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Infrared radiation was used as a tool to heat laser-structured AlSi10Mg for subsequent fusion bonding with thermoplastic carbon fiber-reinforced PA12. When the two adherends are brought into contact, the bond is formed by melting of the surface-near polymer matrix and pressing it into the laser structure of the aluminum alloy. When investigating different fiber volume contents, the amount of fusible material was identified as a key parameter for the achievable bonding strength. Therefore, the best results were achieved with low fiber volume content (25 vol.-%) or under the use of an additional PA12 interlayer. Moreover, the influence of different surface texture parameters was investigated and the aspect ratio between structure depth and width was found to correlate best with the measured shear strengths. Aspect ratios from 0.18 to 1.15 increased the bond strength up to the interlaminar shear strength of the thermoplastic composite. Especially, aspect ratios of 0.61 or greater proved to be very effective, with resulting mean strength values of almost 30 MPa. While even lower ratios allowed higher loads on the joints compared with untreated surfaces, greater aspect ratios show lower bond strengths, as the laser structures were no longer completely filled with fused PA12. [ABSTRACT FROM AUTHOR]

New chamber stapes prosthesis (ChSP) is a middle-ear prosthesis intended for use in ear surgery for restoring the patient's middle ear function. As the prosthesis is an implantable medical device, it must be sterilized before use. However, possible alterations in the material and the functional properties following the sterilization process can influence the safety aspects while using the prosthesis. The purpose of this paper was to determine the effects of ionizing radiation (IR) on the physicochemical and biological properties of the new chamber prosthesis by utilizing EPR spectroscopy, mechanical testing, and cytotoxicity studies. Our research shows that the radiation treatment increases the hardness and the elastic modulus of the polymer, decreases the stiffness of the prosthesis membrane, and does not cause chemical changes in the polymers that may result in cytotoxicity. Furthermore, new ChSPs were successfully tested in preclinical in vitro tests. The test results justify the undertaking of further work, including in vivo biocompatibility tests and clinical trials, which would eventually lead to the increased use of the prosthesis in clinical practice. [ABSTRACT FROM AUTHOR]

This study involved the fabrication and experimental testing of five distinct geometries of triply periodic minimal surface (TPMS) cellular structures characterized by uniform and relative density grading. The specific geometries examined were Schoen-Gyroid, Schwarz-Diamond, Schoen-I-WP, Schwarz-Primitive, and Fischer-Koch S. The experimental tests focused on subjecting these structures to compression loads. Samples were produced with a masked stereolithography (MSLA) printer. The samples had initial and end volume fractions (VFs) ranging from 20% to 60% in increments of 10%, with five varied relative densities. The Taguchi method is utilized to determine the optimal testing parameters, while the Analysis of Variance (ANOVA) test is employed to examine the data. The novelty of this paper is to comprehensively investigate the structural efficiency and versatility of TPMS for various applications by optimizing five different functionally graded TPMSs. The ANOVA findings highlighted the substantial impacts of Initial VF, Final VF, and TPMS type on the observed fluctuations in stress at the first peak. The Initial VF made a significant contribution, demonstrating 28.8% higher effectiveness than the Final VF. The TPMS type had a statistically significant effect on the amount of energy absorbed, revealing that different lattice types have abilities to absorb energy. [ABSTRACT FROM AUTHOR]

The present work summarizes the mechanical, tribological, and corrosion properties of the aluminum 6061 alloy composite that has been strengthened with a novel combination of 2 wt% nano-silicon dioxide (nSiO2) and varying percentages of tungsten carbide (WC) particles. Microstructural analysis, microhardness, tensile testing, impact testing, and porosity measures have all been assessed in addition to wear and corrosion studies. The results showed that adding 2 wt% nSiO2 to the Al matrix caused the porosity of the composites to decrease, and adding WC caused it to rise. All composites exhibited an improvement in hardness but a decrease in impact strength. The composite containing 9 wt% WC (NAC4) has a hardness that is 2.3, 1.58, 1.35, and 1.25 times greater than that of the ACA, NAC1, NAC2, and NAC3 composites, in that order. The addition of nSiO2 and an increasing amount of WC reduces elongation and increases tensile strength. The ultimate tensile strength of the NAC4 composites increased by 46.72, 27.86, 24.59, and 10.65%, respectively, compared to the ACA, NAC1, NAC2, and NAC3 composites. The cracked surface of the nSiO2 with WC-reinforced composites displays a mixed fracture mechanism with dimples, voids, and cracks. In the wear test under 30 N load, the NAC4 composite shows 5.27, 4.72, 4.02, and 1.12 times lower wear rates than ACA, NAC1, NAC2, and NAC3 composites, respectively. As the concentration of WC particles increases, composites become more resistant to corrosion. According to the results, the polarization curve demonstrated a positive shift in Ecorr from − 1.189 to − 0.656 V as the amount of WC increased, and the icorr decreased to 4.974 × 10–4 from 7.695 × 10–4 A/cm2. [ABSTRACT FROM AUTHOR]

Converting scrap tires to a useful form is becoming an acceptable technique for a broad range of applications. This study focuses on the mechanical characterisation of composites containing a high amount of waste tire rubber which are reinforced with different content of aluminium powder. Therefore, a set of experimental test is performed to highlight the effect of metallic fillers reinforcement on the mechanical response of elaborated composites under static and quasi-static tests. Results of this study reveal the high improvement of material properties for the elastomeric matrix reinforced with metallic fillers. In fact, the ultimate strength of composite material has increased to 1.8 MPa for a high reinforcement content. In the second part, a modified visco-hyperelastic model is developed on the basis of experimental results which demonstrate the prominence of the strain-rate-dependent behaviour consideration. Coupled with the Prony's series approximation, the Mooney Rivlin model is actually applied to refine the strain energy potential in order to examine the mechanical behaviour of the composite material under different loadings conditions. Finally, the good concurrence between the numerical and experimental results highlights the impressive efficacy of the proposed model in accurately predicting the mechanical characteristics of the materials under investigation. [ABSTRACT FROM AUTHOR]

The gallbladder tissue is one important functional tissue of the human abdomen, but the biomechanics of the gallbladder tissue has not been much explored due to biosafety and ethical concerns with cadaveric sample testing. This study aimed to develop tissue surrogates by conducting an experimental study to mimic the mechanical properties of human gallbladder tissue. To meet the objectives, 15 candidate test coupons were fabricated with varying compositions and uniaxially tested at varying strain rates to configure the stress versus strain responses. The results of the tested coupons were compared with the literature on human cadaveric gallbladder tissue to determine the test coupons (i.e. surrogates) mimicking the mechanical properties. The hyperelastic curve fit model (Mooney–Rivlin) was used to quantify the non-linear behaviour of the developed gallbladder tissue surrogates. The biofidelic gallbladder surrogates with realistic mechanical properties have been developed for the first time in the literature. Such surrogates would be helpful to better understand injury biomechanics, trauma research, and making different medical models for educational purposes. [ABSTRACT FROM AUTHOR]

Hybrid ramie/flax natural fiber reinforcement along with epoxy resin is used as the matrix material in this research. Compression molding was adopted as the fabrication method. Ramie/flax at 40 wt. % and 1 cm fiber length showed a better tensile strength of 32.67 MPa than other combinations. Hybrid fiber combination from 30 to 40 wt. % created a strong compatibility between fiber/matrix phase and improved stress transfer behavior along with elastic deformation. Flexural strength results showed enhancement from 43.75 to 52.47 MPa with fiber addition and varying fiber length up to 40 wt. % and 0.5 cm. Impact strength of the hybrid combinations increased from 10.23 to 15.97 kJ/m2. A 5 % NaOH treatment had significant tensile properties varying from 28.42 to 32.67 MPa compared to untreated and 8 % surface treated fibers. Alkali treatment a revealed 49.83–52.47 MPa and 49.12–49.99 MPa flexural strength. Maximum tensile strength of 33.46 MPa was observed under a combination of 120 °C temperature, 12 MPa pressure, and 7 min duration. High pressure, high operating temperature and time, lead to a decline in the mechanical properties of the polymer composites. The SEM analysis showed that the combination with 40 wt. % natural fiber had good fiber distribution leading to better properties. Research works dealing with natural fiber addition, fabrication conditions, and surface treatments are rare. [ABSTRACT FROM AUTHOR]

