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The compressive behavior is one of the most fundamental mechanical properties for engineering materials. In this paper, the octahedral structure model of porous materials is used to evolve the mechanical analysis model under compressive loading for the porous composite materials, which are resulted from reticular metal foams with pore struts presenting multilayered structure. Starting from this analysis model, some fundamental mechanical relationships, including those of the safe load-bearing and overall strength, have been deduced for these porous composite materials. The compressive strength has been characterized for the porous composite body, corresponding to the overall failure caused by the prior breakage of the strut core and by the prior breakage of the strut shell, respectively. The nickel foam products manufactured on the production line of enterprise were used to make porous composite materials by coating the pore struts with epoxy resin, and the metal foam composite material was obtained with the composite pore-struts of metal/resin multilayered structure. Using this porous composite material for compression experiments, it is found that the experimental data match well with the mathematical relationship from the present theoretical model. The results verify the feasibility of this analysis model and the practicality of the relevant mathematical relationship. [ABSTRACT FROM AUTHOR]

This paper investigated the effects of heat‐treatment and loading directions on compressive properties of 3D printed continuous carbon fiber reinforced composites (CCFRC). After heat‐treatment at different conditions, specimens with different stacking sequences were compressed under different loading directions. The effect of heat‐treatment on the porosity and crystallinity of composites was investigated. The porosity of short carbon fiber reinforced composites decreased but that of CCFRC increased after heat‐treatment at 200°C. The compressive properties of specimens were investigated in combination with changes in porosity and crystallinity. It was found that the compressive properties of composites usually increased with decreasing porosity induced by heat‐treatment. While the fiber direction was parallel to the applied loading direction, the yield strength of C‐CCFRC and S‐CCFRC increased from 208.1 to 281.6 MPa and from 218.5 to 264.4 MPa, respectively, though the porosity increased. After heat‐treatment at 100°C for 4 h, the crack initiation of CCFRCs was delayed during compressive tests. Besides, heat‐treatment could change failure modes of CCFRC after heat‐treatment at 200°C for 4 h. More specifically, heat‐treatment at 200°C for 4 h could result in delamination and a decrease in energy absorption of C‐CCFRC (from 7.23 to 4.05 J). [ABSTRACT FROM AUTHOR]

This paper investigated the effects of printing directions (path of nozzle movement) and strain rates on the performances of short carbon and glass fibers filled polyamide‐based composites prepared by fused deposition modeling (FDM). Cylindrical specimens printed in three different printing directions were compressed at a wide range of strain rate. The results showed that, for short fiber reinforced polyamide, the compressive properties of cylindrical specimens were affected by printing directions closely associated with the fiber orientation. The highest elastic modulus and yield strength of short fiber reinforced specimens were obtained when the printing direction was parallel to the applied loading direction, because the orientation of short fibers was preferred to the printing direction. However, at large deformation, the orientation of fibers in specimens changed, accompanied by a decrease in stress. With increasing strain rates, the short fiber reinforced polyamide with different fiber orientations showed different failure modes. However, the compressive behaviors of pure polyamide were similar, although they were printed in different printing directions. [ABSTRACT FROM AUTHOR]

This paper investigates the mechanical properties of metal beetle elytron plates (a type of biomimetic sandwich structure) and the elementary unit of the trabecular-honeycomb core structure by compression experiments. The following conclusions are drawn: (1) after reaching the compressive strength, the stress–strain curve of the beetle elytron plate contains a yield plateau that advantageously exploits the material strength of metal and its plastic deformation capacity; (2) the elementary unit of the core structure in beetle elytron plates is proposed explicitly based on the trabecular characteristic; and (3) this elementary unit remains relatively unchanged on the constraint condition of the trabecular structure and has high independence and stability when placed under out-of-plane compression. Thus, the yield plateau and variation tendency of the compressive strength after buckling of this elementary unit are highly consistent with that of the entire structure, which provides the basis for further research on the equivalent parameters and equivalent model of the beetle elytron plate and its trabecular-honeycomb core structure. [ABSTRACT FROM AUTHOR]

This paper mainly introduces a high-distance warp-knitted spacer flexible composite material which is a special material consisting of high-distance warp-knitted spacer fabric and some coating materials. It introduces the designing process as well as the preparation of high-distance warp-knitted flexible composite material. In order to comprehend the influence of internal pressure on the material, the mechanical properties under 100 %, 80 % and 60 % gas pressure have been explored. A compression test under these three kinds of gas pressure was carried out and the related force displacement diagram, the stress-strain curve and the energy strain curve which directly reflects the variation of the mechanical properties of the composites material under the different gas pressure were obtained and presented. A deep investigation and analysis was conducted into knowing the compressive properties of the material and how they are affected by the gas pressure. The experimental results obtained shows that the compressive properties of the high-distance warp-knitted space flexible material is dependent on the amount of gas inserted. Again the compressive strength of the material keeps growing stronger with an increase in the intensity of the gas pressure. [ABSTRACT FROM AUTHOR]

