Composite Structures Research Articles

Numerical Simulation and Design of Progressive Collapse of Steel Frame Composite Structures Considering Falling-Floors Impact

Numerical Simulation and Design of Progressive Collapse of Steel Frame Composite Structures Considering Falling-Floors Impact

Geometric tunability of interlaminar resistance

The inherent weakness and variability in the interlaminar properties of composites and associated delamination pose significant challenges, compromising the performance of composite structures. This study investigates a strategy to tailor the apparent interlaminar resistance by altering the geometry of the interface to control crack propagation. We have developed analytical models, which propose a formulation that links the geometry, i.e. the interface width change rate and shape factor of the crack growth plane, with the reaction force–displacement curve. The results obtained, a family of power law relations followed during interlaminar crack growth, indicate that the analytical formulation is valid for all geometries tested, including those with significant width change rates; however, it may not always be easy to use or interpret. An approximated solution, constrained to slowly varying geometries, is also proposed. The limits of using this model are presented and discussed. The final validation of the models is performed using numerical and experimental approaches, considering the delamination of carbon fibre laminates. This work offers new insights into the design of composites and the fracture process in general, featuring unique shapes and improved crack resistance. It also addresses practical issues, e.g., related to composite repairs, which can enhance the performance and longevity of composite structures. Specifically, the proposed formulations can be easily adopted to obtain optimized patch geometries.

Multi-layer formation by oxidation and solid-state crystallization of cold sprayed amorphous coatings during dry sliding wear

Amorphous alloy coatings, known for the exceptional wear resistance, have emerged as a key solution for enhancing the wear performance of magnesium alloys under harsh environments. In this study, Fe-based amorphous alloy coatings were deposited on magnesium alloy by cold spraying technology, and the influence of microstructural evolution on the wear performance of coatings under dry sliding wear conditions was discussed. The results showed that a dense adherent oxide layer with a thickness of ∼700 nm comprising nanograins of less than 8 nm was formed at the outmost surface, which played a role of self-lubricating. Underneath, a 1 μm thick nanocrystalline-amorphous layer with nanograins of ∼20 nm dispersed in the amorphous alloy matrix was formed through in-situ crystallization induced by flash temperature. This composite structure prevented the formation of shear bands in amorphous alloys and enhanced the durability. Therefore, the transition from abrasive wear to adhesive wear was a consequence of the microstructural evolution from a dual-phase composite layer to a self-lubricating oxide layer.

Development of high flux photocatalytic agcl-cooh-mwcnt/pes ultrafiltration membranes for enhanced waste water treatment and fouling mitigation

A structurally stable AgCl-COOH MWCNT/PES composite membrane was designed and fabricated by combining phase conversion and post-treatment techniques, which can solve the serious membrane fouling in industrial wastewater treatment. The carboxylation of MWCNTs not only enhanced their dispersion but also facilitated their binding with silver chloride, resulting in a stable composite structure that significantly improved contaminant degradation capabilities. The post-treatment technique increased the membrane’s water purification flux by 150 % (reaching 520 L·m2·h−1·bar−1) while maintaining a high BSA retention rate of 95 %. Additionally, the composite membrane demonstrated excellent photocatalytic antifouling properties, with a flux recovery rate of 91.8 % under UV irradiation, and exhibited more than 99 % inhibition of Escherichia coli. This method provides a scalable solution for enhancing the performance of PES membranes in wastewater treatment applications.

