Composites Science and Technology最新文献

The integral structure design is equally crucial to the regulation of electromagnetic components in microwave absorbing materials. In this work, magnetic MXene/polyvinylidene fluoride composites with integral nacre-like structure were prepared by successive hot-pressing process to realize the layered arrangement of Ni anchored MXene (Ni@MXene). The order degree of Ni@MXene from random to orientation can be adjusted by gradually changing compression ratio. Interestingly, increasing the orientation degree of Ni@MXene effectively improves the dielectric constant, minimal reflection loss (RL_min) and effective absorption bandwidth (EAB) of the layered composites. This is attributed to the improved loss ability by increasing the contact areas between Ni@MXene and vertically incident electromagnetic waves, inducing multiple scattering/reflection effect, and the formation of localized conductive pathways. As a result, the layered composite with optimal layered structure delivers the best electromagnetic microwave absorption performance with a RL_min of −69.8 dB and an EAB of 4.77 GHz. Besides, increasing the orientation degree can also optimize the mechanical properties of the layered composites, with the maximum tensile strength and toughness of 32.6 MPa and 115.0 MJ m⁻³, respectively. Therefore, this work proves the adjustability of absorption performance by changing the distribution of absorbents, and integrates the structure and function for microwave absorption materials.

The rapid development of aerospace, intelligent wearable electronics and 5G communications puts forward higher demands for electromagnetic interference (EMI) shielding materials. Herein, the flexible multifunctional magnetic-conductive Janus nanocomposite films with magnetic cobalt carbide nanowires/bacterial cellulose (Co@C NW/BC) blends as the upper side, and conductive Ti3C2Tx MXene as the bottom side are obtained via the layer-by-layer (LBL) vacuum assisted filtration-hot pressing method. The two magnetic and conductive sides endow the Janus nanocomposite films with distinctly different performances in EMI shielding and thermal management. When the electromagnetic waves are incident from Co@C NW/BC side, the films exhibit a high EMI shielding effectiveness (EMI SE) of 49.8 dB with an enhanced microwave absorption (SEA) of 33.9 dB at the ultralow thickness of 43 μm. Meanwhile, the Ti3C2Tx side exhibits improved electrical heating performances with a surface temperature of 120 °C at 6 V voltage, increased photothermal conversion temperature of 77.8 °C upon 2.0 kW/m2 light intensity, as well as excellent thermal stealth properties with a low radiation temperature of 88.4 °C on the 240 °C hot stage. Moreover, the Janus nanocomposite films show a high tensile strength of 80.0 MPa. The resultant Janus nanocomposite films possess great application prospects in highly-efficient EMI shielding and thermal management.

Non-destructive evaluation (NDE) techniques are integral across diverse applications for void detection within composites. Infrared (IR) thermography (IRT) is a prevalent NDE technique that utilizes reverse heat transfer principles to infer defect characteristics by analyzing temperature distribution. Although the forward heat transfer problem is well-posed, its inverse counterpart lacks uniqueness, posing non-unique solutions. The present study performs simulations using finite element analysis (FEA) in defective (a penny-shaped defect) composites through which the heat transfer flux is modeled. A total of 2100 simulations with various defect positions and sizes (depth, size, and thickness) are executed, and the corresponding surface temperature vs. time and vs. distance diagrams are extracted. The FEA outputs provide ample input data for developing an explainable artificial intelligence (XAI) model to estimate the defect characteristics. A detailed feature engineering task is performed to select the representative information from the diagrams. Explainable decision tree-based machine learning (ML) models with transparent decision paths based on derived features are developed to predict the defect depth, size, and thickness. The ML models’ results suggest superb accuracy (R² = 0.92 to 0.99) across all three defect characteristics. The provided workflow sets a benchmark applicable to a range of fields, including health monitoring.

Deformation and fracture of a hydroxyl-terminated polybutadiene (HTPB)/ammonium perchlorate (AP)/aluminum solid propellant under quasi-static tensile loading are investigated by in situ synchrotron X-ray micro computed tomography (CT) and CT-image-based finite element method (FEM) modeling. Bulk stress–strain curve of the solid propellant, and the evolution of particle morphology, and mesoscale strain and particle displacement fields are obtained. Based on tracking and statistics, an automated analytical method is proposed to analyze the relationship between microcrack nucleation and initial structure. The AP particles undergo negligible deformation and orientation changes during tensile loading. Microcracks are mainly nucleated via tension-induced debonding at the maximum surface curvature of the AP particles, and propagate along the curvature gradient around AP particles. Larger AP particles are more prone to debond, and Al particles play a negligible role in deformation and fracture.

Since the inception of fibre-reinforced composite materials, they have been widely acknowledged for their unparalleled weight-to-performance ratio. Nonetheless, concerns are escalating regarding the environmental impact of these materials amidst global warming and pollution. This perspective explores a ground-breaking shift towards harnessing living organisms to produce composite materials. Living composites not only offer sustainable, carbon-capturing alternatives but also afford an unprecedented level of control over shape and anisotropy. Recent advancements in biology, particularly genetic engineering and sequencing, have provided extraordinary control over living organisms. Coupled with ever-evolving additive manufacturing techniques, these breakthroughs enable the construction of engineered living materials from the ground up. Here, we explore the key factors propelling the emergence of engineered living materials for structural applications and delves into the capabilities of living organisms that can be harnessed for creating functional materials, including harvesting energy, forming structures, sensing/adapting, growing and remodelling. Incorporating living organisms can revolutionise manufacturing for renewable and sustainable composite materials, unlocking previously unattainable functionalities.

