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The present study deals with the development of a harmonic structured commercially pure Ti using a novel and newly designed press-milling method to surface-deform the Ti powder particles and subsequent sintering. The harmonic structure is a bimodal distribution of fine and coarse grains where a continuous network of fine grains (shell) surrounds discrete clusters of coarse grains (core). A harmonic structured Ti featuring a shell with an average grain size of ~ 4.3 μm and a core with an average grain size of ~ 12 μm is obtained. The HCP crystal structure in the XRD patterns indicates the absence of any phase transformation due to press-milling. The hardness of the shell region improves ~ 2.5 times that of core regions. The compression studies also show an improved combination of strength and ductility in the harmonic structured Ti. [ABSTRACT FROM AUTHOR]

In this paper, the aim is to discuss the applicability of polyethylene terephthalate fiber-reinforced polymer (PET FRP) in DSTC structures. PET FRP can improve the strength and stability of structures by providing constraints for concrete. Herein, experimental and response surface analyses of the axial compressive properties of PET FRP–concrete–steel double-skin tubular stub columns (DSTCs) based on 26 DSTC specimens subjected to axial compression testing are presented. The height of each DSTC specimen is 600 mm, the outer diameter is between 305 and 315 mm, and the thickness of the added concrete is 43 mm. The main parameters are the number of layers on the PET FRP, the compressive strength of the concrete, and the thicknesses of the steel tubes. The experimental results show that the ultimate load and ultimate axial strain can be significantly increased by increasing the number of PET FRP layers, reaching 27.34% and 28.79%, respectively. When the compressive strength of the concrete increases from C30 to C40, the ultimate load and ultimate axial strain values of the DSTCs increase by 12.54% and 8.99%, respectively. In addition, as the thickness of the steel tube increases from 6 to 8 mm, the ultimate load and ultimate axial strain increase by 34.95% and 118.90%, respectively. These results indicate that the introduction of PET FRP significantly improves the overall performance of DSTCs. Increasing the number of PET FRP layers helps to limit the circumferential strain of DSTCs. P6-S8-C40 has the best ultimate load-bearing capacity and ultimate axial strain capacity, which reach 3356.18 kN and 0.1992, respectively. The main purpose of this paper is to study the influences of the PET FRP thickness (in different layers), steel tube thickness, and concrete strength on the properties, damage mode and damage process of DSTCs. [ABSTRACT FROM AUTHOR]

Ti6Al4V scaffolds were successfully fabricated using selective laser melting followed by vacuum impregnation of gentamicin loaded chitosan. Microstructural observation revealed that Ti6Al4V scaffolds display primary columnar β grains, in which a hierarchical structure of acicular α′ martensites of varying sizes was observed. Compressive tests indicated that a scaffold with 59% porosity exhibited a compressive yield strength of ~ 236 MPa and a failure strain of ~ 30.4%. The drug release behavior of the gentamicin-loaded scaffolds was characterized by an initial burst release of gentamicin lasting up to 184 h, followed by a slower, sustained release over the subsequent period up to 496 h. This research is expected to open up a new avenue for the development of gentamicin-loaded Ti6Al4V scaffolds for practical clinical applications. [ABSTRACT FROM AUTHOR]

In this study, the effects of alloy elements, oxide phases, and created intermetallic compounds of aluminum alloy foams with different percentages of silicon, zinc, and combinations of both these elements were investigated on the compressive properties and fracture behavior of these foams. The results showed that the addition of alloying elements formed intermetallic compounds in the structure of the foam, and the number of intermetallic compounds increased with increasing the percentage of these elements which causes inconsistency between these compounds and base materials. All these factors changed the failure mechanism of these foams so that the failure behavior of pure aluminum foam and zinc-containing foams was a ductile failure, whereas the failure behaviors of silicon-containing foam samples were brittle. The Al–4%Si–4%Zn sample had the highest compressive strength among all of the fabricated samples due to the uniformly distributed intermetallic compounds in the cell wall of these samples, whereas the Al–8%Si, Al–8%Si–4%Zn, and Al–8%Si–8%Zn foam samples were more brittle than the other fabricated foam samples due to the more formation of brittle compounds such as CaAl2Si2 and their accumulation in a certain area which reduced the compressive strength of these foams. Also, it was observed that the energy absorption capacity and yield strength of pure aluminum foam generally increased with the addition of alloy elements due to the increase in the amount of created intermetallic compounds in the structure of these foams. [ABSTRACT FROM AUTHOR]

