Search Results (1,057)

Graphene is a novel material that can bring several advantages in the composite materials manufacturing field, such as improved electrical and thermal properties, and high performance. In particular, functionalizing current composite materials can bring advantages in the aerospace field in thermal management for electric aircraft engines. This paper studies the addition of graphene particles into carbon fiber composites manufactured by the Resin Transfer Molding Process (RTM). Thermal and mechanical properties are evaluated and compared with a conventional composite laminate. Major improvements were achieved on the thermal behavior of the composite material while maintaining general properties, but in particular, the addition of graphene had a negative impact on transverse tensile and mode II fracture toughness due to agglomerates present in the fiber–resin interface. Full article

Multilayer packaging—engineered by integrating complementary materials such as plastics, paper, and aluminum—has become a cornerstone technology for enhancing shelf life, minimizing spoilage, and reinforcing the mechanical integrity of packaging formats including films, pouches, and bottles. In this study, a laminate was developed by thermally bonding polylactic acid (PLA) with a poly(butylene adipate-co-terephthalate) (PBAT)/thermoplastic starch (TPS) matrix embedded with silver nanoparticles (Ag-NPs) at 0–3 wt.%. The resulting structures were systematically evaluated for their barrier performance, physicochemical characteristics, and antimicrobial functionality. Fourier-transform infrared (FTIR) spectroscopy confirmed the absence of chemical interactions between Ag-NPs and the polymer matrix, indicating physical dispersion rather than chemical bonding. However, at higher loading (3 wt.%), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) revealed notable nanoparticle aggregation. Functionally, the multilayer films demonstrated markedly improved water vapor barrier properties compared to single-layer PBAT/TPS films. Migration studies showed that silver release increased with nanoparticle concentration and was significantly enhanced under acidic conditions relative to distilled water. Importantly, Ag-NP-incorporated laminates exhibited pronounced antibacterial activity against Staphylococcus aureus. Collectively, these findings highlight the potential of Ag-NP-enriched, starch-based multilayer laminates as next-generation active packaging systems that combine with effective microbial control. Full article

This paper presents a new plane stress model for the dynamic analysis of multilayer composite beams with interlayer slip effects. In this model, the cross section of a multilayer composite beam is transformed into an equivalent plane stress cross section. Based on the equilibrium, constitutive and geometric equations of the plane stress problem, state equations are derived in terms of a set of state variables. The state variables are then expanded in Fourier series, and the state equations are solved using the state-space method. The proposed computational model makes it convenient to account for slip at each interface and can represent the entire transition of an interface from fully slipped to fully bonded. Interlayer slip and the corresponding interaction forces are incorporated naturally into the derivation of the governing equations, and the model gives accurate results. A steel–concrete–steel composite beam, a four-layer composite beam and a laminated timber beam are analyzed as examples of multilayer composite beams under both static and dynamic loading. The static analysis results are in good agreement with the literature results, with a maximum error of 0.63% for the maximum mid-span deflection and only 0.143% for the maximum interlayer slip value. Compared with finite element results, the natural frequencies and buckling loads obtained from the dynamic analysis exhibit maximum relative errors of 2.87% and 3.77%, respectively. The relationship between axial force and natural frequency is also presented, which verifies the accuracy and reliability of the proposed model and calculation method. Full article

Point-supported connections are an innovative modern connection design that can benefit from the 2-way structural action of cross-laminated timber (CLT) slabs, which is typically not considered in traditional timber design. It also allows for flatter ceiling surfaces where no beams are needed to support the mass timber floor slabs. In an attempt to better understand the structural behaviour of this type of connection in fire conditions, preliminary unloaded fire tests were conducted to evaluate their thermal performance. The test results indicated that, for these tested configurations, the presence of steel connection components does not inherently increase charring rates within adjacent mass timber elements. While the outcomes provided valuable insights on the thermal performance of such assemblies, their actual mechanical behaviour under structural loading in fire conditions remains unknown. This paper presents the results of two structural fire-resistance tests under load: Test 1 had the gap fully exposed to fire, and Test 2 had the gap protected by a firestop. Neither assembly reached failure during the 2 h of standard fire exposure, while the target load could not be fully maintained to the end of the tests. Test 1 experienced charring at the CLT-steel plate interface, while Test 2 did not. Their mechanical behaviours were also similar. Lastly, a preliminary design approach is being proposed, although it requires further validation. Full article

