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A multi-stage precipitation model is formulated to predict the microstructural evolution and explain the high performance of additive friction stir deposited aluminum alloy 7050 (AA 7050) for hole repair. The first stage is the heating process due to the high-temperature thermomechanical process of the stir. In this process, small η precipitates dissolve as they lose their stability with increasing temperature, and this causes the volume fraction of η precipitates to decrease and the concentration of Mg and Zn in the matrix to increase. The second stage is the cooling process at the end of the repair where material feeding ends and the tool is lifted away. Heterogeneous nucleation of η precipitates may occur and as the temperature cools below 250 °C, Guinier–Preston (GP) zones start to form. The final stage is the natural aging process, where the η ′ precipitate starts to grow. The volume fraction and precipitate radius are predicted for each type of precipitate. Furthermore, the fine η ′ precipitates and GP zones with a decent volume fraction improve the material strength and fatigue life. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the biaxial flexural strength of zirconia materials with different translucency before and after aging procedures and to evaluate the effects of aging on hardness and surface characteristics. Materials and Methods: A total of 90 disc-shaped specimens (n = 30 each) were prepared from translucent (Upcera-ST, Upcera Dental), high translucent (Katana HT, Kuraray Noritake), and ultra high translucent (Katana UTML, Kuraray Noritake) zirconia materials to a Ø16 x 1.2 mm thickness. The different translucency discs were then divided into three subgroups; one group was subjected to aging in a chewing simulator (n = 10), one group was aged with thermocycling (n = 10), and one was a control group (n = 10). Biaxial flexural strength, Vickers hardness, and surface characteristics were examined for all discs. The data were analyzed using the Shapiro-Wilk (P = .05), Mann-Whitney U, and Kruskal-Wallis H tests. Fracture strength was determined using biaxial bending strength tests, and Weibull analysis was used to analyze the resulting data. Results: A statistically significant difference was found among zirconia materials with different translucency in terms of fracture strength. On average, fracture strength was highest in the Upcera ST group (1,932.87 MPa) and lowest in the Katana UTML group (1,073.6 MPa; P = .001). The results of Weibull analysis showed a statistically similar distribution for all groups. Conclusions: Aging procedures did not cause significant differences in fracture strength and hardness. The fracture strength of the zirconia materials with different translucency was considered acceptable for intraoral use. [ABSTRACT FROM AUTHOR]

Structural damage and shrinkage cracking were exhibited during the pyrolysis of ceramic aerogels prepared by the polymer-derived ceramics (PDCs) route. Herein, the shrinkage of the ceramic precursor during the pyrolysis was offset by utilizing curled molecular chains to store strain in advance. Microspheres composed of curled molecular chains were prepared using polysilazane (PSZ) as a precursor. The microspheres were linked into a three-dimensional skeleton and further fabricated into precursor ceramic microspheres aerogel (PSZ/MCMSA) with shrinkage resistance. The morphology, thermal insulation, and shrinkage resistance properties of the material were tested. The results indicated that PSZ/MCMSA exhibited outstanding thermal insulation and shrinkage resistance properties. The shrinkage of the precursor ceramic microspheres (PSZ/MCMS) was offset by the strain stored through the curled PSZ molecular chains in the PSZ/MCMS. In addition, the microsphere skeleton structural supporting and gas escape channels were formed during the sintering, and the shrinkage resistance of the precursor ceramic aerogel was further enhanced. [ABSTRACT FROM AUTHOR]

The SiO 2 -Al 2 O 3 refractories and corresponding inks for 3D printing were prepared from silica glass binder suspensions and fused alumina with grain sizes of 75 and 240 μm. Phase analysis (XRD) and morphological studies (SEM) were conducted to investigate the influence of sintering temperature and Al 2 O 3 content on the strength, porosity, and density of the refractories. Rheological studies (rotational viscometry) were carried out determine the effect of polyethylene glycol (PEG) and hydroxypropyl methylcellulose (HPMC) content on the flow behavior of the inks. It was established that firing refractories based on fused silica and fused alumina at 1500 and 1600 °C led to the formation of mullite and aluminosilicate melt on the surface of Al 2 O 3 grains, enhancing the strength of the synthesized materials. Addition of PEG and HPMC to the ink composition was found to improve their rheological properties by increasing yield strength and promoting plastic flow. The ink demonstrated high printability and they are suitable for producing refractories using the Direct Ink Writing method. [ABSTRACT FROM AUTHOR]

This study focuses on improving the mechanical properties and microstructure of cement-based materials, which are crucial for the durability and safety of construction projects. Conventional cement, although commonly used, has certain limitations in terms of its mechanical strength and durability. Therefore, there is a requirement for innovative methods to enhance these properties. This study investigates the potential of nano-TiO2 (titanium dioxide) as an additive to overcome these limitations. The objective of this research is to perform a thorough experimental analysis to examine how different concentrations of nano-TiO2 impact the mechanical performance and microstructural changes in cement paste and mortar. The study examines the influence of nano-TiO2 on the compressive and flexural strengths of cementitious materials. It also explores how nano-TiO2 modifies the microstructure to enhance compactness and resilience. The results suggest that incorporating nano-TiO2 into cement leads to a substantial improvement in both compressive and flexural strengths. This enhancement is particularly notable when the nano-TiO2 concentration is at an optimal level of 1.0% by weight. The SEM and XRD analyses demonstrate that this concentration enhances the microstructure by decreasing voids and facilitating the development of C-S-H crystals. However, excessive concentration may have negative consequences, such as the creation of extra empty spaces. The results indicate that nano-TiO2 has considerable promise in enhancing cement-based materials, thereby aiding the advancement of construction materials that are more long-lasting and effective. This study contributes to the knowledge of how nano-TiO2 improves cement and emphasizes its potential uses in the construction sector. [ABSTRACT FROM AUTHOR]

Highlights During the manufacturing of thermoset‐based carbon fiber‐reinforced polymer (CFRP) structures, a curing process involving thermal, chemical, and mechanical interactions occurs. This process gives rise to micro‐scale residual stresses due to differences in fiber and resin properties, leading to decreased mechanical properties compared to nominal values. A trans‐scale analysis method utilizing the reduced order model (ROM) is applied in this study to establish a connection between the manufacturing and in‐service processes for unidirectional CFRP (UD‐CFRP). By employing this method, the evolution of residual stresses at the micro‐scale during UD‐CFRP manufacturing is predicted, and the impact of these residual stresses on structural performance during service is assessed. Specifically, the manufacturing‐induced residual stresses reduce the material strength by a minimum of 19.31%, while also exploring the correlation between macro‐scale and micro‐scale failures. Notably, the computational cost of this method is significantly lower, with a reduction factor of 103 compared to the finite element method. Empirical evidence supports the effectiveness of this method in accurately predicting outcomes throughout both the manufacturing and in‐service processes. Trans‐scale analysis method links composites manufacturing simulation to in‐service performance. Highly efficient trans‐scale method excels in cost, accuracy, consistency, and convergence. Residual stresses from the curing process significantly impact matrix safety. [ABSTRACT FROM AUTHOR]

Lattice materials are an emerging family of advanced engineering materials with unique advantages for lightweight applications. However, the mechanical behaviors of lattice materials at ultra‐low relative densities are still not well understood, and this severely limits their lightweighting potential. Here, a high‐precision micro‐laser powder bed fusion technique is dveloped that enables the fabrication of metallic lattices with a relative density range much wider than existing studies. This technique allows to confirm that cubic lattices in compression undergo a yielding‐to‐buckling failure mode transition at low relative densities, and this transition fundamentally changes the usual strength ranking from plate > shell > truss at high relative densities to shell > plate > truss or shell > truss > plate at low relative densities. More importantly, it is shown that increasing bending energy ratio in the lattice through imperfections such as slightly‐corrugated geometries can significantly enhance the stability and strength of lattice materials at ultra‐low relative densities. This counterintuitive result suggests a new way for designing ultra‐lightweight lattice materials at ultra‐low relative densities. [ABSTRACT FROM AUTHOR]