Similar atom substitution in 3d transition metal high entropy alloys (HEAs) were employed via Cr, Fe, and Cu equimolarly incorporated into CoNiTiV-base alloy, by which its effects on phase components, microstructures, and mechanical properties were intensively investigated. Results show that phase components of CoNiTiVCr and CoNiTiVFe alloys belong to a single-phase BCC solid solution. In addition to the BCC phase, FCC phase emerges into the CoNiTiVCu alloy as well, which has been confirmed being Cu-rich phase, implying that it might be originated form the ease of Cu segregation. In the mechanical view, the alloys with single-BCC phases are obviously stronger than the multiphase alloy. The yield strengths of CoNiTiVCr, CoNiTiVFe, and CoNiTiVCu HEAs are 1764, 2730, and 1674 MPa, respectively. Furthermore, the CoNiTiVFe alloy also possesses the most promising plasticity of ε ≈ 6.8% due to its relatively uniform composition distribution. As comparison, the Ni-rich dendritic and Cu-rich intergranular phase in the Cr- and Cu-containing HEAs, respectively, take the responsibility for their extremely low plasticity. [ABSTRACT FROM AUTHOR]

In the present work, Fe-Mn-Al-C powder mixtures were manufactured by elemental powders with different ball milling time, and the porous high-Mn and high-Al steel was fabricated by powder sintering. The results indicated that the powder size significantly decreased, and the morphology of the Fe powder tended to be increasingly flat as the milling time increased. However, the prolonged milling duration had limited impact on the phase transition of the powder mixture. The main phases of all the samples sintered at 640°C were α-Fe, α-Mn and Al, and a small amount of Fe2Al5 and Al8Mn5. When the sintering temperature increased to 1200°C, the phase composition was mainly comprised of γ-Fe and α-Fe. The weight loss fraction of the sintered sample decreased with milling time, i.e., 8.3wt% after 20 h milling compared to 15.3wt% for 10 h. The Mn depletion region (MDR) for the 10, 15, and 20 h milled samples was about 780, 600, and 370 µm, respectively. The total porosity of samples sintered at 640°C decreased from ∼46.6vol% for the 10 h milled powder to ∼44.2vol% for 20 h milled powder. After sintering at 1200°C, the total porosity of sintered samples prepared by 10 and 20 h milled powder was ∼58.3vol% and ∼51.3vol%, respectively. The compressive strength and ductility of the 1200°C sintered porous steel increased as the milling time increased. [ABSTRACT FROM AUTHOR]

The compressive mechanical properties, failure modes and foam filler strengthening mechanism and effect of a short basalt fiber-reinforced epoxy resin composite grid beetle elytron plate with a polyvinyl chloride (PVC) foam-filled core (GBEPfc) are investigated via compression experiments and the finite element method. The results are compared with those of a grid plate (GPfc) with the same wall thickness as the GBEPfc. Additionally, a fully integrated preparation method and process are developed for the GBEPfc, with a material composition that is close to the structure and composition of the organism. Increases of more than 20% in the specific compressive strength and specific energy absorption of the GBEPfc relative to the GPfc are ascertained. The foam provides a constraining force for the fiber composite structure; consequently, the trabeculae and honeycomb walls of the core transition from a lower-order deformation that easily occurs to a higher-order deformation that occurs less readily. The interaction between the core composite structure and PVC foam is described. The GBEPfc developed in this paper is simple in structure and easy to prepare, and the material composition is close to biological prototypes and materials used in practical engineerings, which lays a foundation for the application of beetle elytron plates. [ABSTRACT FROM AUTHOR]

