Superior Impact Research Articles

TIG Welding of EN AW-6082 Al Alloy: A Comparative Analysis of Filler Rods on Microstructural and Mechanical Performance

This study investigates the impact of different filler wires (ER5356, ER4043, and ER4047) on the microstructural and mechanical properties of EN AW-6082 Al alloy joints produced by tungsten inert gas (TIG) welding. Butt-welded samples with a single V-groove joint configuration were prepared using optimized welding parameters. The welded samples were subjected to visual inspection, microstructural analysis, hardness testing, tensile testing, and impact toughness evaluation. The results showed that all the welds were free of visible defects. Microstructural examination revealed that the ER5356 filler produced the finest grain structure of 18.03 ± 3 μm, while ER4047 resulted in the coarsest grains of 36.07 ± 5 μm. Correspondingly, the joints made with ER5356 exhibited the highest tensile stress of 278 ± 6 MPa, yield stress of 219 ± 5.4 MPa, hardness values of 72.7 ± 5 HV, and welding efficiency of 86.07%, whereas those made with ER4047 produced the lowest values. The hardness in the weld region was lower than that in the parent metal and heat-affected zone for all samples. However, ER4047 welds demonstrated superior impact toughness and strain-hardening capacity. The findings underscore the importance of filler metal selection in tailoring mechanical properties for high-performance applications.

Evaluation of Impact Energy Absorption by Natural Fiber Composites in Motorcycle Helmets

In response to the growing concerns regarding motorcyclists’ safety and advancements in the motorcycle industry, this study investigated the potential of natural fibers as a sustainable approach for enhancing helmet protection, thus replacing the traditional use of expanded polystyrene. Utilizing statistical tools such as the Shapiro–Wilk test, Chauvenet’s criterion, and the interquartile range, we compared the impact energy absorption of composites reinforced with natural fibers, including sugarcane bagasse, coconut, and sisal, added to expanded polyurethane prototypes. The results, evaluated through confidence intervals, indicated that composites reinforced with 5% sugarcane bagasse, 5% and 10% coconut, and 10% and 15% sisal exhibited significantly superior impact absorption performance compared to pure expanded polyurethane. Composites with agave sisalana fibers exhibited low variability and reliable performance, with the 10% concentration showing the best results. Sugarcane bagasse fiber demonstrated strong stability, especially at a 5% concentration. Coconut fiber performed well at both 5% and 10% concentrations but showed the greatest variability among the fibers tested. These findings underscore the potential of natural fibers in enhancing helmet safety and suggest promising directions for future research into the ideal composite materials for motorcycle helmets, an inquiry that is currently underway.

Wrinkled thermoplastic polyamide elastomer foams with enhanced mechanical properties fabricated by dynamic supercritical CO2 foaming

AbstractWrinkled foams (WF), distinguished by their numerous cell wall wrinkles, exhibit superior impact resistance compared to conventional foams (CF), making them ideal for applications such as sports protection and packaging. Despite their potential, the mechanisms behind wrinkle formation remain underexplored, limiting production and process optimization. In this study, we use a custom supercritical foaming reactor with a sapphire glass viewing window to investigate the differences between wrinkled and conventional thermoplastic polyamide elastomer foams. Our findings suggest that “excessive expansion‐shrinkage” is crucial for wrinkle development. Molecular dynamics simulations reveal that molecular chains align with the flow field of dynamic CO2, which increases the intramolecular stress. The release of intramolecular stress triggers wrinkle formation, driven by thermodynamic instability. Furthermore, comparisons of the impact resistance and compression performance between WF and CF show that wrinkled structures alter the deformation behavior under force. The wrinkles facilitate increased collision, squeezing, and friction between cell walls, thus dissipating energy as heat and creating “micro‐air units” that enhance cushioning capability. These distinctive characteristics make WF a promising material for high‐performance applications in cushioning and energy absorption, such as in sports protection and packaging.Highlights Wrinkled polyamide foams are fabricated by dynamic scCO2 foaming. Chain stretching and shrinkage under scCO2 flow are verified by MD simulation. Excessive expansion‐shrinkage foaming behavior causes the wrinkled structure. Wrinkled structure greatly increases the impact absorption ability.