This paper presents a novel, efficient computational framework for the optimisation of the fundamental frequency of multi-layered composite slabs with consideration of uncertainties. The approach is based on Finite Element Method (FEM) data generation, Deep Neural Network (DNN) surrogate modelling, deterministic optimisation using the genetic algorithm (GA), Morris Sensitivity Analysis (SA), and quantile-based optimisation, including uncertainties and using the GA. Different boundary condition configurations are considered. The surrogate model is trained on FEM-generated samples and subsequently used to replace expensive modal analyses during optimisation, significantly reducing the optimisation evaluation cost for one boundary condition variant. The proposed method achieves near-identical optimal non-dimensional parameter $\mathsf{\Omega }$ values to those reported in the literature for Bayesian Optimisation (BO), with discrepancies of less than 0.5%. To improve robustness to manufacturing tolerances, an additional uncertainty-aware optimisation is performed, in which model parameters are perturbed with normally distributed noise. By maximising the 5% quantile of the non-dimensional parameter $\mathsf{\Omega }$, robust optimal solutions are obtained with minimal loss in performance. Overall, the DNN-GA framework enables fast and accurate optimisation of composite laminates and provides both deterministic and robust design recommendations at a fraction of the computational cost of traditional FEM-based optimisation workflows. Full article

Real-time monitoring of surface cracks in reinforced concrete (RC) beams is critical to structural safety and service performance evaluation. Current structural crack monitoring still faces prominent scientific and technical bottlenecks: conventional unidirectional sensors cannot achieve multi-directional collaborative sensing, rigid piezoelectric materials exhibit poor compatibility with the large deformation of concrete, and there is a lack of quantitative mapping relationships from sensing signals to crack parameters, making it difficult to simultaneously measure crack width, angle, and morphology. This paper presents a novel ring-shaped piezoelectric sensor based on polyvinylidene fluoride (PVDF) and an annular piezoelectric sensing mechanism for real-time monitoring of crack angle, width, and morphology. The sensor incorporates a laminated structure with four strip sensing units for multi-directional strain detection. Experiments were conducted on RC beams under various loading conditions, and finite element analysis was performed using COMSOL Multiphysics. An innovative crack damage index (B) was introduced to assess structural damage quantitatively. Results demonstrate high sensor sensitivity and stable output. Voltage signals increase both with crack width and crack angle, showing responses of 0.045 mV, 0.041 mV, and 0.023 mV for crack angles of 60°, 45°, and 30°, respectively, at a crack width of 9 mm. Strong consistency between experimental and simulation data validates the effectiveness of the mechanism in monitoring the direction, width, and types of cracks. The crack damage index B exhibits a positive correlation with the structural stress response, enabling a quantitative assessment of damage. This study is applicable to the prestressed concrete box girders and T-beams commonly used in large-span bridges, which are typically with a main span of 20–50 m, a beam length of 6–30 m, a section height of 1.2–2.5 m, and designed for Grade C35–C50 concrete. The findings provide a practical foundation for real-time crack monitoring in large-scale bridge beam members. Full article

The submitted paper focuses on linking recycled material processing with digital technologies for monitoring and managing production processes in the context of Industry 4.0 principles. Despite the rapid development of additive manufacturing and Industry 4.0 technologies, limited attention has been devoted to the integration of sustainable recycled materials with real-time digital monitoring and structured manufacturing data management. Existing studies often address either recycled materials or digital process monitoring separately, while their combined implementation in additive manufacturing environments remains insufficiently explored. The introductory part highlights polyvinyl butyral (PVB) recovered from post-consumer laminated glass and its potential application in additive manufacturing. The theoretical section provides an overview of current knowledge in the fields of additive manufacturing, circular economy, production, and digitization, forming a foundation for the practical part of the research. The practical section focuses on the design and implementation of a data collection system for additive manufacturing processes, enabling the real-time digital monitoring and evaluation of selected technological parameters. Previous research conducted by the authors addressed the preparation of recycled PVB filament; however, commercially available PVB filament was used in the present experimental study due to the limited laboratory-scale production capacity of recycled filament. Full article

This paper presents research on reinforced concrete beams strengthened with non-pretensioned and pretensioned near-surface-mounted (NSM) carbon fibre-reinforced polymer (CFRP) strips under self-weight and external preloading. The first part of this paper briefly describes and discusses the results of experimental tests performed on six beams with different reinforcing steel ratios, preloading levels, and strengthening-system configurations. Next, three-dimensional (3D) numerical models of the tested specimens were developed. The models consider the nonlinear behavior of concrete (both in tension and compression), steel bars, and the interface between concrete and CFRP laminates. For these models, the material parameters were established based on experiments and recommendations from the literature. Furthermore, a sensitivity analysis was conducted with respect to the material parameters of the model that were not directly obtained from experimental measurements. The analyses validated the applicability of the numerical model in predicting the flexural behavior of reinforced concrete (RC) members strengthened with near-surface-mounted (NSM) CFRP materials over the full loading range. Furthermore, the developed models were employed to assess the effectiveness of active strengthening relative to passive strengthening methods (i.e., without pretensioning of the laminate). A comparison study of actively and passively strengthened elements indicates that prestressing does not affect the ultimate limit state but enhances serviceability limit states. The presented computational model, together with the adopted computational strategy, demonstrates its effectiveness for analyzing realistic scenarios involving RC beams that are damaged and subjected to loading during the strengthening process. Full article