Experimental investigation on seismic performance of a super high-rise mega frame-double core tube composite structure

Increasing population density and urbanization have intensified the need for high-rise buildings in recent years. The seismic resistance of high-rise buildings should be carefully concerned in seismic regions, especially for super high-rise buildings which are most vulnerable to long-period earthquakes. This paper introduced the model design of a 499 m super high-rise mega frame-double core tube composite structure and presented the shaking table test results of the 1/50 scaled structural model. This super high-rise building possesses many conducive merits to resist seismic hazard, including steel reinforced concrete members, high-strength concrete and double core tube. In the test, there were three groups of long-period earthquakes and four incremental seismic intensity levels considered. The test phenomena indicated that the coupling beams of exterior tube were the first line of defense to resist seismic actions. The existence of inner tube improved the shear resistance of this building and there was no observed shear damage on the walls. Based on the instrumented data, the vibration characteristics, acceleration, displacement and strain responses of the structure were reported. The seismic performance of this super high-rise building meets the requirements of design specifications and its collapse resistance capacity is physically proved under severe earthquakes. However, the whiplash effect of acceleration is serious on the roof due to the reduction of mass and constraint for the mega column end. Furthermore, the inter-story drifts and strain responses of trusses in the top region are significantly larger. For the seismic measurement, great attentions should be paid to the exterior coupling beams and structural members in the top region of this super high-rise building. The presented work provides well experimental confirmation and reference for super high-rise buildings with mega frame-double core tube composite system.

A model-based deep learning framework for damage classification and detection in polycarbonate infused with AEROSIL under dynamic loading conditions

Composite 3D printing is a significant engineering application owing to its robustness, ability to achieve complex geometries, and ease of use. Polycarbonate, particularly when infused with AEROSIL, is an interesting thermoplastic and potential candidate for 3D printing with enhanced properties. The primary objective of this research is to develop a new model-based deep-learning framework to classify and detect damage in this material under dynamic loading conditions. To achieve this, a FASTCAM high-speed camera was placed in front of the SHPB test setup to capture dynamic damage. The test results were then used as label inputs for training the advanced deep learning algorithms, focusing on dense image recognition techniques for detailed damage analysis. The study involved a series of fully convolutional networks (FCNs), evaluating semantic segmentation with U-Net and instance segmentation with state-of-the-art frameworks such as YOLOv8 and Mask R–CNN. A comparative analysis revealed that deep learning models outperform traditional methods, providing efficient and accurate damage classification and detection. The U-Net model demonstrated the ability to recognize cubes and bars but was limited in detecting minor damage regardless of size. YOLO-V8, which specializes in case segmentation, achieved remarkable performance in detecting significant damage but struggled to accurately identify minor damage. By leveraging deep learning techniques, this study enables an efficient and accurate damage assessment, which is crucial for ensuring the reliability and safety of composite structures in various industries.

Investigating the effect MXene reinforcement on the mechanical and vibrational behaviour of honeycomb core sandwich composite structures

Investigating the effect MXene reinforcement on the mechanical and vibrational behaviour of honeycomb core sandwich composite structures

In situ preparations of bi-continuous interpenetrating porous composites with high energy absorption

In this paper, porous composites with bi-continuous interpenetrating aluminum foam (AF) and lattice structure were prepared via different sequences. The effect of the preparation sequence on the mechanical properties was analyzed. The results showed that the composites prepared by disordered-ordered and ordered-disordered sequences had higher mechanical properties than the sum of their single components. Porous composite prepared by the disordered-ordered sequence had a discontinuous interface while the one prepared by the ordered-disordered sequence presented a continuous bonding interface and a bubble-free layer. The energy absorption of the porous composite structure prepared by the disordered-ordered sequence was enhanced by the factors of 0.89 and 1.12 over the sum of their single components, while the ordered-disordered was enhanced by the factor of 1.9 and 3.81, which was attributed to the metallurgical bonding, 3D mechanical constraints and the fraction of bubble-free layer that formed between the interfaces. The continuous interface contributed the excellent mechanical properties of the composites due to its higher failure strength before detaching. The presence of the bubble-free layer increased the interfacial contact area, which can effectively absorb energy and exhibit significant deformation resistance. The porous composite exhibited excellent comprehensive performance, which provided a new idea for the structurally and functionally integrated design of porous composites.

