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• Experimental study was performed on the compressive characteristics of confined square concrete columns by HSSSWR meshes reinforced ECC jacket. • Effects of various parameters on the behavior of the confined concrete columns were revealed. • An analytical model was developed for characterizing the compressive stress–strain relationship of the confined concrete columns. This paper presents experimental and analytical studies on the uniaxial compressive properties and failure mechanics of confined concrete columns with a novel strengthening system, high-strength stainless steel wire rope (HSSSWR) meshes reinforced engineering cementitious composite (ECC) jacket. The effects of the formula of ECC, spacing of lateral HSSSWRs and concrete strength were considered in this experimental study. Test results showed this strengthening system can confine concrete columns effectively due to good bond performance between the jacket and concrete, which changed the concrete failure mode from brittleness to ductile failure and resulted in effective improvements in bearing capacity, deformation capacity, ductility and energy absorption capacity. Multiple fine cracks were observed in the confined concrete columns, which indicated the excellent crack-width controlling ability of the jacket. By embracing path-independence assumption and modifying the relationship of hoop strain and vertical strain for concrete columns confined by HSSSWR meshes reinforced ECC jacket, an analytical model for predicting the load–displacement curve of the HSSSWR meshes reinforced ECC confined concrete columns was developed. The predicted results by using the proposed analytical model were found in good agreement with the experimental results. [ABSTRACT FROM AUTHOR]

Poor sinterability of powder metallurgy TiAl-based alloy is an important factor that restricts its industrial production. In this paper, we improve the sinterability of Ti-48Al alloy by adding Co element. In such case, the relative density of Ti–48Al based alloy sintered at 1250 ℃ increases from 82.6% to 96% with an increase of Co content from 0 to 1.5 at%. The densification improvement is caused by liquid TiAl 2 Co phase, which is formed at 1230 ℃. Then, uniform and fine near-γ microstructure is obtained, and the grain size increases with the increasing of Co content. More than 70% of grains in the Ti-48Al-0.5Co alloy are smaller than 2 µm. Overall, Ti-48Al-0.5Co alloy has better comprehensive performance, with compressive strength of 2533 MPa, yield strength of 683 MPa and fracture strain of 29.5%. [Display omitted] • High-density Ti-48Al alloy with Co addition is prepared using irregular powder. • Liquid TiAl 2 Co phase is formed to promote densification sintering. • Sintering temperature of Co-added TiAl alloy is reduced by 50 ℃. • More than 70% of grains in the Ti-48Al-0.5Co alloy are smaller than 2 µm. • Ti-48Al-0.5Co has superior compressive and yield strengths of 2533 MPa and 683 MPa. [ABSTRACT FROM AUTHOR]

TiZrNbMoxVy high-entropy alloys (HEAs) with x = 0-2, y = 1 and y = 0.3, respectively, were designed and prepared by copper mold casting technology. The phase composition and stability of these HEAs were investigated. It is shown that the HEAs with low content of V are composed of only one type of bcc solid solution phase (SSP), and demonstrate excellent phase stability at 1273 K. The high content of V and Mo results in the formation of two types of bcc SSPs and the decrease of phase stability in the HEAs. Based on the previously proposed criteria, the formation ability of solid solution phase for this kind of HEAs was comprehensively evaluated. The compressive mechanical properties of the as-cast and annealed HEAs were measured. It has been found that Mo plays a strong solid solution strengthening effect on this kind of HEAs. Especially, TiZrNbMo0.3V0.3 has the yield strength and plastic strain of 1312 MPa and >50%, respectively, and still maintains the excellent plastic deformation ability even after annealed at 1273 K for 72 h. The strengthening effect in this kind of HEAs is considered to be due to the shear modulus mismatch. The solubility limit of HEAs is correspondent to shear modulus mismatch of 29. [ABSTRACT FROM AUTHOR]

In this study, experimental procedure and numerical methods were utilized to evaluate the effect of regular and irregular pore distribution as well as loading direction on compressive properties and deformation mechanism of hollow sphere aluminum foams. In order to study scaling laws, different volume fractions of the regular samples were produced and loaded in horizontal and vertical directions to address the loading conditions effects. For this purpose, expanded polystyrene (EPS) grains were expanded to a designed diameter size and positioned in different configurations. Compression test results showed higher elastic properties for irregular sample due to the thicker cell walls while energy absorption capability at high strains was found to be reduced due to the non-uniform deformation in comparison with regular foams. In regular samples, a nonlinear behavior in the elastic regime was observed since the imperfections during casting procedure. Furthermore, similar deformation mechanisms were found for the set of samples with similar pore configurations indicating the feasibility of controlling deformation mechanism by manipulating morphological characteristics. Finite element results well predicted deformation mechanism of structures and plastic properties of regular hollow sphere samples especially for plateau stress with less than 12% relative error. [ABSTRACT FROM AUTHOR]