Hybrid composites, a cornerstone of modern engineering, have been the subject of a groundbreaking investigation. This research delves into the impact of changing the stacking configuration on the characteristics of glass and carbon configuration woven fabric-reinforced laminates. Fabricating different configurations of hybrid laminates using cost-effective hand layup techniques and their performance evaluation through uniaxial tensile test and flexural strength has yielded fascinating results. The tensile strength specimen was prepared as per ASTM D3039 and for flexural test ASTM D7264. The findings demonstrate that stacking laminate CGC has higher tensile strength (418.99 MPa) and flexural strength (342.99 MPa) than other stacking configurations of studied hybrid composites. Also, the fracture analysis evaluates using a high-resolution setup to comprehend the mechanism of failure interply hybrid composites. In addition, design and analytical analysis were done to analyze the tensile and flexural strength of different GC, GCG, and CGC stacking configurations. The finding demonstrates the feasibility of the CGC stacking configuration for load structural applications, marking a significant advancement in materials science and engineering.Article Highlight: The stacking sequence of carbon/glass fiber reinforcement layers substantially influences the performance of hybrid laminates. CGC stacking design for load structural applications, indicating a substantial advance in materials science and engineering With a high-resolution setup, describe the fundamental mechanism of failure, interply hybrid composites An acceptable error was observed in the analytical analysis of the experimental data. [ABSTRACT FROM AUTHOR]

Highlights Agricultural wastes and byproducts offer a vast avenue for replacing commonplace, but environmentally unfavorable, petroleum‐based plastics. Chicken feather fiber (CFF), soy protein isolate (SPI), and jute fabric (JF) are three agricultural materials that can be utilized for creating ‘green’, that is, from nature, resins and composites. This study details the preparation of CFF‐loaded SPI (CFF/SPI) resins and JF/(CFF/SPI) hybrid green composites, both with and without the frequently used toxic crosslinking agent glutaraldehyde (GA), and their respective mechanical properties. Results showed that as CFF loading increased from 0% to 30%, the tensile fracture stress and strain of CFF/SPI resins decreased from 25.2 to 14.3 MPa and from 4.0 to 1.4% respectively, suggesting that CFF acted mostly as filler. JF/(CFF/SPI) composites had higher tensile properties compared to CFF/SPI resins, with fracture stresses and strains ranging from 26.6 to 22.0 MPa and 4.3% to 5.8%, respectively, as CFF loading increased from 0% to 30%. Apart from increasing the flexural modulus, CFF loading did not significantly affect the flexural properties of JF/(CFF/SPI) composites. With any addition of CFF, CFF/SPI resins and JF/(CFF/SPI) composites showed higher mechanical properties than their GA‐crosslinked counterparts, demonstrating that the toxic crosslinker was unnecessary when using the procedure in this work. Fully green composites produced with viability for furniture applications. Mechanical performance of GA‐free SPI resin negated need of toxic crosslinker. CFF reduced warpage when incorporated into SPI resin, and JF/SPI composite. JF/(CFF/SPI) composites found to be superior mechanically to all CFF/SPI resins. JF/(CFF/SPI) composite mechanically optimized at 10/90 CFF/SPI resin ratio. [ABSTRACT FROM AUTHOR]

Binders used in binder jetting often pose health and environmental risks during processing and post processing operations. The print-heads which are used to deposit binder selectively on the feedstock are prone to clogging, despite the trend of print-heads being highly customised to suit different kinds of binders. These factors often hide the advantages of binder jetting as an additive manufacturing process, especially its scalability and its faster printing rates in comparison to powder bed fusion methods. The work presented here takes a step back and focuses on the development of an aqueous, polyvinyl alcohol (PVA)-based liquid binder that is easy to manufacture and store, safe to handle, and can be reliably jetted to print parts. The feedstock considered was Inconel 718, a nickel-based super alloy which can be effectively processed by binder jetting without niobium segregation. PVA was added to the Inconel 718 powder in dry, granular form to manufacture a modified feedstock. The study also investigated the role of molecular weight of the PVA used, sintering environments and post-processing methods like hot isostatic pressing (HIP) on process responses like part densification, tensile strength, and hardness. Three different types of PVA were chosen which had molecular weights 10,000 g/mol (low molecular weight or LMW), 26,000 g/mol (medium molecular weight or MMW), and 84,000 g/mol (high molecular weight or HMW). The compatibility of the liquid, aqueous PVA-based binders with virgin Inconel 718 was examined by measuring the contact angle. The liquid, aqueous binder having MMW PVA reported better wetting with the Inconel 718 powder with a wetting angle of 26.6 which was lower than the wetting angle of 42.4°, seen in case of a commercial resin-based binder. The green strength reported by the MMW PVA liquid binder was 220 kPa which was higher than the other two PVA-based liquid binders. Green parts, upon successful printing, were sintered at 1260 °C. It was observed that a part printed using MMW PVA had a densification of 96.16% when sintered in 99.98% by volume argon gas, which increased to 98.96% after undergoing HIP. The same part reported a densification of 88.69% when sintered in a 95% by volume N2 and 5% by volume H2 gaseous environment, which was later attributed to the uptake of nitrogen by the chromium present in Inconel 718, which prevented necking between particles. Tensile specimens printed using MMW PVA, sintered in a 99.98% argon environment, showed the highest ultimate tensile strength of 220 MPa, which increased to 1010 MPa after the HIP process, which can be compared to commercially available Inconel 718. [ABSTRACT FROM AUTHOR]

It is widely known that glass–epoxy laminates are renowned for their high stiffness, good thermal properties, and economic qualities. For this reason, composite materials find successful applications in various industrial sectors such as aerospace, astronautics, the storage sector, and energy. The aim of this study was to investigate the mechanical and thermal properties of composite materials comprising two different types of epoxy resin and three different hardeners, both at room temperature and under cryogenic conditions. The samples were produced at IZOERG (Gliwice, Poland) using a laboratory hot-hydraulic-press technique. During cyclic loading–unloading tests, degradation up to a strain level of 0.6% was observed both at room temperature (RT) and at 77 K. For a glass-reinforced composite with YDPN resin (EP_1_1), the highest degradation was recorded at 18.84% at RT and 33.63% at 77 K. We have also investigated the temperature dependence of thermal conductivity for all samples in a wide temperature range down to 5 K. The thermal conductivity was found to be low and had a relative difference of up to 20% among the composites. The experimental results indicated that composites under cryogenic conditions exhibited less damage and were stiffer. It was confirmed that the choice of hardener significantly influenced both properties. [ABSTRACT FROM AUTHOR]