In this study, a novel electrochemiluminescent (ECL) sensor for highly sensitive detection of trilobatin (Tri) was developed based on silver metal–organic frameworks (AgMOFs) and nitrogen-doped carbon quantum dots (N-CDs). N-CDs exhibited high ECL intensity but poor ECL stability, while AgMOFs had a large specific surface area, high porosity, and good adsorption properties. Compositing both of them not only improved the ECL stability of N-CDs, but also enhanced the ECL strength of materials, so AgMOF@N-CD composites were used as the luminophore of the sensor. Under the optimized conditions, the ECL sensor showed a linear range of 1.0 × 10−7 M to 1.0 × 10−3 M for the detection of Tri, and the detection limit was as low as 5.99 × 10−8 M (S/N = 3). In addition, the sensor had excellent reproducibility, stability, and anti-interference ability. It could be utilized for the detection of Tri in real samples with recoveries of 95.78–102.26%, indicating that the constructed ECL sensor for detecting Tri possessed better application prospects. [ABSTRACT FROM AUTHOR]

Solid-state bonding can form when metallic microparticles impact metallic substrates at supersonic velocities. While the conditions necessary for impact-induced metallic bonding are relatively well understood, the properties emerging at the bonded interfaces remain elusive. Here, we use in situ microparticle impact experiments followed by site-specific micromechanical measurements to study the interfacial strength across bonded interfaces. We reveal a gradient of bond strength starting with a weak bonding near the impact center, followed by a rapid twofold rise to a peak strength significantly higher than the yield strength of the bulk material, and eventually, a plateau covering a large portion of the interface towards the periphery. We show that the form of the native oxide at the bonded interface—whether layers, particles, or debris—dictates the level of bond strength. We formulate a predictive framework for impact-induced bond strength based on the evolution of the contact pressure and surface exposure. In situ measurements reveal a significant strength gradient at interfaces formed by the supersonic impact of metallic microparticles on metallic surfaces, featuring weak central bonding and a rapid rise to a peak exceeding bulk material strength. [ABSTRACT FROM AUTHOR]

This research investigates the optimization of 3D printer settings to enhance the mechanical properties of polylactic acid (PLA) printed parts. A fundamental aspect of this study involves the design and development of a 3D printer capable of accommodating varied printing parameters. The parameters under consideration include extruder temperature, layer height, print speed, and infill density. Through experimentation, the tensile strength and the bending strength of PLA material are systematically evaluated against these printing parameters. The results unveil significant correlations between printing parameters and mechanical properties. It is observed that increasing the extruder temperature up to 220°C increases the material strength, beyond which a decline is evident due to overextrusion and material degradation. Conversely, increasing the layer height leads to a reduction in strength, attributed to diminished layer adhesion and structural integrity. Moreover, decreasing print speed is found to enhance strength at the expense of increased print time, suggesting a trade‐off between efficiency and mechanical performance. Furthermore, the study demonstrates that augmenting infill density contributes to a notable increase in material strength, underscoring the importance of internal reinforcement in enhancing structural integrity. These findings provide valuable insights into the optimization of 3D printing processes for PLA materials, offering guidelines for achieving superior mechanical properties through precise calibration of printing parameters. [ABSTRACT FROM AUTHOR]

Carbonaceous materials are recognized for their high conductivity and adaptable structures, making them potential candidates for potassium‐ion batteries (PIBs). Yet, their application has been restricted due to challenges like limited potassium storage and slow kinetics. Addressing these issues, this study presents a novel method by anchoring nitrogen‐oxygen‐coordinated bismuth metal atom sites onto honeycomb‐like carbon rods, termed Bi‐N4‐O2@HCR. This aims to enhance PIB performance by exploiting carbonaceous materials' strengths and mitigating their limitations. Through comprehensive experiments and theoretical simulations, it is found that Bi‐N4‐O2 sites enrich potassium storage and facilitate potassium ion migration, thus improving transport efficiency and reaction kinetics. The resulting anode showcased rapid and durable potassium storage, with a remarkable capacity of 190.7 mAh g−1 at 30 A g−1 and maintaining 192.2 mAh g−1 over 4200 cycles at 5 A g−1, outperforming many existing carbon anodes. Additionally, in full cell tests, it exhibited excellent rate performance and ultra‐long cycle life, sustaining up to 8000 cycles with a stable capacity of 88.9 mAh g−1 at 5 A g−1. This research underscores the significance of incorporating unique metal sites on carbon substrates to advance battery technology. [ABSTRACT FROM AUTHOR]

Particle grading is a reliable method to improve mechanical properties of reaction‐bonded silicon carbide (RBSC) ceramics. This work aims to explore the effects of particle grading on thermal and mechanical characteristics of RBSC ceramics. Results showed that the powder grading enabled to increase sintering density of silicon carbide (SiC) ceramics. The use of large particle SiC powder in grading led to a 28% increase in thermal conductivity but a 22% decrease in bending strength. Meanwhile, the addition of finer SiC powder exerted minimal effect on thermal conductivity but noticeably increased bending strength by 10%. Therefore, properly adjusting particle size in grading allows for the control of residual Si content and microstructure, thereby simultaneously increasing thermal conductivity and bending strength of the material. [ABSTRACT FROM AUTHOR]

Zirconia has important application prospects in the field of ceramics. However, during a high-temperature heating process, pure zirconia will undergo martensite transformation, which seriously affects its service performance. Metal oxides, such as Y 2 O 3 –CeO 2 doping ZrO 2, effectively improve the toughness and fire resistance of the material. Thus, the drying of Y 2 O 3 –CeO 2 co-doped ZrO 2 powder is an essential step before practical application. The study employs contemporary microwave drying techniques. The results of the experiment show that the average microwave drying rate increases with an increase in mass, water content, and microwave heating power. When the initial mass was 30 g, the initial moisture content was 12 %, microwave power was 720 W, and the drying rate was the fastest. We used four dynamic models: Modified Page, Quadratic, Wang and Singh, and Page to fit the experiment data. The best model was Modified Page, which describes the kinetic process most accurately. Fick's second law describes how, in the drying process, when microwave power is 720 W, initial mass is 15 g and initial water content is 8 %, the effective diffusion coefficient is 5.25 × 10−16 m2/s. Fourier Transforms of the infrared spectrum of the samples before and after drying were analyzed, the intensity of the O–H absorption peak located at 3442.03 cm/s, and O–H–O absorption peak located at 1594.48 cm/s. Both decreased significantly after drying. To discuss the relationship between the microwave power and the diffusion coefficient, the activating energy of microwave heating was 32.01 W/g. The experimental results show high heating efficiency and selective heating of the microwave method. This study provides a theoretical basis and research data for microwave drying of Y 2 O 3 /CeO 2 co-doped ZrO 2 powder in industry. [ABSTRACT FROM AUTHOR]