Using polyurethane foams integrated with phase change materials (PCMs) that take cooperative advantages of heat insulation and heat storage capacity can meet the demand for thermal comfort and energy conservation purpose in the buildings. One-shot synthesis method, a cost-effective method, was used in this study for fabrication of PU-PCM composite foams. It is ascertained that thermal regulation capacity of composite foams is facilely tunable as latent heat storage properties of composite foams containing 10–20 wt.% n-octadecane as PCM ranged from 17.72 J.g−1 to 34.51 J.g−1. Inclusion of PCM resulted in increasing the cell size of composite foams accompanied with reduced closed-cell content compared with those of pristine PU foam. However, as the PCM fraction increased, the cell size of composite foams tended to decrease. Given the fact that the geometry of foam cells determines specific compressive properties, specific compressive strength and modulus of PU foam dropped from 3.89 ± 0.20 kPa.m3.kg−1 and 77.48 ± 5.72 kPa.m3.kg−1 to 2.67 ± 0.43 kPa.m3.kg−1 and 46.05 ± 9.86 kPa.m3.kg−1, respectively after incorporation of 10 wt.% n-octadecane. However, as the foam cell size reduced by increasing the PCM content, specific compressive strength and modulus were improved and reached 3.44 ± 0.30 kPa.m3.kg−1 and 65.50 ± 1.16 kPa.m3.kg−1, respectively for composite foam containing 20 wt.% n-octadecane which are comparable to those of PU foam. Additionally, the PCM leakage from this composite foam was less than others. This study suggests that by adjusting the PCM content, one-shot synthesized PU-PCM composite foams can provide not only reasonable thermal regulation properties and appropriate thermal reliability but also sufficient mechanical properties. [ABSTRACT FROM AUTHOR]

A set of novel Co-free high-entropy alloys CrxFeNi(3-x)Al (x = 0.25, 0.5, 0.75, 1, 1.25, 1.5) were fabricated by non-self-consumable vacuum melting method, and their solidification microstructures as well as compression properties were investigated. The research results firstly demonstrate that the solidification microstructures of Cr-0.25, Cr-0.5 and Cr-0.75 are composed of primary B2 phase and (FCC + B2) eutectic structure; Secondly, there are primary B2 phase and (FCC + B2) eutectic structure in the solidification microstructure of Cr-1, with a tiny amount of BCC phase distributing on the matrix of primary phase B2; In addition, as a "sunflower-like" structure of BCC phase and B2 phase, the solidification microstructure of Cr-1.25 is identified. Also, the core of the sunflower is B2 phase, and the petals are alternately arranged by BCC phase and B2 phase; Last but not least, it is a fine BCC phase and B2 dual-phase structure that form the solidification microstructure of Cr-1.5. Among the phases mentioned above, the FCC phase is abundant in Ni and Fe elements, the B2 phase is abundant in Ni and Al elements, and the BCC phase is abundant in Cr element. With the ascending trend of Cr content, the strength of CrxFeNi(3-x)Al high-entropy alloy descends initially and then climbs, during which the primary reasons for the rise of strength are solid solution strengthening, fine crystal strengthening and precipitation of BCC phase. The compressive strengths of Cr-1.25 and Cr-1.5 alloys are 2111.5 and 1985.3 MPa, respectively, and the compressibility can attain to 41.36 and 49.87%, respectively, manifesting comprehensive mechanical properties. [ABSTRACT FROM AUTHOR]

The correlation between the internal calice arrangement and compressive behavior of the skeleton of coral Pocillopora verrucosa has been characterized. The internal calices of this skeleton are arranged radially from a central axis in each branch. Such an arrangement of the calices results in a gradient distribution of the compressive properties; the middle part provides a higher strength, and the marginal part of the coral branch can undergo larger deformation to a certain extent. That is to say, the coral skeleton can offer a stronger internal support and a tougher external layer. Thus, the coral skeleton, as a natural porous and mineral material, can effectively undergo the ocean currents and provides a sturdy framework to protect the living polyps. [ABSTRACT FROM AUTHOR]

