Processing Of Composite Materials Research Articles

Multiobjective optimization of carbon fiber–reinforced epoxy composite properties using nonparametric modeling

Carbon fiber–reinforced epoxy composites are widely used in the marine and aviation sectors due to their superior mechanical properties. As research into these materials progresses, the demand for materials with even more complex and superior properties has increased. Traditional trial-and-error methods are limited to optimizing single factors and are plagued by heavy workloads and prohibitive costs when applied to multifactor composite designs. Addressing these problems, this study introduces a nonparametric multiobjective optimization process for composite materials. This approach employs a Gaussian process (GP) to establish a multiobjective regression model and uses nondominated sorting genetic algorithm II (NSGA II) to determine the Pareto front. Pareto solutions were ranked in accordance with their similarity to ideal solutions and on the basis of predetermined preference weights. The results demonstrate variations in optimal outcomes contingent on the weight values assigned. The differences between the optimized results and experimental validations reached 12.9%, with the minimum deviation being 0.6%. The effectiveness of the proposed method was demonstrated. The strategy combines GP and NSGA II to extend design methods for small samples and materials with multiple attributes. This method enables the simultaneous optimization of multiple conflicting objectives, offering greater efficiency than addressing them individually.

Investigation of the influence of morphology on thermal conductivity in hexagonal honeycomb structures and computational models with varied volume fraction and conductivity ratio

The effective thermal conductivity (ETC) is a critical parameter for simulating macroscopic heat transfer processes in composite materials, which estimation is particularly critical where the thermal conductivity of the composite phases is completely different. The huge difference in thermal conductivity of the composite phases makes their volume fraction modulation a classical way to reach the desired thermal conductivity. Nevertheless, the typical manufacturing process of honeycomb cellular structures allows various degrees of stretching of the structure, leading to various honeycomb geometries. In these ‘real’ structures some of the honeycomb wall sides are twice as thick as other parts, modifying the symmetry of the system with respect to honeycomb with uniform wall side thickness. A noticeable example of these composites is that of a hexagonal metallic honeycomb structure filled with phase change material (PCM) which is a widely utilized material in the field of thermal storage and thermal management by exploiting the heat absorbed/released by the PCM phase during its melting/solidification. While the thermal response of a PCM composite during a thermal cycle is not only defined by thermal conductivity (but also by cell size), this represents the basis for the with the optimization of a system based on a composite PCM.For this reason, in this study, steady-state simulations of heat transfer in unit honeycomb cells in different directions perpendicular to the cell axis are conducted to quantify the impact of morphology on the thermal property of the different wall types within honeycomb structures. The results demonstrate that in both SHS and DHS, the porosity exhibiting maximum anisotropy of ETC decreases as the thermal conductivity ratio increases. Moreover, simple predictive models for calculating the ETC in all directions are proposed for each type of honeycomb, considering a wide range of porosity and thermal conductivity ratio, with a relative error limited to 2 %.

Feasibility study of an integrated pre‐curing and forming process for 6061 Al alloy and carbon fiber hybrid composites

AbstractThis article proposes a 6061‐T6 Al alloy and carbon fiber hybrid composite material pre‐curing and forming integrated new process, which can significantly reduce the hybrid composite material processing time, improve the production efficiency, and provide the possibility of hybrid composite materials in automotive parts applications. The process started by placing hand‐stacked carbon fiber reinforced plastic (CFRP) composites on the surface of 6061 Al alloy sheets, followed by bonding and pre‐curing of the CFRP to the Al alloy sheets through two different sets of dies in a hydraulic press, and ultimately full curing in an aging furnace. Mechanical properties of the CFRP/Al hybrid composite material were measured by flexural tests. The results show that the flexural strength of CFRP/Al hybrid composites with different layups ([90]12, [0/45/90/−45]3, and [0]12) was increased by 159%, 93.4%, and 67.9%, respectively, compared with the single 6061 Al alloy. According to the macro‐morphological observation, [90]12 lay‐up parts have the least thinning. According to the microstructure observation, no obvious cracks or voids were found in the [90]12 lay‐up parts. Elongated cracks and void defects could be found in the [0]12 lay‐up parts. For the [0/45/90/−45]3 lay‐up parts, voids are mainly exist in ±45°layups. The results of the spring‐back analysis show that the standard deviation of the formed parts obtained from the three lay‐up methods is within 1 mm, indicating that the forming effect is good.Highlights New process improves productivity and reduces production costs The flexural strength of CFRP/Al hybrid parts is greatly improved [90]°12 lay‐up parts have the least thinning and no cracks were found The forming precision of the three lay‐up parts is good