The quasi-static and dynamic compressive properties of a composite modified double-base (CMDB) propellant were studied over a wide range of strain rates from 10 −4 s −1 to 10 3 s −1 at low temperatures of −40 °C to 0 °C, using a conventional universal testing machine and a split Hopkinson pressure bar apparatus. The experimental results show that the mechanical properties of the CMDB propellant, in terms of yield stress, initial compressive modulus, and ultimate strain, were greatly affected by the applied strain rate and the temperature, and the stress–strain responses exhibited an initial viscoelastic phase, followed by yielding, and then a subsequent strain hardening or softening stage, which was strongly dependent on the strain rate and temperature. It was found that the yield stress increased with both increasing strain rate and decreasing temperature. According to the experimental results, the strain rate effect, but not the temperature effect, was accentuated at higher rates. Moreover, the Eyring cooperative model was employed to predict the yielding behavior, and a master curve of reduced yield stress versus strain rate was built. The results show that the Eyring cooperative model provides reasonable prediction over a wide range of strain rates under low temperatures. [ABSTRACT FROM AUTHOR]

Magnesium alloys have considerably lower density than the aluminum alloy matrices that are typically used in syntactic foams, allowing for greater specific energy absorption. Despite the potential advantages, few studies have reported the properties of magnesium alloy matrix syntactic foams. In this work, Al2O3 hollow particles of three different size ranges, 0.106-0.212 mm, 0.212-0.425 mm, and 0.425-0.500 mm were encapsulated in Mg-AZ91D by a sub-atmospheric pressure infiltration technique. It is shown that the peak strength, plateau strength and toughness of the foam increases with increasing hollow sphere wall thickness to diameter (t/D) ratio. Since t/D was found to increase with decreasing hollow sphere diameter, the foams produced with smaller spheres showed improved performance--specifically, higher energy absorption per unit weight. These foams show better performance than other metallic foams on a specific property basis. [ABSTRACT FROM AUTHOR]

The compression properties of three-dimensional angle-interlock woven E-glass fabric/vinyl ester composite material along thickness direction under quasi-static (0.001 s−1) and high strain rates (800, 1600, and 2700 s−1) were investigated with finite element method and compared with those in experimental. The finite element method model was based on the three-dimensional woven composite microstructure. It was found that the compressive properties are sensitive to strain rate both in finite element method and experimental. The finite element method results showed good agreements with that of experimental in stress–strain curves and fracture morphologies. The obvious strain rate sensitivity of the compression properties and failure modes of three-dimensional angle interlock composites was both verified with the finite element method model and results in experimental. The compressive stiffness and maximum compressive stress increased with the strain rate while the failure strain showed an opposite trend. The failure mode is mainly in shear failure. The compressive failure mechanisms have been analyzed from the different components of the three-dimensional woven composites. [ABSTRACT FROM AUTHOR]

Porous scaffolds of Ti-6Al-4V were produced by mixing of this alloy with different amount of magnesium (Mg) powders. The mixtures were compacted in steel die by applying uniaxial pressure of 500 MPa before sintering the compacts in sealed quartz tubes at 900 °C for 2 h. Employing Archimedes׳ principle and Image Tool software, the total and open volume percentages of porosities within the scaffolds were found to be in the range of 47–64% and 41–47%, respectively. XRD results of titanium before and after sintering showed that no contamination, neither oxides nor nitrides formed during processes. Compressive properties of the scaffolds were studied using an Instron machine. The observed compressive strength and Young׳s module of the scaffolds were in the range of 72–132 MPa, and 37–47 GPa, respectively. Cell attachment and proliferation rate of MG-63 on porous samples were investigated. The results showed that proliferation rate increased with increasing Mg content. However no clear differences were observed between samples regarding cell attachment, so that bridges were observed in all cell gaps within the scaffolds. [ABSTRACT FROM AUTHOR]

Magnesium and its alloys reinforced with nano-size reinforcements display improved mechanical properties without significant reduction in the ductility that is usually associated with the addition of micron size reinforcements, making them an attractive choice for lightweight structural applications. This paper provides a review of magnesium nanocomposites containing ceramic and metallic reinforcements synthesized using liquid based (Disintegrated Melt Deposition Technique) and solid based (Powder Metallurgy and Microwave Sintering) processing techniques. The properties of these nanocomposites will be discussed in terms of microstructure, grain size, hardness, tensile, compressive, dynamic, high temperature, corrosion, fatigue and wear. [ABSTRACT FROM AUTHOR]

Novel ZrB 2 -reinforced zirconium (Zr) alloys with different boron (B) and aluminum (Al) contents were produced by arc-melting technique. Microstructural observation indicated that both the α-lath and the prior-β grain size were significantly refined with increased B content. The thickness of α lath gradually increased with increased solute atom Al content. Compressive test results showed that the modulus and strengths of the alloys improved with increased ZrB 2 and Al contents. The presence of abundant ZrB 2 whiskers and solid solution atom Al were responsible for the increased Young׳s modulus. The strengthening mechanisms can be attributed to strengthening through load transfer between the ZrB 2 whiskers and Zr matrix, morphological changes in alloys resulting from the formation of ZrB 2 whiskers, and solid-solution strengthening caused by Al addition. Fractography confirmed that ZrB 2 whiskers undertook the load transferred from Zr matrix and that crack sources were primarily generated at ZrB 2 whiskers. [ABSTRACT FROM AUTHOR]