In this work, the influences of adding different amounts of molybdenum (0, 0.5, 1, 2, and 4 wt%) on the microstructure and mechanical properties of highly porous steels fabricated using powder metallurgical water-leachable space holder technique were studied. The microstructure of cell walls and morphologies of cells and micro-pores were evaluated using an optical microscope and scanning electron microscope equipped with X-ray energy dispersive spectroscopy. To evaluate the mechanical properties, compression tests were conducted on the highly porous steel specimens. The results demonstrated that about 90 wt% of urea granules are discontinuously removed during the multi-stage leaching process. The relative density of the highly porous steels was measured between the range of 0.18 and 0.22 and it increased by adding the molybdenum content. Ferrite, fine pearlite, and distributed molybdenum islands formed the microstructure of cell walls. The stress–strain curves contained linear elastic region, long saw-toothed plateau region, and fracture point. By changing the amounts of molybdenum from 0 to 4 wt%, mean modulus of elasticity, plateau stress, and density of energy absorption showed 0.75, 7.32, and 6.75 times improvement, respectively. Also, yield strength and failure strain revealed up–down behavior. [ABSTRACT FROM AUTHOR]

The Ti2AlN-reinforced TiAl (WMS) composites with different contents of Ti2AlN were prepared by an in situ method of reactive arc-melting technique. According to the results of X-ray diffraction (XRD) analysis, the Ti2AlN-reinforced WMS composites consist of γ-TiAl, α2-Ti3Al, and Ti2AlN phases. Microstructure analysis results indicate that Ti2AlN reinforcements with rod-like in shape form in the WMS matrix with a α2/γ lamellar structure containing some bulk γ phases. With volume fraction of Ti2AlN increasing, the grain size of the composites decreases significantly and the elasticity modulus (E) increases. The compressive strength and compressive fracture strain of the composite with 3 vol% Ti2AlN have a maximum value of 1,654 MPa and 22.5 %, respectively, which are approximately improved by 45.84 % and 29.31 %, respectively, compared with that of the unreinforced WMS alloy. [ABSTRACT FROM AUTHOR]

Structural collapse caused by uneven stress distribution is one of the main failure modes of Electron Beam Melted (EBM) Ti–6Al–4V porous meshes for medical bone implantation. In this paper, two types of porous meshes with different struts distributions are fabricated by EBM methods and experimentally studied through uniaxial compression tests. The first type (mesh 1) with simplified struts distribution consists of horizontal, vertical and diagonal struts, which are connected by one node. The second type (mesh 2) has relatively complicated struts distribution with four structural nodes connected by vertical, horizontal and diagonal struts, and the inclined struts with an angle of 15° to the vertical or horizontal direction. The mechanical properties of solid Ti–6Al–4V alloy are also tested as reference for model-fitting analysis and the test results show that the EBM specimen can achieve comparable tensile strength (1186.5 MPa) and elastic modulus (106.4 GPa) as that of forging specimen. For the porous meshes, the deformation behavior of the struts along the load orientation is dominated by buckling mechanism and the deformation behavior of the struts inclined to the load orientation is governed by both buckling and bending mechanisms. The test results indicate that mesh 1 with relatively less inclined struts can achieve better compressive resistance than mesh 2 when taking the factor of mesh density into consideration. Such results indicate a simple yet meaningful view that struts distributions of the porous meshes should be designed and optimized based on their stress distribution conditions. [ABSTRACT FROM AUTHOR]

Density reduction has become a topical issue in wood composite materials for application in building and furniture. In this study, lightweight wood–polyurethane (W–PU) composite foams with the addition of 30 wt% wood particles were prepared. Industrial kraft lignin was used as bio-polyol to substitute partial petroleum-based diethylene glycol (DEG) to synthesize rigid W–PU foams. The effect of varying lignin contents (5, 10, 15 and 20 wt% based on DEG mass) on the reactivity, morphology, density, compressive properties, water absorption and thermal stability of the foams was evaluated. Fourier transform infrared (FTIR) analysis confirmed the formation of characteristic urethane linkages in all the foam samples. With the incorporation of lignin, the foam cellular shape became irregular with formation of large cells. W–PU foams exhibited poor cellular structures with a larger number of open cells. The density of W–PU foams increased from 47 to 96 kg/m3 as the lignin content increased from 0 to 20%. Although the foam reactivity was decreased by the incorporation of lignin, both the compressive strength and modulus were increased upon the incorporation of lignin. Furthermore, the specific compressive strength and modulus of W–PU foams increased by 55% and 48% with lignin content increasing from 0 to 20%, and the 20-day water absorption decreased by 38%. Thermal gravimetric analysis showed that the incorporation of lignin did not significantly affect the thermal degradation behaviour of foam, but it rather increased the mass of char residue. This study provides a promising method for value-added utilization of technical lignin in W–PU lightweight composites. [ABSTRACT FROM AUTHOR]