To study the mechanical properties of segregated asphalt mixtures, a novel method was developed to generate three-dimensional finite element models for segregated asphalt mixtures. The virtual uniaxial compression tests under different loading rates and test temperatures were carried out to analyze the effects of aggregate segregation on the strain distribution of asphalt mixtures. Meanwhile, the uniaxial compression tests of segregated asphalt mixtures under the same test condition were carried out in the laboratory. The results show that with the increase of aggregate segregation degree, the strain value as well as the uniformity of strain distribution for AC-13 asphalt mixture decreases, and the strain value of asphalt mortar is much larger than that of aggregate particles. The strain distribution of the asphalt mixture is related to the internal structure of the asphalt mixture, and the loading rates mainly affect the magnitude of the strain value. However, the variation of test temperature not only affects the strain distribution characteristics of the asphalt mixture but also affects the magnitude of strain value. Compared with coarse aggregate segregation of high level, the influence of loading rate and test temperature on the internal strain of nonsegregated AC-13 asphalt mixture is more significant. In terms of the laboratory result, the compressive strength of dense-graded asphalt mixture first increases and then weakens with the increase in the segregation degree of coarse aggregate, while that of open-graded asphalt mixtures enhances after the segregation of fine aggregate. Furthermore, the numerical simulation based on finite element method (FEM) effectually simulates the mechanical properties of segregated asphalt mixtures, which error is less than 6.6% when compared with the results of laboratory tests. The research results can provide some references to analyze the influence of aggregate segregation on the mechanical properties of asphalt mixture without laboratory tests. [ABSTRACT FROM AUTHOR]

316 L stainless steel powder with varying particle sizes was chosen as the raw material for the fabrication of metal hollow spheres using powder metallurgy techniques. The powder's particle size, composition, and micro-morphology were examined, followed by porosity and capillary force calculations, compressive testing, and fracture analysis. The findings reveal significant disparities in the micro-morphology and mechanical properties among the metal powders with different particle sizes. Smaller particle sizes result in denser bonding of the hollow spheres, leading to higher compressive yield strength. Conversely, larger powder particle sizes substantially increase the porosity of the hollow sphere wall, resulting in a sharp decline in mechanical properties and a transition from ductile fracture to brittle fracture in its failure mode. This study's innovation lies in its meticulous examination of the relationship between particle size distribution and the resulting microstructural and mechanical properties of 316 L stainless steel hollow spheres, providing valuable data that enhances the understanding of powder metallurgy processes and drives the development of advanced materials for aerospace applications. [ABSTRACT FROM AUTHOR]

Triply periodic minimal surfaces (TPMSs) are known for their smooth, fully interconnected, and naturally porous characteristics, offering a superior alternative to traditional porous structures. These structures often suffer from stress concentration and a lack of adjustability. Using laser powder bed fusion (LPBF), we have fabricated Inconel 625 sheet-based TPMS lattice structures with four distinct topologies: Primitive, IWP, Diamond, and Gyroid. The compressive responses and energy absorption capabilities of the four lattice designs were meticulously evaluated. The discrepancies between theoretical predictions and the fabricated specimens were precisely quantified using the Archimedes' principle for volume displacement. Subsequently, the LPBF-manufactured samples underwent uniaxial compression tests, which were complemented by numerical simulation for validation. The experimental results demonstrate that the IWP lattice consistently outperformed the other three configurations in terms of yield strength. Furthermore, when comparing energy absorption efficiencies, the IWP structures were confirmed to be more effective and closer to the ideal performance. An analysis of the deformation mechanisms shows that the IWP structure characteristically failed in a layer-by-layer manner, distinct from the other structures that exhibited significant shear banding. This distinct behavior was responsible for the higher yield strength (113.16 MPa), elastic modulus (735.76 MPa), and energy absorption capacity (9009.39 MJ/m3) observed in the IWP configuration. To examine the influence of porosity on structural performance, specimens with two varying porosities (70% and 80%) were selected for each of the four designs. Ultimately, the mechanical performance of Inconel 625 under compression was assessed both pre- and post-deformation to elucidate its impact on the material's integrity. [ABSTRACT FROM AUTHOR]

