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To achieve the synergy among density, strength, ductility, wear performance and thermal stability, a series of newly developed CoCrFeNiMoTix (x = 2 and 16.666 at. %) high entropy alloys (HEAs) via multiple phases nano crystalline structure were successfully fabricated using mechanical alloying (MA) following by spark plasma sintering (SPS). The results demonstrated that the SPSed Ti2-HEA and Ti16.6-HEA have a multiple phases structure consisting of FCC structure (Ni-type as a major phase), two types of BCC structure (Mo-type and Ti-type), topologically close packed (TCP) phases (laves, sigma (σ) and R phases) and geometrically close packed (GCP) phase (L12 precipitates). The micro hardness, strength and specific strength were increased from 711 HV, 1770 MPa and 197 MPa.Cm3/g for the Ti2-HEA to 817 HV, 1830 MPa and 236 MPa.Cm3/g for the Ti16.6-HEA, respectively, which were affected by more percentages of precipitates, intermetallic and BCC phases. Besides, fracture strain, coefficient friction, wear rate and the surface roughness were decreased from 16%, 0.19, 4.9*10−4 mm3 N−1 m−1 and 54.2 for the Ti2-HEA to 14.5%, 0.17, 2.7*10−4 mm3 N−1 m−1 and 31.6 for the Ti16.6-HEA. The ultimate shear strength (USS) values at 300 °C, 400 °C, 500 °C and 600 °C were increased from 960 MPa, 820 MP, 646 MPa and 24 MPa for the Ti2-HEA to 1180 MPa, 1010 MP, 802 MPa and 94 MPa for the Ti16.6-HEA, respectively. The Ti16.6-HEA illustrated higher thermal stability at all temperatures, where the USS slightly was decreased from 300 °C to 500 °C with a sudden drop at 600 °C.

This study investigates the feasibility of using mudstone to enhance poorly graded gravel in certain arid regions of the S21 Altay-Urumqi Highway project in Xinjiang. Despite mudstone typically being considered a poor-quality rock, its combination with higher-performance materials like cement, lime, and fly ash can stabilize expansive soils for use as roadbed fill. In the experiments, 30% and 40% mudstone were added to the gravel mixture. The experiments were compared with unmodified K80 and 35% crushed rock mixes. The findings reveal that adding 30% mudstone substantially increased the California Bearing Ratio (CBR) of the gravel mix by over 20%. However, excessive mudstone inclusion could weaken load-bearing capacity. Moreover, mudstone-modified specimens exhibited superior unconfined compressive strength (UCS), splitting strength, compressive resilience modulus (CRM), drying shrinkage resistance, and temperature shrinkage resistance. Under optimum cement dosage, the UCS of mudstone-modified specimens outperformed unmodified specimens, consistently surpassing fly ash-altered groups. Although mixed fly ash initially exhibited lower strength, it gradually approached cement-stabilized strength with an extended curing time. Incorporating crushed stone into the grading curve significantly increased splitting strength due to its high strength and hardness. In contrast, adding mudstone introduced a notable proportion of fine aggregates, resulting in a looser grading skeleton prone to early cracking. This research demonstrates that mudstone enhancement significantly improves roadbed performance, including increased CBR, splitting strength, and crack resistance. The use of mudstone in arid desert areas enhances overall performance while reducing shrinkage coefficients. The suggested approach for semi-rigid pavements in arid deserts recommends specific mineral proportions, various aggregate sizes, an appropriate amount of cement, and 30% mudstone to create dense structures with a higher quantity of coarse aggregate.

Co-continuous interlocking lattice structures usually present superior compressive properties and energy absorption characteristics. In this study, co-continuous interlocking polydimethylsiloxane/polylactic acid (PDMS/PLA) lattice composites were designed with different strut diameters, and successfully manufactured by combining the fused deposition modeling (FDM) technique and the infiltration method. This fabrication method can realize the change and control of structure parameters. The effects of the strut diameter on the compressive properties and energy absorption behavior of PDMS/PLA lattice composites were investigated by using quasi-static compression tests. The compressive properties of the co-continuous interlocking PDMS/PLA lattice composites can be adjusted in a narrow density range by a linear correlation. The energy absorption density of the co-continuous interlocking PDMS/PLA lattice composites increases with the increase in the PLA strut diameter and presents a higher efficiency peak and wider plateau region. The PLA lattice acts as a skeleton and plays an important role in bearing the compressive load and in energy absorption. The indexes of the compressive properties/energy absorption characteristics and PLA volume fraction of co-continuous interlocking PDMS/PLA lattice composites show linear relationships in logarithmic coordinates. The effect of the PLA volume fraction increasing on the plateau stress is more sensitive than the compressive strength and energy absorption density.