Highlights The automotive, aerospace, and sports industries are increasingly utilizing hybrid composites made from natural fiber reinforcements. This study evaluated the performance of a composite made from kenaf and pineapple fibers, manufactured using the compression molding process, with graphene nanoparticles added at varying weight concentrations of 0.5, 1.0, 1.5, and 2.0 wt%. Results showed that adding 0.5 wt% graphene increased the tensile, flexural, and impact strength of hybrid composite by 133.75%, 90.24%, and 25.67%, respectively. Microstructural analysis revealed that graphene integration has enhanced the interfacial bond between the fiber and the matrix, creating resin‐rich areas. Furthermore, the free vibrational analysis indicated that graphene‐infused composites exhibited higher natural frequencies, improving their energy‐absorbing capabilities. Water absorption tests demonstrated that the inclusion of graphene reduced water penetration by improving interfacial bonding, minimizing voids, and decreasing surface energy, which limited water pathways in the composite. Furthermore, the composites with 0.5 wt% graphene showed a contact angle of 80.8°, indicating lower hydrophilicity compared to neat composites, which had a contact angle of 70.7°. This research emphasizes the advantages of hybrid composite materials derived from kenaf and pineapple fibers, specifically for applications in vehicle interiors and construction, including wall panels and separators. Hybrid composite was prepared using the compression molding process. Adding 0.5 wt% graphene improved the mechanical properties of composites. Hybrid composites with lower wt% graphene had higher natural frequencies. The composites with 0.5 wt% graphene had better water absorption properties. [ABSTRACT FROM AUTHOR]

Ultrasonic metal welding machines are suitable for various complex applications (e.g., battery tabs) through unique mechanical design, special pressure application methods and high-precision welding. This work reports the weldability, forming quality and fractographic analysis of copper multilayered welded joints which were studied by SEM-EDS characterization, micro-hardness testing and tensile testing based on ultrasonic double roller welding (UDRW). Three groups of process parameters (A, B and C) were established to investigate the performance, production quality and welded joint surface interconnections. The tensile testing results of sample under parameter 3 in group A [S-P3(A)] indicate the maximum tensile strength of 69.859 N in T-peel test while the average tensile strength has increased by 58.525 N due to rise in welding time from 2 sec to 5 sec. The results analysis indicates that welding quality features in S-P3(A) joints under 4 bar, 100 mm/s, 45 % have been exploited. The over-welded zone was transformed into good-welded zone. The micro-cracks, fatigue stations and peeling texture in multilayers were reduced. It was found that when the welding energy was 10000 J then the tearing edges and interlayers cracks were minimized while keeping the other parameters constant. Moreover, when the amplitude increased up to 50 %, then numerous micro-cracks and micro-fissure stations were created, which leads to the occurrence of fracture in multi-layer welded joint. The EDS study investigated that the complex features are formed at the interface junction of sample 3 S3(A) in multilayer welds. The complex multilayer microstructures can induce and produce unique hardness properties for battery manufacturing. It leads to high quality and durable welds. Eventually, it is experimentally demonstrated that robust 40 layer welded joints can be obtained by the UDRW process. The datasets used and/or analyzed during the current study are available from the corresponding author upon reasonable request. • Low amplitude used to minimize the damage of a workpiece, reduce metal debris and heat. • The study reports 40 layers of 0.2mm Cu thin foils welded joints using ultrasonic seam welding technology. • Tensile testing of S-P3(A) indicate maximum strength with 69.859N due to incremental upturn in time from 2sec to 5sec. • Welding quality features in S-P3(A) joints under 4bar, 100mm/s, 45%: (a) inside cross-sectional view were investigated. • Weldability, forming quality and fractographic analysis of Cu welded joints were studied by SEM-EDS characterization. [ABSTRACT FROM AUTHOR]

This article presents the concept, research, and modeling of a sandwich composite made from ULTEM 9085 and polycarbonate (PC). ULTEM 9085 is relatively expensive compared to polycarbonate, and the composite structure made of these two materials allows for maintaining the physical properties of ULTEM while reducing the overall costs. The composite consisted of outer layers made of ULTEM 9085 and a core made of polycarbonate. Each layer was 3D-printed using the fused filament fabrication (FFF) technology, which enables nearly unlimited design flexibility. The geometry of the test specimens corresponds to the ISO 527-4 standard. Tensile and three-point bending tests were conducted. The structure was modeled in a simplified manner using averaged stiffness values, and with the classical laminate theory (CLT). The models were calibrated through tensile and bending tests on ULTEM and polycarbonate prints. The simulation results were compared with experimental data, demonstrating good accuracy. The 3D-printed ULTEM-PC-ULTEM composite exhibits favorable mechanical properties, making it a promising material for cost-effective engineering applications. [ABSTRACT FROM AUTHOR]

Composite sandwich structures, which are widely employed in engineering structures, require a multitude of inserts. In certain instances, the necessity for a specialized insert arises from the unique characteristics of a particular application. In applications such as weather radar radomes, double-curved sandwich panels should be designed with electromagnetic (EM) transparency as a primary objective. The use of metal inserts should be restricted to the absolute minimum. Given the limitations of using metal materials to protect against EM radiation and the need to enhance the load-bearing capacity of the joint against pull-out loads, a composite insert has developed as an innovative solution. In this study, a composite insert of a double-curved sandwich dome has been developed using silica nanoparticles, and its mechanical strength against pull-out load has been evaluated through both experimental and numerical analysis. The strength results obtained have been compared with analytical estimates. Additionally, the buckling of the double-curved sandwich dome against a wind speed of 220 km/h has been investigated numerically. The critical buckling load for wind loading for the full-scale sandwich radome was estimated to be 16,303 N. According to the numerical results obtained with the Abaqus finite element (FE) software, the maximum pull-out force applied to the connection area is approximately 10.7 kN. A parametric study of geometric variables and experimental results showed that it is possible to achieve a stronger composite insert (by 1 wt % nano silica particles) by 20.7% lighter and 102.65% more bearing capacity. [ABSTRACT FROM AUTHOR]

Careful material selection is paramount to meet the significant challenges posed by harsh environments in advanced applications. Ceramic matrix composites (CMCs) have come to the forefront of consideration for many of these applications where environmental resistance needs to be combined with structural stability at high temperatures (1200°C+). Many gaps exist in understanding how material variations pose unique material and design challenges that affect the final performance in a particular application. Thorough materials testing at relevant temperatures is required for various candidate materials to realize an analytical approach to materials selection. This review will discuss mechanical and environmental tests and their use at high temperatures including tensile tests, flexure tests, lifetime testing methods, interlaminar tests, and environmentally relevant tests. Challenges for performing these tests at high temperatures and on CMCs will be discussed. A literature review will provide examples of state‐of‐the‐art testing, and the test results from historical work and improvement opportunities will be addressed. This review aims to provide an overview of the current capabilities and practices for high‐temperature testing and recommend best practices for performing high‐temperature tests and interpreting and sharing the results and metadata with the larger community to expand the CMC material property database. [ABSTRACT FROM AUTHOR]

In this study, a "green composite" material made from 60% tree bark and 40% polylactic acid (PLA) was fabricated and evaluated according to its mechanical properties and biodegradability. Biodegradation tests were performed in compost, simulated aquatic environments, and natural soil. In compost, the composite degraded steadily and reached 47% biodegradation after 11 weeks. In soil, the material quickly lost much of its tensile strength, and after 6 weeks, there were signs that the surface and the internal structure had started to deform. Biodegradation in aquatic environments also caused a loss of tensile strength after only a few weeks. Because of the high filler content, excellent biodegradability, and light weight, the composite material has a low environmental footprint. The material could be used in agricultural equipment such as plant pots. [ABSTRACT FROM AUTHOR]

Activated Tungsten Inert Gas (A-TIG) welding, a variant of tungsten inert gas (TIG) welding, was used for welding P91. In Generation IV power plants, P91 welds are prone to premature failure due to the presence and formation of brittle phases and creep at high temperatures. When performing A-TIG welding, the flux composition plays a role in the reversal of the Marangoni flow in the weld pool, which ultimately determines the level of penetration achieved. A-TIG gave a complete penetration of 8 mm in the P91 weld. The weldment exhibited non-uniform growth of microstructures with varying grain sizes and precipitates, resulting in variation in mechanical properties. The weld fusion zone (WFZ) had a martensitic structure. The standard flat tensile test specimens were found to fail in the base metal and the fine-grain heat affected zone (FGHAZ) region. The sub-size flat tensile test specimen gave a high strength of 863 ± 10 MPa, failing in the WFZ. The high temperature tensile test specimens had the tensile strength of 512 ± 10 MPa (at 450 °C) and 469 ± 10 MPa (at 450 °C). In both the high temperature tensile test specimens, failure occurred in the base metal region. The impact toughness was recorded at 76 ± 15 Joules due to the presence of untempered martensite in the AW state, and in the PWHT state, the impact toughness increased up to 98 ± 15 Joules. In the AW state, the coarse grain heat affected zone (CGHAZ) region was observed with a maximum microhardness of 450 ± 5 HV and WFZ 460 ± 5 HV. The post-weld heat treatment (PWHT) was successfully performed to temper the martensite and impart some ductility to the weld. The A-TIG weld had sufficient benchmark strength, and the study successfully concluded its aim. [ABSTRACT FROM AUTHOR]