Copyright of Materials Science / Medziagotyra is the property of Kaunas University of Technology, represented by Prof. Rymantas Jonas Kazys and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As the construction of high-rise building becomes popular, improvement and innovation are required to expand the product line of lightweight concrete. In this paper, two ways of fabricating lightweight concrete were combined to make a new kind of super lightweight concrete. Normal aggregate is replaced with expanded polystyrene (EPS) granule, while foam is introduced to facilitate fabrication process. As a result, super lightweight concrete denoted as EPS foamed concrete is fabricated, whose bulk density is less than 500 kg/m. Compressive properties of EPS foamed concrete with bulk density 300-500 kg/m were investigated by stress-strain curve. It's demonstrated that the compressive strength ranges from 0.7 to 2.5MPa, which is higher than that of similar products. Furthermore, low elastic module and high residual to ultimate strength ratio ensure its excellent deformation and energy absorption capacity. At last, numerical analysis was performed to interpret the inherent variation of elastic modulus and failure mechanism of this material. The results show that EPS foamed concrete is a kind of super lightweight, easy to fabricate material with excellent compressive property and profound utilization potential. [ABSTRACT FROM AUTHOR]

Abstract In this paper graphene platelet (GPL)-reinforced titanium (Ti) composites (GPL/Ti) were prepared using spark plasma sintering to evaluate a new type of structural material. The microstructure, mechanical properties and high temperature compressive properties of the GPL/Ti composites were studied. It was found that GPLs are well dispersed in the Ti matrix and the introduction of GPL results in the refinement of the Ti microstructure. Although x-ray diffraction results imply no traceable reaction products are produced in GPL/Ti composites, scanning electron and element analyses indicate titanium carbide particles are found along the interface between the GPL and Ti matrix. Compressive tests show that GPL/Ti composites exhibit higher yield strength and better compressive performance than the pure Ti samples. A maximum increase of approximately 43% and 37% in yield strength and compressive strength are achieved, respectively. Raman analysis suggests the reaction between GPLs and Ti results in the reduction in the number of the layers in graphene structure. The presented work suggests that GPL/Ti might be of great potential to be used as a structural material in various engineering fields. Highlights • Graphene/Titanium (GPL/Ti) composites were fabricated using sparking plasma sintering. • GPL/Ti composites exhibit excellent compressive performance at various temperatures. • GPL, TiC and the refined microstructure contribute to the attractive properties. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) fabric composite is a newly developed sandwich structure, consisting of two identical parallel fabric decks woven integrally and mechanically together by means of vertical woven fabrics. In this paper, six types of 3D fabric sandwich composites were developed in terms of compressive and flexural properties as a function of pile height (10, 20 and 30 mm) and pile distance (16, 24 and 32 mm) in pile structures. The mechanical characteristics and the damage modes of the 3D fabric sandwich composites under compressive and flexural load conditions were investigated. Besides, the influence of pile height and pile distance on the 3D fabric sandwich composites mechanical properties was analyzed. The results showed that the compressive properties decreased with the increase of the pile height and the pile distance. Flexural properties increased with the increase of pile height, while decreased with the increase of pile distance. [ABSTRACT FROM AUTHOR]

The titanium dihydride (TiH 2 ) powder metallurgy has been attracted a lot of attention, but TiH 2 powder is difficult to press moulding. In this paper, the titanium hydride powder metallurgy including TiH 2 and unsaturated titanium hydrides (TiH 1.5 ) was investigated simultaneously compared with pure titanium metal powder metallurgy. The results indicates that the titanium hydride powder metallurgy is accompanied by the deoxidation self-purification effect during dehydrogenation process for both of TiH 2 and TiH 1.5 , which have higher sintering density than pure titanium. There are the three stages relative to densification rate, namely the slow, rapid and full densification stages for all of three materials. The compressive yield strengths increase rapidly in the rapid densification stage and are unchangeable almost in the full densification stage after holding 2 h at 1300 °C. The titanium hydride powder metallurgy is helpful to obtain much better mechanical properties than the pure titanium metal powder metallurgy. Here the compressive yield strength of the as-sintered TiH 2 compact with the maximum hydrogen content is the best but has very small difference compared with that of the as-sintered TiH 1.5 compact after full sintering densification. [ABSTRACT FROM AUTHOR]

Acid-Freezing rain is one of the most calamity weather phenomenon in Northeast China, it often occurs in early winter or late winter and early spring. In this paper, to investigate the mechanics property after the acid-freezing rain acting, different concrete grades with C15, C25 and C35 were prepared. The acid-freezing rain acting on the concrete was simulated in the laboratory conditions for 7d, 14d and 21d. With the triaxial rock mechanics testing machine, the compressive properties were investigated. The results showed that the surficial layers of the concretes were damaged under the acid-freezing rain and the compressive strength awfully decrease due to the intergranular suction losing. [ABSTRACT FROM AUTHOR]

