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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]

Epoxy composites were prepared by doping nano Zirconia Toughened Alumina (ZTA) which were synthesized by solution combustion method into epoxy resin and hardener. Initially ZTA nanopowder was characterized to check its purity, morphology and to confirm its metal-oxide bonding using XRD, SEM and FTIR respectively. The thermal properties such as TGA and DTG were also analysed. The polymer composites were obtained by uniformly dispersing ZTA nanopowder into epoxy using an ultrasonicator. Polymer composites of various concentrations viz, 0.5, 1, 1.5, 2 and 2.5 wt% were synthesized, all concentrations were prepared on weight basis. All the polymer composites were tested for compression properties, flexural properties and tensile properties. Best results for all the mechanical properties were obtained for epoxy with 1.5 wt% ZTA composites. Electrical properties such as breakdown voltage and breakdown strength were analysed and outstanding results were observed for epoxy with 2.5 wt% ZTA composite. [ABSTRACT FROM AUTHOR]

This paper presents an experimental investigation about the effect of elevated temperature on the mechanical properties of two polyurethane (PUR) foams, with densities of 40 kg/m3 and 93 kg/m3. The experimental campaign included shear and compressive tests over a temperature range of 20°C–200°C, performed to assess the degradation of the mechanical properties of the PUR foams with temperature. To validate the diagonal tension shear test method adopted in this investigation, a numerical study was also performed, namely to assess the (shear) stress state developed within the foam. The results obtained validated the adopted test procedures, showing that the compressive and shear responses are strongly affected by elevated temperature, due to the softening of the polymeric material when it undergoes the glass transition process. For the temperature range considered in this study, both strength and modulus in shear and compression present an approximately linear reduction with temperature. [ABSTRACT FROM AUTHOR]

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

Electron beam melted (EBM) Ti-6Al-4V functionally graded materials (FGM) with continuously graded densities are investigated for dimensional accuracy, compressive properties, fractography and build direction effect in comparison to uniform density counterparts of the same volume. It is found that FGMs exhibit progressive layer-by-layer deformation mode regardless of unit cell designs and build direction. This deformation behavior is highly favourable for uni-directional impact absorption applications compared to uniform density counterparts with random or diagonal failure. Overall, the EBM-built FGM exhibits superior energy absorption than counterparts of uniform density. Significant improvement in the quasi-elastic gradient and energy absorption is obtained by changing the build direction for specific designs. Compared with other FGM or uniform density lattice structures from the literature, the energy absorption of lattice structures with lower relative density could outperform those with higher relative density by changing the unit cell design or density profile.

The effect of aluminum (0, 2, 4, and 6 wt. %) and copper (0, 2, 4, and 6 wt. %) on graphite morphology, microstructure and compressive behavior of ductile iron specimens manufactured by sand casting technique were investigated. The graphite morphology and microstructure were evaluated using optical microscopy (OM) and scanning electron microscopy (SEM) equipped image processing software. To study the mechanical properties, the compression test was conducted on the ductile iron specimens. The results indicated that the surface fraction and nodule count of graphite decreased when the amount of aluminum increased from 0 to 2 wt. % and after that from 2 to 6 wt. %. In addition, the nodularity of graphite increased with the increment of the aluminum amounts. By adding the amount of copper, the surface fraction and nodule count of graphite increased and nodularity of graphite decreased. The addition of aluminum and copper decreased the surface fraction of ferrite and increased the surface fraction of pearlite in the microstructure. By increasing the amounts of aluminum and copper, compressive stress vs. strain curves were shifted upwards, and modulus of elasticity, yield strength, maximum compressive stress, and fracture strain improved. In comparison with copper, aluminum had a greater influence on the mechanical properties of ductile iron.

Composite structures have drawn growing attention for their outstanding characteristics benefiting from the combination of multi materials. This paper aims to investigate the crushing performance of a hybrid system involving an outer thin-walled tube made of carbon fibre-reinforced plastic (CFRP), a medial polyurethane (PU) foam and an inner thin-walled tube made of aluminium alloy (Al). The elastoplastic model of Al, the continuous damage model of CFRP and the compressible foam model of PU were established with assistance of universal material tests. The finite element model of the composite structure, namely CFRP-PU-Al, was validated by the experimental study. Based upon the reliable numerical modelling, the parametric study was carried out for exploring the effects of the wall thickness, diameter and ply orientation of the outer CFRP tube, namely CFRP-O, on the crushing behaviours of the composite structure. It was found that increasing the diameter or wall thickness of CFRP-O was helpful to increase the mean crushing force and energy absorption of CFRP-PU-Al, however, the overall specific energy absorption of the composite sandwich structure was limited by the characteristics of constitutive materials. Compared with the diameter, the wall thickness had a higher impact on the energy absorption characteristics, and increasing the diameter may decrease the specific energy absorption due to the increase of the overall structural mass. In terms of the ply orientation, the composite structure with stacking sequence of [0°/45°]3 possessed higher mean crushing force and energy absorption than the structure with stacking sequence of [0°/90°]3 under axial compression in this study.