Early-age masonry structures require temporary support until they achieve full strength. Nevertheless, there is a limited understanding of the properties of freshly laid masonry and the design of newly constructed, unsupported masonry walls. This situation has led to numerous instances of structural damage and injuries to workers, prompting conservative construction bracing techniques. This paper presents comprehensive experimental studies on early-age mortar cubes and masonry prisms to assess the effects of curing time on the compressive properties of masonry assemblies, which is necessary for the design of temporary bracing. The change in modulus of elasticity and compressive strength of masonry prisms and mortar with curing time has been experimentally assessed. The results indicate that the compressive strength of freshly cast mortar cubes is relatively insignificant until approximately 24 h after construction, when it was observed to increase logarithmically. Regarding the performance perspective, the compressive strength of early-age masonry prisms is inconsiderable, less than 15% of full strength during the first day after construction. By contrast, regarding the life safety perspective, the compressive properties of a mortar joint within a masonry assembly (which is of more practical interest) appear to have no effect on the failure strength of concrete masonry prisms over the range of ages tested. The failure modes of the early-age mortar cubes and early-age masonry prism samples depend on the curing time, and different failure modes occurred before and after the start of the primary hydration phase, which is 20.8 h after construction. It is anticipated that the proposed research will provide valuable material properties leading to efficient design of control devices (e.g., temporary bracing) and improved guidelines for concrete-block masonry construction.

A hydrophobic and ultralight cellulose aerogel (CA) was reinforced by polyethyleneimine (PEI) and functionalized by methyltrimethoxysilane (MTMS). Adding PEI improved the mechanical strength and the elastic resilience of the resulting material due to the flexibility enhancement of the cellulose chains, which prevented the collapse of the pore structure and contributed to the uniform pore size distribution. The hydrophobic property of the aerogels with the functionalization of MTMS was improved, which can prevent the pore structure from collapsing due to the absorption of water. The maximum compression modulus of aerogel reached 1.1 MPa at the strain of 80%, and its hydrophobic water contact angle was up to 112°. The hydrophobic composite aerogels exhibited ultrahigh efficiency in sound absorption across a wide frequency range from 500 to 6300 Hz, and their average absorption coefficient was greater than 0.74. The light weight, high porosity, and environmentally friendly aerogels presented in this work are promising for efficient sound absorption. They have potential applications in noise pollution treatment.

A hydrophobic and ultralight cellulose aerogel (CA) was reinforced by polyethyleneimine (PEI) and functionalized by methyltrimethoxysilane (MTMS). Adding PEI improved the mechanical strength and the elastic resilience of the resulting material due to the flexibility enhancement of the cellulose chains, which prevented the collapse of the pore structure and contributed to the uniform pore size distribution. The hydrophobic property of the aerogels with the functionalization of MTMS was improved, which can prevent the pore structure from collapsing due to the absorption of water. The maximum compression modulus of aerogel reached 1.1 MPa at the strain of 80%, and its hydrophobic water contact angle was up to 112°. The hydrophobic composite aerogels exhibited ultrahigh efficiency in sound absorption across a wide frequency range from 500 to 6300 Hz, and their average absorption coefficient was greater than 0.74. The light weight, high porosity, and environmentally friendly aerogels presented in this work are promising for efficient sound absorption. They have potential applications in noise pollution treatment.

In order to obtain a lightweight, high-strength, and customizable cellular structure to meet the needs of modern production and life, the mechanical properties of four thickness gradient honeycomb structures were studied. In this paper, four types of honeycomb structure specimens with the same porosity and different Poisson’s ratios were designed and manufactured by using SLA 3D-printing technology, including the honeycomb, square honeycomb, quasi-square honeycomb, and re-entrant honeycomb structures. Based on the plane compression mechanical properties and failure mode analysis of these specimens, the thickness gradient is applied to the honeycomb structure, and four structural forms of the thickness gradient honeycomb structure are formed. The experimental results show that the thickness gradient honeycomb structure exhibits better mechanical properties than the honeycomb structure with a uniform cellular wall thickness. In the studied thickness gradient honeycomb structure, the mechanical properties of the whole structure can be significantly improved by increasing the thickness of cell walls at the upper and lower ends of the structure. The wall thickness, arrangement order, shape, and Poisson’s ratio of the cell all have a significant impact on the mechanical properties of the specimens. These results provide an effective basis for the design and application of cellular structures in the future.