The microstructures, compression and corrosion behaviors of the as-cast AlxCrFeMn0.8Ni2.1 high-entropy alloys (0 ≤ x ≤ 2.3) were investigated in this paper. It was found that the crystal structure changed from initial dual FCC structure to mixed FCC and BCC structure, then to BCC structure as the increasing of Al content. Al0.8CrFeMn0.8Ni2.1 alloy exhibited a typical spinodal structure consisting of alternating two phases microstructure. Moreover, sunflower-like microstructure was obtained in the as-cast AlxCrFeMn0.8Ni2.1 alloys (1.0 ≤ x ≤ 2.0). With the increasing of Al, the macrohardness increased while the plasticity decreased in the alloys. The addition of an appropriate amount of Al could improve the compressive fracture strength of the alloys. In addition, the corrosion resistance deteriorated slightly with the increasing of Al in 1 mol/L NaCl solution. [ABSTRACT FROM AUTHOR]

This study aims at assessing the effect of a narrow infill density gap on the compressive properties of 3D printed commercial carbon fibre reinforced ABS. Compressive specimens, with infill densities of 70, 80, 90 and 100 % were 3D printed via an FDM 3D printer and evaluated. The differences in compressive properties at infill densities of 80 and 90 % were statistically not significant although a strong correlation was quantified between the infill density and the compressive properties. This finding can be further employed to determine an appropriate infill density for targeted mechanical properties at a low material consumption for specific applications. [ABSTRACT FROM AUTHOR]

Quasi-static uniaxial compressive experiments were conducted on aluminum foams with a wide range of relative densities (0.134-0.472). The compressive properties and energy absorption capacity were systematically characterized and compared in a more suitable way. The compressive stress instead of compressive strain achieved during energy absorption process was taken into consideration. The results show that aluminum foam is not a kind of energy absorption materials with a stationary plateau region at the plastic deformation stage. There exists a strain hardening phenomenon which makes the stress-strain curve incline at this stage. For every aluminum foam with certain relative density, there exists an optimal stress. Under its optimal stress condition, the foam can absorb the maximum energy compared to foams with whatever different relative densities. The optimal stress and corresponding maximum energy absorption capacity increase with the increase in the foam’s relative density. [ABSTRACT FROM AUTHOR]

The uniaxial compressive tests at different temperatures (223-298 K) and strain rates (0.40-63s−1) are reported to study the properties of hydroxyl-terminated polybutadiene (HTPB) propellant at intermediate strain rates, using a new INSTRON testing machine. The experimental results indicate that the compressive properties (mechanical properties and damage) of HTPB propellant are remarkably affected by temperature and strain rate and display significant nonlinear material behaviors at large strains under all the test conditions. Continuously decreasing temperature and increasing strain rate, the characteristics of stress-strain curves and damage for HTPB propellant are more complex and are significantly different from that at room temperature or at lower strain rates. A new constitutive model was developed to describe the compressive behaviors of HTPB propellant at room temperature and intermediate strain rates by simply coupling the effect of strain rate into the conventional hyperelastic model. Based on the compressive behaviors of HTPB propellant and the nonlinear viscoelastic constitutive theories, a new thermovisco-hyperelastic constitutive model with damage was proposed to predict the stress responses of the propellant at low temperatures and intermediate strain rates. In this new model, the damage is related to the viscoelastic properties of the propellant. Meanwhile, the effect of temperature on the hyperelastic properties, viscoelastic properties and damage are all considered by the macroscopical method. The constitutive parameters in the proposed constitutive models were identified by the genetic algorithm (GA)-based optimization method. By comparing the predicted and experimental results, it can be found that the developed constitutive models can correctly describe the uniaxial compressive behaviors of HTPB propellant at intermediate strain rates and different temperatures. [ABSTRACT FROM AUTHOR]