Path planning for dual-arm fiber patch placement with temperature loss constraints

In the process of composite material molding, the role of robots has become increasingly significant. However, the laying process of composite materials is heavily influenced by factors such as temperature and pressure, which affect the quality of the layup. Currently, existing robot path planning algorithms do not account for temperature constraints, presenting challenges in achieving high-quality composite material layups. This paper proposes the RRT*-MTL (Rapidly-Exploring Random Trees* with Minimum Temperature Loss) path planning algorithm. Firstly, a neural network model for predicting temperature loss is developed. Then, temperature loss is integrated as a constraint into the RRT* (Rapidly-Exploring Random Trees*) path planning algorithm to determine the laying path with minimal temperature loss. Experimental results demonstrate that this algorithm effectively preserves the object's heat retention.

A coupled data-physics computational framework for temperature, residual stress, and distortion modeling in autoclave process of composite materials

It is challenging to obtain the full-field temperature profile during autoclave processes to control the temperature uniformity and minimize the residual stress and distortion of cured composite structures. This paper proposes a coupled data-physics computational framework for full-field temperature reconstruction and the subsequent residual stress/distortion modeling by using limited monitoring temperature data. Firstly, a Long Short-Term Memory (LSTM) model is developed for full field temperature reconstruction. In this LSTM model, a cross-recombination method is proposed to maximize the value of monitored temperature data. The method effectively cuts through the bottleneck of neural network training with limited labeled data. The LSTM model’s prediction stability is enhanced based on the mean-teacher and ensemble learning strategy. To train and validate the proposed method, we perform experiments using an autoclave at the National Institute for Aviation Research (NIAR). The LSTM model’s accuracy is assessed by comparing its predicted results with the thermocouple (TC) data from measurements and high-fidelity simulation data from computational fluid dynamics (CFD). The study shows that the proposed LSTM model can effectively reconstruct the full-field temperature using limited monitoring data and significantly improve accuracy and efficiency compared with the CFD-based counterpart. Then, we create a coupled data-physics computational framework by embedding the data-driven LSTM model into a physics-based thermo-mechanical finite element model to predict residual stress and distortion. The simulation results show that the coupled data-physics framework provides an effective way for process-to-performance modeling and simulation of autoclave curing processes.

Sustainable composite manufacturing from non-expiring carbon fiber/epoxy prepregs based on a vitrimeric matrix

Despite the benefits of manufacturing composite materials from prepregs, its use is nowadays limited to high-production rate industries due to the high costs associated with their limited shelf life. Once this time passes, the material is considered as expired and disposed of as a non-usable waste. To avoid shortening its shelf life, prepregs are stored in refrigerators, increasing energy consumption, and thus magnifying the negative environmental impact. For this reason, the objective of this paper is to develop a new lifelong prepreg material without an expiration date that can be consolidated as a laminate after surpassing the gelation time of the resin, thus allowing composite materials processing technology based on prepregs without the need of freeze storage. To prove this concept, the study is carried out using a vitrimeric resin composed of an epoxy monomer (DGEBA) and 2-Aminophenyl disulfide (AFD) as a hardener. Two prepregs are manufactured and stored for 30 days at different conditions: environmental conditions, considered as the aged or non-conventional prepreg; and at −18 °C in a freezer, to replicate the conventional prepreg conditions. The results of the cured composites show stable glass transition temperatures and curing degrees between the two laminates. Concerning the mechanical properties, it has been proved that the gelation phenomenon of the non-conventional prepreg does not have any negative effect, showing a 11 % and a 21 % improvement of the flexural strength and failure strain, respectively, together with a 10 % increase of the interlaminar shear strength (ILSS) in comparison with the conventional prepreg, proving the potential of the proposed sustainable prepregs.

