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Three‐dimensional multi‐axial warp knitted (3D MWK) reinforced composites are important components of advanced structural composites. The interfacial bonding between fiber and matrix is key to achieving high mechanical properties. In this work, graphene oxide (GO) and poly(oxypropylene) diamines (D400) were grafted on glass fiber (GF) multi‐axial warp knitted (MWK) fabrics to construct a "flexible‐rigid" structure. The surface morphologies of GF were characterized by SEM and EDS. Then, 3D MWK‐reinforced composites were prepared based on four kinds of modified fabrics using the VARTM method. The in‐plane compression properties were obtained at different high temperatures and their failure modes were analyzed. The strain–stress curves showed that the composites exhibited brittle fracture modes. D400 and GO‐modified multi‐scale composites exhibited outstanding compression properties. The strength of the related composited was improved by 55.78%, 76.78%, 52.19%, and 56.78% compared to that of desized composite at 30°C, 60°C, 120°C and 150°C, respectively. The damage to D400‐GO modified and D400 modified composites was the most serious, where shear fracture modes were obvious in addition to layer debonding features. This protocol provides a potential strategy to manufacture of D400 and GO‐modified hierarchical reinforced composites. Highlights: The modified 3D MWK glass fabrics based on poly(oxypropylene) diamines (D400) and graphene oxide (GO) were prepared.The compressive properties of 3D desized, D400‐, D400‐GO‐, and GO‐MWK fabrics reinforced epoxy composites were obtained and analyzed at different temperatures of 30°C, 60°C, 120°C, and 150°C.The failure mechanisms of 3D desized, D400‐, D400‐GO‐, and GO‐MWK fabrics reinforced epoxy composites at different temperatures were analyzed. [ABSTRACT FROM AUTHOR]

Ti‐reinforced AZ61 magnesium matrix composites, demonstrating enhanced strength and plasticity, are synthesized via powder metallurgy method, including mechanical milling and spark plasma sintering. This study investigates the evolution of microstructure and compressive mechanical properties of Ti/AZ61 composites across various Ti weight percentages: 0%, 5%, 10%, 15%, and 20%. The composites at 5, 10, 15, and 20 wt% Ti concentrations are effectively compacted, achieving relative densities of 99.1%, 99.4%, 98.7%, and 98.6%, respectively. The integration of Ti particles facilitates a refinement of the Mg grain size. The average Mg grain size in the AZ61 alloy is refined from 8.7 ± 3.6 to 7.2 ± 4.5 μm and 4.4 ± 2.2 μm upon the addition of 5 and 10 wt% Ti particles. Conversely, incremental Ti concentrations of 15 and 20 wt% result in minor increases in the average Mg grain size to 5.3 ± 2.6 and 5.7 ± 3.2 μm, respectively. Interfacial compounds, notably Al3Ti, are identified. Compressive mechanical properties, including compressive yield stress (CYS), ultimate compressive stress (UCS), and compressive failure strain (CFS), are synergistically enhanced with Ti particle incorporation. Optimal mechanical properties, specifically CYS at 250 MPa, UCS at 502 MPa, and CFS at 13%, are observed in the 10 wt% Ti/AZ61 composite. The enhanced compressive behavior is attributed to strong interfacial bonding between deformable Ti and Mg, effective load transfer, and grain refinement. Additional contributing factors include variations in the elastic modulus and thermal expansion coefficients between Ti and Mg. The fracture mechanisms observed in the Ti/AZ61 composites involve both ductile and brittle modes of failure. [ABSTRACT FROM AUTHOR]

Rice husk ash (RHA), an agricultural by‐product, has been added as supplementary cementitious material (SCM) in concrete mixture to improve the compressive properties of recycled aggregate concrete (RAC) in recent years. This study aimed to optimise the mixture design of RAC considering two variables: the replacement ratio (wt.%) of recycled aggregate (RA) to natural aggregate (NA) with three levels (0%, 50% and 100%) and the replacement ratio (wt.%) of RHA to cement with three levels (0%, 10% and 20%). Compression test was implemented at concrete age of 28 days based on the full factorial experiment. By means of response surface methodology (RSM), the optimised RA replacement ratio and RHA replacement ratio can be calculated with respect to the compressive strength and E‐modulus at 28 days, and vice versa the compressive strength and E‐modulus at 28 days of RAC containing RHA can also be predicted. According to response surface modelling, the compressive strength reaches the maximum value when the RA replacement ratio is 0% and the RHA replacement ratio is 7%, and the E‐modulus would reach the maximum when the RA replacement ratio is 17% and the RHA replacement ratio is 7%. The determination coefficient (R2) and adjusted coefficient (R2adj) for the compressive strength model are 0.9632 and 0.9544 respectively, and for the E‐modulus model are 0.9319 and 0.9157 respectively, showing that the models developed by RSM are relatively well correlated with the experimental results. [ABSTRACT FROM AUTHOR]