To develop lightweight and biomimetic structural materials, in this paper, the compressive deformation and mechanical properties of the grid beetle elytron plate (GBEP) with the same core volume as the end-trabecular beetle elytron plate (EBEP) under compression were investigated for the first time. (1) The B-type deformation mode of trabeculae is clarified, which is a higher stage of independent deformation than the Φ-type deformation mode in the beetle elytron plate (BEP). Additionally, the four deformation modes of the BEP are divided into three stages in succession from easy to difficult: C-type, Φ-type and S (B)-type deformation. This paper verifies that the compressive strength and energy absorption capacity of the GBEP increase by 35% and 87%, respectively, relative to those of the grid plate (GP) with the same volume. (2) Although the number of trabeculae of the GBEP is significantly less than that of the EBEP, each trabecula in the GBEP has one more honeycomb wall constraint than each trabecula in the EBEP. The increase range of the compressive properties of the GBEP relative to the GP is greater than that of the EBEP relative to the honeycomb plate (HP). This confirms the prediction that the compressive properties can be effectively improved by appropriately increasing the constraints on the trabeculae. This paper deepens and enriches the knowledge regarding the biomimetic application system of BEPs, lays the foundation for GBEPs, whose preparation is convenient, and accelerates the applications of GBEPs. [ABSTRACT FROM AUTHOR]

This paper first reviews the research progress of carbon fiber-reinforced sandwich plates with grid cores, truss cores, and foam cores, and the results can be summarized in the following four points. 1) The load-bearing capacity and energy absorption capacity of grid-core and foam-core structures under bending loads have been improved by toughening with short fibers and Z-pinned fibers. 2) The progressive buckling mode of the core layer under compressive loading can significantly improve the energy absorption capacity of a sandwich structure. 3) The compressive failure of a truss-core sandwich structure is closely related to the strength at the nodes. 4) Following a literature review, this paper discusses the existing problems in sandwich structures and the corresponding countermeasures, and the results can be summarized in the following two points. 1) After implementing the current toughening measures, the debonding is improved to a certain extent; however, this approach does not prevent debonding. 2) No method has been presented that can increase the strength of the end nodes in truss-core members. Therefore, it is encouraging that a trabeculae/honeycomb-core sandwich structure composed of fiber-reinforced proteins—mimicking the biological structure found in a beetle forewing—can effectively solve the abovementioned problems. [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]

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

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]

With the increasing awareness of environmental protection, Green Velvet Material (PLON), a renewable and environmentally friendly material, has been widely applied to mattresses. In order to improve the compressive properties of PLON, a series of experiments were carried out with special attention given to the compression deformation characteristics, support performance of the PLON blocks and its effective application in mattress products. The results are: (1) Average slopes of the load-deformation curves' two phases are represented by K1 and K2, respectively. K1 is more sensitive to density changes that range from 30 kg/m3 to 50 kg/m3, while K2 is sensitive to density changes that range from 20 kg/m3 to 50 kg/m3. Their values increase with the rise of density; (2) 25% IFD, 40% IFD, 65% IFD, SF and IHF values are sensitive to density changes and they significantly increase with the rise of density. PLON blocks have excellent supporting properties and are considered to be comfortable according to American FPF Test Standard (ASTM-D3574-B1) when used in mattress bedding; (3) a PLON block density of 30 kg/m3 is preferentially selected for the softer type of mattress, while a PLON block density of 40 kg/m3 is preferentially selected for the harder type of mattress. The compression deformation characteristics and support performance of the PLON blocks were analyzed and the effective application of PLON in mattress products was explored through the above research. [ABSTRACT FROM AUTHOR]

This study investigates the performance of the acrylonitrile-butadiene-styrene (ABS) P400 part, manufactured using fused deposition modeling (FDM), under compressive loading. Effect of varying levels of three FDM process parameters, i.e., raster angle (A), air gap (B), and raster width (C) on three responses, namely compressive stress (C S), percentage deformation (% D), and breaking stress (B S) of the fabricated parts is studied. Experimental results are analysed using analysis of variance (ANOVA), response graphs, and 3D surface plots. Investigations established the anisotropic nature of the ABSP400 part, which causes lower strength of the fabricated parts. Chosen process parameters significantly affect the compressive properties. A complex relationship exists between process parameters and the studied responses. It is also observed that B S is much lower than C S and % D varies in a contradictory fashion with changes in process parameters. Predictive models for the responses are developed and validated through additivity tests. To discover the best combination of FDM process parameters for optimum responses, multi-objective optimization utilizing the desirability function approach is used. Multi-objective optimization results are validated using the confirmatory test. The novelty of the present work is that it explores the effect of three critical parameters of the FDM process not only on compressive stress (C S) but also on other critical compressive properties such as percentage deformation (% D) and breaking stress (B S) of the ABS P400 fabricated parts. [ABSTRACT FROM AUTHOR]