Mathematical modeling of the creation process and aging of polymer composite materials

Based on the analysis of the literature on the possibility of using neural networks to create new materials with high functional properties, the article considers a solution to the problem of determining the operational stability of polymeric composite materials by creating physical and chemically sound mathematical prediction models. Epoxy resins of the UP-637 and EA brands with an isophorone diamine hardener were chosen as the matrix of the model composite material, and oligobutadiene rubber of the SKN-10 KTR brand was chosen as the modifier. It justifies directions of work necessary for development of new materials creation methodology with optimal characteristics, building a model for changing the properties of materials at variation of composition and implementation of full-scale mathematical modeling of physical and chemical processes of polymer composite materials aging at changing level and time of climatic factors influence. Verification of the obtained dependence of service characteristics on the composition of the material and the level of influencing climatic factors was carried out on the basis of data from full-scale tests in a temperate climate. The proposed methodology for modelling the properties of polymer composite materials will reduce the development time of new materials and allow creation of polymer composites based on epoxy resin containing fillers of various natures (carbon, mineral and polymer) with high performance parameters.

A model for the temperature-dependent creep/recovery behavior of dry fiber fabric considering in-plane tension

In the manufacturing process of fiber-reinforced composite materials, the preforming of dry fiber fabrics is typically carried out under specific out-of-plane pressure, in-plane tension, and at designated temperatures. The fabric exhibits significant time and temperature-dependent permanent deformation as well as creep/recovery behavior. Gaining a better understanding of these phenomena and harnessing predictive capabilities will be instrumental in achieving more precise control over fiber volume fraction and material composition. In this paper, creep/recovery experiments and cyclic loading-unloading tests were conducted on CF3031 dry fiber preforms under various in-plane tensions and temperatures, measuring in-plane strains using Fiber Bragg Grating (FBG) sensors. Based on this data, a modified Burgers viscoelastic-plastic model has been proposed to describe the time-dependent creep/recovery behavior of dry fiber fabric preforming under the coupled effects of in-plane tension, out-of-plane pressure, and temperature variations. This model employs a single set of equations and parameters to represent the complete creep/recovery process of the material. The experimental results align well with the predicted outcomes across different compression scenarios.

RESEARCH ON THE RECOVERY OF SOME AGRICULTURAL WASTE FOR THE MANUFACTURE OF COMPOSITE MATERIALS WITH CLAY MATRICES

The article describes the results of the research carried out for the systemic description of the manufacturing technological processes of composite materials with clay matrix and insert from agricultural waste. The objectives of these researches include the valorization of agricultural waste and cheap and abundant resources to obtain composite materials usable in civil constructions or various rural developments, with properties superior to existing ones, for example adobe or clay bricks. The article describes the materials used, the technology of obtaining, the dependence between the output parameters and the input and control parameters.

Batch preparation process of composite materials of quantum dot glass and polystyrene used in backlight displays

All-inorganic CsPbX3 quantum dots (X = Cl, Br, or I) are regarded as a new generation of efficient luminescent materials for displays and solid-state lighting due to their excellent optoelectronic properties. However, the poor stability of CsPbX3 quantum dots severely hampers their commercial applications. Currently, the in-situ growth of CsPbX3 quantum dots in amorphous glass has emerged as a crucial approach to significantly enhance their stability. This study successfully synthesized large-scale CsPbBr3@glass materials using a one-step self-crystallization method involving melting, quenching, and heat treatment. CsPbBr3@glass was blended with polystyrene (PS) through melt blending and extrusion, resulting in the fabrication of a CsPbBr3@glass@PS film. By controlling the content of quantum dot glass in polystyrene and adjusting the film's thickness, a green light film with color coordinates (0.1629, 0.7759) and a Full Width Half Maximum (FWHM) of 19.78 nm was achieved. The film produced through this process demonstrated exceptional stability, retaining 90% of its luminous intensity after 1000 h of rigorous aging experiments. Furthermore, when combined with potassium fluorosilicate composite polystyrene film and a blue light chip, a 7-inch LCD display with a color gamut of 135.8% of NTSC 1953 and 92.8% of Rec. 2020 was successfully assembled. This research holds significant reference value for the commercial application of quantum dot glass.