The influence of 3D printing parameters on compressive properties is an important factor in the application of additive manufacturing processes for products subjected to compressive loads in use. In this study, the compressive strength and compressive modulus of acrylonitrile/butadiene/styrene (ABS) test specimens fabricated using the fused deposition modeling (FDM) process were investigated with the aim of producing products of high-heeled shoes for women. The experimental part of the study includes a central composite experimental design to optimize the main 3D printing parameters (layer thickness, infill density, and extrusion temperature) and the infill geometry (honeycomb and linear at a 45° angle—L45) to achieve maximum printing properties of the 3D-printed products. The results show that the infill density has the greatest influence on the printing properties, followed by the layer thickness and, finally, the extrusion temperature as the least influential factor. The linear infill at a 45° angle resulted in higher compressive strength and lower compressive modulus values compared to the honeycomb infill. By optimizing the results, the maximum compressive strength (that of L45 is 41 N/mm2 and that of honeycomb 35 N/mm2) and modulus (that of L45 is 918 N/mm2 and that of honeycomb is 868 N/mm2) for both types of infill is obtained at a layer thickness of 0.1 mm and infill density of 40%, while the temperature for L45 can be in the range of 209 °C to 254 °C, but for the honeycomb infill, the processing temperature is 255 °C. Additionally, the study highlights the potential for sustainable manufacturing practices and the integration of advanced 3D printing technologies to enhance the efficiency and eco-friendliness of the production process.

The backfill area of tunnel projects may deform or collapse due to the cyclic disturbance of groundwater and train loads. Hence, the anti-deformation and crack resistance performance of backfill materials under cyclic disturbance is critical to engineering safety. In this paper, concrete was produced by mixing 0.85 mm, 1–3 mm and 3–6 mm rubber particles instead of 10% sand, and tested to discuss the effect of rubber particle size on the deterioration of concrete material properties (compressive characteristics and energy dissipation) after bearing cyclic loading. The stress–strain curve and various parameters obtained through the uniaxial compression test and cyclic load test were used to explore the optimal grain size that can be applied to the tunnel engineering backfill area, and numerical simulation was adopted to calculate the deformation of the surrounding rock and the structural stress of different backfill materials. Research shows that the increase in particle size lessens the compressive strength, deformation resistance and cracking resistance of specimens, but after the cyclic loading test, the concrete material deterioration analysis indicates that rubber concrete has lesser and more stable losses compared to ordinary concrete, so the optimum rubber particle size is 0.85 mm. Numerical calculations show that RC-1 reduces the arch top displacement by 0.4 mm, increases the arch bottom displacement by 0.6 mm and increases the maximum principal stress by 11.5% compared to OC. Therefore, rubber concrete can ensure the strength and stability requirements of tunnel structures, which can provide a reference for similar projects.

In this study, an aluminum (Al) alloy matrix reinforced with uncoated and titanium (Ti) -coated diamond were developed using powder metallurgy technique where polymethylmethacrylate (PMMA) particles were employed as space holders. The weight % of uncoated and coated diamond varied as (0, 6, 9, 12, 15, and 20 wt.%). Microstructural and elemental analysis was examined using scanning electron microscopy and energy dispersive spectroscope, respectively. The relative density and porosity that were in the range of 0.72–0.92 and 31–44% respectively, were measured using Archimedes principle. The compressive properties were measured and correlated with microstructure observations. The microstructure of the composite samples revealed presence of well-defined macro pores with good interfacial integrity. The X-ray diffraction revealed the presence of strengthening phases such as Al2Ti, Mg2Sn, AlB12, Cu5Sn6, Al12Mg17 and MgB2 phases formed as a result of addition of metal additives in Al matrix. Further improvement in the strength was obtained by using Ti-coated diamond particles as reinforcement. As Ti formed a good interface between the Al alloy matrix and the diamond thereby preventing the formation of undesirable carbide phases. There was an improvement in plateau stress and energy absorption capacity of 82 and 88% as compared to unreinforced porous sample. The maximum values obtained for the plateau stress and energy absorption capacity were 45.12 MPa and 13.68 MJ/m3 respectively for 9 wt.% of Ti-coated diamond reinforced composites. Uncoated diamond reinforced composites, on the other hand, reduced the strength of porous Al alloy matrix due to the formation of brittle intermetallic compound such as carbides (Al2C3) at the interface. As a result, the coated diamond particle surface modifies and improves the wettability of the Al alloy matrix and diamond interface.