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Two types of composites, consisting of pure magnesium matrix reinforced with two commercially used carbon fibers, were systematically studied in this paper. The composites fabricated by the pressure infiltration method, were subjected to quasistatic and dynamic compression tests. Morphology of fiber strands was observed using scanning electron microscope (SEM). The application of carbon fibre reinforcement led to the stiffening of tested materials, resulting in the limitation of the possible compression to approx. 2.5%. The performed tests revealed the remarkable difference in compression strength of investigated compositions. The cause of that effect was that GRANOC fiber reinforced composite exhibited insufficient bond quality between the brittle fibers and the ductile matrix. T300 reinforced composite presented good connection between reinforcement and matrix resulting in increased mechanical properties. Investigated composites demonstrated higher mechanical strength during deformation at high strain rates. Microscopic observations also proved that the latter fibers with regular shape and dense packaging within the filaments are proper reinforcement when designing the lightweight composite material.

Magnesium-based materials are the most sought-after metallic materials for weight saving applications. Its low density (∼33% lighter than aluminum) makes it an ideal choice for aerospace, space, sports, automobile and electronic industries. Magnesium based components can be even lighter if these components are manufactured hollow. However, studies on the structural integrity of hollow magnesium-based components are limited and hence, this study documents the structural stability of hollow magnesium-based components. Centralized cylindrical holes (1, 1.5, 2 and 3 mm in diameter) were drilled in 8 mm diameter magnesium samples synthesized by disintegrated melt deposition followed by hot extrusion. The effects of these centralized hole on the physical and compression properties were then investigated. Compression test results demonstrated a significant increase in the compressive yield strength (∼62%) and ultimate compressive strength (∼11%) for the 1.5 mm drilled magnesium sample when compared to undrilled monolithic magnesium. Further, the strength (yield and ultimate) to weight ratio was higher for all the drilled samples compared to pure magnesium. These results present an opportunity to light weight magnesium-based components using a controlled defect while improving or maintaining the overall compressive response of the material. Using Finite Element Analysis, an optimum drill diameter was also calculated which can be used as a foundation for future studies.

Abstract 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.

Foamed zinc was prepared by infiltration casting process. The mechanical properties and corrosion resistance of the samples were studied, and the feasibility of the foamed zinc as a bone implant material was discussed. All the compression stress-strain curves of open-cell zinc foams with various cell size (1-4 mm) and porosity (55%-67%) show three stages: elastic stage, plastic stage, and densification stage. The compression strength increases with decreasing density. The smooth stress-strain response indicates a progressively deformation of open-cell zinc foam. In addition, the cell wall or edge bending and fracture are the dominated mechanisms for failure of open cell zinc foam. The immersion test for determining the corrosion rate of open cell zinc foam was conducted in simulated body fluid. It was found that zinc foam with a small cell size and high porosity showed a higher corrosion rate. In addition, open-cell zinc foams can effectively induce Ca-P deposition in immersion tests, showing good bioactivity. Therefore, the open cell zinc foam prepared in this experiment has a good potential application as a human bone substitute material.

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.

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.

Self-compacting concrete (SCC) has been widely used in building structures. However, previous research focused only on the mechanical properties and working properties of SCC at room temperature. Thus, there is limited research on the change of compressive strength of SCC after a fire. This paper aims to investigate the compressive properties of SCC after being cooled from high temperatures. The SCC specimens were firstly heated to a target temperature of 100–700 °C and were then cooled to ambient temperatures by water or in air. The heating and cooling damage to the SCC specimens was assessed by the mass loss and the ultrasonic pulse velocity (UPV) separately. Afterward, the axial compression tests were carried out to investigate the compressive properties of the fire-affected SCC specimens under uniaxial compression. The residual mass, UPV, stress–strain curves, post-fire failure characteristics, and compressive strengths of the SCC specimens were discussed in detail. The mass loss of the SCC specimens showed an obvious increase with the rising temperatures, while the UPV exhibited a converse pattern. The mass loss of the SCC specimens after being naturally cooled increased more significantly, while the two cooling methods used in this experiment had little effect on the UPV. When the SCC specimens were cooled from 100 °C, the compressive strength of the SCC specimens cooled in air or water dropped by 32.54% and 35.15%, respectively. However, while the heating temperature rose to 700 °C, the compressive strengths of the SCC specimens cooled in air or water dropped sharply by 72.98% and 86.51%, respectively. Finally, an improved mathematical model for SCC after cooling from high temperatures was proposed based on Jones and Nelson’s equation. This improved material model matched the experimental results well, which demonstrates that the proposed constitutive model can provide better predictions for the SCC structures after a fire.