Frequency monitoring analysis of milling edge chatter in composites using WPD for frequency band selection

In the milling process of composite materials, the initial chatter frequency is not obvious and is easily swamped by the rest of the signals, making frequency monitoring difficult, so the study proposes a chatter frequency monitoring method based on frequency cancellation algorithms and wavelet packet decomposition. The results of the experiments shown that the frequency cancellation algorithm can successfully remove invalid signals, such as spindle rotation frequency and cutter tooth frequency, and only keep the necessary signals, at which point the chattering frequency may be observed at a frequency of roughly 1333 Hz. The influence of the frequency bands s5, s9, s10, s12, and s13 after de-frequency removal should be avoided because they all have a low energy share of roughly 23 %, 0.9 %, 5 %, 10 %, and 16 %, respectively, and are less sensitive to chatter. For milling edge depths of 0.5 mm, 2 mm, and 4 mm, the average chatter thresholds were around 3.27, 2.9, and 2.89, respectively. It was challenging to pinpoint the chatter of the system because the empirical modal decomposition observed an average chatter energy entropy of just 1.55 and found that its fluctuations at the milling edge depth junction were insignificant. On the other hand, the chattering could be plainly seen since the energy entropy experienced a substantial and dramatic fluctuation at the intersection of the milling edge depth when it was about 2.9, 2.6, and 2.5, respectively. The experimental findings demonstrated that the frequency cancellation technique and wavelet packet decomposition-based chattering frequency monitoring approach can precisely track the chattering state of the system.

Computational and Experimental Analysis of Surface Residual Stresses in Polymers via Micro-Milling.

This research conducts an in-depth investigation into the residual stresses in resin micro-milling processes. Considering that resin is the most crucial matrix material in composites, the construction of a precise machining theory for it is not only key to achieving high-quality- and efficient processing of composite materials but also fundamental to enhancing the overall performance of the materials. This paper meticulously examines the surface integrity and accuracy of epoxy polymers following precision machining, primarily revealing the significance of residual stresses and size effects in extending the lifespan of precision components and promoting their miniaturization. We have adopted an innovative finite element (FE) simulation method, integrated with the Mulliken-Boyce constitutive model, to profoundly analyze the impacts of residual stresses on the surfaces and sub-surfaces of thermosetting polymers. This research further explores the influence of critical machining parameters such as chip thickness, cutting edge radius, feed per tooth, and axial depth on cutting forces, as well as the inherent size effects in polymers. Utilizing X-ray diffraction (XRD) technology, we accurately measured the residual stresses generated during the micro-milling process. The close correlation between FE simulations and experimental results validates the accuracy and effectiveness of our method. This study represents a substantial breakthrough in finite element simulation techniques for high-precision machining of polymer materials, injecting valuable theoretical and practical knowledge into the field.

Progress in preparation, processing, and application of high dielectric polypropylene matrix composite materials

AbstractCurrently, in the era of highly advanced information technology, dielectric materials exhibit extensive potential applications in the realms of energy storage and information transmission. Polypropylene stands as one of the most prevalent plastics, lauded for its exceptional mechanical, thermal, electrical, and processing attributes. This article expounds upon the intricate essence and energy storage principles underpinning dielectric materials while pinpointing the areas in which the current dielectric materials necessitate enhancements. It further delves into the study's selection of polypropylene as the base material, with a focus on the impact of individual fillers (ferroelectric ceramics, carbon materials, etc.) and mixed filler nanoparticles on augmenting the dielectric properties of polypropylene. We also delve into pertinent fabrication techniques and methodologies, such as the solution blending method, melt blending method, and in situ polymerization method. In the context of existing polypropylene‐based composite dielectric materials, this article introduces two quintessential applications: insulation materials for direct current cables and metal capacitor films. Finally, it concludes by summarizing the obstacles and challenges that high‐performance polypropylene‐based dielectric composites confront and offers insights into potential avenues for future research.

A Review on Machining SiCp/Al Composite Materials.