A high-entropy alloy with an atomic composition of Fe40Mn15Cr20Ni22Ti3 with outstanding strength–ductility synergy induced by titanium additions was successfully developed. At room temperature, its ultimate tensile strength can reach 1089 MPa and still maintain 21% elongation. Moreover, at low temperature of 77 K, its ultimate tensile strength and elongation have been increased to 1285 MPa and 35%, respectively. After careful analysis, it is found that the cause for the large increase in elongation is the decrease of the stacking fault energy at low temperature, which leads to the deformation mechanism of the alloy to change from dislocation wave slip to plane slip. In addition, the precipitation strengthening and grain boundary strengthening induced by chrome-rich σ precipitates are the main strengthening contribution. [ABSTRACT FROM AUTHOR]

Highlights The effect of the asymmetric distribution of woven flax fiber on the interlaminar fracture toughness of carbon fiber‐reinforced polymer (CFRP) is investigated experimentally via a double cantilever beam test, and the results are backed by analytical and numerical analysis. Four hybrid configurations are fabricated with different stacking sequences of (CFRP) and flax fiber‐reinforced polymer (FFRP) plies. The results of hybrid specimens are compared with those of all CFRP and all FFRP specimens. The hybrid composite with one carbon/flax fiber layer at the interface requires the highest critical energy release rate, GC, to initiate cracks. A resin layer on top of the flax plies and a carbon fiber imprint in that layer are observed, thus signifying an increase in GC for the hybrid composites with dissimilar interface layers. Varying the number of carbon/flax fiber layers at the interface adversely affects GC. Mode II contribution to the GC was verified analytically for asymmetric hybrid configurations. The agreement between experimental, numerical, and analytical results is excellent. The hybridization of flax with carbon enhances the fracture toughness of CFRP while providing an opportunity to achieve lightweight, high‐performance, and eco‐friendly structures. Flax fiber is used to increase the fracture toughness (GC) of CFRP Asymmetric carbon/flax fiber hybrid composites are designed for this purpose One interface carbon/flax hybrid exhibits a 70% increase in GC Blocking the plies together results in reduced GC and mode‐II fracture as well Numerical and analytical analysis agrees well with experimental results [ABSTRACT FROM AUTHOR]

This study investigates the residual tensile behaviour of hybrid Carbon Glass fibers reinforced thermoplastic PEEK laminates after they were exposed for 5 min to a hydrogen/oxygen flame. This flame results in a severe thermal aggression characterized by a wall temperature ranging from 900 to 1270 °C and with different heat fluxes (from 200 to 800 kW/m2). The thermally-induced damages were examined by means of microscopic observations and micro CT analyses. The results show that the mass loss linearly depends on the measured heat flux for a 5 min exposure. Depending on the fire testing conditions, the mechanical properties in tension (stiffness and strength) are totally degraded after exposure to the highest heat fluxes (600 and 800 kW/m2) but the retention of the tensile properties is moderate (about −35 to −60% decrease in strength and stiffness, respectively) after exposure to a 200 kW/m2 heat flux. The residual tensile properties of CG/PEEK laminates follow master curves representing the correlations between the mass loss and the changes in the tensile properties regardless the heat flux. These master curves provide a relevant design rule for composite parts to be used under critical service conditions (H 2 /O 2 flame exposure). • The influence of a H 2 /O 2 flame on the behaviour of composite materials was studied. • Wall temperature ranges from 900 to 1270 °C for heat fluxes from 200 to 800 kW/m2. • The mechanical properties are totally degraded after exposure to 600–800 kW/m2. • The changes in the tensile properties are correlated to the mass loss. • Master curves provide a criterion to design composite parts under H 2 /O 2 flame. [ABSTRACT FROM AUTHOR]

Composite materials represent a cutting-edge formulation, combining two or more components to achieve multifunctional performance tailored for a range of multidisciplinary applications. In this study, it was focused on the fabrication of epoxy resin with glass fiber to produce a composite material. Furthermore, it explored the incorporation of carbon nanotubes (CNTs) into this formulation, paving the way for the development of self-healing composite sheets capable of withstanding bullet impacts. Characterization of the formulated composites involved a comprehensive comparative analysis utilizing attenuated total reflectance Fourier transform infrared spectroscopy (AT-FTIR) to assess chemical composition, alongside topographical studies employing scanning electron microscopy (SEM) and atomic force microscopy (AFM) to evaluate surface morphology as well as the thermal analysis study. Mechanical properties were rigorously analyzed using coherent gradient sensing (CGS) and mechanical testing methodologies. Our findings unveiled a remarkable compatibility between the epoxy resin and glass fibers in the presence of CNTs, indicating a synergistic enhancement in composite performance. Moreover, the remarkable self-healing capability post-bullet impact was substantiated through SEM imaging and advanced imaging techniques, affirming the efficacy of CNTs incorporation in bolstering composite resilience and durability. [ABSTRACT FROM AUTHOR]

Dissimilar metal welded (DMW) joint plays a crucial role in constructing and maintaining ultra-supercritical (USC) nuclear power plants while presenting noteworthy environmental implications. This research examines different welding techniques utilized in DMWJ, specifically emphasizing materials such as P91. The study investigates the mechanical properties of these materials, the impact of alloying elements, the notable difficulties encountered with industrial materials, and the concept of buttering. The USC nuclear power plants necessitate welding procedures appropriate for the fusion of diverse metal alloys. Frequently employed methodologies encompass shielded metal arc welding (SMAW), gas tungsten arc welding (GTAW), gas metal arc welding (GMAW), and flux-cored arc welding (FCAW). Every individual process possesses distinct advantages and limitations, and the choice of process is contingent upon various factors, including joint configuration, material properties, and the desired weld quality. The steel alloy known as P91, which possesses high strength and resistance to creep, is extensively employed in advanced ultra-supercritical (AUSC) power plants. P91 demonstrates exceptional mechanical characteristics, encompassing elevated-temperature strength, commendable thermal conductivity, and notable resistance against corrosion and oxidation. The presence of alloying elements, namely chromium, molybdenum, and vanadium, in P91, is responsible for its improved characteristics and appropriateness for utilization in (AUSC) power plant applications. Nevertheless, the utilization of industrial materials in DMW joint is accompanied by many noteworthy concerns, such as the propensity for stress corrosion cracking (SCC), hydrogen embrittlement, and creep deformation under high temperatures. The challenges mentioned above require meticulous material selection, process optimization, and rigorous quality control measures to guarantee the dependability and sustained effectiveness of DMW joint. To tackle these concerns, a commonly utilized approach referred to as buttering is frequently employed. When forming DMW joint in nuclear facilities, it is customary to place a buttering coating on ferritic steel. This facilitates the connection between pressure vessel components of ferritic steel and pipes of austenitic stainless steel. The primary difficulty in DMW joint manufacturing is in mitigating the significant disparity in material characteristics resulting from carbon migration and metallurgical alterations along the fusion interface between ferritic steel and austenitic stainless steel. The process of buttering entails the application of a compatible filler material onto the base metal before the deposition of the desired weld metal. The intermediate layer serves as a mediator, enhancing the metallurgical compatibility, diminishing the probability of fracture, and enhancing the overall integrity of the joint. Buttering is still a new research area with a wide scenario of scope in terms of development, which could revolutionize developing high-temperature. These long-term sustainable joints could serve under critical conditions like AUSC power plants and reduce CO2 emissions by increasing the overall efficiencies of the systems. [ABSTRACT FROM AUTHOR]