Multicomponent metallic glasses (MGs) are a fascinating class of advanced alloys known for their exceptional properties such as limit-approaching strength, high hardness and corrosion resistance, and near-net-shape castability. One important question regarding these materials that remains unanswered is how the different elements and atomic bonds within them control their strength and deformability. Here, we present a detailed visual and statistical analysis of the behaviors of various elements and atomic bonds in the Zr47Cu46Al7 (at%) MG during a uniaxial tensile test (in the z-direction) simulated using molecular dynamics. Specifically, we investigate the identities of atoms undergoing significant shear strain, and the averaged bond lengths, projected z-lengths, and z-angles (angles with respect to the z-direction) of all the atomic bonds as functions of increasing strain. We show that, prior to yielding, the Zr element and the intermediate (Zr-Zr, Cu-Al) and stronger (Zr-Al, Zr-Cu) bonds dominate the elastic deformation and strength, while the Cu and Al elements and the weaker Al-Al and Cu-Cu bonds contribute more to the highly localized shear transformation. The significant reconstruction, as signified by the cessation of bond-length increment and bond-angle decrement, of the intermediate and the stronger bonds triggers yielding of the material. After yielding, all the elements and bonds participate in the plastic deformation while the stronger bonds contribute more to the residual strength and the ultimate (fracture) strain. The results provide new insights into the atomic mechanisms underlying the mechanical behavior of multicomponent MGs, and may assist in the future design of MG compositions towards better combination of strength and deformability. [ABSTRACT FROM AUTHOR]

Background: Surface treatment of the intaglio surface of zirconia is important for bonding. However, it could affect the strength of the materials. The purpose of this study is to compare the effect of laser, etching, and air abrasion surface treatment methods to a control group on the flexural strength of three zirconia materials with two different thicknesses. (1) Methods: A total of 120 disks were divided into three groups according to the type of zirconia and the ceramic thickness. Then, according to the surface treatment method, the groups were divided into four subdivisions. The change in the microstructure of the ceramic material was investigated through Scanning Electron Microscope (EVO LS10, Carl Zeiss SMT Ltd. Oberkochen, Germany). Phase identification was performed using an X-ray diffraction device (XRD; Ultimate IV X-ray Diffractometer, Rigaku Inc., Tokyo, Japan). The flexural strength was assessed with a biaxial flexural strength test in a universal testing machine. Data were analyzed using SPSS Software (SPSS version 26.0.Armonk, NY: IBM Corp). A three-way ANOVA and a post hoc Dunnett T3 test were employed to evaluate the effect of the yttria concentration, thickness, and surface treatment on the flexural strength of zirconia (α = 0.05). (2) Results: At 0.8 mm thickness, air abrasion significantly increased the flexural strength of 3Y-TZP (1130.6 ± 171.3 MPa) and 4Y-TZP (872 ± 108.6 MPa). However, air abrasion significantly decreased the flexural strength of 5Y-TZP materials (373 ± 46.8 MPa). Laser irradiation significantly decreased the flexural strength of 5Y-TZP (347 ± 50.3 MPa), while etching significantly decreased the flexural strength of both 3Y-TZP (530 ± 48.8) and 4Y-TZP (457.1 ± 57.3). When the thickness increased to 1 mm, air abrasion continued to significantly decrease the flexural strength of 5Y-TZP materials. (3) Conclusions: There was a negative effect of surface treatment on the flexural strength at 0.8 mm thickness rather than at 1 mm thickness. Air abrasion enhances the flexural strength of 3Y-TZP and 4Y-TZP materials but significantly reduces the flexural strength of 5Y-TZP materials. Zircos-E etching and Er:YAG surface treatment methods did not significantly reduce the flexural strength of 5Y-TZP materials at 1 mm thickness and can be recommended as an alternative surface treatment for 5Y-TZP materials. [ABSTRACT FROM AUTHOR]

Before clinical trials are initiated, studying the mechanical performance of modern CAD/CAM restorative materials exposed to aging conditions would provide insights on their performance in service. This study evaluated the impact of thermomechanical aging on various resin composite, ceramic, hybrid, and nano-filled resin composite materials after two polymerization modes. Specimens (3 × 4 × 14 mm3) were fabricated using (n = 12 per group) a universal composite (Filtek Supreme XTE photo-polymerized for either 40 s or 120 s per layer), hybrid ceramics (BRILLIANT Crios, GC Cerasmart, Lava Ultimate, VITA ENAMIC), glass ceramics (IPS e.max CAD, VITA Suprinity PC, Straumann n!ce), or feldspar ceramics (VITABLOCS Mark II, GC Initial LRF). In each group, half of the specimens underwent thermomechanical aging. A three-point bending test was applied to all specimens and the results were statistically analyzed (α = 0.05). Glass ceramics and hybrid ceramics presented higher flexural strength values than feldspar ceramics and the universal composite before and after aging (p < 0.05). Thermomechanical cycling affected the flexural strength of all materials (p < 0.05) except Lava Ultimate, Straumann n!ce, and GC Initial (p > 0.05). The highest decrease in flexural strength after aging was found in the universal composite (40 s polymerization) (p < 0.001) and Vita Enamic (p < 0.001), while the lowest decrease was in the hybrid ceramics, Cerasmart and Lava Ultimate (p < 0.05). Extending polymerization duration reduced the aging effect on the universal composite tested. Thermomechanical aging affected the flexural strength of most materials tested. Universal composites and feldspar ceramics presented similar flexural strength values. [ABSTRACT FROM AUTHOR]

The focus of the present study is to rigidize the toroidal member of an inflatable space antenna using a novel rigidization technique. This technique involves embedding heat-actuated Shape Memory Alloy (SMA) wires between laminated Kapton layers to provide structural strength. Finite Element Analysis (FEA) is performed to assess the strength of the torus under a heating environment. The analysis considers the approach of constraining torus deployment in all directions, simulating the conditions it would experience during deployment and operation. By subjecting the torus to a heating environment, the behavior of the SMA wires can be observed, which in turn affects the rigidity and strength of the structure. In addition to the numerical analysis, experiments are conducted to verify the feasibility of the design and strategy. The material properties of the involved materials, such as Kapton and SMA wires, have been determined through separate experimental investigations and incorporated into the FEA tool as input parameters. Furthermore, a parametric study is conducted to examine the impact of design and material parameters on the strength of the toroidal structure. The study demonstrates that a 1-meter diameter toroidal structure based on SMA wires can offer structural strength during partial or complete venting scenarios. [ABSTRACT FROM AUTHOR]

Subcritical damage in sandwich panels refers to damage that occurs in the skins or core of the panel due to loading below the ultimate strength of the materials, and it can reduce the strength and durability of sandwich panels, leading to premature and unpredicted failure. In this work, a computational tool was developed for designing sandwich structures and optimizing their subcritical impact response. The model was validated experimentally on sandwich panels comprising an aluminium honeycomb core with carbon fiber reinforced epoxy skins. The study investigates subcritical damage in aluminium honeycomb and CFRP sandwich panels through mechanical experiments and finite element simulations. A novel computational tool was developed to optimize the impact response of these structures. Experimental validation was performed using standardized tests, and numerical simulations were conducted using Abaqus. Key findings indicate that the developed tool accurately predicts damage and stiffness reduction, offering significant potential for optimizing sandwich panel designs. [ABSTRACT FROM AUTHOR]