With the increasing demand for plastic components, the development of lightweight, high strength and functionalized polypropylene (PP) from a cost-effective and environmentally friendly process is critical for resource conservation. In situ fibrillation (INF) and supercritical CO2 (scCO2) foaming technology were combined in this work to fabricate PP foams. Polyethylene terephthalate (PET) and poly(diaryloxyphosphazene)(PDPP) particles were applied to fabricate in situ fibrillated PP/PET/PDPP composite foams with enhanced mechanical properties and favorable flame-retardant performance. The existence of PET nanofibrils with a diameter of 270 nm were uniformly dispersed in PP matrix and served multiple roles by tuning melt viscoelasticity for improving microcellular foaming behavior, enhancing crystallization of PP matrix and contributing to improving the uniformity of PDPP's dispersion in INF composite. Compared to pure PP foam, PP/PET(F)/PDPP foam exhibited refined cellular structures, thus the cell size of PP/PET(F)/PDPP foam was decreased from 69 to 23 μm, and the cell density increased from 5.4 × 106 to 1.8 × 108 cells/cm3. Furthermore, PP/PET(F)/PDPP foam showed remarkable mechanical properties, including a 975% increase in compressive stress, which was attributed to the physical entangled PET nanofibrils and refined cellular structure. Moreover, the presence of PET nanofibrils also improved the intrinsic flame-retardant nature of PDPP. The synergistical effect of the PET nanofibrillar network and low loading of PDPP additives inhibited the combustion process. These gathered advantages of PP/PET(F)/PDPP foam make it promising for lightweight, strong, and fire-retardant polymeric foams. [ABSTRACT FROM AUTHOR]

The hydrogenation behavior of Ti44Al6Nb1Cr2V (at%) alloy at temperature range of 1373–1693 K and its effect on microstructure and room-temperature mechanical properties were studied systematically in this study. The results show that hydrogen content increases with the increase in temperature, and the maximum hydrogen content is 0.126 wt% at 1693 K. The heat of solution of hydrogen is calculated as 82.9 kJ·mol−1 by curve fitting, indicating that hydrogen absorption in TiAl alloys is endothermic. Hydrogen promotes the lamellar colony size because hydrogen promotes the diffusion of elements. Hydrogen stabilizes B2 phase during hydrogenation resulting in more residual B2 phase in the hydrogenated alloy. The nanohardness and elastic modulus decrease after hydrogenation due to that hydrogen weakens the bonds. The Ti44Al6Nb1Cr2V alloy exhibits higher plasticity and lower flow stress hydrogenation with 0.039 wt% H, and the ultimate compressive strength decreases from 1220 to 1130 MPa, while the fracture strain is enhanced by 26%. [ABSTRACT FROM AUTHOR]

The aim of the present research is to provide a novel technique for preparing gradient Al2O3-ZrO2 ceramic foams. This technique used epispastic polystyrene spheres to array templates and centrifugal slip casting to obtain cell struts with gradient distribution of Al2O3 and ZrO2 particles and high packing density. Aqueous Al2O3-20vol.% ZrO2 slurries with 20vol.% solid contents were prepared and the dispersion and rheological characteristics of the slurries were investigated. The settling velocity and mass segregation of Al2O3 and ZrO2 particles at different centrifugal accelerations were calculated and studied. The drying behavior, macrostructure, microstructure, compressive property and resistance to thermal shock of the sintered products were also investigated. The results show that the difference of settling velocity of Al2O3 and ZrO2 particles increases and mass segregation becomes acute with an increase in centrifugal acceleration. The cell struts prepared at a centrifugal acceleration of 1,690 g have high sintered density (99.0% TD) and continuous gradient distribution of Al2O3 and ZrO2 particles. When sintered at 1,550°C for 2 h, the cell size of gradient Al2O3-ZrO2 foam is approximately uniform, about 1.1 mm. With the porosity of gradient Al2O3-ZrO2 ceramic foams increasing from 75.3% to 83.0%, the compressive strength decreases from 4.4 to 2.4 MPa, and the ceramic foams can resist 8-11 repeated thermal shock from 1,100°C to room temperature. [ABSTRACT FROM AUTHOR]

Abstract: A space holder method in power metallurgy has been used to prepare porous coppers of low to medium porosities with good control of pore size, shape as well as distribution. The compressive properties of the porous coppers have been investigated. While the modulus is found to decrease in terms of porosity, it appears to be insensitive to powder size. The yield strength shows a linear relationship with porosity, and is found to follow a Hall–Petch relationship with powder size. The deformation mechanism of the porous metals has been studied by a displacement controlled uniaxial compression. Results show that under a quasi-static condition, porous coppers with low to medium porosities deform homogeneously throughout the material, behaving more like a solid metal rather than a foam material. This paper focuses on the experimental study of the compressive strength of the porous coppers. Details of the preparation of sample materials and the microstructure study, as well as constitutive modelling are to be presented elsewhere. [Copyright &y& Elsevier]

In this paper, biomedical porous Ti–Nb–Ta–Zr with 40% porosity and 166 ± 21 μm macro-pore size was successfully fabricated by space holder method. The microstructure, Vickers hardness, compressive and electrochemistry behavior were studied. It results that a few second phases exist in β matrix of the porous Ti–Nb–Ta–Zr. Its Young's modulus is 0.8 GPa, close to 0.01–3 GPa for trabecular bone. The total recovery strain ratio and pseudoelastic strain ratio are 8.8% and 2.7%, respectively. It fails mainly by brittle cleavage with the fan-shaped and smooth cleaved facets. Although, local ductile fracture by a few dimples and a small amount of transcrystalline fracture with the cleavage of similarly oriented laths in a colony are observed on the fracture surface. The impedance spectrum of porous Ti–Nb–Ta–Zr has the characteristics of half capacitive arc resistance, showing good corrosion resistance in SBF solution.