Many heart diseases can change the elasticity of myocardial tissues, making elastography a potential medical imaging strategy for heart disease diagnosis and cardiovascular risk assessment. Among the existing elastography methods, ultrasound elastography is an appealing choice because of ultrasound’s inherent advantages of low cost, high safety, wide availability, and deep penetration. The existing investigations of cardiac ultrasound elastography were implemented based on a bulk model of heart tissue, treating the waves generated in the myocardial tissues as shear waves. In this pilot study, we considered the distinct geometric characteristics of heart tissue, i.e., being a layered structure and its dispersive nature as biological tissue. Based on these considerations, we modeled heart tissues as a layered-dispersive structure and developed a new ultrasound elastography method, ultrasonic guided wave elastography, to characterize the myocardial elasticity. The validity of this layered-dispersive model and the reliability of the developed guided wave elastography were first verified on tissue-mimicking phantoms. Then, the guided wave elastography was applied to an ex vivo imaging of a rat heart tissue specimen in real-time during the biaxial planar mechanical testing. The comparison of the real-time myocardial elasticity obtained from guided wave elastography and mechanical testing demonstrated strong matching, verifying the reliability of the developed cardiac guided wave elastography as a potential method for characterizing myocardial elasticity. [ABSTRACT FROM AUTHOR]

Cribellate silks, produced by ancient spiders, are fascinating because they feature a highly sophisticated, 3D hierarchical structure consisting of filaments with different diameters and shapes. Here, the smallest and thinnest constituents of the cribellate silk are investigated: nanofibrils that form a dense mesh that is supported by larger fibers. Analysis of their structure via atomic force and transmission electron microscopies shows that they are flattened fibrils, only ≈5 nm thick — thinner than any other natural spider silk fibrils previously reported. In this work, the first mechanical tensile testing experiments on these fibrils are carried out, which reveals that the fibrils show an outstanding extensibility of at least 1100%, almost twice as much as the most stretchable spider silk previously reported. Based on these extraordinary findings, this work significantly expands the parameter space of materials properties attainable by spider silks and provides further insights into their nanomechanics. [ABSTRACT FROM AUTHOR]

The woven lattice sandwich composites (WLSCs) are susceptible to damage during service, which leads to a decline in their mechanical properties. Therefore, it is crucial to develop repair methods that specifically target the mechanical properties of WLSCs. In this study, repair techniques for the common types of skin and core damage in WLSCs were propose. The repair process begins with identifying the type of structural damage and removing the damaged section. Subsequently, the skin and core layers are repaired accordingly. The mechanical properties before and after repair are then compared through experimental evaluations. The results demonstrate that the carrying capacity of the repaired WLSCs is 85% higher than that of the original, unrepaired structure using the selected repair method. Highlights: Typical damage modes of woven lattice sandwich composites were classified.Repairing methods are proposed for woven lattice panels based on damage modes.Core‐foaming and skin patch adhering perfectly rehabilitate the damaged sandwich.Bearing capacity of the repaired sandwich slightly surpasses its original structure. [ABSTRACT FROM AUTHOR]

Lightweight and bendy plastic‐based perovskite solar cells (PSCs) are considered strong emerging rivals to the rigid heavy‐block photovoltaics made of conventional crystalline‐silicon. To further increase the competitiveness of these devices, the research community is nowadays searching for compatible, effective and scalable strategies to achieve efficiencies of >20%, while their development using lower‐cost and greener materials is also increasingly investigated. From the precursor solutions and prenucleation state of perovskites to the fully crystallized materials, this disclosure provides key findings that benefit fundamental understanding for streamlining antisolvent quenching methods toward the development of high‐performance and stable flexible‐plastic PSCs under ambient atmospheric conditions. Evidencing the importance of the concurrent consideration of a series of antisolvent physical properties for a group of primary and secondary monohydric alcohols, a breakthrough achievement is attained. Mirror‐like, pinhole‐free, monolayered vertically‐aligned (high‐aspect‐ratio) grained and mechanically‐robust ambient‐air‐processed perovskite structures are developed using 2‐butanol as a non‐toxic and benign‐to‐plastics (evidenced by nano‐mechanics) antisolvent alternative to the reference chlorobenzene. To this end, a new literature record of 20.09% for scalable carbon‐based flexible PSCs is achieved (power‐to‐weight performance 1.05 Wg−1, at 190 gm−2), also demonstrating highly‐robust unencapsulated devices under the ISOS‐D‐1 protocol conditions (T85 >1000 h) and bending fatigue (T80(5‐mm‐radius) >5000 bending cycles). [ABSTRACT FROM AUTHOR]

Introduction: The Jaipur foot is a low-cost prosthetic foot developed in Jaipur, India. Despite its worldwide use, few data are available on its mechanical properties. In general, there is a lack of objective data on the mechanical performance of prosthetic feet, hindering the objectivity of the prosthetic foot prescription process. The aim of this project was to compare the properties of the Jaipur foot with three prosthetic feet of differing activity levels (a SACH foot and two ESPFs) used commonly in the UK National Health Service (NHS), specifically evaluating loading-displacement relationships and energy-storing properties. Materials and Methods: Static proof testing was performed on the four prosthetic feet (BMVSS Jaipur foot, 1D10 Dynamic, 1C30 Trias, and 1C60 Triton) using ISO:10328 methods. Loading-displacement graphs for the forefoot and heel were produced, from which instantaneous stiffness at forces typical of walking and running was produced and energy-storing properties were calculated. Results: The Jaipur foot demonstrated the highest heel stiffness at both walking and running forces, the highest forefoot stiffness at walking forces, and the lowest energy return of the four feet overall. The ESPFs demonstrated the lowest forefoot stiffness, along with the highest energy returns. Conclusions: Although low cost and cultural requirements should be taken into account, these data have demonstrated the inferior energy-storing properties of the Jaipur foot compared with Western prosthetic feet, using ISO methods to allow future cross-study comparison. Clinical Relevance: The mechanical and energy-storing data from this study can be compared with other research using ISO methods to make the prosthetic prescription process more objective, allowing the most appropriate choices to be made for patients. [ABSTRACT FROM AUTHOR]

Background: In recent years, the medical community has witnessed a notable increase in high-energy traumatic injuries, leading to a surge in complex fracture patterns that challenge existing treatment methodologies. Among these, the posterior approach to acetabular fractures stands out for offering direct visualization of the retro-acetabular surface, with current fixation methods relying on 3.5 mm low-profile reconstruction plates and various other implants. Despite the effectiveness of these methods, there is a burgeoning demand for a singular, adaptable implant that not only streamlines the surgical process but also optimizes patient outcomes. Methods: In an innovative approach to address this need, three-dimensional (3D) models of the posterior acetabular wall were meticulously crafted using AutoCAD® software. The chosen material for the implant was 316L surgical steel for its durability and strength. The design of the implant featured a low-profile mesh structure, which was instrumental in facilitating osteosynthesis. This design allowed for the placement of screws of varying lengths in multiple directions, ensuring the initial reconstruction of the joint in an anatomical position without hindering the placement of the definitive implant. The primary objective was to secure the fixation and stabilization of the fracture by specifically targeting the smaller bone fragments. A comparative analysis was then conducted between this novel plate and a conventional 316L surgical steel, seven-hole, 3.5 mm reconstruction plate through finite element analysis. Results: The comparative analysis unveiled that both plates demonstrated comparable deformation capacities, with no significant differences in load-bearing capabilities observed. This finding suggests that the innovative plate can match the performance of traditional plates used in such surgeries. Conclusions: The finite element analysis revealed that the newly developed anatomical plate for posterior wall acetabular fractures meets the necessary physical and mechanical criteria for permanent implementation in patients with these fractures. This breakthrough represents a promising advancement that could simplify surgical procedures and potentially elevate patient outcomes. Level of Evidence II: This study is classified as a Level II, diagnostic study. [ABSTRACT FROM AUTHOR]