Green Velvet Material (PLON), which is prepared from polyester slices, has been called a green material based on its ester composition, its ability to be degraded, and the possibility of recovering the value of used material by reprocessing. PLON is expected to be used as a material for the padding layer of upholstered furniture. This paper presented a comparative study of traditional flexible polyurethane foam and Green Velvet Material as the upholstered furniture’s padding layer. The compression mechanical properties of Green Velvet Material and flexible polyurethane foam, such as indentation force deflection, support performance, compression set, and resilience property, were analyzed. The results showed that Green Velvet Material had lower surface hardness and higher comfort compared to flexible polyurethane foam. In terms of resilience, both high-density and low-density Green Velvet Material performed better than the foam control group, but Green Velvet Material had a poorer ability to regain its shape after prolonged pressure. The 30 kg/m3 density Green Velvet Material was the closest to the compression and resilience properties of flexible polyurethane foam. The conclusions provide theoretical data for the effective and reasonable application of Green Velvet Material in upholstered furniture.

Green Velvet Material (PLON), which is prepared from polyester slices, has been called a green material based on its ester composition, its ability to be degraded, and the possibility of recovering the value of used material by reprocessing. PLON is expected to be used as a material for the padding layer of upholstered furniture. This paper presented a comparative study of traditional flexible polyurethane foam and Green Velvet Material as the upholstered furniture’s padding layer. The compression mechanical properties of Green Velvet Material and flexible polyurethane foam, such as indentation force deflection, support performance, compression set, and resilience property, were analyzed. The results showed that Green Velvet Material had lower surface hardness and higher comfort compared to flexible polyurethane foam. In terms of resilience, both high-density and low-density Green Velvet Material performed better than the foam control group, but Green Velvet Material had a poorer ability to regain its shape after prolonged pressure. The 30 kg/m3 density Green Velvet Material was the closest to the compression and resilience properties of flexible polyurethane foam. The conclusions provide theoretical data for the effective and reasonable application of Green Velvet Material in upholstered furniture.

A novel type of tubular structure with negative Poisson's ratio based on gyroid-type triply periodic minimal surfaces (TPMSs) is proposed in this study. This work is an attempt to design auxetic tubular structures based on TPMS. A series of auxetic tubular structures were designed and then fabricated using laser power bed fusion. Compressive behaviours of the fabricated auxetic tubular structures were investigated using experimental and numerical methods. To obtain optimal designs of tubular structures with controllable auxetic properties, the influence of several parameters were investigated comprehensively. Subsequently, several graded auxetic tubular structures were designed based on the parametric analysis and studied numerically. The mechanical properties of the tubular structures could be controlled effectively using the proposed approach. The proposed method can be used for guiding the design and optimisation of auxetic tubular structures, showing excellent potential for various applications such as biomedical devices, vehicle crashworthiness, and protective engineering.

With the recent development of additive manufacturing technology represented by 3D printers, various lattice structures have emerged because their mechanical properties can be designed artificially according to their structural characteristics. This study aims to develop knowledge that will contribute to the design of lattice structures with tailored and desired mechanical properties. Among the many unit cell topologies in the lattice structures that have been designed in numerous studies, there are several basic structures and a variety of additional structures that were derived from these basic structures. However, there is a degree of ambiguity as to which of these structures should be regarded as the basic structures. In this study, the basic structures of a lattice structure with orthogonal symmetry were derived by determining the edges of the struts using a mathematical combination approach. Then, the deformation characteristics of them were evaluated through elasto-plastic finite element analysis. Five basic structures were determined by designing the unit cell of the lattice structure such that the struts pass through the vertices, the midpoints of the edges, and the centers of the faces in the cubic design region. It was found that structures with the same strut directions in their unit cells have similar stiffness distributions, and the basic structures obtained can be classified accordingly into three types. Finite element analysis of the compression of a micro-lattice structure composed of these basic structures confirmed that different deformation characteristics appeared during plastic collapse for each type of classified basic structure, and that the strut deformation type determined the overall deformation characteristics. Evaluation of the stiffness and the plastic collapse stress showed that with stretch-dominant strut deformation, lattice structures can be made lighter in weight while still maintaining some stiffness and some plastic collapse stress.