Aluminum foams with different silicon content have been produced by the Alporas method, where calcium and calcium carbonate are used as a thickening and foam agent, respectively. Performing quasi-static compression tests, mechanical behavior such as strain–stress diagram, deformation behavior, and energy absorption properties of the produced foams were investigated in this study. By adding silicon, calcium, and agitation of molten metal Si, SiO2, CaAl2Si2, CaAl2Si2O8 phases were created. These phases increased melt viscosity and improved foamability. The effect of physical properties, foam structure, alloy microstructure, pore size, and distribution on the mechanical behavior of metal foams was investigated in the present study. The foam with 8 wt% Si showed minimum density and maximum foamability, while it possessed a complete peak of stress. Thinner cell walls in Al–Si foams were observed, which could be attributed to the effect of silicon on melt's surface tension. Results suggested that foams with 0 and 8 wt% Si are suitable for use as an energy absorber. [ABSTRACT FROM AUTHOR]

Lattice structures are competitive to fabricate sandwich structures for their excellent mechanical properties and large internal space volume. A non-planar cross-shaped part as a regular building block has been designed and manufactured using glass fiber-reinforced thermoplastic composites. Identical cross-shaped parts can be assembled into 120-unit cell lattice structures by a mechanical interlocking method. The compressive properties of unit cell lattice structures assembled with different connections pins and sequences were investigated. Lattices with steel pins possess higher compressive modulus and strength than those with composites pins. The compressive moduli of unit cell structures are more sensitive to assembly sequence than that of multi-cell structures. When the structures change to multi-cell from unit-cell with the same assembly sequence, the compressive moduli significantly decrease. The connection between face sheets and core by the ultrasonic welding improves the compressive properties of the structures. The reversible disassembly and strong designability of lattice structures are helpful to satisfy multifunctional requirements, meanwhile realizing energy saving and emission reduction. [ABSTRACT FROM AUTHOR]

• NC porous Mg was synthesized by a combined process without using blowing agents. • The sample possesses higher porosity, more uniform pores sizes and distribution. • The energy absorption of the HD-SPSed porous Mg could reach up to 14.9 MJ/m3. Porous magnesium is a new structural and functional composite material. Its special structure gives it excellent properties and widely application prospect. In this paper, nano-crystalline porous magnesium was synthesized by a combined processing of hydrogenation-dehydrogenation (HD) and spark plasma sintering (SPS) process without using blowing agents. Compared with those samples prepared by traditional powder metallurgy (TPM) method containing blowing agents, the HD-SPSed sample possesses higher porosity (28.7%) and smaller sizes and more uniform distribution of the pores. Therefore, relatively higher compression yield strength (29 MPa) and plateau stress are acquired in the compressive stress-strain curve. Furthermore, the relatively smoother stress plateau stage of the sample reveals its great potential in the application of energy absorption materials. The energy absorption, maximum energy absorption efficiency and ideal energy absorption efficiency of the HD-SPSed porous Mg could reach up to 14.9 MJ/m3, 1.90 and 1.41, respectively. [ABSTRACT FROM AUTHOR]

In this study, glue-pressed engineered honeycomb bamboo (GPEHB) was prepared, and the dependence of the compressive properties of the produced GPEHB on the load–slenderness ratio, longitudinal strain–slenderness ratio, and ultimate strain–slenderness ratio was examined. The detailed failure modes were also investigated. The main failure modes of the short GPEHB specimens were squashing, crushing, and splitting, and the bearing capacity was mainly dependent on the compressive strength of the bamboo units. Buckling failure modes involving significant lateral deflection were observed for the long GPEHB specimens. With increasing slenderness ratio, the bearing capacities of the GPEHB specimens decreased significantly. The ultimate load of the GPEHB specimens decreased significantly as the slenderness ratio increased from 4 to 6 (GPEHB length increased from 736 to 1,104 mm). The ultimate deformation behaviors of the specimens were fit well by a quadratic function of the slenderness ratio. The GPEHB was also analyzed and modeled via finite element analysis (FEA). The experimental results, theoretical calculations, and FEA analysis results were compared. [ABSTRACT FROM AUTHOR]