The efficiency of a repair strategy applied to a honeycomb/carbon-epoxy sandwich beam was analyzed in this work. Experimental tests were performed considering three-point bending loading of undamaged, damaged and repaired specimens. In the damaged case, the central part of the core and of one of the skins were removed. The repair scheme consists of bonding a plug of honeycomb into the core and repairing the carbon-epoxy skin considering a scarf patch. A finite element analysis incorporating cohesive zone mixed-mode I + II analysis was performed. The resultant load-displacement numerical curves were compared with the experimental ones. It was verified that the repair procedure is efficient regarding recovery of the initial stiffness and strength of the undamaged case, and it was concluded that the proposed numerical model is a valid tool to deal with repair of sandwich beams. [ABSTRACT FROM AUTHOR]

Fatigue tests of nickel-based single-crystal superalloys with inclined film cooling holes (FCHs) at 1000°C were conducted to investigate the effects of crystal orientation and to quantify the fatigue performance of the high-temperature structures. Fractographic analysis and computations of stress concentrations revealed competitive failure mechanisms between mode I crack nucleation and fatigue crack growth in crystallographic plastic slip systems, whereas crack nucleation around inclined FCHs can be characterized by the known fatigue criteria derived for smooth specimens. A life prediction model based on the crystal slip mechanism and the theory of critical distance was introduced to predict the fatigue life of FCH structures and provided reasonable accuracy for different FCH specimens. [ABSTRACT FROM AUTHOR]

Glass fibre-reinforced polymer (GFRP) is a suitable substrate material for constructing a Conformal Load-Bearing Antenna Structure (CLAS). The relative permittivity of the CLAS substrate, which determines its resonant frequency, is affected by damage sustained by GFRP. This paper investigates the effects of damage (induced by mechanically loading the substrate) on the resonant response of the CLAS. Decoupling the antenna from the substrate was essential to evaluate the CLAS's true response to the induced damage. This paper details a systematic investigation examining how the frequency response of a "pristine" antenna and a surface-mounted antenna respond to a substrate subjected to quasi-statically induced mechanical damage and cyclic fatigue loading. The results demonstrate that the resonant frequency of the CLAS varies as a function of the substrate's mechanical damage. The prepared CLAS is tolerant to a certain degree of mechanical loading and related damage with its resonant frequency remaining within an acceptable bandwidth. [ABSTRACT FROM AUTHOR]

This study examines the mechanical properties, specifically strength and stiffness, of technical hemp and flax fibers grown in Romania. Tensile testing was employed to determine stress–strain curves and the Young's modulus and to assess the failure strength of both fiber types. Although samples of various lengths were tested, no significant length-dependent variations were observed. However, a strong dependence on fiber diameter was noted, with the smallest diameters approaching the documented strength of elementary fibers. Due to the considerable variability in the experimental results pertaining to the characteristics of the reinforced fibers, a statistical analysis using a two-parameter Weibull distribution was employed. The analysis revealed three distinct stress–strain curve profiles, i.e., linear, bi-linear, and tri-linear patterns, with the average ultimate stress ranging from 412 to 566 MPa for hemp and 502 to 598 MPa for flax. [ABSTRACT FROM AUTHOR]

Cord-rubber composites are subjected to a wide range of loads in various applications. However, their fatigue behavior remains relatively under-researched. To address this gap, a set of representative specimens was developed, and a validated numerical model was employed to assess fatigue-relevant parameters. In this study, we present the results from two series of tests with different strain ratios (R values). One series was subjected to a pure pulsating tensile strain (R ~0), while the second series experienced an increased mean strain with an R ratio between 0.2 and 0.3. A direct comparison of the two series demonstrated that a higher strain ratio results in a longer service life. This is reflected in an increase in the slope (k) from 13 to 23, as well as an increase in the ultimate fiber strain from 8% to 11% at Nd = 50,000 load cycles for a survival probability of 50%. Both series indicate a comparable scatter in the test results. This comparative analysis shows that the strain ratio significantly impacts the fatigue behavior of cord-rubber composite materials based on cyclic tests under different loading conditions. The findings of this study demonstrate the necessity of considering different load situations when evaluating or designing components. [ABSTRACT FROM AUTHOR]

This article discusses the impact of hybrid nanoparticle reinforcements on the mechanical properties of Epoxy-Polylactic Acid (PLA) composites. The researchers conducted experiments and numerical analysis to investigate the effects of adding different fillers on the tensile and bending strength of the composites. The results showed that the addition of nanofillers, such as SiO2, graphene nanoplatelets (GNPs), and multi-walled carbon nanotubes (MWCNTs), improved the mechanical properties of the composites. The study provides valuable insights for researchers and engineers working with epoxy-PLA composites. Additionally, the article references two related articles that provide further insights into the mechanical behavior of composite materials. [Extracted from the article]

Hollow fan blades made of titanium alloy are widely used in turbofan engines, and the residual stress (RS) inside the blades directly affects the performance of the blades and even the engine. Therefore, it is crucial to measure and study the RS distribution of titanium alloy hollow fan blades. This paper aims to investigate the RS distribution on the cross-section of a wide-chord hollow fan blade made of Ti-6Al-4 V titanium alloy. The multiple-cut contour method is utilized to determine the RS. A theoretical model of the multiple-cut contour method for fan blades is established, and the specimen was cut three times, followed by contour measurement of the cut planes, data processing and elastic finite element analysis. The RS map of the three cut planes is finally presented. The normal RS on three cross-sections of the fan blade is uniformly distributed, ranging from -50 MPa to 50 MPa. The normal RS distribution at different positions for the hollow fan blade can be obtained by the proposed multiple-cut contour method. The findings of this research provide a comprehensive insight into the distribution of RS in wide-chord hollow fan blades made of Ti-6Al-4 V titanium alloy. [ABSTRACT FROM AUTHOR]

This study evaluated the influence of various printing layer thicknesses with silicon dioxide nanoparticles (SiO 2 NPs) incorporated as a reinforcement material on the flexural strength of 3D-printed denture base resins. Asiga (DentaBASE, Asiga, Erfurt, Germany) and NextDent (Denture 3D+, NextDent B.V., Soesterberg, The Netherlands) 3D-printed resins were modified with different concentrations of SiO 2 NPs (0.25 % and 0.5 wt%). A total of 180 specimens (bar-shaped, 64 × 10 × 3.3 mm) were fabricated (N = 90/resin). Each resin was subdivided into three groups (n = 30) according to the SiO 2 NP concentration (0 %, 0.25 %, and 0.5 wt%) Each concentration was divided into three groups (n = 10) according to the printing layer thickness (50 µm, 75 µm, and 100 µm). Specimens were printed according to the manufacturer's instructions and then subjected to 10,000 thermal cycles. A three-point bending test was used to measure the flexural strength (MPa). One-way analysis of variance (ANOVA) and Tukey's post hoc tests were used to analyze the data (α = 0.05). For both resins, printing layer thicknesses of 50 µm and 75 µm exhibited significantly higher flexural strength than 100 µm (P < 0.001). The 50 µm thickness showed the greatest flexural strength values (81.65 ± 4.77 MPa and 84.59 ± 6.21 MPa for Asiga and NextDent, respectively). The 100 µm thickness showed the lowest flexural strength values (74.35 ± 5.37 and 73.66 ± 5.55 MPa) for Asiga and NextDent, respectively. The flexural strength significantly increased with the addition of SiO 2 NPs with printing layer thicknesses of 50 µm and 75 µm (P < 0.001), whereas the modified and unmodified groups printed with a 100 µm layer thickness did not differ significantly. Asiga 0.25 %/50 µm and NextDent 0.5 %/50 µm showed the highest flexural strength values (97.32 ± 6.82 MPa and 97.54 ± 7.04 MPa, respectively). Scanning electron microscopy fractured surfaces analysis revealed more lamellae and irregularities with lower printing layer thicknesses and SiO 2 NP concentrations. The flexural strength increased with printing layer thicknesses of 50 µm or 75 µm combined with SiO 2 NP reinforcement. [ABSTRACT FROM AUTHOR]