SiCp/Al composite materials are widely used in various industries such as the aerospace and the electronics industries, primarily due to their excellent material properties. However, their machinability is significantly weakened due to their unique characteristics. Consequently, efficient and precise machining technology for SiCp/Al composite materials has become a crucial research area. By conducting a comprehensive analysis of the relevant research literature from both domestic and international sources, this study examines the processing mechanism, as well as the turning, milling, drilling, grinding, special machining, and hybrid machining characteristics, of SiCp/Al composite materials. Moreover, it summarizes the latest research progress in composite material processing while identifying the existing problems and shortcomings in this area. The aim of this review is to enhance the machinability of SiCp/Al composite materials and promote high-quality and efficient processing methods.

Evaluation of new nano-cutting fluids for the processing of carbon fiber-reinforced composite materials

Carbon fiber-reinforced composites (CFRP), known for its impressive specific strength and modulus, finds extensive applications in defense, aerospace, automotive, and various other industries. Nevertheless, the widespread application of dry cutting in machining Carbon Fiber Reinforced Polymer (CFRP) presents significant challenges, including dust pollution, fiber layer delamination, and uneven surface quality. These issues make the machining of CFRP a formidable task. In the present investigation, a novel nanohybrid cutting fluid was successfully prepared by adding molybdenum disulfide (MoS2)/silicon carbide (SiC) nanoparticles to a base-cutting fluid synthesize from ethanol, polyethylene glycol, and sodium dodecyl sulfate. Moreover, employing minimal lubrication techniques, the nano-cutting fluid was applied to the milling process of CFRP. The feasibility of applying the cutting fluid to CFRP machining was demonstrated through short beam shear tests. Horizontal comparative milling tests were executed on CFRP, varying operational parameters and cooling-lubrication scenarios. The cooling-lubrication mechanisms of the nanofluid were analyzed, providing further validation of the effectiveness of the cutting fluid in CFRP machining. The results suggest that the nanofluid has a negligible impact on the interlaminar shear strength of CFRP, with only a 3.85% reduction. In comparison to other cooling-lubrication conditions, milling CFRP with the novel nanofluid resulted in a reduction of milling forces by 4.78%–24.84%, a decrease in milling temperatures by 15.38%–69.37%, a lowering of surface roughness by 10.78%–35.93%, and a reduction in tool tip wear by 6.25%–53.81%. Observable phenomena such as fiber pull-out and fracture were significantly reduced.

Study on the synergistic effect of calcium carbide residue -fly ash enhanced desulphurisation gypsum under high temperature maintenance condition

The preparation of cementitious materials from bulk industrial solid waste is an effective way to replace cement. Based on the multi-component synergistic coupling effect, the influence law of different dosage of fly ash (FA) and calcium carbide residue (CCR) on the performance of flue-gas desulfurization gypsum (FGDG) slurry was investigated, and the hydration process of composite cementitious materials was discussed through the analysis of hydration products, micro morphology and pore structure by the characterisation methods such as XRD, FTIR, MIP and SEM-EDS. The results show that FA incorporation can improve the flow properties of the slurry, and under the action of CCR and FGDG, the alkalinity of the whole system rises, and the FA vitreous body undergoes dissolution corrosion, releasing reactive SiO2 and Al2O3, and forming C-S-H gel and AFt. In addition, some of the tiny FA particles fill up the pore spaces and microcracks, and the structure becomes denser, and all these effects together contribute to the development of the mechanical properties. This research is conducive to the application of new green cementitious materials and promotes the resourceful use of industrial solid waste.

Advancing Free-Form Fabrication: Industrial Robots' Role in Additive Manufacturing of Thermoplastics

This paper presents a comprehensive study on the advancements and potential of industrial robots in the field of additive manufacturing of thermoplastics. As the manufacturing industry continues to embrace Industry 4.0 and smart manufacturing principles, the integration of robotic systems has gained significant attention due to their flexibility, precision, and automation capabilities. This article explores the utilization of industrial robots in achieving free-form fabrication, particularly focusing on the additive manufacturing process for composite materials. It looks into the hardware setup, software systems configuration, and platform development that combines FDM with robotic arm technologies. It discusses the merits, limitations, and prospective uses of freeform additive manufacturing and the interoperability between traditional additive manufacturing and robotic additive manufacturing. The experimental results show that this integration is feasible and advantageous, with better process flexibility and production capacities when compared to typical FDM systems.