The compressive behaviour of epoxy based syntactic foams filled by ceramic microballoons is experimentally investigated in this study. Nine different types of syntactic foams are fabricated with three different microballoon sizes and three different microballoon fractions. All of the syntactic foam specimens are tested at various strain rates from quasi-static to high strain rates. Analysis of the results is carried out on the effect of the volume fraction, microballoon size and strain rate on the compressive behaviour of syntactic foams. Also, scanning electron microscopy is used to understand the fracture mechanisms of tested specimens. The results show that as the microballoon volume fraction increases the compressive strength, compressive modulus, failure strain and plateau stress decreases for all types of syntactic foams at all strain rates. Although, this decrease is slight for 20% and 40% volume fraction, it is considerable for 60% microballoon volume fraction syntactic foam. The results indicate that reducing the microballoon size or increasing the strain rate of testing would enhance the compressive strength. [ABSTRACT FROM AUTHOR]

This article reports on the compressive, dynamic mechanical and dielectric properties of microcellular polycarbonate foams with unimodal or bimodal cell-size distributions fabricated using the environment-friendly supercritical carbon dioxide. The effects of cell morphologies such as relative density, cell-size distribution and porosity on the compressive strength, Young’s modulus, storage modulus, loss modulus, dielectric constant and loss tangent of the microcellular polycarbonate foams are investigated quantitatively. Experimental values of the compressive strength and Young’s modulus fit very well with the theoretical values calculated from the Gibson–Ashby model at low relative densities. The higher relative density leads to higher storage modulus and loss modulus. The bimodal foams significantly improve the compressive and dynamic mechanical properties compared to the unimodal foams with the same relative density. The dielectric properties of microcellular foams depend only on the total porosity, but not on the cell-size distribution or microstructure of the foams. With increasing porosity, the dielectric constant of the microcellular foams gradually decreases, and agrees very well with the curve calculated from the Maxwell-Garnett-spheres model. [ABSTRACT FROM PUBLISHER]

It is known that the mechanical properties of bone-mimicking porous biomaterials are a function of the morphological properties of the porous structure, including the configuration and size of the repeating unit cell from which they are made. However, the literature on this topic is limited, primarily because of the challenge in fabricating porous biomaterials with arbitrarily complex morphological designs. In the present work, we studied the relationship between relative density (RD) of porous Ti6Al4V EFI alloy and five compressive properties of the material, namely elastic gradient or modulus (Es20-70), first maximum stress, plateau stress, yield stress, and energy absorption. Porous structures with different RD and six different unit cell configurations (cubic (C), diamond (D), truncated cube (TC), truncated cuboctahedron (TCO), rhombic dodecahedron (RD), and rhombicuboctahedron (RCO)) were fabricated using selective laser melting. Each of the compressive properties increased with increase in RD, the relationship being of a power law type. Clear trends were seen in the influence of unit cell configuration and porosity on each of the compressive properties. For example, in terms of Es20-70, the structures may be divided into two groups: those that are stiff (comprising those made using C, TC, TCO, and RCO unit cell) and those that are compliant (comprising those made using D and RD unit cell). [ABSTRACT FROM AUTHOR]

The effect of thermal degradation on the compression strength, ultimate compression strain, color and mass loss of four limestones extracted from the Yucatan Peninsula was studied. The samples sets were independently subjected to 25, 100, 200, 300, 400, 500 and 600 °C during one hour for each temperature. The thermal degradation of the investigated rocks and their chemical composition, microstructure and porosity is also investigated. The results show a correlation between the mechanical properties, thermal behavior, the presence of minerals and porosity in each type of limestone rock. The variation of the limestones color with temperature was described in terms of standard space color parameters and their diffuse reflectance. [ABSTRACT FROM AUTHOR]

Ten groups of bamboo scrimber samples between 0° (parallel to the grain) and 90° (perpendicular to the grain) were chosen for compression test. The effect of different angles between load and grain on compressive properties of bamboo scrimber was studied. Fold failure, shearing failure and crushing failure were observed at 0-10°, 20-50° and 60-90°, respectively. From 0 to 90°, average ultimate strength and proportional limit strength decreased from 133.4 to 25.7 MPa and 113.9 to 14.9 MPa. The predictive accuracy of the Hankinson formula was higher comparing to the result of GB 50005 formula. The Norris criterion was inclusive for the majority of the testing values, making it secure during application. Furthermore, compressive properties could be predicted using maximum stress theory, which adequately explained the cause of different failure types for longitudinal compression strength, shear strength and transverse compressive strength. The study of strength models now provides a theoretical foundation for the rational use of bamboo scrimber. [ABSTRACT FROM AUTHOR]