Characterization and Optimization of Mechanical Properties in Laser Powder Bed Fusion Manufactured 316L Stainless Steel

This study investigates the mechanical properties and microstructure of 316L stainless steel fabricated using laser powder bed fusion (PBF-LB) additive manufacturing with different layer thick nesses and orientations. Impact toughness is evaluated under various conditions as well as bending fatigue performance to understand the influence of layer thickness and surface quality on fatigue lim its. Microstructural analysis using scanning electron microscopy (SEM) provides insights into grain structure. Key findings include the superior impact toughness of the vertical orientation, particularly notable in specimens with a layer thickness of 40 µm. Bending fatigue tests revealed distinctive behav ior influenced by layer thickness and surface quality, with the 80 µm thickness and vertical orientation demonstrating lower fatigue limits. These insights contribute to optimizing manufacturing processes and enhancing material suitability for diverse applications.

The Consumption of Beeswax Alcohol (BWA, Raydel®) Improved Zebrafish Motion and Swimming Endurance by Protecting the Brain and Liver from Oxidative Stress Induced by 24 Weeks of Supplementation with High-Cholesterol and D-Galactose Diets: A Comparative Analysis Between BWA and Coenzyme Q10.

The prolonged consumption of D-galactose (Gal) has been associated with severe damage in the liver and brain via exacerbation of oxidative stress, non-enzymatic glycation, and the aging process. The current study was initiated for a comparative assessment of beeswax alcohol (BWA, final 0.5% and 1.0% w/w) and coenzyme Q10 (CoQ10, final 0.5% and 1.0% w/w) against high-cholesterol (HC, final 4%, w/w) and -galactose (Gal, final 30%, w/w)-induced adverse events in zebrafish during 24 weeks of consumption. The survivability of zebrafish decreased to 82.1% due to HC+Gal exposure, but this was substantially improved (91.0%) with the consumption of 0.5% and 1.0% BWA. In contrast, no protective effect of CoQ10 consumption (1.0%) was observed on the survivability of zebrafish. Nevertheless, both BWA and CoQ10 displayed a significant (p < 0.001) preventive effect against HC+Gal-induced body weight enhancement. The HC+Gal-induced cognitive changes, marked by staggered and confused swimming behavior, and retarded swimming speed and motion patterns (restricted to the bottom of the tank), were efficiently restored by BWA. A significantly higher residence time in the upper half of the tank, 3.1-and 4.5-fold reduced latency time along with 3.5-fold and 4.1-fold higher swimming distance, was logged in the 0.5% and 1.0% BWA groups, respectively, than the zebrafish that consumed HC+Gal. In addition, BWA effectively enhanced plasma ferric ion reduction (FRA) and paraoxonase (PON) activity and alleviated the total cholesterol (TC), triglyceride (TG), and blood glucose levels disrupted by the consumption of HC+Gal. Also, the HC+Gal-alleviated plasma high-density lipoprotein-cholesterol (HDL-C) was 2.6-fold (p < 0.001) enhanced in the group that consumed 1.0% BWA, which was significantly 1.5-fold (p < 0.001) better than the effect of 1.0% CoQ10. Similarly, BWA displayed a superior impact over CoQ10 to mitigate HC+Gal-induced plasma AST and ALT levels, hepatic IL-6 production, generation of oxidized species, cellular senescence, and fatty liver changes. Moreover, BWA protects the brain against HC+Gal-induced oxidative stress, apoptosis, and myelin sheath degeneration. Conclusively, compared to CoQ10, BWA efficiently can the HC+Gal-impaired brain and liver functionality to subside and improves the dyslipidemia and cognitive behavior of zebrafish.