Some lattice structures with different relative densities (0.15–0.5) are designed by topology optimization and fabricated by selective laser melting. The temperature history of lattice structures is monitored experimentally to reveal the forming reason of the deviation of relative densities. The effect of relative densities on compressive properties of lattice structures, including mechanical properties, failure mechanism, and energy absorption capabilities, are systematically investigated. The results show that compressive properties of lattice structures vary dramatically with the changing of relative densities. Due to the existence of surface‐shaped struts, the compressive strength of topology‐optimized lattice structures has superior performance comparing to most of the other structures with rod‐shaped struts. The failure mechanism of lattice structures can be changed from shear‐ to bending‐dominated when increasing relative densities as a result of decreasing the thickness of struts. A systematic investigation of the fracture generation of struts is conducted through both deformation analysis and the finite element method. The fitting curves are established successfully to predict the mechanical properties of designed lattice structures. The aforementioned results verify the feasibility of designing high‐performance cellular structures via topology optimization. Moreover, herein a comprehensive solution to tailor desired properties for satisfying the requirements of functional components is provided. [ABSTRACT FROM AUTHOR]

In this paper, a new type of concrete-filled Glass Fiber Reinforced Polymer (GFRP) tubular hollow composite column is tested and analyzed by finite element analysis. The axial pressure test of 27 concrete-filled GFRP tubular hollow composite columns is made to investigate the compressive properties of the specimens, including the failure mode, ultimate bearing capacity under axial compression, load-strain relationship and load-displacement relationship. The effects of the three parameters of hollow ratio, diameter-to-thickness ratio of GFRP tube and concrete strength grade on the axial compressive properties of concrete-filled GFRP tubular hollow composite columns are studied, and some key principles of designing concrete-filled GFRP tubular hollow composite columns are presented. The parameters of hollow ratio, diameter-to-thickness ratio of GFRP tube, and concrete strength grade are analyzed by using the verified finite element model. An ultimate bearing capacity adjustment coefficient is proposed, which takes into consideration the influence of hollow sections. A recommended formula is given for the axial bearing capacity of concrete-filled GFRP tubular hollow composite columns. [ABSTRACT FROM AUTHOR]

Origami-inspired metamaterials are receiving increasing attention because they can provide unusual and favorable mechanical properties that are determined by their unique patterned geometry. In this paper, a novel design based on Miura-ori pattern, with varying geometries throughout its volume, is proposed and analyzed under quasi-static compression. Both experiments and numerical simulations indicate that the new design, both two-dimensional graded (2DG) and three-dimensional graded (3DG), can generate periodically graded stiffness as well as superior energy absorption. The sensitivity of the graded behavior to various parameters of the problem is studied. It appears that both in-plane and out-of-plane graded stiffness can be accomplished with an appropriate introduction of the geometric gradients. As to the coupling effect, when the 3DG model is compressed in the z-direction, the existence of the x-directional gradient tends to reduce the stress level and specific energy absorption (SEA), whereas when compressed in the x-direction, the opposite trend is observed regarding the z-directional gradient. Comparing with the conventional design, the proposed design can achieve an increase of 129.68% in SEA in the optimal case. In general, the proposed origami metamaterial, whose behavior can be customized and programmed, shows great potential in engineering applications where a non-uniform response is needed. Unlabelled Image • Gradient design was introduced into the origami structure consisting of Miura-ori unit cells. • Compressive properties were investigated by experiments and numerical simulations. • Periodically graded stiffness and superior energy absorption were achieved three-dimensionally. [ABSTRACT FROM AUTHOR]

• Durability of GFRP connectors in alkaline solution at elevated temperatures was tested. • SEM micrographs confirmed degradation in fibre/matrix interfacial bonding after conditioning. • Ageing conditions degraded tensile and compressive properties of GFRP connectors. • A prediction model for tensile and compressive strength of GFRP connectors was proposed based on Arrhenius equation. Glass fiber-reinforced polymer (GFRP) connectors are the key components in precast concrete sandwich panels, because they not only provide continuity between two concrete wythes but also promote thermal efficiency of the panels. This paper presents an experimental study on durability of GFRP connectors in alkaline solution (simulated concrete environment) with variable parameters of temperature (40, 60, and 80 °C) and conditioning time (3.65, 18, 36.5, 92 and 183 days). A total of 160 specimens were immersed in the alkaline solution with a composition specified in ACI 440.3R-12 at elevated temperatures. Scanning electron microscope (SEM) was used to observe the degradation mechanism of the specimens, and the phenomenon of debonding between fibers and resin could be observed more obvious with the increase of erosion time and temperature. The test results also showed that, after 183 days of immersion at 60 °C, tensile strength and modulus of elasticity of the specimens decreased about 38.85% and 21.45% respectively, while compressive strength and modulus of elasticity of the specimens decreased about 40.18% and 27.62%. Finally, a prediction model of tensile and compressive strength after conditioning over time at varied temperatures was proposed based on Arrhenius equation. [ABSTRACT FROM AUTHOR]