In this paper, the compressive characteristics of closed-cell aluminum foams (with different percentages of elemental Mn) after immersion in simulated seawater are investigated and the effect of corrosion process on the yield strength and energy absorption capacity is studied systematically. Results show that corrosion process changes the compressive deformation mode from ductile fracture to brittle fracture. Meanwhile, the corrosion process dramatically deteriorates the yield strength and energy absorption capacity. Fortunately, elemental Mn significantly reduces the effect of corrosion process on the deformation mode and compressive behaviors of foams. Statistical results show that the foam with Mn percentage of 1–2 wt.% possesses optimal yield strength and energy absorption capacity loss rates under the present conditions. Electrochemical test, morphology observation and XRD detections are applied to explain the reasons. [ABSTRACT FROM AUTHOR]

At present, all of the cork used to manufacture natural stoppers is air dried for a minimum of 6 months. This study evaluates the feasibility of applying a kiln drying technique to cork planks. We used a sample of 65 planks, each of which was divided into two pieces. One sub-set of planks was air dried for 6 months following the traditional procedure, while the other was kiln dried for 14 days. The evolution of moisture content was controlled, and both methods were compared by means of a statistical analysis of the thickness, quality, porosity coefficient, color and compressive properties of the cork. The reduction in moisture content was similar for both traditional air drying and kiln drying. At the end of the drying, cork thickness increased with both methods, although a larger increase was observed for the kiln drying method. Statistically significant differences were not found for the mean porosity coefficient or quality. Although statistically significant differences in the color of the cork were detected, it would be necessary to verify if such differences are detectable by the human eye. No differences were found in the compressive properties of the cork for a significance level of less than 1%. This feasibility study concludes that kiln drying is a suitable technique as it significantly reduces the drying time and holding costs of the raw material. The application of this technique would constitute an innovation in the transformation process by controlling the climatic variables that affect the drying process. [ABSTRACT FROM AUTHOR]

Compressive strength is one of the most important considerations when designing fibre-reinforced polymer (FRP) composite structures. This property is obtained from the stress-strain response of FRP specimen loaded in compression. Compression tests using shear-loading or end-loading methods usually cause premature failure of the specimens or failure near to/in tabs. Therefore, the purpose of this study is to design a test rig for compression testing that combines both shear- and end-loading methods. Computer-Aided Three-Dimensional Interactive Application software was used to design parts and the whole system of the test rig, namely UiTM dual guide compression test fixture. The performance of the test rig was evaluated by conducting compression tests on woven carbon, glass and Kevlar fibre-reinforced polymer composites samples. It was observed that all specimens failed within the specimen gauge length, implying that the tests were successful. [ABSTRACT FROM AUTHOR]

The application of magnesium oxychloride cement (MOC) is promising, but its poor water resistance seriously hinders its development and application. In this paper, we describe a new type of MOC with excellent water resistance, prepared using fly ash and hexadecyltrimethoxysilane (HDTMS). SEM, XRD, FTIR, TG/DSC, and other microscopic-scale studies were conducted to investigate the mechanism underlying the water-resistance enhancement of the new MOC. It was found that adding 20% fly ash and 3% HDTMS can strengthen the water resistance of MOC while retaining high mechanical properties. In particular, the residual coefficient remained at 0.91 after 7 days of immersion. This is because these two additives, when used together, can increase the content of the gelling 5-phase of MOC, as well as optimize the pore structure of MOC.

Size irregularity gradient and cell wall gradient, combined as the density gradient in previous studies, affect the macroscopic mechanical properties of the gradient metal foam. More and more complex mesostructures are designed and applied in metal foams, and the density gradient becomes insufficient to describe the difference in mesostructures. To explore the effect of mesostructures carefully, this study focuses on the effect of the size irregularity gradient on the macroscopic compressive properties of metal foams. A series of metal foam models were developed using the 3D Voronoi technique. These models have the same average relative densities, the same average diameters and different size irregularity gradients. Simulation results indicated that the macroscopic mechanical properties of cell wall gradient metal foams are significantly different from those of size irregularity gradient metal foams, though these models have the same relative density gradient. To explore the effect of size irregularity gradient, a theoretical model was developed to characterize the compression process from the first cell-collapse to full condensation. Theoretical results showed a linear relationship between the nominal stress and the current relative density. These findings can provide efficient guidance for the design and applications of gradient metal foams., Competing Interests: The authors declare no competing interests., (© 2022 The Author(s).)

In this study, the Zn-0.8Mg-0.28CaO wt.% composite was successfully prepared using different conditions of ball milling (rotations and time) followed by a direct extrusion process. These materials were characterized from the point of view of microstructure and compressive properties, and the correlation between those characteristics was found. Microstructures of individual materials possessed differences in grain size, where the grain size decreased with the intensified conditions (milling speed and time). However, the mutual relation between grain size and compressive strength was not linear. This was caused by the effect of other factors, such as texture, intermetallic phases, and pores. Material texture affects the mechanical properties by a different activity ratio between basal and pyramidal slips. The properties of intermetallic particles and pores were determined in material volume using micro-computed tomography (µCT), enhancing the precision of our assumptions compared with commonly applied methods. Based on that, and the analysis after the compressive tests, we were able to determine the influence of aspect ratio, feret diameters, and volume content of intermetallic phases and pores on mechanical behavior. The influence of the aspects on mechanical behavior is described and discussed.