Carbon fibers (CFs) were used as reinforcement in developing a polyethylene terephthalate glycol (PETG)-based polymer composite using the fused deposition modeling (FDM) 3D printing technique. The influence of CF and process factors (infill percentage, layer thickness, infill pattern) were studied by measuring the prepared polymer composite's tensile, flexural, and compressive properties. The innovative work that was carried out for this study and the tests that were performed revealed that it is difficult to predict the position of the specimen break area before a test. The PETG-reinforced polymer only showed enhanced flexural and tensile strength at a layer thickness of 0.25 mm and a maximum infill percentage of 20% for a solid structural design. Compressive strength improved in reinforced PETG hexagonal and circle structures. The confirmation of the numerical modeling applied to determine the mechanical properties of PETG for FDM additive manufacturing is one of the goals suggested in this research, along with a comparison of experimental and computational data. Scanning electron microscopy examination of the fractured sample surfaces revealed various fracture mechanisms and morphologies for the materials tested. The research found that the 3D-printed composite could further expand the application of PETG as an engineering material.

The cell structure and compressive properties of extruded polyethylene terephthalate (PET) foam with different densities were studied. The die of the PET foaming extruder is a special multi-hole breaker plate, which results in a honeycomb-shaped foam block. The SEM analysis showed that the aspect ratio and cell wall thickness of the strand border is greater than that of the strand body. The cells are elongated and stronger in the extruding direction, and the foam anisotropy of the structure and compressive properties decrease with increasing density. The compression results show typical stress–strain curves even though the extruded PET foam is composed of multiple foamed strands. The compression properties of PET foam vary in each of the three directions, with the best performing direction (i.e., extrusion direction) showing stretch-dominated structures, while the other two directions show bending-dominated structures. Foam mechanics models based on both rectangular and elongated Kelvin cell geometries were considered to predict the compressive properties of PET foams in terms of relative density, structure anisotropy, and the properties of the raw polymer. The results show that the modulus and strength anisotropy of PET foam can be reasonably predicted by the rectangular cell model, but more accurate predictions were obtained with an appropriately assumed elongated Kelvin model.

FeCoCrNiMo high-entropy alloy was melted by vacuum arc melting. The alloys were vacuum annealed at 873, 1,073, and 1,273 K, respectively. X-ray diffractometer (XRD), scanning electron microscope (SEM), simultaneous thermal analyzer, microhardness tester, and universal testing machine were used to study the microstructure, the thermal stability, hardness and compression mechanics of as-cast and annealed FeCoCrNiMo alloys. The results show that the alloy is composed of face-centered cubic (FCC) phase and σ phase in both as-cast and annealed states, and the σ phase and μ phase can maintain structural stability at 873 K annealing temperature. The μ phase decomposes to form the σ phase after annealing at 1,073 K, and part of the σ phase dissolves in the FCC phase when annealed at 1,273 K. Both the as-cast and annealed alloys have a typical dendritic structure. The σ phase is enriched in dendrites, and the FCC phase exists between the dendrites. The microstructure of the alloys in the annealed state is more refined than that of the alloy in the as-cast state. In the 1,073 K annealed state, the FeCoCrNiMo alloy has the highest hardness, yield strength, and fracture strength. The fracture mechanism of the alloy is intergranular brittle fracture and cleavage fracture.