As a core crushing equipment in mining, building materials, and related industries, the cone crusher relies heavily on the optimal design and health state prediction of its mantle liner to enhance equipment reliability and reduce maintenance costs. This paper proposes a comprehensive approach integrating dynamic modeling, intelligent optimization, and health prognosis. First, a virtual prototype model is established based on laminated crushing theory and multibody dynamics simulation to analyze the motion and force characteristics of the mantle liner. Second, for the two key parameters—counterweight mass and motor speed—an improved butterfly optimization algorithm (IBOA) incorporating Cauchy mutation and an adaptive weight is proposed to achieve efficient global optimization. Furthermore, vibration signal features are extracted at different wear stages; a comprehensive health indicator curve is constructed by combining PCA dimensionality reduction with adaptive feature fusion (ASFF), and the Weibull degradation model is employed for life extrapolation prediction. Finally, fuzzy C-means (FCM) clustering is applied to autonomously partition the health states. Parameter optimization reduces the standard deviation of the force acting on the mantle liner by approximately 15.4%, markedly improving system operational stability. Health prognosis reveals that the liner enters a faulty state after 785 h, and the health condition is effectively classified into four stages: healthy, good, degraded, and faulty. The results demonstrate that the proposed optimization and health prognosis methods can effectively improve the operational efficiency and reliability of cone crushers, exhibit favorable engineering applicability, and provide a quantitative basis for condition monitoring and maintenance decision-making. Full article

The persistence of petrochemical plastics necessitates high-performance and recyclable alternatives, yet balancing mechanical robustness with component-level closed-loop recovery remains challenging for biomass-based plastic-replacement films. Here, a high-performance, thermo-malleable, and closed-loop recyclable composite film is constructed by integrating a highly crystalline enzyme-treated mulberry paper (Enzyme-MP) fiber network with an in situ formed polyimine (PI) vitrimer network via capillary-assisted infiltration. This process induces densification and extensive interfacial hydrogen bonding, forming a confined interpenetrating architecture that enhances stress transfer and restricts chain mobility. As a result, the composite film achieves a tensile strength of 70.3 MPa and a Young’s modulus of 2.37 GPa, together with excellent thermomechanical stability over a broad temperature range. The dynamic imine exchange enables thermo-malleability, allowing seamless self-welding and thickness-scalable lamination at 120 °C. The dense structure also acts as an effective barrier, reducing water uptake to 14.3% and providing resistance to various organic solvents. Furthermore, full-component closed-loop recycling is realized via room-temperature transimination, enabling selective depolymerization of the matrix while preserving the crystalline cellulose fiber network. This work demonstrates a viable strategy to integrate high-strength film performance, processability, and chemical recyclability in biomass-based composite films, while providing a basis for future cradle-to-cradle material circulation in recyclable plastic-replacement films. Full article

Dowel-laminated timber (DLT) is a composite structural material manufactured entirely from wood. Increasing awareness of the sustainability, end-of-life recyclability, and potential health concerns associated with synthetic adhesives used in cross-laminated timber (CLT) and glulam has intensified industry and academic interest in adhesive-free mass-timber systems like DLT. In Australia, however, DLT remains under-researched. This paper addresses global and local knowledge gaps by developing a linear-elastic numerical modelling method for DLT using Australian finite element analysis software Strand7 and investigating structural optimisation strategies, including the use of Australian hardwoods. A finite element model captured the characteristic response of a DLT beam from the University of Liverpool within the linear-elastic range. Reduced dowel spacing, alteration of lamella thicknesses and targeted dowel placement in the shear zones increased global stiffness in the parametrisation study. Incorporating Australian hardwood in the outer lamellae further improved bending performance. Structural viability in the Australian context was indicated through the design of a project-scale DLT beam prototype assessed to relevant Australian Standards. The modelling approach and findings are presented alongside a discussion of behavioural nuances, contributing to the growing body of research on DLT. Full article