The effects of Ti on the microstructures, macrohardness and compressive properties of the as-cast Al0.5CrFeNi2.1Mn0.8Tix HEAs were investigated. The results showed that the microstructures of as-cast Al0.5CrFeNi2.1Mn0.8Tix alloys was changed from FCC phase to a mixture of FCC and BCC phases, then to a mixture of BCC phase and Ti-containing intermetallic compound as the increasing of Ti content. Chrysanthemum-like eutectic microstructure was obtained in the Al0.5CrFeNi2.1Mn0.8Ti0.5 and Al0.5CrFeNi2.1Mn0.8Ti alloys. The area of flower core was composed of BCC2 phase, and eutectic microstructure was achieved in the petal area which contained BCC1 phase and BCC2 phase. Moreover, the macrohardness of the as-cast alloys increased with the increasing of Ti, and the Al0.5CrFeNi2.1Mn0.8Ti0.5 alloy showed excellent comprehensive compressive properties. [ABSTRACT FROM AUTHOR]

Al2O3 hollow particles were used to manufacture 7055 Al-matrix syntactic foams using a simple gravity infiltration casting method. The effects of infiltration temperature and heat treatment process on microstructures, compressive properties, and energy absorption properties of the prepared Al-matrix syntactic foams were studied. The average density and porosity of the Al-matrix syntactic foams are 1.73 g cm-3 and 40.89 %, respectively. The maximum compressive yield strength and compressive strength of the as-cast Al-matrix syntactic foams are 78.23 and 79.52 MPa, respectively. After solution-aging treatment, the compressive strength and yield strength of the Al-matrix syntactic foams are significantly improved. After normalizing, the average compressive plateau stress and energy absorption performance are the best. The highest energy absorption capacity and specific energy absorption are 48.14MJ m-3 and 28.04 kJ kg-1, respectively. This result reached or exceeded the energy absorption properties of many Al-matrix syntactic foams prepared by other processes reported in recent years. [ABSTRACT FROM AUTHOR]

An open-cell Ni-Mo-Cr foam was newly manufactured using electrostatic powder spraying process and its room-temperature compressive properties were investigated in this study. For manufacturing Ni-Mo-Cr foam, Ni-Mo-Cr powders were sprayed on the polyurethane pre-form by electrostatic powder spraying process. And then, Ni-Mo-Cr powder sprayed pre-forms were sintered at 1200°C, 1250°C, and 1300°C, respectively. The relative densities of Ni-Mo-Cr foams were measured at 4 ~ 5%. Room temperature compressive curves of ESP Ni-Mo-Cr foams represented the typical compressive 3-stages (elastic, plateau, densification) of open-cell metallic foam. As a result of observation of deformed specimen, the fracture mode found to be changed from brittle to ductile as sintering temperature increased. Based on these findings, correlations between structural characteristics, microstructure, and compressive deformation behavior were also discussed. [ABSTRACT FROM AUTHOR]

Ti44Al6Nb-based alloy ingots with different cerium (Ce) contents (0, 0.05, 0.10, 0.15, 0.20; at%) were prepared by non-consumable vacuum arc smelting furnace (WK-II). The surface quality, macrostructure, microstructure, compressive properties and fracture morphology of these ingots were studied. The results show that Ce has few influences on the surface quality. Ce can refine grain size and the average grain size decreases from 0.50 to 0.19 mm with the increase of Ce content. Meanwhile, the microstructure morphology of these ingots changes from large lamellar microstructure to dual-phase microstructure. With addition of Ce, CeO and AlCe3 are formed during melting and solidifying, which act as the core of heterogeneous nucleation and refine the grain. The compressive testing results show that Ce can improve strength and ductility. The ultimate compressive strength increases from 1156.2 to 1472.2 MPa with Ce content increasing from 0 at% to 0.20 at%. The compression ratio is improved from 10.2 % to 15.3 % with Ce content increasing from 0 at% to 0.10 at%. The refined crystalline strengthening and grain boundary strengthening are the main reasons for the improvement of compressive property. [ABSTRACT FROM AUTHOR]

The longitudinal compressive behavior of the three-dimensional four-step braided composites after cyclic hygrothermal aging was investigated using a split Hopkinson pressure bar (SHPB) apparatus under high strain rates (1100~1250 s−1, 1400~1600 s−1, 1700~1850 s−1, respectively). The SEM micrographs were examined to the damage evolution of the composites after cyclic hygrothermal aging. A high-speed camera was employed to capture the progressive damage process for the composites. The results indicate that the saturated moisture absorption of the composites was not reached during the whole 210 cyclic hygrothermal aging days. The composites mainly underwent epoxy hydrolysis and interfaces debonding during continuous cyclic hygrothermal aging time. The peak stress of the composites still behaved as a strain rate effect after different cyclic hygrothermal aging days, but the dynamic stiffness modulus clearly had no specific regularity. In addition, the peak stress and the dynamic stiffness modulus of the composites after 210 cyclic hygrothermal aging days almost decreased by half when subjected to longitudinal compression. [ABSTRACT FROM AUTHOR]