Graphene origami with enhanced impact resistance and energy absorption performance

The ancient art of origami has recently shown its potential in engineering intricate three-dimensional graphene structures with unique properties. This study employs molecular dynamics simulations to investigate the dynamic mechanical behavior of graphene origami structures (GOS) under hypervelocity ballistic impact. The analysis of residual velocity, kinetic energy loss, and specific penetration energy shows that GOS exhibit superior impact resistance and energy absorption performance compared with pristine graphene. One reason for the enhancements is that highly flexible GOS can unfold to produce a conical impact zone with larger out-of-plane deformation. Another reason is that three-dimensional folded regions possess more mass, enabling them to dissipate more kinetic energy from the projectile. The impact behavior of GOS is further analyzed concerning projectile size, impact position, and surface roughness. It is found that the impact resistance and energy absorption capacity of GOS can be adjusted by altering the surface roughness, specifically the folding degree and pattern geometry. This GOS holds promise for diverse applications in impact protection, such as combat armor and spacecraft shields.

Enhancing Industrial Safety Helmets: Development and Evaluation of Epoxy-Based Glass and Basalt Fiber Composites

Abstract Employing personal protective equipment, including helmets for safety, at industrial sites is the ultimate step in averting disasters, and such equipment is commonly recognized the disposable items. Industrial safety helmets employ Polypropylene Terephthalate (PET) or polypropylene (PP) resins is the primary material for shell to efficiently absorb impacts. Additionally, they exhibit a commendable level of heat resistance. Nevertheless, there is currently a lack of active initiatives to develop novel materials using a straightforward fabrication approach. The objective of this work was to enhance safety behaviour of industrial helmets by using epoxy resin as the matrix to develop composite material consisting of glass fiber and basalt fiber in a direct cross-ply arrangement. Subsequently, the performance of this composite material was evaluated in relation to glass and basalt composites, and PET plastic. The samples are produced through compression molding method. The tensile strength (TS), flexural strength (FS), impact strength (IS), and inter laminar shear strength (ILSS), and their heat resistance capabilities are assessed using thermo gravimetric analysis (TGA). The impact energy absorptions of BFRP, BF/GFRP, and GFRP were 6.3, 6.1, and 5.2 times higher than that of PET plastic correspondingly. Superior heat resistance was demonstrated by specimens built of Basalt Fiber Reinforced Polymer (BFRP) and Basalt Fiber/Glass Fiber Reinforced Polymer (BF/GFRP), as compared to the other scenarios. For instance, when compared to PET plastic, BFRP was 24.9 times stronger while BF/GFRP was 12.7 times stronger. The outcomes of this research work are showed that the basalt and glass fiber reinforced composites (BF/GFRP) exhibit the superior impact energy absorption than PET plastic.

Superior impact resistance conferred by hierarchical nacre-inspired nanocomposites: A molecular dynamics study

Superior impact resistance conferred by hierarchical nacre-inspired nanocomposites: A molecular dynamics study

Study on Damage Characteristics of Non-equimolar High Entropy Alloy under High-Speed Impact Conditionsalloy

Abstract To analyze the damage characteristics of high-entropy alloys (HEAs) under the coupling of kinetic and chemical energy, we conducted tests on fragment penetration through spaced target A combination of experimental and theoretical analyses was employed to study the damage characteristics and mechanisms of HEAs. The results indicate that, with an increase in impact velocity, the damage area caused by the fragments on both steel and aluminum targets gradually expands, and the energy release process becomes more prolonged. In the study of the damaging effects of HEA fragments on fuel tanks under high-speed impact conditions, the chemical energy of the HEA fragments is released, forming a wide-ranging high-temperature deflagration field, which rapidly ignites upon contact with oil-gas mixtures, resulting in large-area combustion. This, in turn, ignites the remaining kerosene inside the fuel tanks and elucidates the mechanism of fuel tank damage by HEA fragments. The findings demonstrate that the non-equimolar ratio Zr42Ti15Nb20Ta20Al3 (at.%) high-entropy alloy possesses not only excellent penetration capabilities but also superior impact energy release potential, making it a promising candidate for use as an energetic structural material (ESM).