Alkali‐activated materials (AAMs) were prepared using tungsten tailings via pressure molding and casting, and their high‐temperature resistances were analyzed. Variations in their compressive strength, gel, and physical phase transformation, pore structure, and morphology at different temperatures were investigated and comparatively analyzed. Results showed that the compressive strength of both AAMs first increased and then decreased with increasing temperature. At 600°C, the pressure‐molded AAM exhibited a considerably higher compressive strength (152.38 MPa) than the cast‐molded AAM (42.05 MPa). Thermogravimetric–differential scanning calorimetry, XRD, and FTIR analyses showed that the pressure‐molded AAM contained more gel phases than the cast‐molded AAM at the same temperature. The gel phase further polymerized and decomposed at high temperatures (>800°C), forming nepheline and zeolite crystals. Mercury intrusion porosimetry and scanning electron microscopy results revealed that pressure molding increases the contact between the gel and unreacted materials, effectively reducing the porosity and densifying the AAM. The pressure‐molded AAM had a considerably smaller pore diameter than the cast‐molded AAM; thus, the former had considerably higher compressive strength. The porosity and pore size of the pressure‐molded AAM gradually increased with the temperature, which polymerized the gel phase and eventually decomposed it; this increased its compressive strength first and then decreased. [ABSTRACT FROM AUTHOR]

The reliable jointing of SiCf/SiC is considered to be a key factor limiting the application in the field of nuclear cladding. In this work, a jointing layer with interconnected SiC nanowires (SiCNWs) toughening network is prepared by a typical two‐step routine. The high‐viscosity slurry containing the precursor is pyrolyzed to form a porous SiC‐based jointing layer, which is then densified by chemical vapor infiltration. Besides, SiC powders are introduced into the slurry to further increase the density of the jointing layer. The homogeneous SiC jointing material enables the strength and effectively avoids the mismatch between the thermal expansion coefficient of the jointing layer and SiCf/SiC composites, and the apparent shear strength of the jointing specimen reaches 7.211 MPa. It is found that the joint with SiCNWs shows better shear strength than the joint without SiCNWs, and the improved mechanical properties could be attributed to the pull‐out and bridging of SiCNWs. [ABSTRACT FROM AUTHOR]

The acoustoelastic technique shows considerable potential for in situ stress measurement in concrete. However, the current technology is not fully developed, and challenges primarily arise from the intricate nature of concrete, along with various factors affecting its acoustoelastic properties, such as material strength, aggregate size, porosity, temperature, and humidity. A comprehensive understanding of how these factors influence the acoustoelastic characteristics of concrete is essential for advancing acoustoelastic technology in engineering applications. This study specifically focuses on the material strength, a pivotal factor influencing the quality of concrete, and explores its correlation with the acoustoelastic coefficient (AEC). An initial theoretical investigation was conducted to establish a theoretical model between the two factors, involving two steps: (1) integrating the empirical formula correlating material strength and Young's modulus into the acoustoelastic equations for bulk waves to derive the formula connecting AECs and concrete strengths; (2) applying qualitative analysis and statistical methods to assess the monotonic properties of the formula within its defined domain. To validate the accuracy of the theoretical model, acoustoelastic tests were conducted on prismatic concrete specimens with five different strength levels under axial compressive stress. The findings revealed a consistent pattern, demonstrating that the AECs of concrete decrease with an increase in material strength under axial compressive stress. The outcomes of this study make a substantial contribution to establishing a theoretical foundation for the development of concrete stress monitoring technology based on the ultrasonic method. Practical Applications: The safety of concrete structures is paramount. Currently, structural performance assessment relies primarily on on-site inspections and evaluations by professionals to detect visible cracks and deformations. Typically, cracks become apparent only once the damage has reached a critical level. Failure to identify deterioration processes before reaching this critical stage necessitates significant repairs to prevent premature failure of concrete structural components. If the in situ stress information of structures can be nondestructively obtained would be highly beneficial for warning the early deterioration, tracking the evolution of crack or damage, and forecasting the remaining service life of structures. Acoustoelastic techniques have demonstrated significant potential in achieving this objective. Nonetheless, concrete acoustoelastic effects are influenced by various factors, such as material strength, aggregate size, porosity, and environmental conditions, which impede further advancement of this technology. Therefore, this study investigated the dependence of concrete acoustoelastic effects on material strength. Correlation equations between concrete strength and acoustoelastic coefficients have been formulated. The application of these equations in practice can mitigate the impact of material strength on acoustoelastic measurements. This research contributes to advancing the engineering applications of acoustoelastic techniques in concrete stress assessment. [ABSTRACT FROM AUTHOR]

A new structural typology of a Steel-Reinforced Wooden (SRW) purlin made of rectangular laminated wood and C-section type cold-formed steel is presented in this article. The steel C-section profile is fitted onto the wooden purlin so that both work together as a composite unit. Although the wooden sections are weaker and have a lower elastic modulus than the steel sections, the overall dimensions of the SRW purlins are no larger than the steel C-section purlin sizes. The SRW purlins also form lighter structures than either plain steel or wooden purlins and they therefore have lower CO2 emissions. In addition, lighter purlins reduce the load on the main structure, which in turn reduces the material needed for the main structure of the building. So, reinforcement of the wooden purlin with steel sections within certain areas notably improved performance when compared with ordinary single-material purlins. The use of the SRW purlins can, therefore, improve the overall sustainability of a building. The improvements were analyzed in terms of sustainability and lower weight, as a function of span length and design load. The behaviors of the single material purlins and the SRW purlin were also compared. Both material strength and deformation design criteria and their influence were studied using an analytical approach based on loading and span length. The simple, innovative, and reliable design procedure described in this study ensured compliance with all technical requirements. Moreover, the savings relating to material weight were evaluated, neutralizing the carbon footprint in all cases under analysis. [ABSTRACT FROM AUTHOR]

To meet the strength requirements of aluminum/polytetrafluoroethylene (Al/PTFE) in practical applications, tungsten (W) whisker is added into the traditional formula Al/PTFE (26.5%/73.5%) to improve the dynamic compressive strength of the reactive material. Mechanical properties of reactive material specimens prepared by sintering are tested. In the results, it is shown that the dynamic compressive strength of Al/PTFE‐reactive material reinforced by tungsten whisker with volume fraction of 13.1% can reach 141 MPa at strain rate of 1800 s−1. The constitutive model of dynamic compression for tungsten‐whisker‐enhanced Al/PTFE‐reactive material is constructed, and the results are basically consistent with the experimental results. The quantitative impact energy release of reactive material specimens under vacuum environment are performed by using the two‐stage light gas gun loading system, and the quantitative impact release energies of Al/PTFE‐reactive material reinforced by tungsten whisker under different whisker percentage content and diameter are obtained. [ABSTRACT FROM AUTHOR]

The splash of molten Ag under arc erosion is the major reason for the failure of Ag‐based contact materials. Changing the size of the molten pool may manipulate the splash process and suppress the arc erosion. Herein, the size effect by fabricating a SnO2 network with pores smaller than the typical Ag molten pool is investigated. Silver is subsequently infiltrated into the SnO2 network to form Ag–SnO2 interpenetrating contact materials. It is found that the SnO2 network with small pore sizes separates the Ag matrix into smaller regions, reducing the melting volume. Compared with the particle‐dispersed one, the interpenetrating composite decreases ≈90% mass loss and temperature rise, as well as provides superior microstructure stability. This finding demonstrates a promising way to improve the arc erosion resistance of contact materials by tailoring the size of molten pool, benefiting long‐lifetime contact materials for smart grid applications. [ABSTRACT FROM AUTHOR]

Because of its excellent mechanical qualities and weldability, titanium alloy is used in many different biomedical applications. Wire electrical discharge machining may be used to machine materials with such greater strengths and intricate forms. Using Taguchi-data envelopment analysis-based ranking (DEAR) approach and zinc-diffused coated brass wire electrode to improve Titanium alloy machining was the goal of this research project. The quality metrics that were taken into consideration were surface roughness, kerf width, and material removal rate. Among the selected factors, with an error of 2.7%, the optimal configuration of input factors was determined to be 130 µs (Ton), 40 µs (Toff), 50 V (SV), 6 A (IP), and 8 kg (WT). Due to its relevance in the process of deionization, the Ton is the highest influential parameter for creating quality measurements. [ABSTRACT FROM AUTHOR]