Microstructure design and realization is an effective way to achieve strength-ductility synergy in high-entropy. In this work, two novel non-equiatomic Co-free low-cost medium-entropy alloys (MEAs), Fe30Cr30Al20Ni20 and Fe20Cr20Al30Ni30, were designed and prepared using an arc-melting method. Its phase constitution, microstructure, mechanical and wear properties, as well as the strengthening mechanisms were investigated. It showed that both the MEAs are composed of BCC and B2 phases, rich in Fe–Cr and Ni–Al, respectively. The microstructure analysis indicated that the two MEAs have heterogeneous structures containing high-density precipitates and two alternant dual-phase eutectic structures. Significantly, the two MEAs possess excellent mechanical properties, better than most FeCrAlNiCo-based and FeCrAlNi-based HEAs reported previously. In the two MEAs, Fe20Cr20Al30Ni30 exhibits more excellent comprehensive mechanical and wear properties, with the compressive yield strength of 1154.5 MPa, maximum strength of 3271 MPa, maximum strain of over 40% and wear rate of 0.989 × 10−5 mm3N−1m−1, attributed to the novel heterogeneous microstructure. These results showed that the Co-free low-cost MEAs could have great prospects in practical engineering applications.

Intersection annealing (different time and temperature) was carried out on Fe-clad pure Mg bars processed by four-pass ambient equal channel angular pressing (ECAP). Microstructures, textures and compressive properties of the as-annealed samples were investigated in detail. The results indicate that average grain size is the finest after intersection annealing at 150 °C × 30 min. Texture intensity after intersection annealing at 200 °C × 30 min is the strongest due to preferred grain growth. Compressive yield strength (CYS) is the best after intersection annealing at 150 °C × 30 min, ultimate compressive strength (UCS) and compressive strains (CS) all decrease with increasing grain size due to elevated annealing temperatures.

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.

While the mechanical performance of fused filament fabrication (FFF) parts has been extensively studied in terms of the tensile and bending strength, limited research accounts for their compressive performance. This study investigates the effect of four process parameters (layer height, extrusion width, nozzle temperature, and printing speed) on the compressive properties and surface smoothness of FFF parts made of Polylactic Acid (PLA). The orthogonal Taguchi method was employed for designing the experiments. The surface roughness and compressive properties of the specimens were then measured and optimized using the analysis of variance (ANOVA). A microscopic analysis was also performed to identify the failure mechanism under static compression. The results indicated that the layer height had the most significant influence on all studied properties, followed by the print speed in the case of compressive modulus, hysteresis loss, and residual strain; extrusion width in the case of compressive strength and specific strength; and nozzle temperature in the case of toughness and failure strain. The optimal design for both high compressive properties and surface smoothness were determined as a 0.05 mm layer height, 0.65 mm extrusion width, 205 °C nozzle temperature, and 70 mm/s print speed. The main failure mechanism observed by SEM analysis was delamination between layers, occurring at highly stressed points near the stitch line of the PLA prints.

AbstractSemi-finished thermoplastic foam panels can be transformed into structural foams—a sandwich-like structure with high-density skins—through thermoforming. This transformation enables the production of mono material sandwich panels, which allow a significant increase in bending properties without increasing the part weight. This study describes the effect of process parameters on skin formation in thermoplastic structural foams manufactured in a two-step isochoric and isothermal hot press process. Process data recorded during foam manufacturing was analyzed and compared to foam behavior in quasi-static isothermal compression tests performed at different levels of temperature and crosshead speeds. The effect of skin-core structure on bending properties is compared to theoretical models from the established literature. It was found that a rule of linear mixture that considers the relative skin thickness allows adequate prediction of both bending modulus and strength. Preferable process design—especially combinations of tool temperature and maximum compaction speed—is described based on the comparison of measured and predicted performance.

The lattice-reinforced cementitious composites prepared by placing 3D printed lattices in cementitious matrix has been proved to be effective in improving the bending mechanical properties of cement-based materials, such as improving ductility and brittleness. However, the compressive properties of 3D printed lattice-reinforced cementitious composites are still an open question. In this paper, the compressive properties of 3D printed polyamide 6 (PA6) lattice-reinforced cementitious composites with different structural forms were studies. Six kinds of lattices were fabricated by multi jet fusion (MJF) technique. The volumes of these lattices are identical to ensure that the volume enhancement ratio of the lattices in the cementitious composite specimen is the same. The plain cementitious matrix without lattice was set as the control group, and two nondestructive testing methods, AE and DIC, were used to compare the compressive properties between plain cementitious matrix and lattice-reinforced cementitious composites with different structural forms. The experimental results show that the 3D printed lattice can significantly improve the mechanical properties and failure modes of cement-based materials under uniaxial compression. In contrast, the six lattice forms used in this study can improve the maximum compressive bearing capacity and deformation capacity of the cement-based materials under uniaxial compression test, and reduce the damage of cement-based materials in the elastic deformation stage. This paper confirms that 3D printed lattices can improve the compressive properties of cement-based materials and provide a new method for improving the compressive strength of cement-based materials. At the same time, it provides new ideas for the development of ideal substitutes for steel bars in corrosive environments, energy conservation and emission reduction and the development of green buildings.