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.

Concrete with manufactured sand (MSC) requires adequate compressive properties, which may be caused by stone powder. This present study investigated the effect of different stone powder content (0%, 3%, 5%, 7%, 9% and 11%) on compressive properties of MSC. The properties of fresh MSC were evaluated by three tests, compressive strength, axial compressive strength and elastic modulus. Measure results showed that stone powder as part of fine aggregate replacement improved compressive properties of MSC. The content ranging from 5%–7% increased compressive strength. The content of 11% could greatly improve axial compressive strength. The elastic modulus had a slightly enhancement when the stone powder was within 9%. Predictive models were proposed for the prediction of long-term compressive strength of MSC. [ABSTRACT FROM AUTHOR]

The incorporation of nano carbon reinforcement is a useful strategy to broaden the engineering applications of metal foams. In this work, carbon nanotubes (CNTs) reinforced aluminum (Al) matrix composite foams (CNTs/Al composite foams) with different CNTs content are prepared by combining ball-milling technique with powder metallurgy method. The result shows that the appropriate content of CNTs can reduce the pore size, improve the circularity, and enhance the compressive properties. Especially, the 1.0 wt% CNTs/Al composite foams possess the optimal compressive properties of yield stress (7.90 MPa), plateau stress (8.75 MPa) and energy absorption capacity (5.19 MJ/m3), which have an enhancement of 23.24%, 98.41% and 84.70%, respectively. Composite foams undergo shear deformation throughout the quasi-static compression process, and the failure mode performs as the brittle mode combined with ductile mode. Meanwhile, the incorporation of CNTs can contribute to the inhomogeneous distribution of the Si phase, provide more nucleation sites, and significantly refine the pore size. It is confirmed that the CNTs in composite foams contribute the grain refinement and the formation of micro stacking faults, making the mechanical properties of CNTs/Al composite foams outperform the counterpart of Al-Si foams. Moreover, due to the weak interfacial reaction, the low content of aluminum carbide is formed, which can promote the load transfer between CNTs and Al. The present finding provides a theoretical and practical design strategy to the future preparation of CNTs/Al composite foams. • The CNTs/Al composite foams with CNTs content of 1.0 wt% show a superior improvement of the compressive properties. • The incorporation of CNTs can contribute to the inhomogeneous distribution of the Si phase and refine the grain size. • The deformation and failure mode of CNTs/Al composite foams are affected by the content of CNTs. • The formation of aluminum carbides and micro stacking faults benefit to promote the compressive properties of composite foams. [ABSTRACT FROM AUTHOR]

To explore new channels for the effective recycling of red mud (RM) in the field of construction-related materials, and study the feasibility of applying biochar (BC) and RM into capturing CO 2 , this study developed the artificial lightweight cold-bonded aggregates mixed with high volume of RM (RM-ALCBAs). Different amount of BC (0%, 5%, 10% and 15%) was also added to the RM-ALCBAs, and a set of quantitative devices for assessing carbon absorption of RM-ALCBAs was innovatively developed. Meanwhile, its compressive strength, water absorption rate and apparent density were tested, and then the microscopic properties of RM-ALCBAs were also investigated by using TGA, XRD, SEM-EDS, MIP. Finally, the sustainability and heavy metal leaning behavior of RM-ALCBAs were assessed. It was found that the total carbon uptake of RM-ALCBAs was about 30.58–33.06 kg/tons, indicating that RM-ALCBAs show the obvious carbon-capturing potential, and when the biochar dosage was increased from 0% to 15%, its compressive strength was 1.28 MPa-1.98 MPa, and the water absorption rate and apparent density of RM-ALCBAs before carbonation were 17.96%-20.46% and 1.85 g/cm3-1.98 g/cm3, while the water absorption rate and apparent density of RM-ALCBAs after carbonation were 16.71%-17.04% and 2.02 g/cm3-1.83 g/cm3, respectively, which is in accordance with the specification of LWAs in China. With the increase of BC doping, the porosity in RM-ALCBAs gradually increased, the proportion of micropores gradually decreased, and the proportion of macropores gradually increased. More importantly, converting RM into RM-ALCBAs can effectively lower the toxic leaching and the concentration of heavy metals is also meet the Chinese requirements. RM-ALCBAs mixed with 5% BC has the lowest energy consumption per-unit compressive strength, carbon emission per-unit compressive strength with about 26.0–29.1 kg/t, and cost per-unit compressive strength with much lower than that of FA-ALCBAs and GGBFS-ALCBAs. Overall, the RM-ALCBAs have obvious eco-friendly potentials and belong to the carbon-negative construction materials that can effectively recycle solid waste of RM, which can provide some new insights and useful data for the development path of low-carbon ALCBAs. • The green ALCBAs with capturing CO 2 were designed with red mud and biochar. • Adding 75%-90% RM into ALCBAs can achieve the excellent comprehensive properties. • Biochar and RM can improve the carbon-sequestration capacity of green RM-ALCBAs. • Biochar in green RM-ALCBAs can sequestrate the CO 2 from air obviously. • Green RM-ALCBAs have promising sustainable performance. [ABSTRACT FROM AUTHOR]

