ABSTRACT Despite growing interest in engineered bamboo for sustainable construction, the post‐heating compressive behavior and failure mechanisms of glued laminated bamboo (GLB) remain inadequately understood, hindering reliable post‐fire safety evaluations. This paper presents a multi‐scale investigation on the compressive behavior and failure mechanisms of post‐heated GLB. Specimens were exposed to temperatures ranging from 20°C to 250°C and subsequently tested under axial compression at ambient conditions. The study characterizes failure modes, stress–strain responses, mass loss, compressive strength, and elastic modulus, supplemented by thermal analysis, microstructural imaging, and acoustic emission (AE) monitoring. The results reveal a distinct temperature‐dependent transition in failure mechanisms: fiber buckling and mixed‐mode failures dominate below 150°C, whereas adhesive‐layer splitting and brittle fracture prevail above 200°C. Compressive strength initially increases up to 150°C but then drops sharply, attributable to carbonization; conversely, the elastic modulus remains largely unaffected, suggesting that fiber stiffness is preserved after heat exposure. Thermal analysis indicates that the phenolic resin adhesive retards bamboo decomposition and facilitates residual char formation, creating a protective layer that enhances thermal stability. Microstructural evidence confirms progressive pyrolysis of parenchyma cells, interfacial debonding, and adhesive aging with rising temperature, while AE signals consistently corroborate the heightened brittleness of post‐heated specimens. By elucidating the coupled thermo‐mechanical pyrolysis mechanisms across multiple scales, this study provides essential experimental data and theoretical insights for post‐fire assessment and rehabilitation of bamboo structures.
ABSTRACT This study presents a comprehensive approach to optimizing key processing parameters using the vacuum‐bag‐only hand lay‐up method for unidirectional carbon fiber‐reinforced polyamide 11 laminates intended for novel lightweight hydrogen pressure vessels. The influence of processing parameters: consolidation temperature (200°C–300°C), dwell time (15–60 min), and cooling rate (slow, medium or fast) on mechanical behavior was systematically investigated through experimental multiscale analysis. All tensile tests were conducted under a loading condition perpendicular (90°) to the fiber orientation in the composite matrix to investigate the effect of process parameters on the quality of fiber/matrix adhesion. The measured cross‐sectional void area fraction decreased from 3.53% at 200°C to 0.25% at 210°C and 0.02% at 220°C–230°C, demonstrating markedly improved consolidation. Consequently, structural defects are significantly reduced at 220°C and 230°C, supporting the superior tensile strength and modulus obtained from quasi‐static tests in this window. Additionally, machine learning models were employed to predict optimal fabrication conditions. The combined experimental and AI‐assisted analysis identified 225°C, 30 min of dwell time, and medium cooling rate as the optimal processing parameters providing a favorable balance between mechanical performance and microstructural integrity. Experimental validation at the identified optimal processing conditions demonstrated close agreement between the predicted and measured values, with prediction accuracies of 94.9%, 93.2%, and 96.8% for ultimate tensile strength, elongation at break, and Young's modulus, respectively. These findings highlight the potential of AI‐assisted process optimization to enhance the manufacturing efficiency for sustainable hydrogen storage applications.
ABSTRACT Natural fiber‐reinforced polymer composites (NFRPCs) have emerged as sustainable alternatives to conventional synthetic fiber composites, owing to their low density, renewability, biodegradability, and favorable specific mechanical properties. In the past 5 years, they have demonstrated considerable promise in numerous applications spanning aerospace, automotive, wind energy, rail transit, marine engineering, and sports equipment. This review synthesizes the recent advancements in natural fibers and their polymer composites from 2021 to 2026, covering the classification and extraction of natural fibers, and the fabrication, interface modification, and performance characterization methods of NFRPCs. The current application landscape of NFRPCs is further discussed, including both conventional engineering sectors and emerging frontier domains. Although notable achievements have been made in fiber extraction, surface modification, interface engineering, multifunctional structural design, and performance optimization of specific polymer composites, large‐scale applications remain constrained by several challenges, including interfacial debonding, limited thermal resistance, fiber batch‐to‐batch variability, and long‐term durability. To address these issues, this review suggests that future research should prioritize advanced interface design, green low‐consumption processing technologies, hybrid reinforcement strategies, and multifunctional bio‐based composites. This work aims to provide a resourceful data resource for future research in the efficient extraction and performance regulation of novel natural fibers, as well as for the structural design and performance optimization of NFRPCs.
ABSTRACT The ability to tailor material properties within a single composite structure is becoming increasingly important for lightweight applications requiring a balance of stiffness, toughness, and thermal stability. In this study, multiplexed co‐extrusion was integrated with additive manufacturing–compression molding (AMCM) to fabricate skin–core thermoplastic composites. The hybrid consisted of a glass‐fiber‐reinforced polycarbonate (PC/GF) skin surrounding a carbon‐fiber‐reinforced acrylonitrile butadiene styrene (CF/ABS) core, combining the heat and impact resistance of PC/GF with the high stiffness of CF/ABS. Morphological analysis confirmed preservation of the skin–core architecture and preferential carbon‐fiber alignment along the print direction. Rheological characterization revealed shear‐thinning behavior in both materials and a reduction in their viscosity contrast with increasing angular frequency. CF/ABS exhibited the highest tensile strength (84.27 MPa) and modulus (14.92 GPa), whereas the hybrid achieved a tensile strength of 64.16 MPa and a flexural modulus of 5.19 GPa, the latter representing an approximately 56% increase relative to PC/GF. Under the tested flatwise, print‐direction impact configuration, the hybrid exhibited approximately 130% and 15% higher impact resistance than CF/ABS and PC/GF, respectively, demonstrating the influence of the skin–core architecture on impact response. The hybrid also exhibited a heat deflection temperature approximately 9°C higher than that of CF/ABS while retaining distinct thermomechanical transitions associated with both constituent phases. These results demonstrate the potential of the integrated multiplexed co‐extrusion and compression‐molding process for manufacturing architected thermoplastic composites with tailored mechanical and thermomechanical performance for lightweight structural applications.
ABSTRACT Embedded co‐cured damping composites (ECDCs) have been developed as a potential approach to address the stiffness–damping trade‐off in lightweight load‐bearing structures. By embedding viscoelastic layers during co‐curing, ECDCs reduce the interfacial limitations associated with conventional bonded damping treatments while maintaining structural performance. This review summarizes ECDC systems from structural design to performance prediction. Recent progress in interfacial mechanisms, multiscale structural evolution, theoretical modeling, numerical simulation, and experimental characterization is reviewed, with emphasis on the relationship between material architecture and mechanical, dynamic, and vibro‐acoustic responses. The literature indicates a shift from material‐level damping modification toward multiscale structural design and performance‐driven development. However, existing investigations are yet to fully address challenges such as fabrication‐ and assembly‐induced damage, preload relaxation during long‐term service, environmental degradation, and lifecycle reliability assessment. By consolidating current knowledge across structural design, modeling, simulation, and experimental validation, this review provides an integrated overview of ECDC development and identifies key issues affecting their engineering application.