High strength concrete (HSC) with superior strength advantage has been gaining widespread attention and engineering endorsement in recent years. For a better understanding of the mechanical responses and failure mechanisms of HSC, a novel three‐dimensional (3D) mesoscale model considering the meso‐structural features of concrete was proposed in this paper. First, a series of uniaxial compressive tests were conducted to investigate the compressive properties of HSC specimens with a strength of 80–90 MPa. After that, a 3D three‐phase mesoscale model consisting of mortar, coarse aggregate, and the interfacial transitional zone (ITZ) between them, was developed to perform the mesoscopic simulations of HSC. Then, systematic analysis and discussions on the compressive properties of HSC were presented in terms of the stress–strain curves, compressive strengths/toughness, failure patterns, cracking process, etc. Results indicate that HSC exhibited obvious brittle failure characteristics, and its strength was significantly related to the water‐to‐cement ratio and mineral admixture. At meso‐level, the cracking behaviors of mortar and ITZ phases were well modeled using the developed mesoscale model. Additionally, it was found that the cracking behavior of HSC was significantly associated with the ITZ characteristics. The developed mesoscale modeling approach has been proven to simulate and investigate concrete's compressive properties in a reliable manner, and can be applied further to the property analysis of concrete materials and structures. [ABSTRACT FROM AUTHOR]

Herein, FeCoCrNiAlx (x = 0, 0.5, 1.0) high‐entropy alloys (HEAs) are fabricated by the laser melting deposition (LMD) technique. With the increase of Al content, the LMD‐ed microstructure transitions from a single face‐centered cubic (FCC) phase to a dual‐phase structure containing a small amount of body‐centered cubic (BCC) phase (5.3%), and the proportion of the final BCC phase increases significantly to 98.2%. In addition to the compression tests, four strengthening models are used to evaluate the theoretical strength of the three alloys. The addition of Al element as grain refiner can improve the ultimate compressive strength of HEAs; however, the yield strength and plasticity do not improve, as theoretically expected. The FCC phase with more slip systems leads to higher plasticity in the LMD‐ed FeCoCrNi HEA but results in lower yield strength. The LMD‐ed FeCoCrNiAl0.5 HEA exhibits the best combination of strength and plasticity. Therefore, to meet the required service requirements, the content of Al in the FeCoCrNiAlx HEA should be carefully controlled under the premise of considering the actual working conditions. [ABSTRACT FROM AUTHOR]

A hybrid auxetic structure, named re‐entrant chiral auxetic structure (RCA), is recently developed based on topological features of both re‐entrant and chiral auxetic honeycombs. Herein, the in‐plane quasistatic and dynamic performances of the RCA are compared. Experimental specimens for both the quasistatic and dynamic tests are designed to have identical dimensions and fabricated from polyamide12 (PA12) using an additive manufacturing process, Multi Jet Fusion (MJF). Compressive tests are conducted at constant velocities of 0.066 mm s−1 on a Zwick Roell machine and of 5 m s−1 on an Instron VHS 8800 high‐speed machine for quasistatic and dynamic compressions, respectively. Numerical models are developed using ABAQUS/Explicit and verified by experiments. Results evidence that performances of the RCA are sensitive to the crushing velocity. Moreover, the base material (PA12) displays poor ductility under impact loads; therefore, fracture of the structural members dominates the deformation of the structure when it is dynamically crushed. Energy absorption of specimens that are quasistatically crushed outperforms those under dynamic compression. Furthermore, discrepancy in Poison's ratio curves is observed under quasistatic and dynamic tests due to the change in the deformation modes. [ABSTRACT FROM AUTHOR]

Designing the foam structures in terms of density and morphology gives the chance to tune their mechanical and functional properties to the specific application. Nowadays, this design has been leveled up by the introduction of graded foams which are characterized by spatially nonuniform densities and/or morphologies. Graded foams have proved superior compared to uniform one in numerous examples and loading conditions but in pure compressive loading, where properties such as the Young's modulus of graded foams are always inferior to uniform ones. When using sintered beads foams, macroscopic pure compression may induce local bending on the single bead, which can be exploited to induce stiffening. This thesis was investigated on both polystyrene and thermoplastic polyurethane samples made by foamed beads sintered in a cylindrical mold. The response to compressive tests of graded foams made by sintering beads having nonuniform cells structures was compared to the uniform counterparts. The results evidenced that, at same average density, foams had up to a 30% ca. of increase of the Young's modulus when the beads are characterized by a denser outer layer. [ABSTRACT FROM AUTHOR]