• The cyclic mechanical response of the auxetic structures FFF-printed by four different materials were revealed. • The auxetic structure properties were predicted by the mathematical equations of material property parameters. • The recovery behavior of the structure was simulated and useful information of structural design was provided. The influence of lattice structural design on the mechanical property has been abundantly investigated, however, the effect of material on the load-carrying performance and energy absorption was seldom studied. In the current work, the auxetic structures fabricated using four materials including polyamide (PA), carbon fiber (CF) reinforced PA (PA/CF), polyether ether ketone (PEEK) and PEEK/CF were 3D-printed, and the compression performance and deformation behavior were compared and explored. The results showed that the deformation mode of auxetic structure were similar, which was not dependent on the material type. However, the compressive strength and modulus of the auxetic structure showed strong dependence on the material properties. Besides, PA and PA/CF auxetic structures displayed better rebound behavior after compression, which was perhaps attributed to the good resilience of PA resin. Therefore, mathematical equations were utilized to predict the compressive property based on the material parameters, showing a good agreement. On the other hand, the simulation of compression process was established and conducted, which confirmed the deformation process as experimental presented. The rebound behavior was further predicted by a loading-releasing cycle with different compression strains. Accordingly, the compression parameters showed great relations with material parameters but little effect on the deformation behavior. [ABSTRACT FROM AUTHOR]

In view of the requirement of thermal management system in aerospace, heat-dissipating materials (HDMs) that possess exceptional thermal conductivity in the through-plane direction, especially for serving in harsh settings are immediately required. In the current work, an expanded graphite/graphene composite (EGC) by integrating graphene oxide (GO) into expanded graphite (EG) via a vacuum-assisted self-assembly method followed by compaction and graphitization was designed and constructed. The prepared EGC was endowed with remarkable thermal conductivity, whose through-plane and in-plane thermal conductivity achieved 18.6 and 129.9 W m−1 K−1, respectively with the optimized GO amount of 3.5 wt%. GO exhibited a pronounced bridging effect, facilitating the establishment of the phonon transmission "bridge" between the layers of EG. Notably, the "bridges" existed both within EG particles and among multiple EG particles, which dominated the thermal conductivity's augment in the composite. Moreover, the EGC demonstrated favorable compressive stress of 7.9 MPa at a 15 % strain ratio, exceeding that of EG. [Display omitted] [ABSTRACT FROM AUTHOR]

• ZA22/Al interpenetrating composite (IPC) was prepared for the first time. • Specimens were prepared using a two-step air pressure infiltration method. • ZA22/Al IPC has a high compressive stress plateau and a high damping capacity. • The microstructure origin of excellent comprehensive properties of IPC was discussed. A ZA22/Al interpenetrating phase composite (IPC) was prepared by a two-step infiltration method for the first time. The ZA22 alloy and the Al matrix were well bonded together, and a layer with ultrafine grains containing Al, Zn and O elements was formed between them. Lamellar eutectoid structure (LES) in original ZA22 alloy transformed to granular eutectoid structure (GES) with submicron sized α and η phases, resulting in a significant increase in phase interface density. The property test results showed that the IPC has a high compressive stress plateau and a high damping capacity up to 0.2. Correlated mechanisms were discussed. [ABSTRACT FROM AUTHOR]

In order to solve the difficulties in the utilization of aluminum dross resources, non-fired bricks with aluminum dross with high nitrogen concentration as the main raw material were prepared. Three process parameters, including forming pressure, mixing-water amount, and aluminum dross particle size, were subjected to single-factor experiments. Based on the response surface method, a mathematical model was established between the process parameters and the non-fired bricks’ compressive properties, which were subjected to ANOVA. The process parameters were optimized and then verified experimentally. According to the results, the established regression model is able to accurately predict the compressive properties of non-fired bricks. The difference between the experimental value and the model’s predicted value was only 0.36%. The optimal process parameters for aluminum dross to prepare non-fired bricks are as follows: forming pressure is 18 MPa, mixing-water amount is 15% and particle size range is 80–130 mesh. The compressive strength of the prepared non-fired bricks is 24.66 MPa, which meets the requirement of MU20 non-fired bricks in Non-fired Rubbish Gangue Bricks.