In order to improve the mechanical properties of TiAl alloys, micro-nano Ti 2 AlC-reinforced TiAl composites were successfully fabricated by means of spark plasma sintering (SPS) using the ball-milled multilayer graphene oxide and Ti–48Al–2Nb–2Cr pre-alloyed powders. The micro-nano Ti 2 AlC phase precipitated at the interface between α 2 -Ti 3 Al and γ-TiAl phases utilizing the reaction of TiAl and high-activity graphene. Fully lamellar structure was obtained after sintering above 1300 °C, and Ti 2 AlC phase characteristic were depended on sintering temperature and graphene content. The compressive strength and fracture strain of TiAl-0.5G alloy were improved at room temperature and elevated temperature, which was improved by 23.61% and 5.03% compared to the TiAl-0G alloy at room temperature. The tribological properties of TiAl composites were significantly improved by micro-nano Ti 2 AlC at the room temperature, and the average friction coefficient of TiAl-0.5G alloy is 0.217 compared with TiAl-0G alloy is 0.312, and the wear mechanism is ploughing wear. The micro-nano Ti 2 AlC improves the strength and oxidation resistance of TiAl composites at 650 °C, which is detrimental to the wear resistance due to the lower ductility and the third wear by the loose oxide particles at elevated temperature. • Micro-nano Ti 2 AlC-reinforced TiAl alloys was fabricated via SPS. • The compressive strength and plasticity were improved simultaneously by micro-nano Ti 2 AlC phase. • The room-temperature tribological property was significantly improved by Ti 2 AlC. [ABSTRACT FROM AUTHOR]

This paper presents an experimental and numerical study on the compressive behaviors of a new carbon fiber-reinforced cement-based composite (CFRCC) that is composed of magnesium oxysulfate cement, carbon fiber and some chemical admixtures. Parametric studies on the effects of carbon fiber content and strain rate on the compressive behaviors of CFRCC, are conducted using a series of quasi-static and dynamic compressive tests. The research item includes the failure morphology, stress-strain curve, dynamic increase factor (DIF), etc. Besides, a three-dimensional (3D) mesoscale modelling approach is proposed to simulate and analyze the mechanical responses and the failure mechanisms of CFRCC subjected to dynamic compressive loading, where the random dispersion of chopped fibers are realistically considered. The results indicate that the cracking and failure modes of CFRCC are significantly affected by the bridging effect of carbon fibers randomly dispersed in cement matrix. With the increase of fiber content, the dynamic peak stress and peak strain of CFRCC at similar strain rates show an increasing and decreasing trend, respectively. An evident strain-rate hardening effect could be found on the initial elastic modulus and the peak stress of CFRCC as well. While the relationship between the DIF of CFRCC and the logarithm of strain rate could be described using a quadratic function. Moreover, the mesoscale modelling approach has been validated by a good agreement between the numerical and tested results, demonstrating the feasibility of the developed mesoscale model in simulating and investigating the dynamic behaviors of CFRCC. All in all, the CFRCC has proven to be of great significance in resisting to impact loads, and more insights should be provided into its dynamic properties. [Display omitted] • A new carbon fiber-reinforced composite (CFRCC). • Quasi-static and dynamic compressive tests of CFRCC. • A new 3D mesoscale model for fiber-reinforced composites. • Effects of strain rate and fiber content on the CFRCC. • Multi-scale analysis on the compressive behaviors of CFRCC. [ABSTRACT FROM AUTHOR]

In the present work, Ti 2 AlC/TiAl composite with a bioinspired laminated structure was fabricated by an in-situ reactive vacuum hot-pressing sintering using flake powder metallurgy (flake PM) with Ti powders, Al powders and graphene nanosheets (GNSs) as raw materials (atomic ratio of Ti–44Al-2.6C). The phases, microstructure and compressive properties of the composite at room temperature were systematically investigated. The results have showed that the composite mainly consist of laminated Ti 2 AlC, needle-like Ti 2 AlC and lamellar γ-TiAl/α 2 -Ti 3 Al matrix. The laminated Ti 2 AlC particles are in-situ synthesized during the sintering process, and the Ti 2 AlC/TiAl interface is mostly an incoherent interphase boundary. The needle-like Ti 2 AlC particles are formed due to the different solubility of C in γ-TiAl and α 2 -Ti 3 Al during the cooling stage, and are preferentially precipitated from TiAl(111) plane and grown along Ti 2 AlC(0001) plane. Furthermore, the room-temperature compressive strength and strain of the Ti 2 AlC/TiAl composite in our work could reach 1477.1 MPa and 16.3%, respectively. The comparisons with other TiAl alloys and TiAl matrix composites have indicated that the Ti 2 AlC/TiAl composites with a bioinspired laminated structure could maintain a better balance of strength and ductility. The characteristic of fracture morphology is mainly crack arresting, pullout and kinking of the laminated Ti 2 AlC particles. • The Ti 2 AlC/TiAl composite with a bioinspired laminated structure was fabricated. • The two kinds of Ti 2 AlC particles possesses different morphology, i.e. laminated and needle-like. • The formation mechanisms of laminated and needle-like Ti 2 AlC particles are different. • The compressive strength and compressive strain of the Ti 2 AlC/TiAl composite maintain a better balance. [ABSTRACT FROM AUTHOR]