Comparison of the effects on coagulation function and safety of bivalirudin and heparin in patients undergoing percutaneous coronary intervention: A randomized trial.

To analyze the effects on coagulation function and safety of bivalirudin and heparin in patients undergoing percutaneous coronary intervention (PCI) and provide clinical evidence for their application. A total of 42 patients with coronary heart disease undergoing PCI treatment from July 2019 to January 2022 at Datong Third People's Hospital in China were divided into 2 groups: the bivalirudin group and the heparin group. The former received perioperative administration of bivalirudin, while the latter received heparin. After 24 hours of treatment, blood indicators, coagulation functions, as well as cardiac, hepatic, and renal markers were evaluated. Additionally, Thrombolysis In Myocardial Infarction (TIMI) flow graded infarct-related vessel blood flow was assessed in both groups. Adverse cardiovascular and cerebrovascular events were monitored for a duration of 12 months. The Activated clotting time (ACT), D-dimer (D-D), and prothrombin time (PT) levels in the bivalirudin group were significantly lower than those in the heparin group (P < .05). Both the bivalirudin and heparin groups showed significant improvement in TIMI flow grade after PCI (P < .05). The levels of Creatine Kinase-MB (CK-MB), N-terminal Pro-B-type Natriuretic Peptide (NT-proBNP) in the bivalirudin group were significantly lower than those in the heparin group (P < .05). There were no serious adverse cardiovascular and cerebrovascular events in either group. Bivalirudin has a slightly superior impact on coagulation function and safety profile in patients undergoing PCI compared to heparin, and the preventive effect of both on postoperative cardiovascular events is similar.

High impact resistance and energy absorption composite reinforced via shear thickening gel/angle interlocking for flexible wearable protective

The study reveals the combination of shear thickening gel (STG) with angle interlocking fabrics with different thickness direction binding modes to prepare flexible composites. The effect of thickness direction binding modes on flexible composites' ballistic performance and failure mechanisms are systematically investigated. The results reveal that the bullet penetrates STG and yarn simultaneously during the impact phase, causing STG to produce the shear thickening effect. Flexible composites produce synergistic energy absorption. The layer-to-layer structure has a 4.49 % higher ballistic limit than the through-thickness structure, proving superior impact resistance. This investigation aims to enhance the design of lightweight ballistic composites by examining the failure mechanisms of flexible composites in response to ballistic impacts.

Enhancing the flexural capacity of RC beams under various loading rates through strengthening with ultra-high-performance fiber-reinforced concrete

This study investigates the enhancement of impact resistance in reinforced concrete (RC) beams using ultra-high-performance fiber-reinforced concrete (UHPFRC). Three types of steel fibers and two fiber volume fractions (0.75% and 1.5%) were considered. UHPFRC-strengthened RC beams exhibited an increase in flexural strength by approximately 6% at a fiber volume fraction of 1.5% compared to plain RC beams, due to effective crack suppression. Steel fibers in the UHPFRC strengthening layer inhibited the deep propagation of cracks into the compressive zone, resulting in a more gradual decrease in the neutral axis depth of RC beams. Under impact loading, UHPFRC-strengthened beams showed up to 7% lower deflection, with straight steel fibers providing superior impact resistance. RC beams strengthened with UHPFRC including straight steel fibers demonstrated improved residual flexural strength at higher fiber volumes. This highlights UHPFRC's effectiveness in enhancing impact resistance of RC beams according to the fiber type and volume fraction.

