated with obtained results. The least reduction of residual strength of 1.2% and 3.2% in HS composites confirmed the better impact damage resistance as compared with all other configurations. Finally, microstructural analysis was performed to correlate the impact induced damage mechanisms. HS composites exhibited the least residual dent of 0.89 mm Impact load bearing capacity of HS composites was drastically improved by 280% Strong interfacial adhesion between the banana fiber and SS mesh was observed HS composites showed greater impact resistance under both velocities There is no significant reduction of residual strength in HS composites [ABSTRACT FROM AUTHOR]

Adaptation of Farfugium japonicum (L.) Kitam. var. japonicum (Asteraceae) to the strong wind environment of coastal areas has been shown to reduce lamina size and shorten petioles; however, their effects on other traits of this species remain unknown. Our morphological analyses showed that shortening of the scape of this species is correlated with shortening of the petiole in coastal areas. The results suggested that when the height of the scapes became higher than that of the petioles, the wind stress on the scapes became stronger and their growth was suppressed. Therefore, the populations in coastal areas with strong winds had significantly shorter scapes than inland populations, and the height of petioles and scapes in the coastal populations were correlated. Further mechanical analysis by three-point bending tests revealed that the scapes had higher strength than the petioles. This species is evergreen and can produce new leaves regardless of the season, even if it loses its leaves by strong winds; however, because scapes only develop above ground for a limited period of the year, the loss of the scapes by strong winds has a significant impact on reproduction in that year. Therefore, even though the scapes were stronger than the petiole, shortening the scapes plays an important role in reducing strong wind stress in coastal areas. [ABSTRACT FROM AUTHOR]