TiC-graphene dual-reinforced Al matrix hybrid nanocomposites (AMHNs) were synthesised by powder metallurgy. Microstructures, compressive and tribological properties of the AMHNs with different fractions of graphene nanoplatelets (GNPs) were studied and compared with Al2024 alloy, and TiC or GNPs singly reinforced Al composites. The results show the microstructures and distributions of TiC and GNPs are homogenised with the increasing content of GNPs. The compressive properties and wear resistance of the composites are improved efficiently by synergistic influences of TiC and GNPs. Significantly, Al-5.0 wt% TiC-1.0 wt% GNPs has the most superior compressive properties and highest wear resistance with a wear rate of 4.62 × 10−4 mm3/Nm, which is a 94.4% reduction compared with that of unreinforced Al alloy. • Al2024/TiC/GNPs hybrid nanocomposites were fabricated by powder metallurgy. • Distributions of precipitates, TiC and GNPs are improved as GNPs content increases. • Mechanical properties of AMHCs are improved with the increasing content of GNPs. • Superior wear resistance is obtained for Al2024/5.0 wt% TiC/1.0 wt% GNPs. [ABSTRACT FROM AUTHOR]

Three-dimensional woven spacer composites (3DWSCs) have a great potential to applied in aerospace or transportation fields due to their high strength-to-weight and stiffness-to-weight ratios, with excellent skin-core debonding resistance. Among these properties, the compressive strength of the 3DWSCs which is most critical, and still needs to be improved to meet the highly requirements in practical applications. In this study, we designed and manufactured 3DWSCs with highly enhanced compressive strength and energy absorption by adopting bulked glass fibers (BGFs) as pile yarns to weave its core layer to absorb more epoxy resin. Consequently, the specific compressive strength of 3DWSCs woven by BGFs as pile yarns with saturated epoxy resin absorption was 52.54 MPa g−1 cm3, 180% higher than that of the 3DWSCs woven by regular glass fiber (RGFs). Furthermore, the work of fracture of 3DWSCs woven by BGFs as pile yarns with saturated epoxy resin absorption was 14.82 N m, which enhanced 474% compared with that of 3DWSCs woven by RGFs. The failure cross sections depicted multiple brittle fractures of the pile yarns for both composites under compression, which caused multiple peaks in their stress–strain curves. [ABSTRACT FROM AUTHOR]

In this study, novel cellular structures were derived from the bird's feathers. Experimental and numerical analysis of the fused filament fabricated (FFF) structures subjected to uni-axial compressive and three-point bending load is carried out. The effect of strut thickness, shape, loading direction and functional grading on compressive behavior is studied. The comparison between the novel bio-inspired designs and other types of cellular structures already reported in the literature showed the superior compressive performance of bird's feather-inspired designs. Furthermore, the effect of strut shape on the flexural properties is studied using a three-point bending test. The flexural performance of the bird feather inspired panels is compared with the honeycomb and topology optimized panels. Both honeycomb and topology optimized based panels showed global failure after the first crack. However, the bio-inspired panels keep on absorbing energy even after the complete failure of the bottom plate of the panels. Overall, these novel designs hold potential for lightweight multi-functional 3D printed structures. • Designed, fabricated and tested the novel cellular structures and sandwich panels that are inspired from bird's feather. • The structures are printed with ABS material using FFF process. • Structures and panels are studied under compressive and three-point bending load. • Mechanical response of bio-inspired structures is similar to stretch-dominated structures. • Both experimental and numerical results showed better performance of novel lightweight structures. [ABSTRACT FROM AUTHOR]

By means of the introduction of the classic laminate theory with considering hygrothermal effect into the finite element method, by measuring the hygrothermal expansion coefficient, and introducing the damage criterion of composite structure, simulated the process of the composites mechanical properties damaging in hygrothermal environment. The composites panel absorption were studied on in the 70 °C/85 %RH and 80 °C/85 %RH hygrothermal environment, and the compressive experiment were carried on in RT and hygrothermal environment. The results of experiment and simulation were contrasted and analyzed, and they were better fitted. [ABSTRACT FROM AUTHOR]