Against the backdrop of the global energy transition and China’s dual-carbon strategy, the photovoltaic (PV) industry is entering a new stage of large-scale, intensive development, where efficiency improvement and cost control in module encapsulation have become the core of industrial competition. To address the drawbacks of traditional silicone plate laminators—frequent consumable replacement, high maintenance costs, and poor adaptability to dual-glass module encapsulation—this paper proposes a flat-plate laminator technical scheme. By replacing flexible silicone plates with rigid pressure plates and optimizing pressure transmission paths and sealing structures, we achieved efficient, low-cost lamination. We first compared the working principles of flat-plate and silicone plate laminators, completed the structural design of five core modules with an optimized rigid platen and annular silicone sealing system, developed a modular retrofitting scheme for existing equipment, and verified performance via engineering tests. Tests show that the retrofitted equipment achieves a module thickness deviation ≤ ±0.06 mm, a product yield of 99.88%, annual cost savings of USD 342,000 per unit, and a 0.61-year investment payback period. This work provides theoretical support and an engineering reference for technical innovation in PV module encapsulation equipment, with significant promotion and application value. Full article

This paper analyzes the vibrational characteristics of a novel sandwich plate configuration composed of an auxetic honeycomb (AH) core and laminated functionally graded carbon nanotube-reinforced composite (FG-CNTRC) face sheets, hereafter referred to as the SD-AuCNT plate. Based on Reddy’s third-order shear deformation theory (SDT), which accurately accounts for transverse shear effects without requiring shear correction factors, the equations of motion are derived using Hamilton’s principle and subsequently solved using a pb-2 Ritz formulation combined with the Newmark time integration scheme for dynamic response analysis. By combining an auxetic core with negative Poisson’s ratio characteristics and laminated FG-CNTRC face sheets featuring tailored CNT distribution patterns and orientations, the hybrid SD-AuCNT plate can improve structural stiffness, energy absorption, and dynamic performance; however, it has not been thoroughly investigated in the existing literature. After verifying the accuracy of the proposed computational procedure, the effects of auxetic core geometry, CNT distribution patterns, thickness ratios, and boundary conditions on the natural frequencies and transient responses of the plate are comprehensively investigated. The results provide new insights into the dynamic behavior of advanced sandwich plates and offer practical guidance for the design of high-performance lightweight structures in aerospace, marine, defense, and other engineering applications. Full article

In the field of dynamic characteristic testing of automotive grade IGBT modules, high-frequency noise interference and stray inductance are universal technical challenges faced by the industry. High frequency noise and stray inductance can interfere with signal integrity, seriously reducing the testing accuracy of the platform and causing deviations in the dynamic characteristic evaluation of IGBT modules. To address this issue, this paper proposes a software hardware collaborative optimization strategy and designs a high-precision dynamic characteristic testing platform for automotive grade IGBT modules. At the software level, Savitzky–Golay filters are introduced and designed to process the test data, filter out high-frequency noise interference. After filtering, the noise mean square error and peak to peak value of the platform are generally reduced by 48–68%, and the switch ringing or peak value is reduced by about 45–53%. In terms of hardware optimization, an improved PCB laminated busbar was designed to reduce the overall stray inductance of the platform through simulation analysis of the structural parameters and via factors of the laminated busbar using ANSYS 2023 R1. The test results verification shows that the stray inductance of the testing platform is only 23 nH. The absolute error between the parameters measured by the testing platform and the reference values of the tested module is within 5%. Full article

The composition and type of polymers used as feedstocks in the pyrolysis of plastic waste determine the decomposition process and the proportions of the final products. This paper examines the effect of feedstock heterogeneity on pyrolysis efficiency and pyrolysis gas composition. Four types of plastic waste were considered: real polyolefin waste of municipal origin, LDPE, Alu-PEX laminates, and an alternative refuse-derived fuel (RDF). Low-temperature pyrolysis (450 °C) was conducted in a laboratory reactor, and the gas composition was analyzed using GC-TCD/FID gas chromatography, which allowed for the determination of light hydrocarbons, oxygenates, and sulfur content. Compared to RDF, both municipal and LDPE polyolefin wastes produced gas with a higher calorific value and a predominance of light C₁–C₄ hydrocarbons, while Alu-PEX laminates produced gas rich in C₁–C₂ and low in sulfur, suitable for direct use. RDF was characterized by increased CO₂ and non-flammable gas production and significantly higher sulfur content, requiring advanced purification. The results emphasize the importance of feedstock segregation and standardization and demonstrate that pyrolysis of polyolefins and Alu-PEX laminates can provide higher-quality energy gas than RDF, supporting the circular economy and energy self-sufficiency of industrial installations. Full article