The purpose of the work is to present issues related to the influence of surface treatment on the strength of adhesive joints of C45 steel sheets by grinding based on experimental research. These issues were related to determining the impact of the gradation and type of abrasive material on the strength of adhesive joints of the steel sheets. The grinding was carried out manually using an angle grinder with a disc diameter of 125 mm and a rotational speed of 11.060 min-1, using abrasive materials with grains made of: ceramics, zirconium and electro-corundum with a gradation of P40, and sandpaper with grains made of electro-corundum with various grain sizes with three gradations P40, P220, P400 (according to European FEPA standards). To make the adhesive joints of steel sheets, the epoxy adhesive was used, which contains an epoxy resin based on bisphenol A and a triethyleneteramine curing agent. A profilographometer from Hommel - Etamic was used to determine selected 2D and 3D surface roughness parameters, and the strength tests of the steel sheets adhesive joints were performed on a ZWICK/ROELL Z150 testing machine. The analysis of the tests showed a significant impact of the surface treatment method on the attained shear strength of the steel sheets adhesive joints. Comparing the samples prepared with electrocorundum of the variable gradation, the tests exhibited that the samples prepared with P40 paper had the highest roughness, while samples prepared with P400 paper had the highest shear strength. Roughness analysis indicated that in the comparison group of samples prepared with abrasives of the various abrasive materials, ceramics showed the highest roughness parameters and the shear strength of the adhesive joints after this treatment. [ABSTRACT FROM AUTHOR]

A significant need within the design of materials for vehicles or other engineering structures is to determine their potential to mitigate impact loads. The material acting as a shield during an impact absorbs energy, dissipating the excess in a process of irreversible deformation. In order to prevent this, or to limit the areas of damage as much as possible, have begun to be used materials that absorb impact energy without drastically compromising their strength. Energy absorbing composite structures (EACS) have the ability to convert impact energy into some form of energy absorbed through deformation. Compared to homogeneous materials, a number of factors also point to the increasing advantage of using composite sandwich structures, which, in addition to their high strength ratings, have a lower weight and a much more effective ability to absorb shock or impact load energy. This paper presents the results of damage tolerance testing of epoxy-glass sandwich composites with chemical modified matrix. The damage tolerance of the composites was determined using an Instron CEAST 9340 testing machine with an impact energy ranging from 5 J to 35 J and indicated the value at which visible damage to the composite occurs while it retains some of its strength properties. It was the most important test to determine the damage tolerance, but additional tests to characterize the strength of the composite more comprehensively were also performed. Experimental studies were used to present a methodology for the preliminary characterization of the material strength and to analyse the relation between structure and mechanical response of the composite. [ABSTRACT FROM AUTHOR]

High-performance thermal interface materials (TIMs) are highly sought after for modern electronics. Two-dimensional (2D) materials as vertical aligned fillers can optimize the out-plane thermal conductivity (k⊥), but their excessively high content or intrinsic rigidness deteriorate TIMs softness, leading to worsening for thermal contact resistance (Rcontact). In this study, 2D graphene materials are fabricated into lightweight and soft graphene foams (GFs) with high-orientation, acting as vertical filler frameworks to optimize the k⊥ and Rcontact for vertical GF (VGF) TIMs. The VGF-TIM has a high k⊥ of 47.9 W·m−1·K−1 at a low graphene content of 15.5 wt.%. Due to the softness and low filler contents of GFs, the VGF-TIM exhibits a low compressive module (4.2 MPa), demonstrating excellent compressibility. The resulting TIM exhibit a low contact resistance of 24.4 K·mm2·W−1, demonstrating 185.1% higher cooling efficiency in practical heat dissipating scenario compared to commercial advanced TIMs. This work provides guidelines for the design of advanced TIMs and their applications in thermal management. [ABSTRACT FROM AUTHOR]

To control spontaneous combustion of sulfide ores, the compound inhibitor was prepared by selecting physical resistance raw materials(Na2CO3), chemical resistance raw materials(Melatonin), Cetyltrimethylammonium bromide(CTMAB) and hydroxyethyl cellulose(HEC). With the help of the simultaneous thermal analyzer, different concentrations of inhibitors were prepared and the thermal behavior of the ore samples with 10, 15, and 20 wt% inhibitor at four heating rates of 5, 10, 15, and 20 K/min was determined. The Flynn-Wall-Ozawa method was applied to calculate the activation energy of sulfide ores with different concentrations. The results showed that: Gradually increasing the heating rate will increase the reaction intensity of each ore sample in the first weight loss stage of thermal decomposition, and then reduce the mass of the ore samples involved in the second weight loss stage; The thermal stability of each resisted ore sample is better than that of the original ore sample; The increase in the concentration of inhibitor can inert the reaction process of ore samples in the thermal decomposition stage, weakening the exothermic effect of ore samples; The inhibitor with 15 wt% had a better effect on preventing spontaneous combustion of sulfide ores, and its property value is higher than other concentrations. [ABSTRACT FROM AUTHOR]

In light of the anticipated 50% increase in global energy demand by 2050, the demand for innovative, environmentally conscious, efficient, and dependable energy technologies is paramount. Solid oxide fuel cells (SOFCs) offer a promising solution for sustainable energy production. This comprehensive review provides a detailed analysis of SOFCs, covering their fundamentals, materials, performance, and diverse applications, while also addressing technological challenges and future prospects. The review emphasizes the key advantages of SOFCs, including their high efficiency of up to 60% and minimal environmental impact. It explores the significance of impurity resistance and durability in materials and manufacturing processes for SOFC components. Comparative evaluations demonstrate the superior energy efficiency and ecological effects of SOFCs compared to other fuel cell technologies. SOFCs' versatility and potential are showcased through their applications in transportation, power generation and storage, portable devices, and residential usage. However, challenges such as cost, longevity, reliability, and integration with other energy systems are identified, emphasizing the need for supportive policies and regulations. [ABSTRACT FROM AUTHOR]

Silica aerogel materials exhibit exceptional properties, including unique light, heat, fluid, and ion characteristics with vast potential. Despite similarities in composition to glass, silica aerogel lacks ductility and is prone to breakage upon impact. Therefore, the development of advanced engineering aerogel ultra materials that combine the mechanical strength of engineered materials with the ultralight superinsulation of aerogels remains a significant challenge. Herein, a multidimensional and multiscale gradient‐pore strategy is proposed for the scalable production of nanostructured silanized cellulose (SiCell) nanofibrous frameworks through colloidal self‐assembly using an active earth‐abundant biopolymer from the wood as a functional component. The configuration of the SiCell/polymer‐crosslinked silica‐aerogel‐powder (SiAP)‐locked structure creates a regional framework that forms SiCell/polymer‐crosslinked SiAP‐locked aerogels (SiCSiPA) with a 3D nanoporous architecture. With an ultralow thermal conductivity of 15.9 mW m−1 K−1, the lightweight super insulating SiCSiPA emerges as a prime candidate for thermal insulation, offering exceptional strength for practical applications. Moreover, SiCSiPA exhibits superior strength, stiffness, and toughness, making it the best insulating material. Owing to its outstanding strength‐to‐weight ratio and robust thermomechanical stability, SiCSiPA introduces a new technology for lightweight construction applications requiring superior thermal insulation. [ABSTRACT FROM AUTHOR]