Experimental investigation on the local damage behavior of reinforced concrete-stainless steel membrane composite material structures subjected to large-scale missile impact

Large-scale membrane liquefied natural gas (LNG) storage tanks may experience missile impacts caused by wind or explosions during operation. However, the damage and dynamic response of reinforced concrete (RC) and stainless steel membrane (SSM) composite structures of the tank under such impacts remain unclear. This study addresses this gap by investigating the damage characteristics and dynamic responses of RC-SSM composite structures through eight large-scale missile impact tests. The findings reveal that the RC plates exhibit penetration, scabbing, and perforation damage. Failures at the interface between the SSM insulation system and the RC component are attributed to reverse tensile stress exerted on the rear surface of the RC plate, coupled with rebar-induced actions, ultimately resulting in detachment of its protective layer. Additionally, indirect effects from concrete conical plugs and scab fragments contribute to damage in the SSM insulation system. The impact loads cause the corrugations and knots of the stainless steel membrane to flatten, effectively absorbing a significant amount of impact energy. This observation suggests that the corrugated membrane exhibits superior impact resistance compared to flat films. To meet the requirements of "airtightness," this study establishes five damage modes and proposes an evaluation methodology for RC-SSM composite structures under large-scale missile impacts.

The effects of loading direction on the dynamic impact response of additively manufactured M350 maraging steel-Al0.5CoCrFeNi1.5 hybrid plates

Despite the impressive impact strength of maraging steels, which informs their application in the defence industry, they are highly susceptible to cracking resulting from adiabatic shear band (ASB) nucleation when subjected to dynamic loading. Hence, a potential solution to mitigate this problem is needed. In this study, a hybrid plate containing layers of M350 maraging steel and Al0.5CoCrFeNi1.5 high entropy alloy was fabricated using laser-based directed energy deposition (L-DED) additive manufacturing with the aim of combining the high impact strength of M350 maraging steel with the ductility and ASB-resistant properties of Al0.5CoCrFeNi1.5. To determine the effect of loading direction on the impact strength and absorbed energy of the hybrid specimens, cylindrical specimens, with the layers oriented longitudinally and transversely to the cylinder's axis, were cut out of the hybrid plate. High-strain rate testing was performed using an instrumented split-Hopkinson pressure bar (SHPB) to determine the dynamic mechanical response of the specimens. Statistical analyses of the results using generalised additive models (GAM) showed that layer orientation with respect to the direction of impact significantly affects the hybrid specimens' impact strength and absorbed energy. The longitudinally oriented specimens demonstrated superior impact strength across all tested impact momenta. However, the transversely oriented specimens showed higher absorbed energy up to an impact momentum of 32.8 kg ms−1. The Al0.5CoCrFeNi1.5 layer contributed significantly to energy absorption, strain hardening, and the inhibition of ASB propagation in the hybrid specimens.

Non-destructive AC impedance spectroscopy (ACIS) analysis to characterize the evolution of impact damage in UHPC

Ultra-high performance concrete (UHPC) widely serves as protection material owing to superior impact resistance. Rapid and effective assessment of impact damage level is crucial for ensuring structural safety. The non-destructive AC impedance responds sensitively to impact-induced microstructural changes, providing important information for understanding the damage development mechanism. Therefore, this paper intends to investigate the feasibility of AC impedance spectroscopy (ACIS) for UHPC impact damage detection. UHPC specimens with different types and volume fractions of steel fibers were prepared, subjected to multiple repetitive low-velocity hammer impacts to induce cumulative damage, and the impedance responses were simultaneously tested in the frequency range of 10 Hz-5 MHz. Additionally, the effects of steel fiber distribution characteristics and pull-out mechanism on the conductive path and impact resistance were explained through microstructural analysis and 3D reconstructed model. The results show that ACIS exhibits a strong correlation with impact damage, where the increment of the imaginary part can be used as an effective and sensitive indicator to achieve whole-process damage assessment. Compared to straight steel fibers, hooked-end and corrugated fibers greatly enhance the impact resistance of UHPC but cause a nonlinear response in impedance due to extracted deformations and orifice complexities. These findings demonstrate the potential application of ACIS for detecting impact damage in UHPC and warrant further investigation.