CoCu0.5FeNiVTix (x = 0, 0.5, 1, 1.5, 2) high-entropy alloys (HEAs) were prepared using vacuum arc melting. The microstructures, crystal structures, hardness, compressive properties and wear resistances of the alloys were studied. The alloys always contained face-centred cubic (FCC) and body-centred cubic (BCC) solid solution regardless of the increase in Ti content. The microstructure of alloys exhibited typical dendritic characteristics, which were more and more unapparent with the increase in the Ti content. The alloys with a high content of Ti had a high compressive strength and low ductility. Owing to the formation of nano-precipitates and BCC as the major phase, the CoCu0.5FeNiVTi1 alloy exhibited the highest compressive strength of 2747 MPa and a plastic strain limit of 7.4%. As the content of Ti was increased, the wear resistance of CoCu0.5FeNiVTix alloys displayed a rapid increase and reached the highest value when x = 1, and finally decreased. Because of the large volume fraction of BCC, the CoCu0.5FeNiVTi1 alloy exhibited high hardness so exhibiting the best wear resistance. Adhesive wear and abrasive wear dominated the wear behaviour of CoCu0.5FeNiVTix alloys during sliding against SUJ2 steel. [ABSTRACT FROM AUTHOR]

In recent years, composite bearings are increasingly employed in marine and heavy load situations due to the specific properties of composites. However, for the tape winding composite bearings, the tension in process has not been studied in depth. In this study, a device was manufactured to apply tension to the process and the prepreg tape was T300/epoxy. Specimens with different tension values were selected for the experiment and the autoclave technology was applied to the curing process. Then, the appearance image and roundness of the bearing composites were acquired. Meanwhile, physical and mechanical properties of the specimen as well as the residual stress were measured. The experimental results show that the influence of tension in winding process on bearing composites is significant and the optimum tension can be defined. Subsequently, the article analyzes the function of the tension and it is concluded that the wrinkles and waves on the surface of the T300/epoxy bearing composites can be eliminated using proper method and the optimum tension should be determined through testing and experiment. [ABSTRACT FROM AUTHOR]

Five equiatomic alloys (TiZrHfVNb, TiZrHfVTa, TiZrNbMoV, TiZrHfMoV and ZrNbMoHfV) composed of five elements with high melting temperature, respectively were prepared by arc-melting to develop a novel high temperature alloy. The five alloys exhibit different dendritic and interdendritic morphologies. The TiZrHfVNb, TiZrHfVTa and TiZrNbMoV alloys formed disordered solid solution phases with body-centered cubic structure, and exhibited high compressive strength and good plasticity. The TiZrHfMoV and ZrNbMoHfV alloys are composed with Laves phase (HfMo2) and disordered solid solution phases with body-centered cubic structure. The TiZrHfMoV and ZrNbMoHfV alloys are harder and more brittle than the other three alloys due to the existence of hard and brittle Laves phases. At high temperatures, the strength decreases to below 300 MPa for the TiZrHfVNb and TiZrHfMoV alloys. Solution strengthening is the primary strengthening mechanism of the TiZrHfVNb, TiZrHfVTa and TiZrNbMoV alloys, and brittle Laves phase is the main cause for the low ductility of the TiZrHfMoV and ZrNbMoHfV alloys. [ABSTRACT FROM AUTHOR]

In order to improve the mechanical properties of TiAl alloys, especially the ductility at room temperature, and to study the effect of boron (B) on TiAl alloys, different contents (0, 0.1, 0.3, 0.6, 0.9, 1.2, at.%) of B were added into Ti-44Al-6Nb alloys to prepare ingots. The surface quality, macrostructure, microstructure, compressive properties and fracture surface of the ingots were studied. The results show that B has little influence on the surface quality except that there are some dark spots on the surface when the content of B is 0.9%. B can refine the grains. The average grain size decrease from about 0.8 mm to 0.088 mm with increasing B content. Meanwhile, the grain morphology of these ingots changes from big equiaxed grains with lamellars to fine equiaxed grains. When the content of B is 1.2%, the primary TiB2 phase forms in the liquid phase and increases the nucleation rate, leading to further refinement of the grains. The compressive testing results show that B can increase the strength and the ductility, the compressive strength and compressibility can reach 2,037.8 MPa and 26.7% from 1,156.2 MPa and 10.2% when the boron content is 0.6%, which is resulted from grain refining and grain boundary strengthening. It is found that the compressive strength and the compressibility are relatively stable when the B content is more than 0.3%. [ABSTRACT FROM AUTHOR]