Size irregularity gradient and cell wall gradient, combined as the density gradient in previous studies, affect the macroscopic mechanical properties of the gradient metal foam. More and more complex mesostructures are designed and applied in metal foams, and the density gradient becomes insufficient to describe the difference in mesostructures. To explore the effect of mesostructures carefully, this study focuses on the effect of the size irregularity gradient on the macroscopic compressive properties of metal foams. A series of metal foam models were developed using the 3D Voronoi technique. These models have the same average relative densities, the same average diameters and different size irregularity gradients. Simulation results indicated that the macroscopic mechanical properties of cell wall gradient metal foams are significantly different from those of size irregularity gradient metal foams, though these models have the same relative density gradient. To explore the effect of size irregularity gradient, a theoretical model was developed to characterize the compression process from the first cell-collapse to full condensation. Theoretical results showed a linear relationship between the nominal stress and the current relative density. These findings can provide efficient guidance for the design and applications of gradient metal foams.

Polyurethane foams obtained with low global warming potential and low ozone depletion potential blowing agent.

Microcapsule self-healing technology is an effective scheme to improve the durability of cementitious composites. In this paper, the compressive properties of microcapsule-based self-healing cementitious composites after freeze-thaw cycles were studied using acoustic emission (AE), and the changes in AE characteristics, compressive strength, mass loss rate, and electric flux of microcapsule-based self-healing cementitious composites with different microcapsule contents and freeze-thaw cycles were studied. The results show that if the content of the microcapsule is appropriate, with the increase in the number of freeze-thaw cycles, the AE hits will generally increase first and then decrease, and the early AE events will also decrease. Because of the different contents of microcapsules, the improvement effect and defect effect change dynamically with the number of freeze-thaw cycles, which is also reflected in the dynamic process of compressive strength. After 100 freeze-thaw cycles, the compressive strength of self-healing cementitious composite samples with 5% content of microcapsules and 3% content of microcapsules is the highest. The changes in mass loss rate and electric flux are similar to the AE characteristic parameters, which further verifies the results of AE. The research results of this paper provide experimental data and experimental methods for the engineering application of microcapsule self-healing cement-based composites in cold areas.

To study the compressive properties of an elastomeric porous cylinder, a 360° 3D digital image correlation (DIC) system is proposed. This compact vibration isolation table system captures different segments of the object from four different angles and fields of view, enabling a comprehensive measurement of the full surface of the object. To increase the stitching quality, a coarse–fine coordinate matching method is presented. First, a three-dimensional rigid body calibration auxiliary block is employed to track motion trajectory, which enables preliminary matching of four 3D DIC sub-systems. Subsequently, scattered speckle information characteristics guide fine matching. The accuracy of the 360° 3D DIC system is verified through a three-dimensional shape measurement conducted on a cylindrical shell, and the maximum relative error of the shell’s diameter is 0.52%. A thorough investigation of the 3D compressive displacements and strains exerted on the full surface of an elastomeric porous cylinder are investigated. The results demonstrate the robustness of the proposed 360° measuring system on calculating images with voids and indicate a negative Poisson’s ratio of periodically cylindrical porous structures.

AlCrFeNiCuWx high entropy alloys were fabricated on 316 L stainless steel substrate using laser metal deposition technique. The microstructural and mechanical characteristics of these alloys were studied by advanced characterization techniques. The results revealed that the alloys exhibited a dual phase structure with BCC (body centered cubic) and FCC (face centered cubic) solid solution phases. The presence of tungsten (W) particles in the HEA matrix changed the shape of grains from columnar to aquiaxed. The alloys that contained W possessed higher plasticity at maximum compressive stress. They also showed better performance when they were evaluated for wear and corrosion.

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.

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.

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.

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.

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.