The ameliorative potential of platelet-rich plasma and exosome on renal ischemia/reperfusion-induced uremic encephalopathy in rats.

Uremic Encephalopathy results from the elevation of toxins and blood-brain barrier (BBB) disruption. Renal Ischemia/Reperfusion (I/R) injury is the principal cause of acute kidney injury and brain tissue injury. The present study was crafted to estimate the restorative impact of platelet-rich plasma (PRP) and exosome injection before the reperfusion phase on the kidney following renal I/R injury and its influence on brain tissue by tracking the histopathological, biochemical, and Doppler ultrasonography alternations in both kidney and brain tissue. Forty mature male rats were divided into five groups as follows: control, I/R, PRP, exosome, and Exosome + PRP. Renal Doppler ultrasonography was traced for all rats. Serum kidney functions and acetylcholine esterase enzyme (AchE) were evaluated. Both Gamma-aminobutyric acid (GABA) and glutamate were assessed in brain tissues. The oxidative stress (malondialdehyde), anti-oxidative (glutathione and catalase), and pro-inflammatory (Tumor necrosis factor- α and interleukin-6) markers were estimated in renal tissues. Additionally, morphometric histological examination was performed in both renal and brain tissues. Both PRP and exosome-received rats exhibited a significant improvement in both serum kidney functions and AchE compared to I/R rats. There was a 3.39-fold increase in GABA and a 2.27-fold decrease in glutamate levels in the brain tissue of PRP rats compared to the I/R rats. A significant elevation (P ≤ 0.0001) of glutathione and catalase besides a significant reduction in the expression of TNF-α and IL-6 was observed in renal tissue compared to I/R rats. A significant severe reduction (P < 0.0001) in the number of Purkinje cells, pyramidal cells in the cerebellar cortex, and the CA1 region in the hippocampus was observed in I/R rats which was significantly alleviated by both PRP and exosome. Furthermore, there was a significant improvement in Doppler parameters. PRP exerted a significant superior impact on the restoration of kidney functions and repairing uremic-induced damage in brain tissue.

Fireproof Cavity Structure with Enhanced Impact Resistance and Thermal Insulation toward Safeguarding.

Developing devices emphasizing safety protection is becoming increasingly important due to the widespread occurrence of impact damage and thermal hazards. Herein, the F-SSG/TPU-based circular cavity structure (FC) is developed through a convenient and efficient template method, which can effectively achieve anti-impact and thermal insulation for protection. The flame-retardant shear stiffening gel/thermoplastic urethane (F-SSG/TPU) is synthesized through the dynamic interaction between the SSG, TPU, and modified ammonium polyphosphate (APP@UiO-66-NH2) by thermo-solvent reactions. The developed FC can dissipate the impact force from 4.19 to 0.99 kN at 45 cm impacting heights, indicating good anti-impact performance. Moreover, the thermal insulation test demonstrates that the FC achieves a temperature drop of 76 °C at 160 °C attributed to the unique cavity structure design. Under the continuous shock of high-temperature flame, FC remains intact, and its performance is almost undamaged. These results elaborate that the designed FC can effectively resist various damage, such as high-temperature shock and collision. Then, a wearable wristband integrated with FC is developed which exhibits superior impact resistance and heat insulation properties compared with commercial wristbands. In short, this cavity structure based on high-performance F-SSG/TPU material shows promising potential applications in the protection field.