Highly durable yarn-based strain sensor with enhanced underwater monitoring capabilities and rapid drowning detection for safety applications

Flexible strain sensors have garnered significant attention for their outstanding performance in fields such as telemedicine, motion management, and human–machine interfaces. However, in the demanding marine environments, these advanced sensors face challenges related to mechanical weakness, stability, and durability under wet conditions, which are critical for expanding their range of practical applications. In this study, a stable and durable yarn sensor was developed specifically tailored for underwater activity monitoring. This was achieved by using polydopamine to immobilize silver nanoparticles, thereby creating a highly conductive layer, followed by applying an impregnation coating to establish a hydrophobic layer. The resulting composite structure featured a micro-convex layer of silver nanoparticles, which provided a durable hydrophobic surface resistant to mechanical wear and capable of maintaining its electrical properties even under high-velocity water impacts. More significantly, a FWAS was engineered, which is activated by pre-stretching the yarn sensor using a water-soluble vinylon yarn. The FWAS automatically alters its resistance within 1.3 s upon detecting someone falling into the water, thereby sending out an accurate distress signal to the external world by transmitting Morse code signals via gesture movements. This innovation provides a straightforward and effective approach for timely rescue operations from drowning, demonstrating the versatility of yarn-based flexible strain sensors for use not only in air but also in underwater scenarios.

Research on microstructure evolution of laser surface quenching of ductile cast iron

Abstract Ductile cast iron is widely used in the manufacturing of components and dies due to its excellent performance and low cost. Laser surface quenching can further improve its performance and extend its service life. This article uses scanning electron microscopy, electron backscattered scattering detection and microhardness tester to systematically analyse the microstructure evolution of the melted zone, hardened zone, and matrix of ductile cast iron with laser surface quenching. The hardening zone can be divided into two layers: one layer contains a large amount of martensite, graphite, and bits of residual austenite, and the other layer contains a composite structure of graphite, ferrite, layered martensite+austenite+Fe3C. On the basis of microstructure research, the determination and optimization methods of the depth of the laser surface hardening zone and the process are formed, providing a basis for the selection and optimization of the laser surface hardening process for ductile cast iron.

Fracture properties of bamboo fibrous composites: a systematic review

As a fast-growing grass, bamboo has received a great deal of attention due to the excellent mechanical performance. The unique properties of bamboo come from its natural composite structure - a kind of natural fiber reinforced composites, which is composed of bamboo fibers (reinforcement) and parenchyma tissue (matrix). Based on raw bamboo, man-made bamboo fibrous composites such as engineered bamboo and bamboo fiber reinforced polymeric composites have emerged. These materials eliminate some inherent shortcomings of bamboo, which can provide more stable material performance and achieve dimension alteration according to requirements. All of these bamboo fibrous composites have orthotropic structure, the mechanical properties of which in the longitudinal direction far exceed that in the transverse direction, and the tensile strength and compressive strength can reach 111-114.8 and 104.7-115.7 MPa respectively. Besides, the interfacial zone between fiber and matrix is weak, in which some defects are usually existed, such as micro-cracks and adhesive voids. As a result, cracks in the composites are inevitable, which are easy to extend in the longitudinal direction and result to fracture failure. Consequently, fracture studies become necessary for evaluating the crack-resistance ability of bamboo fibrous composites. This paper systematically introduces the previous research works on the fracture properties of bamboo fibrous composites. Firstly, this paper summarized the test methods for different fracture modes including Double cantilever beam (DCB), Single-edged notched beam (SENB), Compact tension (CT), etc., meanwhile the corresponding calculation theories such as Compliance calibration (CC), Modifed compliance calibration (MCC) and Modified beam theory (MBT) are also elucidated. Subsequently, the fracture behaviors and mechanisms of various bamboo fibrous composites are analyzed, in which the fracture parameters and crack-resistance capabilities are compared. In addition, considering the limitations of current research, the future research in need on the fracture properties of bamboo fibrous composites are discussed, the conclusion can be used in providing important reference for the safety evaluation of bamboo fibrous composites.