Abstract: A novel attempt is made to synthesize and study the isolated effects of less than two volume fraction TiB2 nanoparticulates (60nm) on pure magnesium. New light weight Mg–TiB2 nanocomposites with superior mechanical properties compared to pure magnesium are synthesized using disintegrated melt deposition technique followed by hot extrusion. The microstructural characterization studies revealed that the samples exhibited fairly uniform distribution of TiB2 nanoparticulates with minimal porosity and good interfacial integrity between Mg matrix and TiB2 particulates. The coefficient of thermal expansion results indicates that the addition of 0.58, 0.97, and 1.98vol.% TiB2 nanoparticulates marginally improves the dimensional stability of pure magnesium. A significant improvement in the room temperature tensile properties of pure magnesium was observed with the addition of less than two volume fraction TiB2 nanoparticulates. The synthesized Mg 1.98vol.% TiB2 nanocomposite revealed the best room temperature tensile properties with a significant increase in the 0.2% tensile yield strength by ~54%, ultimate tensile strength by ~15% and fracture strain by ~79% when compared to pure Mg. The X-ray diffraction studies indicated changes in the basal plane orientation of pure Mg with the addition of nano-TiB2 particulates. A maximum tensile fracture strain of ~16% is achieved with the addition of 0.97vol.% TiB2. The room temperature compressive properties of the nanocomposites reveal that the addition of 1.98 TiB2 increases the 0.2% compressive yield strength of Mg by ~47% and ultimate compressive strength by ~10% with a marginal increase in the fracture strain (~11%). Reduction in tensile–compression yield asymmetry was observed for Mg 0.58 & 0.97vol.% TiB2 nanocomposites which can be attributed to the weakening of the strong basal texture of pure Mg. [Copyright &y& Elsevier]

The compressive behaviors of nanoclay-reinforced syntactic foams filled by ceramic microballoons are investigated. Eighteen different types of nano syntactic foams are fabricated with three different microballoons volume fraction, each containing six different weight fraction of nanoclay in their matrix. Quasi-static tests are carried out using an Instron 5500 machine test and Split Hopkinson Pressure Bar (SHPB) apparatus is used to perform the high strain rate tests. Also, scanning electron microscopy (SEM) is used to understand the fracture mechanisms and the microstructure of the tested specimens. [ABSTRACT FROM AUTHOR]

In this paper, effects of elevated temperatures on the compressive behaviour of rubber crumb and steel fibre reinforced recycled aggregate concrete (RSRAC) are presented. RSRAC is a new concrete material proposed by the authors. In the RSRAC, steel fibre is used to improve the performances of concrete before exposure (e.g. ductility, cracking) and after exposure (explosive spalling) to evaluated temperature, and the inclusion of rubber particles is mainly for the consideration of environment protection and reducing the risk of spalling after exposure to high temperatures. A series of concrete mixes were prepared with Ordinary Portland Cement (OPC), recycled concrete coarse aggregates (RCA) or natural coarse aggregates (NCA), 1% steel fibre (by volume) and rubber particles with different fine aggregate (sand) replacement ratios. The compressive properties, including compressive strength, Young's modulus (stiffness), stress–strain curves and energy absorption capacity (toughness) of the different concrete mixes subjected to elevated temperatures (25 °C, 200 °C, 400 °C and 600 °C), were obtained in accordance to ASTM standards. The results of weight loss and failure modes were recorded and presented in this study. The results showed that both the compressive strength and stiffness of concrete mixes decreased after exposure to elevated temperature, with higher replacement of fine aggregate by rubber leading to lower compressive strength and stiffness magnitude. Nevertheless, rubber crumbs significantly enhanced the energy absorption capacity and explosive spalling resistance. [ABSTRACT FROM AUTHOR]

Highlights: [•] First attempt is made to synthesize and characterize Mg–Ti nano materials. [•] Significant increase in RT tensile and compressive strengths of pure Mg was observed. [•] Increase in hardness of Mg–Ti nano materials indicate superior tribological properties. [ABSTRACT FROM AUTHOR]

The influence of palm oil fuel ash (POFA) inclusion on the compressive properties and chloride resistance of engineered cementitious composites (ECC) were experimentally investigated. In the material development, pozzolanic reactivity of POFA, direct tensile test and matrix fracture test were performed for evaluating the performance of ECC with POFA. Different ECC mixes with varying POFA content and water-binder ratios were used. The results show that the use of POFA should be helpful for achieving strain-hardening behavior by enhancing the fracture toughness and interfacial bond between matrix and PVA fiber. Moreover, at 28 and 90 days, increasing the POFA/cement ratio up to 0.2 led to an increase in the compressive strength of the ECC. The ECC mix with 1.2 POFA-cement ratio achieved a compressive strength of 30 MPa at 28 days, which is within the normal range of concrete strength for many applications. In addition, the test results show that mechanically pre-loaded POFA-ECC specimens exposed to chloride solution remain durable. The results also indicated strong evidence of self-healing of micro-cracked POFA-ECC specimens, which can still carry considerable flexural load. The rapid chloride permeability test reveal that the total charge passed was gradually reduced with the inclusion of higher amount of POFA. The results presented in this study provide a preliminary database for the durability of cracked and uncracked POFA-ECCs under chloride environment or/and combined mechanical loading. [ABSTRACT FROM AUTHOR]