There is tremendous interest in the development of highly wear‐resistant coatings for metallic materials to reduce energy loss and prolong service life. In this study, the authors propose an approach to develop nanocomposite coatings featuring deformable nanocrystals embedded in amorphous matrix for self‐lubrication and superior wear resistance. The dual‐layered nanocomposite coatings are prepared by plasma electrolytic oxidation (PEO) on a Ti‐Nb‐Ta‐Zr‐Hf (TNZTH) refractory multi‐principal element alloy (RMPEA) and commercially pure Ti (cpTi). The inner layers of PEO coatings are composed of substrate element oxides (amorphous TNZTH─O oxide or anatase TiO2), while their outer layers exhibit typical nanocomposite structures. Different from the cpTi‐based PEO coating outer layers composed of brittle rutile TiO2 nanoparticles dispersed in an amorphous matrix of SiO2 and Na2O·nSiO2, the outer layers of TNZTH‐based PEO coatings are featured by deformable Na2Zr(Hf)O3 nanocrystals heterogeneously embedded in an inhomogeneous amorphous matrix composed of TNZTH─O oxide, SiO2, and Na2O·nSiO2. As a result, the TNZTH‐based PEO coatings exhibit favorable self‐lubricating performance and superior wear resistance, while the cpTi‐based PEO coatings are completely destroyed after sliding wear. Thus, this study offers valuable insights into the design and development of self‐lubricating coatings with superior wear resistance for metallic materials. [ABSTRACT FROM AUTHOR]

Lignin, one of the most abundant biomaterials and a large‐scale industrial waste product, is a promising filler for polymers as it reduces the amount of fossil resources and is readily available. 3D printing is well‐known for producing detailed polymer structures in small sizes at low waste production. Especially light‐assisted 3D printing is a powerful technique for production of high‐resolution structures. However, lignin acts as a very efficient absorber for UV and visible light limiting the printability of lignin composites, reducing its potential as a high‐volume filler. In this work, the decolorization of lignin is presented for high‐resolution 3D printing of biocomposites with lignin content up to 40 wt.%. Organosolv lignin (OSL) is decolorized by an optimized low‐energy process of acetylation and subsequent UV irradiation reducing the UV absorbance by 71%. By integration of decolorized lignin into bio‐based tetrahydrofurfuryl acrylate (THFA), a lignin content of 40 wt.% and a resolution of 250 µm is achieved. Due to the reinforcing properties of lignin, the stiffness and strength of the material is increased by factors of 15 and 2.3, respectively. This work paves the way for the re‐use of a large amount of lignin waste for 3D printing of tough materials at high resolution. [ABSTRACT FROM AUTHOR]

IVB–VIA transition metal dichalcogenides (TMDs) MX2 (M = Zr, Hf; X = S, Se) and related Janus MXY (M = Zr, Hf; X = S, Y = Se) have garnered significant attention due to their unique optoelectronic properties. To further explore their potential in flexible photonics, their mechanical, band dispersion, and optical dielectric properties using orbital hybrid theory are investigated. The results reveal that the out‐of‐plane linear compression resistance of these materials is considerably lower than their in‐plane resistance, primarily because van der Waals interactions are much weaker compared to ionic bond interactions. This characteristic makes them less susceptible to external pressure and torsional forces, positioning them as promising candidates for flexible optoelectronic devices. Furthermore, the presence of multiple energy bands at the same momentum state suggests a tendency toward metal–insulator transitions. Notably, the materials exhibit a high photon flux, indicating robust photoelectric conversion capabilities, making them suitable for applications in photoelectric transducers. This study not only deepens the understanding of the optoelectronic and mechanical properties of IVB–VIA TMD materials, but also offers theoretical guidance for the development and application of flexible optoelectronic devices based on IVB‐VIA TMDs and related Janus materials. [ABSTRACT FROM AUTHOR]

As demand for sustainable building materials rises, the use of waste rubber in civil engineering is gaining attention. This study proposes a method to modify waste rubber using polyvinyl alcohol (PVA) to enhance its material properties and expand its applications. A dataset was created focusing on the mechanical strength of cementitious materials incorporating PVA-modified waste rubber, and multiple machine learning methods were used to develop regression prediction models, particularly evaluating the support vector regression (SVR) model. Results show that the SVR model outperforms others, achieving mean squared errors of 1.21 and 0.33, and mean absolute errors of 2.06 and 0.15. Analysis indicates a negative correlation between waste rubber content and the water-to-cohesive ratio (w/c) with strength indexes, while a positive correlation exists between curing age and PVA. Notably, waste rubber content significantly affects strength. The mechanical strength of cementitious materials was notably enhanced by PVA-modified waste rubber, likely due to PVA's dispersion and bridging effects. This study presents a novel approach to sustainably recycle waste rubber, highlighting its potential in construction materials. [ABSTRACT FROM AUTHOR]

An efficient method to fabricate titanium nitride (TiN)-doped titanium (Ti) nanocomposites through a combination of plasma milling, plasma spheroidization, and laser powder bed fusion (LPBF) was developed to obtain Ti-based materials with high strength and ductility from commercially pure titanium (CP-Ti). Nitrogen plasma milling and plasma spheroidization were used to fabricate Ti-TiN nanocomposites, which were mixed with CP-Ti powder at a 1:9 ratio and printed by LPBF forming. The resulting materials possessed a dual-scale morphology with both coarse lath-like and fine acicular-like grains. The Ti-TiN nanocomposites possessed higher hardness and tensile strength and lower ductility than those of the control sample without TiN. The mechanical properties of the LPBF-printed Ti-TiN nanocomposites were improved compared with those of LPBF-printed CP-Ti because of the TiN particles and resulting dual-scale structure. Nitrogen plasma milling provides a simple route to fabricate TiN nanophase-reinforced Ti-based nanocomposites suitable for LPBF printing. [ABSTRACT FROM AUTHOR]

During petroleum drilling, the reciprocating motion in the seal device leads to piston and sleeve wear, which may cause leakage of the sealing medium. Selecting appropriate materials for the piston and sleeve, along with surface modifications, can effectively prolong the seal service life of the seal. The friction and wear properties of piston and sleeve pairs of different materials in a metal sealing device were simulated by the laboratory "pin-on-block" reciprocating friction test. Pins made of 45# steel, 35CrMo, and 20Cr13 were used to simulate piston bulges, while 35CrMo samples were used to simulate sleeves. Additionally, the influence of DLC (diamond-like carbon) coating and QPQ (Quench–Polish–Quench) nitriding on the wear resistance of the materials was studied. Based on this, the friction and wear properties, along with the wear mechanism of different material pairs, were analyzed. The results show that the friction coefficient curves of the three piston base materials and the 35CrMo sleeve are similar, and the friction coefficient of 45# steel is lower than that of 35CrMo and 20Cr13 at the initial stage. The DLC surface coating exhibited the best anti-wear performance, with the lowest friction coefficient, minimal wear, and the most stable friction coefficient. Surface QPQ nitriding treatment can also improve the wear resistance of the base material. However, due to the oxide formed during nitriding being prone to flaking, the friction coefficient fluctuates significantly at the initial stage of testing, and its anti-wear performance was inferior to that of the DLC coating. This study on material pairing and surface modification provides theoretical support for material selection and surface modification design of pistons and sleeves in oil drilling sealing devices. [ABSTRACT FROM AUTHOR]