Porous magnesium alloy foams have gained tremendous interest from scientists because of their super lightweight, unique mechanical and physical properties. Despite numerous studies suggesting these advanced materials for structural and functional applications, their manufacturing processes remain poorly understood. In this paper, the porous Mg‐9 wt. %Al‐1 wt. % Zn alloy foam was prepared through the reactive sintering principle (i. e. the element metal powder reaction principle) by using the powder metallurgical method that is combined with a pore‐making agent. The chemical and phase compositions of the cell wall microstructure were investigated by X‐ray diffraction and scanning electron microscope equipped with energy dispersive spectrometer. The compressive properties of the foams were evaluated by quasi‐static compression testing. The results of the analysis reveal that low‐temperature sintering can produce qualitative magnesium alloy foams with good mechanical properties by taking advantage of the intermetallic/or intermediate compounds which are formed in the cell wall through metal elements powder diffusion and reaction. Particularly, the foam samples sintered at 380 °C for 12 h gave the best compressive properties owing to the alloy intermetallic contents and the relative density of the foams. [ABSTRACT FROM AUTHOR]

Summary: The usage of mineral basalt fibers is a relatively novel and popular topic nowadays due to its abundant availability, low cost, and higher temperature resistance. In addition, the establishment of analytical models is beneficial because the experimental work is more time‐consuming and expensive. Therefore, in this study, the inorganic mineral basalt fibers with different length and content in hybrid fiber concrete composite are investigated to assess its suitability at room temperature and under high temperature. In addition, a new analytical model for stress‐stain curve of hybrid fiber concrete composite is developed and compared with the models in previous studies. The microstructure examination is also conducted after exposure to high temperature to explore the fiber morphology and interaction with matrix. The substantial improvement was indicated by addition of basalt fiber in hybrid fiber concrete for stress‐strain response, peak stress, elastic modulus, peak strain, ultimate stain, toughness, and specific toughness at room temperature and at 850°C. It was revealed that the basalt fiber had demonstrated overall good appropriateness in the hybrid fiber concrete composite for all the compressive properties. Moreover, the proposed analytical model could be useful for prediction of analytical behavior from experimental data under high temperature for the research and design purposes. [ABSTRACT FROM AUTHOR]

Metal matrix syntactic foams (MMSFs, often referred as composite metal foams (CMFs)) are lightweight materials with high specific strength. MMSFs are on the borderline between metal matrix composites and metal foams. On one hand MMSFs are composites, because they are filled by hollow particles and the particles may add strength to the material. On the other hand, they are foams, because the hollow particles ensure porosity to the material. Among metallic foams, MMSFs exhibit outstanding specific mechanical properties due to the hollow inclusions that are typically made from ceramics or high strength alloys, therefore they can be applied as structural materials. The goal of this paper is to summarize the available data on the mechanical properties of MMSFs with aluminum matrix in order to give a strong support to the design engineers. Since the foams are most frequently loaded in compression, the main part of this paper is organized around the available standard related to the compressive properties of porous materials and metallic foams. The quasi‐static results are complemented by properties measured at higher strain rates. Besides this, some insight into the basic fatigue properties as well as into the toughness of MMSFs is also provided. [ABSTRACT FROM AUTHOR]

The Fe–Ni–P–Cu alloys with different copper content (0, 0.5, 1, and 2 wt%) are fabricated by liquid phase sintering (LPS) at 950 °C. The nano‐Cu powder is mechanically mixed for 90 min with Fe–Ni–P composite powder using the ethanol as the medium. The microstructure, microhardness and compressive properties of Fe–Ni–P–Cu alloys are investigated. The results indicate that the copper is beneficial to improve the mechanical properties of sintered specimens. The sample contains a small amount of γ‐(Fe, Ni) phase when the copper content is 1 wt%, which results in its the highest compressive yield strength (948.1 MPa). The highest microhardness of 371 HV is accessible in Fe–Ni–P–Cu alloy with 2 wt% Cu. The fracture surface analysis indicates that sintered specimens with Cu addition exhibit a typical intergranular mode. [ABSTRACT FROM AUTHOR]