Highlights: [•] Aluminum alloy metal foams were experimentally tested for compression. [•] Two metal foams were analyzed: uniform cell structure and dual-size cell arrangement. [•] The structures were manufactured by lost-wax casting using 3D printed components. [•] Results indicate higher efficiency of the dual-size (DS) structures. [•] DS structures may be suited for components subjected to impact or compression loading. [ABSTRACT FROM AUTHOR]

Accurate material models and associated parameters of atherosclerotic plaques are crucial for reliable biomechanical plaque prediction models. These biomechanical models have the potential to increase our understanding of plaque progression and failure, possibly improving risk assessment of plaque rupture, which is the main cause of ischaemic strokes and myocardial infarction. However, experimental biomechanical data on atherosclerotic plaque tissue is scarce and shows a high variability. In addition, most of the biomechanical models assume isotropic behaviour of plaque tissue, which is a general over-simplification. This review discusses the past and the current literature that focus on mechanical properties of plaque derived from compression experiments, using unconfined compression, micro- indentation or nano-indentation. Results will be discussed and the techniques will be mutually compared. Thereafter, an in-house developed indentation method combined with an inverse finite element method is introduced, allowing analysis of the local anisotropic mechanical properties of atherosclerotic plaques. The advantages and limitations of this method will be evaluated and compared to other methods reported in literature. [ABSTRACT FROM AUTHOR]

The variation of the density and compressive properties through a single closed-cell aluminium alloy foam block were evaluated. For this purpose a rectangular block of aluminium foam was fabricated and cut into identical small cubic representative volume specimens in three horizontal layers (bottom, middle and top). The mechanical characteristics of these cubic representative volume specimens were determined using quasi-static and dynamic compression tests, parallel and perpendicular to the foaming direction. The visual observation of the cubic representative volume specimens revealed that the pore size and the relative density vary across the original foam block, particularly on the different horizontal layers. Accordingly, the variation of the compressive properties and the energy absorption characteristics also proved to be significant. [ABSTRACT FROM AUTHOR]

This study evaluated the polymerization shrinkage, flexural and compressive properties of low-shrinkage resin composites. For the study, four methacrylate-based and one silorane-based resin composites were light cured using three different light-curing units (LCUs) and their polymerization shrinkage, flexural (strength (FS) and modulus (FM)) and compressive (strength (CS) and modulus (CM)) properties were evaluated. Data were statistically analyzed using ANOVA and a post-hoc Tukey test. The polymerization shrinkage ranged approximately 7.6-14.2 μm for 2-mm thick specimens depending on the resin product and LCU. Filtek LS showed the least shrinkage while the rest shrank approximately 13.2-14.2 μm. However, Filtek LS showed the greatest shrinkage difference for the used LCUs. FS and CS of the tested specimens ranged 96.2-152.1 MPa and 239.2-288.4 MPa, respectively, depending on the resin product and LCU. The highest and lowest FS and FM were recorded for the methacrylate-based resin composites. Among the specimens, Filtek LS showed the lowest CS and CM. [ABSTRACT FROM AUTHOR]

Microcapsule self-healing technology is an effective scheme to improve the durability of cementitious composites. In this paper, the compressive properties of microcapsule-based self-healing cementitious composites after freeze-thaw cycles were studied using acoustic emission (AE), and the changes in AE characteristics, compressive strength, mass loss rate, and electric flux of microcapsule-based self-healing cementitious composites with different microcapsule contents and freeze-thaw cycles were studied. The results show that if the content of the microcapsule is appropriate, with the increase in the number of freeze-thaw cycles, the AE hits will generally increase first and then decrease, and the early AE events will also decrease. Because of the different contents of microcapsules, the improvement effect and defect effect change dynamically with the number of freeze-thaw cycles, which is also reflected in the dynamic process of compressive strength. After 100 freeze-thaw cycles, the compressive strength of self-healing cementitious composite samples with 5% content of microcapsules and 3% content of microcapsules is the highest. The changes in mass loss rate and electric flux are similar to the AE characteristic parameters, which further verifies the results of AE. The research results of this paper provide experimental data and experimental methods for the engineering application of microcapsule self-healing cement-based composites in cold areas., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Hao, Hao, Kanwal and Jiang.)

Metal foams possess remarkable properties, such as lightweight, high compressive strength, lower specific weight, high stiffness, and high energy absorption. These properties make them highly desirable for many engineering applications, including lightweight materials, energy-absorption devices for aerospace and automotive industries, etc. For such potential applications, it is essential to understand the mechanical behaviour of these foams. Producing metal foams is a highly challenging task due to the coexistence of solid, liquid, and gaseous phases at different temperatures. Although numerous techniques are available for producing metal foams, fabricating foamed metal still suffers from imperfections and inconsistencies. Thus, a good understanding of various processing techniques and properties of the resulting foams is essential to improve the foam quality. This review discussed the types of metal foams available in the market and their properties, providing an overview of the production techniques involved and the contribution of metal foams to various applications. This review also discussed the challenges in foam fabrications and proposed several solutions to address these problems.