The in situ nano-TiC x /Al–Zn–Mg–Cu composites with different TiC x content (20, 25 and 30 vol.%) were successfully fabricated by combustion synthesis and hot press consolidation in Al–Ti–C/CNTs systems. The compressive properties and abrasive wear resistance of the composites improved with the increase in the TiC x content. The transformation of carbon source from pure C black to the mixture of C black and CNTs to pure CNTs in Al–Ti–C/CNTs systems leaded to a significant improvement in the compressive properties and wear resistance of the composites as well as a significant decrease in the average size of TiC x particles. The average size of the nano-TiC x particles in 30 vol.% TiC x /Al–Zn–Mg–Cu composite synthesized by the carbon source of CNTs reached 81 nm, moreover, the yield strength ( σ 0.2 ), the ultimate compression strength ( σ UCS ) and the fracture strain ( ɛ f ) of the composite reached 597 MPa, 882 MPa and 21.7%, respectively. [ABSTRACT FROM AUTHOR]

The effects of tungsten addition on the microstructure and mechanical properties of near-eutectic AlCoCrFeNi high-entropy alloy were investigated in this paper. The AlCoCrFeNiW alloys comprised the primary BCC phase plus eutectic FCC/BCC phases. It was found that W element can both promote the formation of the primary BCC phase and act as a solid solution strengthening element. The hardness of the AlCoCrFeNiW alloys increased from HV 293 to HV 356.2 with the increase in W content. The addition of W element improved the strength of alloys but reduced ductility. Thereinto, the AlCoCrFeNiW alloy showed the most excellent compressive properties with the fracture strength of 2785.9 MPa and the plastic strain of 0.42, respectively, which implied the potential industrial application values. [ABSTRACT FROM AUTHOR]

Multi-walled carbon nanotubes (MWCNTs) were mixed with Unsaturated polyester resin (UPR) using the stir method at high temperatures. The mixing temperature and hardener ratio were optimized based on compression properties and the exothermic temperature. In the experiment, 60 °C and 1 wt.% of Methyl ethyl ketone peroxide (MEKP) were chosen for the mixing condition and catalyst concentration, respectively. MWCNTs with different weight fractions (0.05, 0.1, 0.2 and 0.3 wt.%) were dispersed to investigate the effect of MWCNTs on tensile properties of the UPR, and it was found that 0.1 wt.% of MWCNTs showed the best performance in this range of fiber weight fraction due to a higher strength (42.14 %), modulus (14.33 %) and fracture strain (37.17 %) than pure UPR. The state of dispersion and arrangement of fibers were examined by a Field emission Scanning electron microscope (FE-SEM) according to fracture surfaces. Similarly, the FE-SEM also showed better results with 0.1 wt.% of MWCNTs mixed in the UPR. [ABSTRACT FROM AUTHOR]

The paper designs and prepares warp-knitted spacer fabric and tests its properties based on the three-dimensional warp-knitted spacer structure. Polysulfonamide (PSA) yarn is selected for the surface layers and polyvinylidene fluoride (PVDF) filament for the spacer structure. Six kinds of samples are designed and the compressive properties are tested. It analyses and compares the diagrams of sample's stress and strain and the relevant parameters to get the factors influencing the compressive properties of the fabric. The results show that with the increase of the compaction of the surface structure, the spacer monofilament can be more stable and the fabric can support heavier load. Therefore, the compressive properties are better. And the compressive properties can also get better as the thickness increases. [ABSTRACT FROM AUTHOR]