Achieving optimum balance between mechanical properties and gloss of acrylonitrile–styrene–acrylate resin through control of rubber particle size distribution

AbstractPreparation of acrylonitrile–styrene–acrylate (ASA) with high gloss and superior impact properties is still challenging. Here, we developed a new strategy for the preparation of ASA resins by a selective redox initiation method based on a semi‐continuous emulsion polymerization technique. A series of ASA core‐shell impact modifiers were firstly obtained by grafting styrene (St) and acrylonitrile (AN) onto poly(n‐butyl acrylate) (PBA) seeded latexes of different sizes. The ASA core‐shell impact modifier was then used to toughen the styrene–acrylonitrile copolymer (SAN). The synergistic effects between the single particle size of the rubber phase and different particle sizes were systematically investigated, and the mechanical properties of SAN‐toughened resins at various particle sizes of the rubber phase were analyzed. The results revealed that toughened SAN with small particle sizes possessed better gloss, and the impact strength of the doped small‐particle toughened SAN was much higher than that of the single particle size toughened SAN. The ASA graft powders synthesized from large particle PBA (particle size 316 nm) and small particle PBA (particle size 99 nm), respectively, were mixed at a 50/50 ratio and blended with SAN resin, a gloss level reaching 95, and an impact performance of 275 J/m values almost twice those of a single particle size toughened SAN.Highlights Acrylonitrile–styrene–acrylate resins with an impact strength of 275 J/m and gloss of 95 were prepared. The balance between mechanical properties and gloss of acrylonitrile–styrene–acrylate resin was obtained. Polymerization was initiated at low temperature.

Biomimetic Structural Hydrogels Reinforced by Gradient Twisted Plywood Architectures.

Naturally structural hydrogels such as crustacean exoskeletons possess a remarkable combination of seemingly contradictory properties: high strength, modulus, and toughness coupled with exceptional fatigue resistance, owing to their hierarchical structures across multiple length scales. However, replicating these unique mechanical properties in synthetic hydrogels remains a significant challenge. This work presents a synergistic approach for constructing hierarchical structural hydrogels by employing cholesteric liquid crystal self-assembly followed by nanocrystalline engineering. The resulting hydrogels exhibit a long-range ordered gradient twisted plywood structure with high crystallinity to mimic the design of crustacean exoskeletons. Consequently, the structural hydrogels achieve an unprecedented combination of ultrahigh strength (46±3MPa), modulus (496±25MPa), and toughness (170±14MJ m-3), together with recorded high fatigue threshold (32.5kJ m-2) and superior impact resistance (48±2kJ m-1). Additionally, through controlling geometry and compositional gradients of the hierarchical structures, a programmable shape morphing process allows for the fabrication of complex 3D hydrogels. This study not only offers valuable insights into advanced design strategies applicable to a broad range of promising hierarchical materials, but also pave the ways for load-bearing applications in tissue engineering, wearable devices, and soft robotics.

Rapid production of high-performance unilaterally surface-densified wood through integrating mechanical compression and thermochemical modification

Enhancing the mechanical performance and dimensional stability of fast-growing wood in an efficient and eco-friendly manner remains a challenge. This study introduces a straightforward and highly efficient technique for fabricating unilaterally surface-densified (USD) wood from fast-growing poplar wood. This process involves a pre-drying treatment, high-temperature compression at 250 ℃, and subsequent cooling, all completed within a total compression time of 300 s. The produced USD wood exhibits outstanding physical and mechanical properties, along with excellent dimensional stability. Notably, the USD wood achieved a hardness of 4.3 kN, a modulus of rupture of 117.0 MPa, and a modulus of elasticity of 12.2 GPa, representing increases of 104.7 %, 72.0 %, and 38.6 %, respectively, compared to untreated wood, aligning with the properties of several premium hardwoods. Furthermore, the USD wood showed superior impact resistance and bending stiffness, alongside minimal irreversible thickness swelling (2.29 %) under humid and high-temperature conditions, evidencing its robust mechanical and dimensional stability. These improved performances are attributed to the formation of a densified layer with an intact cell wall structure, which benefits from the favorable effects of high temperature-induced plasticization of cell walls and thermal degradation of hemicellulose. The efficacy of this high-temperature compression technique highlights its significant potential for the mass production of high-performance wood from fast-growing species. Consequently, the resulting USD wood is ideally suited for value-added applications in the furniture and construction industries, offering a pathway towards sustainable and eco-friendly manufacturing solutions.