There is an inevitable trend toward exploring new, environmentally friendly fibers that can be used as raw material for mattresses with moderate hardness and air-permeable characteristics. Ethylene-propylene side by side (ES), high-shrinkage fibers, and thermoplastic polyester elastomer (TPEE) chips were introduced into polyethylene glycol terephthalate (PET)/polybutylene terephthalate (PBT) chip by melt blending to modify PET/PBT fiber. The modified PET/PBT (hereinafter referred to as PLON) is more suitable for mattress filling material than PET/PBT. To explore the compressive properties of PLON cushion made of PLON fiber and expand the scope of the PLON cushion’s application, a layered hardness test, hardness classification test and variance analysis were used to comprehensively evaluate the surface hardness, core hardness, bottom hardness and hardness classification of the mattress made of PLON cushion. The conclusions are: (1) The materials of the support layer have a significant effect on the hardness grade S. The hardness of the mattress with PLON as the support layer is between the spring and the coir; (2) when PLON is used as the material of the support layer, it possesses higher supporting force than coir and the characteristics of light weight and high resilience, which coir does not have; it is also softer than a spring mattress. As cushion material, it provides higher support for mattresses than foam. Practical applications, densities and structure were clarified through the above research, with implications for broader applications for PLON blocks in mattress products.

Electron beam melted (EBM) Ti-6Al-4V functionally graded materials (FGM) with continuously graded densities are investigated for dimensional accuracy, compressive properties, fractography and build direction effect in comparison to uniform density counterparts of the same volume. It is found that FGMs exhibit progressive layer-by-layer deformation mode regardless of unit cell designs and build direction. This deformation behavior is highly favourable for uni-directional impact absorption applications compared to uniform density counterparts with random or diagonal failure. Overall, the EBM-built FGM exhibits superior energy absorption than counterparts of uniform density. Significant improvement in the quasi-elastic gradient and energy absorption is obtained by changing the build direction for specific designs. Compared with other FGM or uniform density lattice structures from the literature, the energy absorption of lattice structures with lower relative density could outperform those with higher relative density by changing the unit cell design or density profile. [ABSTRACT FROM AUTHOR]

Mg–Ceramic–Ni hybrid foams were fabricated via continuousdepositing micro-arc oxidation (MAO) ceramic coating and electroless Ni coating on the surface of the AZ91D foam struts. Mechanical tests from room temperature (RT) to 300 °C were carried out to evaluate the compressive properties and energy absorption capacities of two types of foams, i.e., AZ91D alloy foams and corresponding hybrid foams. The effect of composite coatings and test temperature on the compressive property of the foams was studied. The experimental results show that the MAOand Ni coatings enhance the Mg foam struts, resulting in high compressive strength and energy absorption capacity at each testing temperature. In addition, the compressive properties are also depending on testing temperature. The different mechanical responses of the composite foams under various temperature conditions are mainly attributed to the different deformation behaviors and failure modes of the foam struts, which are confirmed by scanning electron microscopy (SEM) observation.

Epoxy polymer composites embedded with thermally conductive nanofillers play an important role in the thermal management of polymer microelectronic packages, since they can provide thermal conduction properties with electrically insulating properties. An epoxy composite system filled with graphitic-based fillers; multi-walled carbon nanotubes (MWCNTs), graphene nanoplatelets (GNPs) and ceramic-based filler; silicon carbide nanoparticles (SiCs) was investigated as a form of thermal-effective reinforcement for epoxy matrices. The epoxy composites were fabricated using a simple fabrication method, which included ultrasonication and planetary centrifugal mixing. The effect of graphite-based and ceramic-based fillers on the thermal conductivity was measured by the transient plane source method, while the glass transition temperature of the fully cured samples was studied by differential scanning calorimetry. Thermal gravimetric analysis was adopted to study the thermal stability of the samples, and the compressive properties of different filler loadings (1–5 vol.%) were also discussed. The glass temperatures and thermal stabilities of the epoxy system were increased when incorporated with the graphite- and ceramic-based fillers. These results can be correlated with the thermal conductivity of the samples, which was found to increase with the increase in the filler loadings, except for the epoxy/SiCs composites. The thermal conductivity of the composites increased to 0.4 W/mK with 5 vol.% of MWCNTs, which is a 100% improvement over pure epoxy. The GNPs, SiCs, and MWCNTs showed uniform dispersion in the epoxy matrix and well-established thermally conductive pathways.