Numerical Simulation and Experimental Research on Heat Transfer Characteristics Based on Internal Meshing Screw

The mixing and processing of high-viscosity materials play a pivotal role in composite material processing. In this context, the internal meshing screw mixer, rooted in volume extensional rheology, offers distinct advantages, including heightened mixing efficiency, exceptional material adaptability, and favorable thermomechanical properties. This research endeavors to advance our understanding of these qualities by presenting an in-depth exploration of internal meshing screw mixing. To facilitate this, an internal meshing screw mixing experimental apparatus was meticulously constructed, accompanied by extensive numerical simulations and experimental investigations into its heat transfer characteristics. Two distinct heat transfer modes are established: Mode 1 entails the transfer of the high temperature from the outer wall of the stator to the interior, while Mode 2 involves the transmission of the high temperature from the inner wall of the rotor to the exterior. The ensuing research yields several notable findings: 1. It is evident that higher rotational speeds lead to enhanced heat transfer efficiency across the board. However, among the three rotational speeds examined, 60 rpm emerges as the optimal parameter for achieving the highest heat transfer efficiency. Furthermore, within this parameter, the heat transfer efficiency is superior in Mode 1 compared to Mode 2. 2. As eccentricity increases, a corresponding decline in comprehensive heat transfer efficiency is observed. Moreover, the impact of eccentricity on heat transfer efficiency becomes increasingly pronounced over time. 3. A lower gap dimension contributes to higher heat transfer within the system. Nevertheless, this heightened heat transfer comes at the expense of reduced stability in the heat transfer process. 4. It is demonstrated that heat transfer in Mode 1 primarily follows a convection heat transfer mechanism, while Mode 2 predominantly exhibits diffusion-based heat transfer. The heat transfer efficiency of Mode 1 significantly surpasses that of Mode 2. This research substantiates its findings with the potential to enhance the heat transfer efficiency of internal meshing screw mixers, thereby making a valuable contribution to the field of polymer engineering and science.

Effect of Citric Acid-Modified Chitosan on Hydration Regulation and Mechanism of Composite Cementitious Material System

The temperature stress caused by the large temperature difference is the main factor causing harmful cracks in large-volume concrete. The introduction of admixtures is beneficial to reduce the temperature difference inside and outside the large-volume concrete. This study investigated the mechanism of how citric acid-modified chitosan (CAMC) affects the hydration heat release process and hydration products of composite cementitious materials. Through methods such as hydration heat, X-ray diffraction (XRD), mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM), and nuclear magnetic resonance (NMR), the mechanism of how CAMC controls the hydration heat release process and hydration products of composite cementitious materials was revealed. The results show that the addition of CAMC delayed the hydration process of cementitious materials without affecting the type of hydration products but affected the content of each phase of hydration products. As the hydration process proceeded, the total porosity of all samples decreased, the volume of large pores decreased, and the volume of small pores increased. As the content of CAMC increased, the pore diameter of the hardened paste gradually became smaller, the proportion of large pores decreased, and the later hydration microstructure became more dense. The increase in CAMC dosage resulted in a decrease in the peak intensity of Q2 in the paste, indicating that Al atoms in Q2 (1Al) existed in the form of Alcoordination, which proves that CAMC reduced its hydration degree and delayed cement hydration.

High-temperature tribological performance of functionally graded Stellite 6/WC metal matrix composite coatings manufactured by laser-directed energy deposition

Wear-driven tool failure is one of the main hurdles in the industry. This issue can be addressed through surface coating with ceramic-reinforced metal matrix composites. However, the maximum ceramic content is limited by cracking. In this work, the tribological behaviour of the functionally graded WC-ceramic-particle-reinforced Stellite 6 coatings is studied. To that end, the wear resistance at room temperature and 400 °C is investigated. Moreover, the tribological analysis is supported by crack sensitivity and hardness evaluation, which is of utmost importance in the processing of composite materials with ceramic-particle-reinforcement. Results indicate that functionally graded materials can be employed to increase the maximum admissible WC content, hence improving the tribological behaviour, most notably at high temperatures. Additionally, a shift from abrasive to oxidative wear is observed in high-temperature wear testing.