Acellular matrices have historically been applied as biologic scaffolds in surgery, wound care, and tissue engineering, albeit with inconsistent outcomes. One aspect that varies widely between products is the selection of decellularization protocol, yet few studies assess comparative effectiveness of these protocols in preserving mechanics, and protein content. This study characterizes bladder acellular matrix (BAM) using two different detergent and enzymatic protocols, evaluating effects on nuclei and DNA removal (≥90%), structure, tensile properties, and maintenance of extracellular matrix proteins. Porcine bladders were decellularized with 0.5% Sodium Dodecyl Sulfate (SDS) or 0.25% Trypsin-hypotonic-Triton X-100 hypertonic (TT)-based agitation protocols, followed by DNase/RNase agents. Characterization of BAM included decellularization efficacy (DAPI, DNA quantification), structure (histology and scanning electron microscopy), tensile testing (Instron 345C-1 mechanical tester), and protein presence and diversity (mass spectrometry). SDS and TT data was directly compared to the same native bladder using two-tailed paired t-tests. Native, TT, and SDS cohorts for tensile testing were compared using one-way ANOVA; Tukey's post-hoc tests for among group differences. Effective nuclei removal was achieved by SDS- and TT-based protocols. However, target DNA removal was achieved with SDS but not TT. SDS more effectively maintained qualitative tissue architecture compared to TT. The tensile modulus of the TT cohort increased, and stretchability decreased after decellularization in both SDS and TT. UTS was unaffected by either protocol. Higher overall diversity and quantity of core matrisome and matrisome-associated proteins was maintained in the SDS vs TT cohort post-decellularization. The results indicated that detergent selection affects multiple aspects of the resultant BAM biologic product. In the selected protocols, SDS was superior to TT efficacy, and maintenance of gross tissue architecture as well as maintenance of ECM proteins. Decellularization increased scaffold resistance to deformation in both cohorts. Future studies applying biologic scaffolds must consider the processing method and agents used to ensure that materials selected are optimized for characteristics that will facilitate effective translational use. [Display omitted] [ABSTRACT FROM AUTHOR]

The integration of natural fibre thermoplastic composites, particularly those combining flax fibres with polypropylene, offers a promising alternative to traditional synthetic composites, emphasising sustainability in composite materials. This study investigates the mechanical properties of flax/polypropylene composites manufactured using flashlamp automated tape placement and press consolidation, individually and in combination. Tensile, compression, three-point bending, and double cantilever beam tests are utilised for comparing these manufacturing processes and the mechanical performance of the resulting composites. The microstructure of the tapes is investigated using cross-sectional microscopy, and the thermophysical behaviour is analysed utilising thermogravimetric analysis and differential scanning calorimetry. The temperature during placement is monitored using an infrared camera, and the pressure is mapped with pressure-sensitive films. The natural fibre tapes show a good aptitude for being manufactured with automated tape placement. The tensile performance of tapes manufactured with automated tape placement is close to that of press consolidated samples. Compression, flexural properties, and the mode I fracture toughness critical energy release rate all benefit from a second consolidation step. [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]

Fiber-reinforced polymer (FRP) composites are promising materials already being used in bridge construction. Lightweight deck panels, mainly used in the rehabilitation or replacement of existing bridges, are the most commonly used FRP bridge components. However, FRP decks are prone to damage due to delamination, matrix cracking, interlaminar cracking, and debonding. In addition, due to their microstructure, FRP materials tend to deteriorate in ways that are not easily detected by visual inspection. Therefore, nondestructive methods should often complement visual inspections aimed at assessing the technical condition of the structure. New measurement techniques are constantly being researched and developed to assist in the evaluation of FRP structures. Distributed fiber optic sensing (DFOS) has been chosen as the main measurement technique of the newly developed FRP bridge deck panel because this technique provides extended advantages compared to the conventional spot gauges. The concept of a component with an integrated DFOS-based system capable of structural control and detection of overloaded vehicles has been developed and verified both in laboratory conditions. The novelty of the presented approach is that sensors (strain-sensing fibers) are precisely embedded in FRP laminates for simultaneous internal strain and vertical displacement (shape change) measurements and delamination detection. The experimental verification of a full-scale deck under static and dynamic loading is described in the paper. The performance of the DFOS system was verified using reference techniques. The results proved the system to be a reliable tool for diagnosing FRP bridge decks. [ABSTRACT FROM AUTHOR]

This paper explores how the examination of additively manufactured auxetic componentry can be applied in human-centred design settings with particular focus on biomedical products. Firstly, the design applications of auxetics are detailed followed by a review of the key problems facing practical researchers in the field with the treatment of boundary conditions identified as a key issue. The testing setup that is then introduced utilises a novel method of part mounting and facilitates optical analysis and real-time force–displacement measurements. A study is advanced that analyses three different auxetic structures (re-entrant, chiral, and semi-rigid), a set of samples of which were additively manufactured in flexible TPU material. A range of parameters were varied across the three designs including interior geometry and wall thicknesses in order to demonstrate the effectiveness of the setup for the examination of the different structures. The results from these examinations are subsequently discussed and a number of suggestions made regarding how this kind of analysis may be integrated into novel design development workflows for achieving human-centred biomedical devices which often require detailed consideration of ergonomic and usability factors. [ABSTRACT FROM AUTHOR]

Material extrusion‐based additive manufacturing (AM) process builds the objects/structures through a precise feedstock deposition in a layer‐by‐layer manner. Polylactic acid (PLA) is a popular biodegradable feedstock in AM, while octyl methoxycinnamate (OMC) is known for its eco‐friendliness and ultraviolet (UV) protection properties. The present study focuses on the novel infusion methodology of OMC‐based microcapsules into PLA to develop self‐healing composite filaments. Post‐composition iterations, the optimum compositions for the filler and plasticizer were determined, and the filaments were extruded. Microcapsule‐infused PLA and the neat PLA samples were printed as per the American Society for Testing and Materials (ASTM) standard. The uniaxial tensile test results showed that the failure strain endured by the microcapsule‐infused samples was about 10 times more than the neat PLA counterparts. It is attributed to the effective load distribution and the complex polymerization reaction (due to the interaction of OMC with the matrix). Fracture surface morphology of the samples via optical microscopy (OM) and field emission scanning electron microscope (FESEM) affirmed the strong PLA‐OMC interface. A depreciation in the Brinell Hardness for the microcapsule‐based samples was due to the localized indenter force, causing greater damage in a narrow area than microcapsule ruptures' healing ability. Highlights: The optimized composition of PLA: plasticizer:microcapsule is 1:0.04:0.05.Microcapsule‐infused PLA has improved Young's modulus and failure strain.Interaction with microcapsules improves elastic behavior and self‐healing.FESEM reveals close bonding of microcapsule with the PLA matrix. [ABSTRACT FROM AUTHOR]

Abstract Hybrid composites, a cornerstone of modern engineering, have been the subject of a groundbreaking investigation. This research delves into the impact of changing the stacking configuration on the characteristics of glass and carbon configuration woven fabric-reinforced laminates. Fabricating different configurations of hybrid laminates using cost-effective hand layup techniques and their performance evaluation through uniaxial tensile test and flexural strength has yielded fascinating results. The tensile strength specimen was prepared as per ASTM D3039 and for flexural test ASTM D7264. The findings demonstrate that stacking laminate CGC has higher tensile strength (418.99 MPa) and flexural strength (342.99 MPa) than other stacking configurations of studied hybrid composites. Also, the fracture analysis evaluates using a high-resolution setup to comprehend the mechanism of failure interply hybrid composites. In addition, design and analytical analysis were done to analyze the tensile and flexural strength of different GC, GCG, and CGC stacking configurations. The finding demonstrates the feasibility of the CGC stacking configuration for load structural applications, marking a significant advancement in materials science and engineering.