Numerical analysis of fiber reinforced composite material for structural Component Application

Nowadays, convectional metallic material replaced by composite materials, because composite materials have superior than metallic materials properties such as light weights, higher strength-to-weight ratio, high tensile strength, Low cost, greater design flexibility, better fatigue resistance, renewability, and biodegradability. These properties of composite material are the most basic & common attractive features that make them useful for industrial applications. The main objective of this work is to contribute for a better understanding of the static behavior of structure made from fiber reinforced composite materials, specifically for the case of plate structures. The plate model is created using SOLIDWORKS 2017 and then imported into ANSYS R18.1. The study specifically examines three stacking sequences of the composite plate (angle ply, cross ply, and multidirectional ply) to analysis stress and deformation resulted from the loads. The static analysis of a Carbon/Epoxy with honeycomb plate composite reveals that the equivalent stress and deformation are lower in the cross-ply stacking sequence compared to the angle ply and multidirectional ply for the same load carrying capacity. This suggests that the composite plate with a cross ply configuration is more suitable for manufacturing composite structures due to its improved performance.

Highly transparent inorganic superhydrophilic coatings with sustainable anti-fogging and mechanically robust underwater anti-oil-fouling capabilities

Inorganic coatings with high transparency and superhydrophilicity have attracted tremendous attention because of their potential applications in marine environment monitoring, and oily wastewater treatment. However, the transparency and superhydrophilicity are usually mutually exclusive. Herein, we present a new facile strategy for fabricating highly transparent and mechanically robust superhydrophilic inorganic coatings with outstanding anti-fogging ability and anti-oil-fouling performance for high-viscosity oils. In this strategy, amorphous calcium phosphate (ACP) coatings are mineralized on the surface of polydopamine and polyethylenimine (PDA/PEI) membranes under the synergistic effect of magnesium ions, citric acid, and poly(acrylic acid) at room temperature, forming an organic-inorganic composite structure with a uniform texture on various substrates. Owing to the strong hydration capacity of ACP, these coatings are highly efficient at preventing surface fogging and avoiding underwater crude oil fouling. Meanwhile, the ACP coating without grain boundaries or pores can reduce light scattering, thus maintaining the high transparency of the substrate. Moreover, the organic-inorganic composite structure endows the coatings with robust mechanical properties. This PDA/PEI-ACP mineralized coating can be deposited on various substrates, showing potential applications in underwater optical lenses, oily wastewater treatment, microfluidic devices, and other areas.

Fabrication and multiscale heat transfer modeling of high thermal conductivity Cf/HfB2-SiC composites

With the increasing Mach numbers of hypersonic vehicles, extreme aerothermal environments impose substantial challenges on vehicle materials. High thermal conductivity materials facilitate rapid heat redistribution to diminish localized thermal accumulation and reduce material thermal damage, providing a viable route for further enhancing the operational temperature of materials. Here, we successfully fabricate high thermal conductivity Cf/HfB2-SiC composites through the solid–liquid combination process, achieving an x-direction thermal conductivity of 161.11 W/(m·K), which represents an order of magnitude improvement over traditional carbon fiber-reinforced ultra-high temperature ceramic composites. 3D X-ray computed tomography (CT) is employed to analyze the structural composition of the high thermal conductivity Cf/HfB2-SiC composites, and the Gaussian Mixture Model is applied to segment the CT images, thus establishing a mesoscale representative volume element (RVE) model based on CT. Combining theoretical models and finite element analysis, we propose a multiscale heat transfer model for high thermal conductivity Cf/HfB2-SiC composites, which effectively investigates the heat transfer mechanisms of the composites. The fabrication and multiscale heat transfer modeling of high thermal conductivity Cf/HfB2-SiC composites provide a theoretical basis and guidance for enhancing material performance and design optimization.