It is known that 3D-printed PETG composites reinforced with carbon or Kevlar fibres are materials that can be suitable for specific applications in the aeronautical and/or automotive sector. However, for this purpose, it is necessary to understand their mechanical behaviour, which is not yet fully understood in terms of compression. Therefore, this study intends to increase the knowledge in this domain, especially in terms of static behaviour, as well as with regard to creep and stress relaxation due to the inherent viscoelasticity of the matrix. In this context, static, stress relaxation and creep tests were carried out, in compressive mode, using neat PETG and PETG composites reinforced with carbon and Kevlar fibres. From the static tests, it was found that the yield compressive strength decreased in both composites compared to the neat polymer. Values around 9.9% and 68.7% lower were found, respectively, when carbon and Kevlar fibres were added to the PETG. Similar behaviour was observed for compressive displacement, where a reduction of 20.4% and 46.3% was found, respectively. On the other hand, the compressive modulus increased by 12.4% when carbon fibres were added to the PETG matrix and decreased by 39.6% for Kevlar fibres. Finally, the stress relaxation behaviour revealed a decrease in compressive stresses over time for neat PETG, while the creep response promoted greater compressive displacement. In both situations, the response was very dependent on the displacement/stress level used at the beginning of the test. However, when the fibres were added to the polymer, higher stress relaxations and compressive displacements were observed.

Additive manufacturing (AM), also known as 3D printing, has greatly promoted the development of lattice structures with complex configurations. However, these lattice structures usually consist of periodically arranged nodes and struts. Here, inspired by the three-dimensional crystalline microstructure of selective laser melted (SLM) Al–Si alloy, a type of novel cellular structure with irregular nodes and struts was designed and fabricated by the SLM process with Al–Si alloy powder. The as-fabricated cellular structures were multi-scale materials from nano- to macro-scale. Electron backscatter diffraction (EBSD) analysis revealed that compared with the edge region, the central region of the struts had larger grain size, dominant (001) grain orientation, and worse toughness. Most importantly, compared with the regular lattice structures, the novel cellular structures brought about maximum 32.8% and 38.3% improvement in volumetric energy absorption W v and specific energy absorption W s , respectively. Furthermore, the finite element simulation was employed to reveal the stress distribution and energy absorption mechanism of cellular components during compression. Finally, the different fracture modes between the edge and central regions of the struts were investigated. The Al–Si crystalline microstructure inspired cellular structures have potential applications in biomaterials, vibration and thermal insulation. [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]

Polylactide (PLA), a biopolymer, was reinforced with three fillers (two organic reinforcements and one inorganic filler). The processing technique used to fabricate the composites was the melt-blending technique. The composites and the unreinforced PLA were subjected to microhardness, compression and biodegradation characterisations. Data obtained are presented in this article as raw data. Data from microhardness and compression tests were used to predict the fracture toughness. The biodegradation of the composites was also examined, and the data obtained reported in this article. The data presented in this article allow for a comprehensive understanding of the mechanical behaviour and the biodegradation profile of three composites of PLA with respect to their applications as biodegradable implants. It also helps in the selection of fillers for biopolymers such as PLA.

Most cellular solids presented random structure, while practically periodic models were often used in structure-property relations and numerical models. The finite element method was used to create a 2D random model that replicated the deformation characteristics of cellular models. The influences of porosity and strain rate on the deformation characteristic, energy dissipation mechanisms were investigated. The Poisson’s ratio evolution during compression was also studied. The simulated load-displacement curves were found to be consistent with experimental results, both containing elastic stage, plateau stage, hardening stage and densification stage. The yield load and plateau load were insensitive to the strain rate. In addition, it was also found that the generation and propagation of multiple random shear bands were responsible for the load-displacement characteristic. At the cell/membrane level, four failure modes and corresponding energy dissipation mechanisms were revealed. Moreover, the Poisson’s ratio decreased first and then increased with strain, which right manifested the compressibility of 2D foam in the initial stage and the densification in the end of compression. Meanwhile, the change of the Poisson’s ratio with porosity didn’t follow monotone function relation.

Fe-Cr-B alloy is a material with precipitation of boride inside Fe matrix, and it features outstanding hardness and wear resistance properties. However, Fe-Cr-B alloy is a difficult material to process, making it difficult to use as a bulk type structure material which requires delicate shapes. This study attempted to manufacture Fe-Cr-B alloy using a 3D printing process, laser metal deposition. This study also investigated the microstructure, hardness and compression properties of the manufactured alloy. Phase analysis results is confirmed that α-Fe phase as matrix and (Cr, Fe)2B phase as reinforcement phase. In the case of (Cr, Fe)2B phase, differences were observed according to the sample location. While long, coarse, unidirectional needle-type boride phases (~11 μm thickness) were observed in the center area of the sample, relatively finer boride phases (~6 μm thickness) in random directions were observed in other areas. At room temperature compression test results confirmed that the sample had a compression strength is approximately 2.1 GPa, proving that the sample is a material with extremely high strength. Observation of the compression fracture surface identified intergranular fractures in areas with needle-type boride, and transgranular fractures in areas with random borides. Based on this results, this study also reviewed the deformation behavior of LMD Fe-Cr-B alloy in relation to its microstructures.