Ultrasonic metal welding machines are suitable for various complex applications (e.g., battery tabs) through unique mechanical design, special pressure application methods and high-precision welding. This work reports the weldability, forming quality and fractographic analysis of copper multilayered welded joints which were studied by SEM-EDS characterization, micro-hardness testing and tensile testing based on ultrasonic double roller welding (UDRW). Three groups of process parameters (A, B and C) were established to investigate the performance, production quality and welded joint surface interconnections. The tensile testing results of sample under parameter 3 in group A [S-P3(A)] indicate the maximum tensile strength of 69.859 N in T-peel test while the average tensile strength has increased by 58.525 N due to rise in welding time from 2 sec to 5 sec. The results analysis indicates that welding quality features in S-P3(A) joints under 4 bar, 100 mm/s, 45 % have been exploited. The over-welded zone was transformed into good-welded zone. The micro-cracks, fatigue stations and peeling texture in multilayers were reduced. It was found that when the welding energy was 10000 J then the tearing edges and interlayers cracks were minimized while keeping the other parameters constant. Moreover, when the amplitude increased up to 50 %, then numerous micro-cracks and micro-fissure stations were created, which leads to the occurrence of fracture in multi-layer welded joint. The EDS study investigated that the complex features are formed at the interface junction of sample 3 S3(A) in multilayer welds. The complex multilayer microstructures can induce and produce unique hardness properties for battery manufacturing. It leads to high quality and durable welds. Eventually, it is experimentally demonstrated that robust 40 layer welded joints can be obtained by the UDRW process. Data availability: The datasets used and/or analyzed during the current study are available from the corresponding author upon reasonable request.

In this research, the variational mode decomposition (VMD) method is used for the drive-by health monitoring of bridges. Firstly, the problem of a half-trailer tractor moving over a bridge is formulated. Next, a Finite Element (FE) code is developed and verified against modal analysis results where complete agreement is found. The vehicle's output signals are decomposed through VMD and then analyzed to identify and precisely locate damage in the bridge structure. The range of applicability of this technique is examined from different perspectives by including various road classes, damage severity and location, and noise. The results prove the robustness and reliability of using VMD for drive-by damage detection. The method outcomes indicate that through the VMD method, cracks with a depth of 10% to 20% of the beam height can be detected even in the case of a rough road profile. A comparison of the results of the VMD and the well-known empirical mode decomposition (EMD) method has also been conducted. This comparison reveals that by implementing the VMD, precise damage locations can be determined, whereas the EMD fails to detect any damage under the conditions considered in this study. The effects of noise and moving vehicle speed are also investigated in the research, and it is found that processing the output signals using VMD can yield reliable estimates of the damage location(s).

This article explores the electromechanical performance of poly(vinylidene fluoride) (PVDF) films with silver nanoplatelets on smooth polydimethylsiloxane (PDMS) substrates. PVDF, a semi‐crystalline polymer, shows piezoelectric properties when processed at low temperatures, making it ideal for energy harvesting and sensors. This research addresses a gap by examining high strain rate and complex electromechanical characteristions of PVDF composites, which are underexplored. Films, fabricated using a non‐vacuum rod coating method, underwent dynamic electromechanical tests (strain rate ~ 2 s−1), including stretching, twisting, combined stretching and twisting, and forced vibrations. Results show the films function up to 17% applied strain with a gage factor of 10.57. In twisting tests, the laminates perform up to 387° in slow twisting (gage factor = 28.34) and 341° in fast twisting (gage factor = 7.65). Combined stretching and twisting tests show performance decreases, with functionality up to 6.24% strain at a twist angle of 330.1°. Vibration tests reveal that increased amplitude reduces performance, with the laminates enduring frequencies between 4.35 and 12.14 Hz. The films also exhibit a linear piezoelectric response, with a maximum open circuit voltage of 37.2 V under an impact load of 1112 N, underscoring the potential of PVDF/Ag nanocomposites for advanced MEMS applications. [ABSTRACT FROM AUTHOR]

Dual-phase (DP) steels with their dual phase microstructures (hard martensite and soft ferrite) are used in many industrial applications, especially in the automotive industry, thanks to their desired mechanical properties and formability. These properties are directly related to their phase distribution in microstructure obtained as a result of the production conditions. The most important step of the production of cold rolled DP steels is the annealing process. In this study, the effect of boron alloying with line scale heat treatment cycle on the microstructure and mechanical properties of cold rolled DP steel was investigated. For this purpose, mechanical test, formability and weldability tests were carried out. The materials were characterized by optical microscopy (OM) and scanning electron microscopy (SEM/EBSD) studies. According to the results, alloying with boron delays the formation of ferrite and pearlite/bainite during the cooling process and increases the martensite formation rate. Boron alloyed cold rolled DP steel shows improved yield and tensile strength without significant loss of elongation. On the other hand, alloying with boron does not have a detrimental effect on the weld properties.

Purpose: This in vitro study aimed to evaluate and compare the physical and antimicrobial properties of provisional resin modified with two different nanoparticles, namely, silicon dioxide (nano-SiO2) and titanium dioxide (nano-TiO2). Methods: A commonly used commercially available polymethyl methacrylate (PMMA) provisional resin (Unifast III; GC Corp) was modified with nano-SiO2 and nano-TiO2 at different concentrations (1% wt. and 2.5% wt. respectively), while one unmodified group was used as a control. Rectangular specimens (60 × 10 × 3.3 mm) for strength (MPa) and elastic modulus, and square specimens (10 × 10 × 3.4 mm) for surface roughness (Ra, µm), hardness (VHN), and Candida albicans adhesion (colony forming unit, CFU/mL) were prepared and grouped into five groups (n = 10) according to (nanoparticles) NPs type and concentration. After polymerization, the specimens were finished and polished and then subjected to thermal cycling (5000 cycles). Analysis of variance and post-hoc Tukey test were used for data analysis (α = 0.05). The scanning electron microscope (SEM) was used for fracture surface analysis and C. albicans count. Results: The addition of 1% nano-SiO2 significantly increased the flexural strength, and 1% nano-SiO2 contributed to the highest flexural strength value, while 2.5% nano-SiO2 and nano-TiO2 showed non-significant increases (p > 0.05). The elastic modulus increased significantly for both NPs. Among the NP-modified groups, the nano-SiO2 groups showed an increased elastic modulus compared to the nano-TiO2 groups. The hardness significantly increased with NPs addition with no significant differences between NPs-modified groups. Surface roughness increased with 2.5% nano-TiO2 addition, while 1% nano-TiO2 and nano-SiO2 showed non-significant differences. Nano-SiO2 and nano-TiO2 significantly decreased C. albicans adhesion, and nano-TiO2 groups were significantly superior in their antimicrobial effect compared with nano-SiO2. Conclusions: Low nano-SiO2 addition increased the flexural strength of provisional resin. The addition of NPs increased elastic modulus and hardness and decreased the C. albicans adhesion to provisional resin. Nano-SiO2 did not alter the surface roughness, while 2.5% of nano-TiO2 increased the surface roughness.