Biomimetic structure-driven high strength and toughness in continuous SiC skeleton-reinforced graphite composites

Graphite-matrix structural composites with excellent mechanical properties and long-term reliability are ungently required in aerospace and nuclear industries. However, the enhancement of graphite-matrix composites by mainstream surface coating techniques or second-phase particle reinforcement is rather limited. Inspired by the structural-functional feature of plant cells, silicon carbide (SiC, cytoderm) coated mesocarbon microbeads (MCMB, cytoplasm) powders were prepared by combustion synthesis (CS), which were then densified via spark plasma sintering (SPS) to obtain the biomimetic cellular-structured SiC-reinforced MCMB (M@SiC) composites. The in-situ formed SiC ‘cytoderm’ ensures good interfacial bonding and contributed to the densification of the composites. Additionally, the continuous SiC skeleton and cellular-structured configuration improved the mechanical properties of M@SiC composites. Owing to the complex crack deflection, branching and bridging effects at the MCMB/SiC interfaces and graphite nanoflakes inside MCMB, the biomimetic M@SiC composite with SiC content of 47 vol% exhibited strengthening and toughening, with flexural strength and fracture toughness of 245 MPa and 3.82 MPa m1/2, respectively. The developed biomimetic graphite-matrix composites with excellent mechanical properties are expected to be applied in reusable spacecrafts and high-temperature gas-cooled reactors.

First Data on the Structure and Lithological Composition of the Kola Fjord (Bay) Deposits Section

Studying the materials from drilling of engineering-geological wells and other data the structure of a sedimentary cover of the Kola fjord on its total thickness is for the first time lighted. The characteristics of the structure and lithological composition of a section of deposits, and the main forms of a relief of the underlying crystalline substrate are provided. Situations of the formation of deposits and the graben structure of the gulf are considered. It is noted that the deglaciation has served as the trigger mechanism that has started processes of the differentiated block uplift, development of fracture, and a fault formation which has caused initial “exogenous” phases of neotectonic destruction of crust. The horizontal movements have led to the stretching of the earth’s crust and separation of blocks with a graben formation in Kola Bay according to the authors with the influence of stress fields coming from developing young oceanic spreading basins.

Thermal Protection Performance Evaluation Based on Structural Composition Changes of the Intermediate-Layer Fabric in Thermal Protective Clothing

This study is a follow-up to ‘Research on the Development of Fabrics for Industrial and Firefighting Protective Clothing and Comparison of Flame Retardant Performance,’ focusing on the thermal protection performance of clothing designed to protect the human body from high temperatures and heat in industrial settings and fire scenarios. In this study, additional thermal protection performance tests were conducted to provide a more comprehensive analysis. Aside from the flame-retardant performance evaluation conducted according to ISO 15025 on 12 base fabrics with different yarn compositions, the following thermal performance studies were carried out: radiant heat protection (ISO 9151), convective heat protection (ISO 6942), and combined radiant and convective heat protection (ISO 17492). The heat-transfer index of the intermediate layer, which plays a crucial role in the thermal protection performance of thermal clothing, was also assessed. The results indicated that although most of the 12 base fabrics offered a certain level of thermal protection, some of them melted and failed to provide adequate thermal protection.

Additive manufacturing of polymer composite millimeter‐wave components: Recent progress, novel applications, and challenges

AbstractWith the advent of 5G/6G for radar and space communication systems, various millimeter‐wave (MMW) components are rapidly innovated for multi‐functional, higher integrated and miniaturized solutions across diverse industries and applications. Polymer composites‐based additive manufacturing (AM), an advanced manufacturing technique, can manufacture MMW components with high fabrication resolution, intricate structural design, adjustable dielectric properties, and functionally gradient distribution characteristics. This paper outlines the state‐of‐the‐art polymer composite MMW components, their design, and manufacturing techniques. An integrated “material‐structure‐manufacturing‐performance” design conceptual framework of polymer composite MMW components is discussed in terms of material design, structure design, and process design. Moreover, multi‐functional polymer composite MMW structures focus on electromagnetic wave absorption and electromagnetic interference (EMI) shielding functions. Moreover, novel applications of MMW polymer composite components enabled by AM on radar/sensing, communication, enclosure, and miscellaneous applications are discussed. Furthermore, future perspectives and current challenges are identified to provide new insights into multi‐functional 3D‐printed MMW products, exploring new possibilities for next‐generation advanced MMW technology.Highlights The 3D‐printed MMW components and additive manufacturing are reviewed. The integrated “material‐structure‐manufacturing‐performance” concept is introduced. 3D‐printed MMW components are discussed on radar, enclosure, and miscellaneous applications. Future perspectives and challenges of 3D‐printed MMW components are addressed.