The additive manufacturing (AM) of carbon fiber reinforced plastic (CFRP) composites continue to grow due to the attractive strength-to-weight and modulus-to-weight ratios afforded by the composites combined with the ease of processibility achievable through the AM technique. Short fiber design factors such as fiber content effects have been shown to play determinant roles in the mechanical performance of AM fabricated CFRP composites. However, this has only been investigated for tensile and flexural properties, with no investigations to date on compressive properties effects of fiber content. This study examined the axial and transverse compressive properties of AM fabricated CFRP composites by testing CF-ABS with fiber contents from 0%, 10%, 20%, and 30% for samples printed in the axial and transverse build orientations, and for axial tensile in comparison to the axial compression properties. The results were that increasing carbon fiber content for the short-fiber thermoplastic CFRP composites slightly reduced compressive strength and modulus. However, it increased ductility and toughness. The 20% carbon fiber content provided the overall content with the most decent compressive properties for the 0–30% content studied. The AM fabricated composite demonstrates a generally higher compressive property than tensile property because of the higher plastic deformation ability which characterizes compression loaded parts, which were observed from the different failure modes.

The current study reports on the evolution of microstructure, variations in compressive properties and the ignition resistance of Mg through compositional variation, using alloying elements and nanoreinforcement. The alloys were designed with the use of a singular alloying element, Ca, and a binary alloying element, Ca+Sc, to develop Mg1Ca (wt.%) and Mg1Ca1Sc (wt.%) alloys. B4C nanoparticles were addedas the reinforcement phase in the Mg1Ca1Sc alloy to create the Mg1Ca1Sc/1.5B4C (wt.%) nanocomposite. The most effective compressive properties and level of ignition resistance was displayed by the developed composite. The grain sizes were significantly reduced in the Mg alloys (81%) and the composite (92%), compared with that of the Mg. Overall, the microstructural features (i.e., grain refinement, the formation of favorable intermetallic compounds, and hard reinforcement particles with an adequate distribution pattern) enhanced both the compressive strength and strain of the alloys and the composite. The ignition resistance was progressively increased from the alloys to the nanocomposite, and a peak ignition temperature of 752 °C was achieved in the composite. When compared with the ignition resistant of Elektron 21 (E21) alloy, which met the Federal Aviation Administration (FAA) requirements, the Mg1Ca1Sc/1.5B4C nanocomposite showed a higher specific yield strength and better ignition resistance, asserting it as a potential candidate material for lightweight engineering applications, including aerospace and defense sectors.

With the increasing awareness of environmental protection, Green Velvet Material (PLON), a renewable and environmentally friendly material, has been widely applied to mattresses. In order to improve the compressive properties of PLON, a series of experiments were carried out with special attention given to the compression deformation characteristics, support performance of the PLON blocks and its effective application in mattress products. The results are: (1) Average slopes of the load-deformation curves’ two phases are represented by K1 and K2, respectively. K1 is more sensitive to density changes that range from 30 kg/m3 to 50 kg/m3, while K2 is sensitive to density changes that range from 20 kg/m3 to 50 kg/m3. Their values increase with the rise of density; (2) 25% IFD, 40% IFD, 65% IFD, SF and IHF values are sensitive to density changes and they significantly increase with the rise of density. PLON blocks have excellent supporting properties and are considered to be comfortable according to American FPF Test Standard (ASTM-D3574-B1) when used in mattress bedding; (3) a PLON block density of 30 kg/m3 is preferentially selected for the softer type of mattress, while a PLON block density of 40 kg/m3 is preferentially selected for the harder type of mattress. The compression deformation characteristics and support performance of the PLON blocks were analyzed and the effective application of PLON in mattress products was explored through the above research.

Featured Application: Development of hybrid cellular structures for aerospace component manufacturing and repair. Drilling is used in creating cylindrical through-holes for various applications. While optimizing drilling parameters is widespread, the effect of a drilled through-hole on the structural stability of components is not fully documented. The base material, along with other parameters, such as drill diameter, drill location and its orientation affect structural stability. Since carrying out tests on different base materials can be time consuming, simulation software can instead be used to provide valuable information. However, the comparison between experiments and simulations gets difficult; hence, this study attempts to provide a basis for effective comparison by studying simulations and compression tests, comparing the two, and documenting the role of drill hole orientation on the compressive response of magnesium, a material with immense potential in light-weight components. Simulations and experiments were carried out on three through-hole orientations and were compared to the undrilled scenario. Results demonstrate significant differences in compression behaviour. While the compressive yield strength increased in all three drill orientations, ultimate strength and ductility was reduced in horizontal and angular drill hole orientations. These observations, therefore, provide valuable insight into choosing the right orientation for different applications. [ABSTRACT FROM AUTHOR]

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