Fully utilizing solid waste as supplementary cementitious materials (SCMs) while ensuring the mechanical properties of cement-based materials is one of the pathways for carbon reduction in the cement industry. Understanding the effects of the two solid wastes-limestone powder (LP) and rice husk ash (RHA) on the mechanical properties of cement-based materials is of great significance for their application in concrete. This study investigates the impact of LP and RHA on the strength of cement mortar at various ages and the microhardness of hardened cement paste. The results suggest that two materials have a certain synergistic effect on the mechanical properties of the cementitious materials. The addition of RHA effectively addresses the issues of slow strength development, insufficient late-stage strength of the cementitious material, and the low strength blended with a large amount of LP, while a suitable amount of LP can promote the strength increase in the cement-RHA system. Based on the comprehensive analysis of compressive strength and microhardness, the optimal solution for achieving high mechanical properties in composite cementitious materials is to use 10% each of LP and RHA, resulting in a 9.5% increase in 28 d strength compared to a pure cement system. The higher the content of LP, the greater the increase caused by 10% RHA in compressive strength of the composite system, which makes the strength growth rate of cementitious material mixed with 10% LP at 3–56 d 62.1%. When the LP content is 20% and 30%, the addition of 10% RHA increases the 28 d strength by 44.8% and 38.8%, respectively, with strength growth rates reaching 109.8% and 151.1% at 3–56 d. [ABSTRACT FROM AUTHOR]

The aim of this investigation was to evaluate the effect of etching protocols on bond strength, surface roughness, and mechanical properties of a zirconia-reinforced lithium silicate (ZLS) CAD/CAM-ceramic. In total, 100 bars (ISO 6872), 75 plaques, and 25 cubes were cut from ZLS blocks(Vita Suprinity®). The surfaces were standardized, crystallized and divided into five groups: 1. control (no/treatment-C), 2. 5%-Hydrofluoric-acid (HF)/20 s (HF5%20s), 3.HF5%60s, 4.HF10%20s, and 5.HF10%60s. Flexural strength (FS) (three-point bending test, 1 mm/min), roughness (Pa), and micro-shear bond-strength (µSBS) tests were performed. The data were statistically analyzed with one-way ANOVA, Tukey's test (p ˂ 0.05) and Weibull (FS data). C showed higher Pa (1.176 ± 0.370 µm) than HF10%60s (0.627 ± 0.236 µm) and all other groups. Groups C and 20 s showed the most irregular surface patterns. The FS results were not influenced by etching protocols, while the Weibull modulus was, with the 5%HF groups being the most reliable (m: 5.63/6.70), while C and HF10%60s (m: 2.78/2.73) were the least reliable. All fractures originated from surface defects on the treated side of specimens. The 5%HF groups showed higher µSBS (20 s: 21.35 ± 4.70 MPa; 60 s: 23.50 ± 4.27 MPa) than the 10%HF groups (20 s: 14.51 ± 2.47 MPa; 60 s: 16.54 ± 3.12 MPa) and C (6.46 ± 2.71 MPa). The most prevalent failure pattern was "mixed" for etched groups, and "adhesive" for C. Etching protocols affect the evaluated properties by roughening materials' surface and, in some cases, regularizing surface defects. The best overall outcomes were achieved when applying 5%HF. [ABSTRACT FROM AUTHOR]

Using a Taguchi experimental design, this research focuses on utilizing indigenous bacteria from the Danube River to enhance the self-healing capabilities and structural integrity of cementitious materials. Bacillus licheniformis and Bacillus muralis were used as individual bacterium or in co-culture, with a concentration of 8 logs CFU, while the humidity variation involved testing wet and wet–dry conditions. Additionally, artificial neural network (ANN) modeling of the compressive strength of cement samples results in improvements in compressive strength, particularly under wet–dry conditions. By inducing targeted bacterial activity, the formation of calcium carbonate precipitates was initiated, which effectively sealed formed cracks, thus restoring and even enhancing the material's strength. In addition to short-term improvements, this study also evaluates long-term improvements, with compressive strength measured over periods extending to 180 days. The results demonstrate sustained self-healing capabilities and strength improvements under varied environmental conditions, emphasizing the potential for long-term application in real-world infrastructure. This study also explores the role of environmental conditions, such as wet and wet–dry cycles, in optimizing the self-healing process, revealing that cyclic exposure conditions further improve the efficiency of strength recovery. The findings suggest that autochthonous bacterial co-cultures can be a viable solution for enhancing the durability and lifespan of concrete structures. This research provides a foundation for further exploration into bio-based self-healing mechanisms and their practical applications in the concrete industry. [ABSTRACT FROM AUTHOR]

The potential of Fe‐rich non‐ferrous metallurgical slag (NFMS) in alkali‐activated materials has been demonstrated, exhibiting promising mechanical strength and fire resistance. However, the durability of alkali‐activated NFMS (AA‐NFMS) in terms of sulfate salt resistance remains unexplored. Additionally, the variability in the chemical composition of NFMS presents challenges in directly assessing the durability of AA‐NFMS. This study investigates the interplay between the Ca/Si and Mg/Ca ratios in Fe‐rich NFMS and the resulting MgSO4 resistance of the AA‐NFMS made thereof. To do so, mass change and compressive strength retention were monitored for six months on AA‐NFMS immersed in 5 wt% MgSO4, whereas microstructure was investigated using scanning electron microscope (SEM) and electron probe microanalyzer (EPMA). The results show that the MgSO4 solution attacked selectively the reacted binder matrix of AA‐NFMS rather than the unreacted slag. The corrosion primarily occurs at the sulfate exposure surface of AA‐NFMS, forming a dense, thin layer of Mg(OH)2, which acts as a barrier and impedes further attack. Dissolution of Ca is the most pronounced among the major elements (Ca, Fe, Al, and Si) in the NFMS. The mass of the specimens increased linearly with the initial Ca content. The medium Ca concentration (∼10%) retained the highest strength. [ABSTRACT FROM AUTHOR]

The need to improve existing structures has led to extensive research on strengthening techniques. Textile‐reinforced mortar (TRM) systems, which involve the integration of high‐strength fibers with inorganic matrix, have emerged as a highly promising and viable alternative. The objective of this research is to investigate the mechanical characteristics of inorganic mortar by examining different compositions involving sand, fibers, and cementitious materials. Various combinations were tested to evaluate their compressive strength, split tensile strength, and flexural strength. The findings indicated that a composite mixture (sample 12) comprising microsilica, silica sand, and optimized fibers demonstrated enhanced strength in all three assessments. Research highlights the significance of accurate mixing, additional components, and appropriate fibers to achieve intended performance of the mortar. The compatibility of the mortar is checked with substrate surface and textile sheet. Mortar is evaluated for splitting bond strength, slant shear test, direct pull‐off bond strength, and pull‐out strength. These results provide information about the strength and bonding characteristics of the mortar in different test scenarios. Values indicate how well the mortar performs with the substrate surface and the textile sheet under various types of stresses and loading conditions. [ABSTRACT FROM AUTHOR]

The ongoing requirement for the lightweight design of automotive resulted in the wide application of ultra-high-strength steel (UHSS), such as the 1500 MPa made by hot stamping (TS1500) and 1180 MPa manufactured by cold rolling (SPC1180). In the present research, cold metal transfer (CMT) lap welding was employed to join TS1500 and SPC1180 dissimilar metals. A thermal–mechanical coupled model was developed, and the associated behaviors that occurred in CMT process were reproduced efficiently by the in-house FE code JWRIAN-Hybrid. The high-temperature material properties of TS1500 were clarified. The predicted temperature field, residual stress distribution and welding deformation were verified experimentally. The analyzed and measured results showed good agreement with each other. The critical phase transformation temperatures of TS1500, including Ac1, Ac3 and Ms, were gauged as 740, 810 and 390 °C, respectively. On the UHSS welded joint, the largest tensile stress was located on the outside of heat affected zone on TS1500 sheet, which can reach about 650 MPa, while the peak on SPC1180 sheet was only 120 MPa. It presented the significant influence of both material strength and constraint conditions. There was a compressive stress about − 130 MPa at the weld zone due to the martensite transformation. The out-of-plane deformation modes were the convex shape in both the longitudinal and transverse directions. The maximum out-of-plane displacement-Z in the center of welded joint was about 1.38 mm. For the UHSS CMT welded lap joint, the strength grade of steel couple had a significant effect on welding deformation rather than the residual stress. [ABSTRACT FROM AUTHOR]