Adsorption Properties and Mechanisms of Methylene Blue by Modified Sphagnum Moss Bio-Based Adsorbents.

The abundant pore structure and carbon composition of sphagnum peat moss render it a bio-based adsorbent for efficient methylene blue removal from wastewater. By utilizing sphagnum moss sourced from Guizhou, China, as raw material, a cost-effective and highly efficient bio-based adsorbent material was prepared through chemical modification. The structure and performance of the modified sphagnum moss were characterized using SEM, EDS, FTIR, and TGA techniques. Batch adsorption experiments explored the effects of contact time, adsorbent dosage, pH, initial dye concentration, and temperature on adsorption performance. Kinetics, isotherm models, and thermodynamics elucidated the adsorption behavior and mechanism. The modified sphagnum moss exhibited increased surface roughness and uniform surface modification, enhancing active site availability for improved adsorption. Experimental data aligned well with the Freundlich isotherm model and pseudo-second-order kinetic model, indicating efficient adsorption. The study elucidated the adsorption mechanism, laying a foundation for effective methylene blue removal. The utilization of modified sphagnum moss demonstrates significant potential in effectively removing MB from contaminated solutions due to its robust adsorption capability and efficient reusability.

Regulations of Thermal Expansion Coefficients of Yb1−xAlxTaO4 for Environmental Barrier Coatings Applications

Environmental barrier coatings (EBCs) are widely used to protect ceramic matrix composites (CMCs, SiCf/SiC, and Al2O3f/Al2O3), and they should have low thermal expansion coefficients (TECs) matching the CMCs and excellent mechanical properties to prolong their lifetime. Current EBC materials have disadvantages of phase transitions and insufficient mechanical properties, which affect their working temperatures and lifetime. It is necessary to develop new oxide EBCs. Ytterbium tantalate (YbTaO4) is a stable and novel EBC material, and we have improved the mechanical properties and TECs of Yb1−xAlxTaO4 (x = 0.05, 0.1, 0.2, 0.3, 0.4, 0.5) ceramics by replacing Yb with Al. XRD, SEM, and EDS are used to verify the crystal and microstructures, and nano-indentation is used to measure the modulus and hardness when changes in TECs are measured within a thermal expansion device. The results show that the phase structure of Yb1−xAlxTaO4 (x = 0.05, 0.1, 0.2, 0.3, 0.4, 0.5) is stable at 25–1400 °C within air atmosphere, and their high-temperature TECs (6.4–8.9 × 10−6 K−1, 1400 °C) are effectively regulated by introductions of different contents of Al, which enlarge their engineering applications for SiCf/SiC and Al2O3f/Al2O3 CMCs. The evolutions of TECs are analyzed from structural characteristics and phase compositions, and the increased TECs make Yb1−xAlxTaO4 potential EBCs for Al2O3 matrixes. Due to the high bonding strength of Al–O bonds, hardness, as well as Young’s modulus, are enhanced with the increasing Al content, with Yb1−xAlxTaO4 (x = 0.05, 0.1, 0.2, 0.3, 0.4, 0.5) having a nano-hardness of 3.7–12.8 GPa and a Young’s modulus of 100.9–236.6 GPa. The TECs of YbTaO4 are successfully regulated to expand their applications, and they match those of Al2O3 and SiC matrixes, as well as displaying improved mechanical properties. This work promotes applications of YbTaO4 as potential EBCs and provides a new way to regulate the TECs of tantalates.