The comparative study of rigid polyurethane foam (RPUF) nanocomposites based on graphene nanosheets (GNSs) and carbon nanotubes (CNTs) has been reported. A GNS content of 0.3 wt% in polyol turns to be optimal for its foamability with the isocyanate component, as verified by rheology measurements. Scanning electron microscopy and transmission electron microscopy observations reveal a homogeneous dispersion of GNSs and CNTs in the RPUF nanocomposites. Only 0.3 wt% loading of GNSs and CNTs led to 36% and 25% improvement respectively in the compressive modulus of the RPUF nanocomposites. Meanwhile, 16 °C and 14 °C improvements in the glass transition temperature confirm the important role of both the nanofillers in the heat resistance of RPUF nanocomposites. These results additionally indicate that GNSs work more effectively than CNTs in mechanical property and heat resistance enhancement of the RPUF nanocomposites. The superiority of GNSs over CNTs can be attributed to their wrinkled surface structure, unique two-dimensional geometrical morphology and higher specific surface area, which results in stronger interaction and restriction of segmental motion at the interface between the GNSs and the RPUF matrix. In addition, changes in the thermal conductivity of the nanocomposites are negligible, indicating that incorporation of GNSs and CNTs will not hinder the application of RPUF nanocomposites as thermal insulators. On the contrary, the enhancement in mechanical properties and heat resistance will undoubtedly expand the application range of polyurethane foam materials. Copyright © 2012 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The effects of heat treatments on the compressive properties of a lattice‐structured AlSi10Mg alloy with a body‐centered‐cubic‐type unit cell fabricated by selective laser melting are investigated. The as‐fabricated lattice specimen fractures and does not exhibit plateau region. Fractography suggests that the crack preferentially propagates along the α‐Al/Si eutectic microstructure near the α‐Al grain boundaries in the as‐fabricated lattice specimen. The heat treatments at 300 °C for 2 h and at 530 °C for 6 h decrease the flow stress and improve the ductility. The heat‐treated lattice specimens exhibit the plateau regions with stress drops, caused by the formation of shear bands. The shear band formation of the lattice specimen heat treated at 530 °C for 6 h is more significant than that of the lattice specimen heat treated at 300 °C for 2 h. X‐ray‐computed tomography reveals that struts in the shear band are deformed locally in a bending manner. [ABSTRACT FROM AUTHOR]

Aluminum matrix syntactic foams with the density of 1.68–2.05 g cm−3 are prepared by the stir casting method. Al2O3 hollow spheres with a volume fraction of 38–48% are chosen as reinforcement and their diameters had three ranges. Ca particles increased melt viscosity to ensure uniform dispersion and good interfacial wettability of the hollow spheres in matrixes. Quasi‐static compression tests are performed. The results show that the mechanical properties and energy absorption capacity increased with decreasing size of the hollow spheres and increasing density of syntactic foams. For the same size hollow spheres and the same density gradient, the T6‐ZL111 matrix syntactic foams had the highest properties, while the cpAl matrix syntactic foams had the lowest values. Macroscopically, relative to plastic collapse, brittle fracture of syntactic foams dominated in compression process. The microscopic deformation and failure mechanism related to matrix plasticity, heat treatment, and density of syntactic foams. [ABSTRACT FROM AUTHOR]

The focus of the current study is to investigate the challenges encountered in processing an interstitially alloyed stainless steel powder by means of an extrusion process derived from the manufacture of ceramics with subsequent pressureless sintering. Previous investigations reveal a distinct loss of nitrogen during conventional sintering in pure argon atmospheres due to the temperature/time regimes applied and the absence of a suitable partial pressure of nitrogen. Consequently, different flushing gases (consisting of argon and nitrogen) are used to keep the nitrogen content in the pre‐alloyed steel powder constant during consolidation. The resulting chemical compositions of the manufactured compacts are determined, as are the microstructures and the mechanical properties, which are recorded under quasi‐static compressive loading. A detailed analysis is conducted to determine the reasons for the loss of interstitial elements in the materials studied, a phenomenon caused by oxidation and reduction reactions throughout the processing chain. In addition, the differences between the materials in their work‐hardening behavior and in the kinetics of the TRansformation Induced Plasticity (TRIP) effect are discussed as a function of the amount of interstitial elements remaining in the sintered materials. [ABSTRACT FROM AUTHOR]

Fused deposition modeling (FDM) as a rapidly growing additive manufacturing technology is successfully applied to several industries. In this study, effects of printing layer thickness, reinforcement types, and silicon carbide nanowire (SiCnw) brushing layers on compressive properties are investigated by comparing the strength and modulus of the FDM specimens acquired from compression tests. First of all, the printing layer thickness determines the strength of the printed specimens, the pure polylactic acid (PLA), the PLA reinforced by short carbon fiber (Cf/PLA), and the PLA reinforced by graphene (G/PLA). The results indicate that both strength and elastic modulus of the printed specimens increase with the decrease of the printing layer thickness. Therefore, the effects of different reinforcement types on the mechanical properties are further investigated at the same printing layer thickness. It indicates that the printed Cf/PLA receives the highest elastic modulus up to 1.69 GPa due to the high modulus of carbon fiber. Finally, the SiCnw brushing layers between the printed PLA layers are found to significantly increase the compressive modulus and there is a growth of 55.1% from pure PLA to PLA with three SiCnw brushing layers. [ABSTRACT FROM AUTHOR]