Material heterogeneity gives composite constructions unique mechanical and physical qualities. Combining multiple materials takes full use of these features in stress‐constrained topology optimization. Traditional research in this field often assumes a consistent yield criterion for all possible materials but adapts their stiffness and strengths accordingly. To cope with this challenge, an innovative single‐variable interpolation approach is proposed to enable the simultaneous inclusion of distinct yield criteria and material strengths. A stress‐constrained topology optimization formulation is presented based on this yield function interpolation method, which can independently support various materials with different elastic characteristics, material strengths, and yield criteria. Then, the large‐scale problem of local stress constraints can be effectively solved by the Augmented Lagrangian (AL) method. Several two‐dimensional (2D) and three‐dimensional (3D) design scenarios are investigated to reduce the overall mass of the structure while considering stress constraints. The optimal composite designs exhibit several crucial benefits resulting from material heterogeneity, including the enlargement of the design possibilities, the dispersion of stress, and the utilization of asymmetry in tension‐compression strength. [ABSTRACT FROM AUTHOR]

Highlights The fused filament fabrication (FFF) is an additive manufacturing process in which thermoplastic strands are deposited. Due to thermal fusion of the strands, the FFF can be characterized as a plastic welding process. The resulting weld seams are weak points in the component structure and, thus, determine the mechanical properties. Thereby, the weld seam quality is significantly influenced by the process temperatures. To estimate the mechanical properties, knowledge of the resulting weld seam quality is required. In the context of material development, the weld seam quality can also be used as a criterion for the basic evaluation of the processability. In the present study, the influence of particulate fillers on the weld seam quality of a thermoplastic polymer matrix is investigated. With regard to the material, the influences of the filler type and the filler volume fraction are considered. In terms of the process, the influence of the process temperatures on the weld seam quality is evaluated. The aim is the description of the resulting weld strength and the comparison to the base material strength by means of the welding factor. For this purpose, an existing method is applied and adapted with regard to process reliability and comparability. Test plan is determined on the basis of a thermal analysis Method adaptation enables faster and reliable specimen manufacturing Higher process temperatures lead to higher weld seam strengths Filled polymers show a significantly reduced weld seam strength Relationship between filler content and weld seam strength is shown [ABSTRACT FROM AUTHOR]

Mechanical properties of wood-inspired cell wall geometries were considered through compression testing and Finite Element Analysis (FEA) with ANSYS simulation. Six models, including earlywood, latewood, and various array configurations, were fabricated via 3D printing using acrylonitrile butadiene styrene (ABS) filament. Compression tests highlighted the annual ring model's robustness, exhibiting a maximum load of 12707 MPa, while the 4x3 matrix displayed the lowest strength at 4247 MPa. Shifting rows led to reduced strength, which was particularly evident in vertical prints. An analysis of variance revealed significant differences in mechanical properties. Discrepancies between experimental tests and FEA results ranged from -45.9% to 35.2%. Earlywood exhibited a maximum deformation of 2.6 mm, whereas latewood showed lower deformation, indicating geometry's influence on material behavior. Mesh quality remained consistent, ensuring dependable simulation outcomes. These findings underscore the pivotal role of geometry in compression resistance, laying the groundwork for future studies on wood densification mechanisms and the development of customized wood composites. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to investigate the effect of steel fibers on the mechanical and tribological properties of FeS/Cu–Bi self-lubricating materials. Design/methodology/approach: The microstructure of the material was characterized by scanning electron microscopy. Tests on the crushing strength, impact toughness and tribological properties of materials were conducted using a universal electronic testing machine, a 300 J pendulum impact testing machine and an M200 ring-block sliding tribometer, respectively. Findings: The mechanical properties of the material initially increased and then stabilized with increased copper-plated steel-fiber length. When the length of the copper-plated steel fiber was 7 mm, the mechanical properties of the material reached stability. Compared with the material without a copper-plated steel fiber, its crushing strength and impact toughness increased by 32.6% and 53%, respectively. A copper-plated steel fiber with a length of 7 mm lay flat in a copper matrix can strengthen the friction interface and enrich the lubricant. Accordingly, the antifriction and wear resistance of the materials increased by 17.6% and 55%, respectively. Originality/value: The effects of copper-plated steel fibers on the properties of FeS/Cu–Bi self-lubricating materials were clarified. This work can serve as a reference for improving material performance and its engineering applications. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to investigate the effect of mullite on the mechanical properties and friction of carbon fiber (CF)-reinforced friction material. Design/methodology/approach: CF-reinforced friction materials with varying content of mullite were fabricated by hot press molding, and then the tribological properties were tested on the MRH-3-type tribometer under ambient conditions with the ring-on-block configuration. Findings: The experimental results indicated that the addition of mullite increased the density and compressive strength of friction material. However, the flexural strength of friction material decreased by 16% with the addition of 15 Wt.% mullite. The friction coefficient was proportional to the mullite content. Friction material with 12.5 Wt.% mullite showed the highest friction stability under different loads, whereas friction material with 10 Wt.% mullite exhibited the highest friction stability under different sliding speeds. Originality/value: By boosting the resistance to deformation under load and increasing the specific heat capacity, mullite contributed significantly to the friction stability of the friction material. [ABSTRACT FROM AUTHOR]

Mechanical qualities play a critical role in increasing the industrial applications of carbon-carbon composite materials as their porosity determines the strength of the material. In this study, carbon blocks with improved packing properties were produced by controlling various particle size distributions of coke particles. Particle-size diversity and geometric packing structure favorably affected the packing properties of the powder. Coke samples with tap densities up to 1.258 g/mL were prepared by controlling the size distribution of the coke particles. The porosity of the carbon block was calculated using three density definitions. The closed pores were reduced by up to 13.68% through the packing density of the particles, and the open pores were controlled by the coke/pitch mixing conditions regardless of the tap density. The carbon block showed a total porosity of 21.61% and a maximum compressive strength of 131 MPa by controlling the tap density of the coke. The proposed technique will be useful in various industries that require appropriate tap density control and will improve the compressive strength of composite materials. [ABSTRACT FROM AUTHOR]

The compressive strength of composite materials is critical for designers. This study investigates how seawater immersion influences the mechanical properties and compressive behaviour of solid and open-hole glass/epoxy laminates used in aircraft structures. The specimens were divided into three groups: first not immersed, second immersed in seawater for 30 days, and last sun-dried 12 hours after immersion. Immersion in seawater lowered the compressive strength of solid and open-hole specimens by 40 % and 33 %, respectively. The sun-drying process after seawater immersion increased the compressive strength of solid and open-hole specimens by 5 % and 17 %. After drying, the residual strength of solid and open-hole GFRP was 65 % and 84 %, respectively. In solid GFRP composites, the seawater immersion and drying process is irreversible; besides, in open-hole composites it can be reversible. The compressive examination was numerically duplicated using a finite element method (FEM) model of the composite material. [ABSTRACT FROM AUTHOR]