Aiming to solve the problem of spontaneous combustion on titanium via electrospark deposition (ESD), two AlCoCuFe-based high-entropy alloys (HEAs), AlCoCuFe- x ( x = CrSiTi, NiSi), were produced by vacuum arc melting as electrodes in ESD process. The thermodynamic analysis of AlCoCuFe-based HEAs were carried out using the concept of mixing enthalpy matrix and a powerful thermodynamic calculation toolbox (HEA-Thermo-Calcu). The microstructure and mechanical properties of the two alloys were investigated. The AlCoCuFeCrSiTi alloy contains a body-centered cubic (BCC) phase and a face-centered cubic (FCC) phase. The AlCoCuFeNiSi alloy is composed of two BCC phases and an FCC phase. Addition of CrSiTi and NiSi to AlCoCuFe-based alloys makes the enthalpy of mixing to be sizably more negative than for the other AlCoCuFe-based HEAs. Notwithstanding the fact that the thermodynamic parameters do not agree with Yang's proposition, the two alloys form simple solid solutions. The electronegativity difference (Δ χ) favors a formation of the solid solution when Δχ ≤ 14.2. The hardness of AlCoCuFe- x ( x = CrSiTi, NiSi) alloys reaches 935 HV and 688 HV, respectively. The yield strength, fracture strength, and ultimate strain of AlCoCuFeNiSi are larger, i.e., 29, 30, and 45%, respectively, than those of the AlCoCuFeCrSiTi alloy. [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]

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]

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]

Lasers have many favorable features as a light source owing to their monochromaticity and coherence. This study examined the mechanical properties of composite resins that were light-cured using a diode-pumped solid state (DPSS) laser. Eight composite resins were light-cured using four different light sources (one quartz-tungsten-halogen (QTH), two light-emitting diodes (LEDs), and one DPSS laser with a wavelength of 473 nm). The light intensity of the DPSS laser and remaining light-curing units were approximately 500 and 900 mW/cm, respectively. The microhardness, flexural properties, and compressive properties were evaluated using the Vickers hardness test, three-point bending test, and compression test, respectively. In most cases, the microhardness, flexural properties, and compressive properties of the specimens light-cured using the DPSS laser were similar to those obtained using the other light-curing units. Within the limits of the study, the microhardness, flexural modulus, and compressive strength were linearly correlated with the filler content (in weight percent). The flexural modulus and compressive modulus were also linearly correlated with the microhardness. Even with a much lower light intensity, the DPSS laser with a wavelength of 473 nm can polymerize composite resins and give comparable mechanical properties to those obtained using the other light-curing units. [ABSTRACT FROM AUTHOR]

On the basis of previous studies, the structural model of 3-D hollow integrated sandwich composites for the compressive analysis was built by using the finite element software ANSYS. In the paper, the influence of pile height (6, 8 and 10 mm), pile density (4, 6 and 8 mm), elastic modulus (36, 38 and 40 GPa) and poisson ratio (0.30, 0.35 and 0.40) of the 3-D composites on the compressive properties were studied, and the effects of these factors were analyzed and discussed. The results revealed that the maximum value of the stress appeared in the interface between the piles and the face-sheets when the 3-D composites were subject to compressive loads, in which the composites damaged easily. The compressive properties of the 3-D composites increased with the increase of the pile density and poisson ratio, and decreased with that of the pile height. Elastic modulus has little influence on the compressive properties of the 3-D composites. The study provides a reference for the structural optimum of the 3-D composites. [ABSTRACT FROM AUTHOR]

The Tersoff-potential based MD (molecular dynamics) method was used to simulate the radial compression of one (10,0) BN nanotube, and its compressive properties was compared with those of one (10,0) carbon nanotube. The semi-empirical PM3 QC (Quantum chemistry) method was adopted to calculate the electronic structures of the compressed BN-tube, and the effect of the radial compression on the electronic structures of the BN-tube was discussed. It is shown that (i) BN-tube has comparable radial compressive stiffness to carbontube, but lower energy-absorbing, load-support and deformation-support capabilities, and (ii) with the increase of compressive strain, the HOMO energy of the BN-tube increases, the LUMO energy and the LUMO-HOMO energy-gap decrease, and its chemical activity and conductance increase. [ABSTRACT FROM AUTHOR]

The foamed aluminum alloys with different densities were fabricated by melt foaming technique. The compressive properties and energy absorption of the foamed aluminum alloy with different densities were analyzed. The results reveal that the compressive stress-strain curves follow the typical behavior of cellular foams with three deformation stages. Under the same strain, the energy absorption capability decreases with the decrease of density. However, with increasing the strain, the energy absorption efficiency of foamed metal increases initially and then decreases. The lower the density, the longer the plateau region, within the range of high strain, the energy absorption efficiency is always high. [ABSTRACT FROM AUTHOR]