This study presents a novel computational model to investigate the bending behaviour of thin- and thick-walled composite pipes made from fully bonded fibre-reinforced thermoplastic composite materials. The primary objective is to analyse the stress state and predict potential failure modes of these pipes, which have gained significant interest in the oil and gas industry due to their advantageous properties. The developed model is validated through comparisons with finite element analysis and published results, demonstrating its accuracy and adaptability. Utilising the validated computational model, safety zones for composite pipes with various stacking sequences are established, providing valuable insights into the optimal design of composite pipes under bending loads. Furthermore, the method is employed to determine the maximum bending moment and critical bendable radius of the pipe, revealing the direct correlation between maximum bending moment and bending stiffness, independent of the bending radius. The findings of this study offer practical guidance for the design and optimisation of composite pipes in the oil and gas industry, promoting their adoption as a viable alternative to traditional metal pipes. The developed computational model serves as an efficient and reliable tool for engineers to make informed decisions in the design and selection of advanced composite materials for pipe applications, enabling the optimisation of pipe performance under various bending load scenarios.

Substantial waste of wool textiles, along with a lack of effective treatment technology, has resulted in a significant resource and environmental constraints. Integrating wasted wool textiles with polymer is an effective way to prepare lightweight structural materials, but the resulting properties is closely linked to the interfacial interaction. Here, we proposed an interfacial manipulation strategy to direct interfacial diffusion and aggregation of amide-based nucleating agents (WBG) in polypropylene (PP)/wool fiber (WF) composites. Accordingly, the branched WBG fibers were anchored onto the WF surface to construct an interlocking interface between WF and PP so as to strengthen the interfacial interaction. The formation and regulation mechanism of the branched WBG fibers were demonstrated. Benefited from mechanical interlocking and β-nucleating function of the branched WBG fibers, the interfacial interaction between the WF and PP matrix was enhanced while the formation numerous β-PP was cultivated, endowing the composite with excellent strength and ductility. To demonstrate the application potential of this strategy, waste wool textiles were alternately embedded between WBG-containing PP sheets to create an interlocking interfacial laminate with an exceptional combination of strength and toughness, which is important to upcycle waste wool textiles.

The complex and demanding environments of high humidity, heat, altitude, and intricate electric fields necessitate higher standards for the mechanical, thermal stability, and electric insulation properties of insulating paper. However, a single nanomaterial alone struggles to enhance overall performance. Hence, we propose employing two-phase nanomaterials with distinct dimensions to synergistically enhance the performance of cellulose insulation paper. Accordingly, “simulation design directly guided experimental research” was utilized in constructing nano-BN/nanocellulose/cellulose (nano-BN/NFC/cellulose) models through molecular dynamics simulation, and its mechanical parameters, dielectric properties, thermal stability, and so on were simulated and calculated. Based on simulation results, suitable proportions of nano-BN/NFC/cellulose insulating paper were prepared. Nano-BN and NFC synergistically enhance the mechanical properties of insulating paper. The nano-BN, CNF, and cellulose are arranged layer by layer under the action of gravity, allowing the fillers to overlap diagonally along the plane, synergistically forming a thermally conductive network conducive to heat transfer. Additionally, a strong interfacial effect is formed between the three-phase materials, reducing the overall structure's polarization effect and charge accumulation, and synergistically enhancing electrical insulation performance. The 12%nano-BN/NFC/cellulose (P12) exhibits optimal overall performance and is expected to be used in power equipment operating in special environments with high humidity and heat.

Silica is an important filler of “green tires” while its dispersion in the aid of silane coupling agents emits volatile organic compounds during rubber compounding and its invariably agglomeration in nonpolar rubber matrices enhances strain softening. Herein a highly active deep eutectic solvent (DES), synthesized using stearic acid as hydrogen bond donor and tetrabutylammonium chloride as hydrogen bond acceptor, is used to tailor reinforcement and softening behaviors and to replace the silane coupling agents for preparing volatile organic compounds-free nanocomposites. The results show that DES can regulate the crosslinking network structure of rubber matrix and accelerate the vulcanization by reacting with non-rubber components in natural rubber (NR) and by improving the proportion of disulfidic linkage. Furthermore, DES is able to improve the dispersion of silica, crosslinking density of NR and the interfacial interaction between silica and NR, and slow down the thermo-oxidative aging behavior. It could also weaken the damping and softening accompanying Mullins effect for the nanocomposites vulcanizates at high strains. In comparison with silane, DES endows the nanocomposites with superior vulcanization and mechanical properties, providing guides to mediate the reinforcement and strain softening behaviors and manufacture high-performance “green tires” in an energy-efficient approach.

Knitted fabrics with easily deformable loop structure have the potential in the development of shape memory polymeric composites with large recovery deformations. The knitted fabric reinforced shape memory epoxy polymer composites (SMPC) were prepared in this work. The effects of loop densities, orientations and bending radii on shape memory properties of SMPC were investigated. The shape fixity ratio and shape recovery ratio of SMPC subjected to U-shaped bending radius of 5 mm are above 98 %. The shape recovery force of SMPC can reach up to 5.9 N. The thermodynamic properties of SMP were also characterized to obtain mechanical parameters and a user-defined material subroutine (UMAT) of shape memory epoxy polymer (SMEP) was written. Based on viscoelastic theory and the multi-scale geometrical structures, the macroscopic homogeneous thermodynamic model and mesoscopic thermodynamic model of knitted fabric reinforced SMPC were established to study the macro-scale stress distribution and meso-scale deformation evolution during shape memory process, respectively. The neutral surface position of SMPC during bending deformation is offset inner. The unique anisotropic loop structure of knitted fabric determines the shape memory behavior of the SMPC. Finally, micro-CT characterizations of knitted fabric reinforced SMPC were conducted to further understand the loop deformation mechanism during shape memory process. This study will provide important theoretical and technical support for large deformation structure design and deformation prediction of smart composites.