Processing Of Composite Materials Research Articles

Modeling on the effect of automated fiber placement induced gaps in curved composite laminates

Automated placement technology has been widely used due to its excellent processing adaptability for large composite components with complex geometric structures. Whereas, it still poses challenges to study the effect of manufactured gaps induced by automated placement on curved composite parts. This study proposes a new geometric reconstruction approach based on consolidation and sweeping formation to model manufactured gaps. Additionally, a mechanical model incorporating the reconstructed geometry and the cohesive layer method is established to predict the physical behaviors of curved laminates. The micrograph of automated placement-induced gaps with 90° orientation was used to verify the rationality of the geometric reconstruction approach of gaps forming in the preparation process of composite materials. According to predictions of the proposed mechanical model, the effect of − 45° oriented gap defects on curved laminates was validated via four-point bending tests that confirmed alignment between predictions and experimental results for peak load, crack propagation, and failure patterns. Experimental results show that due to the differences in spatial local geometric features, orientations of gap defects would reduce the bending strength to different degrees and significantly affect the failure pattern of curved laminates. Furthermore, curved laminates with wider gaps experience a more considerable reduction in load-bearing capacity.

Distribution and reinforcement effect of carbon fiber at the interface in injection welding of polyamide 6 composites

AbstractTo meet the lightweight production requirements of automobiles and achieve high strength, reinforced thermoplastic composite materials are gradually replacing metal materials. Injection molding is the preferred manufacturing method to enable the production of complex‐shaped parts, facilitate production, and reduce costs. In this study, carbon fiber (CF) was added to the commonly used resin‐reinforcing material, polyamide (nylon) PA6, to create a CF‐reinforced thermoplastic composite (polyamide 6 [PA6]/CF) that was welded using injection molding. This study not only investigates the impact of different welding conditions on shear strength but also discusses the sequence of welding. Achieving 85% of the shear strength of the PA6 base material under ideal circumstances. The CF distribution and reinforcement mechanism were analyzed by observing the connection interface and cross section using a polarizing microscope and a scanning electron microscope. When PA6/CF was used as the secondary molded body, the welding results were better. The addition of CF had a significant strengthening effect on the strength of the PA6 injection welding.Highlights Carbon fiber‐reinforced thermoplastic composite materials were prepared, and welding with PA6 was achieved using the injection molding method. The optimal welding parameters were determined by varying the mold, injection speed, injection temperature, and order of injection. The maximum welding shear strength reached 85% of the base material shear strength. The positive effect of specific fiber distribution on welding strength was analyzed by observing the interface using a scanning electron microscope and a polarizing microscope. This study provides valuable insights into the optimization of welding processes for carbon fiber thermoplastic composite materials, offering possibilities for connecting dissimilar materials with poor compatibility.

Polymer-silicate composites based on ultra-high molecular weight polyethylene and organo-modified montmorillonite

In this paper, the influence of organo-modified montmorillonite (oMMT) on the properties and structure of ultra-high molecular weight polyethylene (UHMWPE) are studied. The technology of preliminary mechanical activation of oMMT in a planetary mill was proposed. The structure and morphology of oMMT before and after mechanical activation in a planetary mill were investigated using scanning electron microscopy and IR spectroscopy. It was found that preliminary mechanical activation leads to dispersion and increase in the porosity of oMMT. Heat treatment at the temperature of the composite material processing does not lead to the destruction of organic modifiers. Studies of the mechanical properties of polymer-silicate composites have revealed that the introduction of preliminary mechanically activated oMMT contributes to the increase of tensile and compressive strength of the composite material based on ultra-high molecular weight polyethylene.

Preparation and Mercury Removal Performance of Mg-MOF-74 Composites

A metal–organic framework (MOF) material Mg-MOF-74 was prepared by a solvothermal method, and the influence of the solvent volume and mass–liquid ratio on the preparation process was investigated. Based on the iron-based modified biochar FeCeCu/BC obtained by the sol–gel method, functionalized modified MOF-based biochar composites were prepared by the physical mixing method, co-pyrolysis method, sol–gel method and in situ growth method. The mercury removal performance and structural characteristics of the samples were studied, and the adsorption mechanism and key action mechanism were studied by using the adsorption kinetic model. Increasing the solvent volume and the mass liquid ratio will make the crystallization and pore structure of Mg-MOF-74 worse and its mercury removal performance poor. For MOF-based FeCeCu/BC composites, the mercury removal performance of the composite samples prepared by the sol–gel method and co-pyrolysis method is the best, at 31% and 46% higher than that of modified biochar, respectively. Mg-MOF-74 plays a role in promoting pyrolysis and changing the pore structure in the composite. The mercury removal process of composite materials is the result of physical adsorption and chemical adsorption, external mass transfer and internal diffusion.

In situ formation mechanism of the honeycomb structure of a vitrified-bond diamond composite

Vitrified-bond diamond composites are materials commonly used for grinding wheels in the grinding process of silicon wafer production. In this study, the mechanism of the in situ honeycomb structure formation in the sintering process of composite materials was explored by changing the binder content without adding a pore-forming agent.The results show when the content of vitrified bond is 55 wt%, the in situ honeycomb structure forms, resulting in a porosity of 60.68 % and bending strength of 23.03 MPa.The X-ray diffraction (XRD), Raman spectroscopy (RS), and thermogravimetry-differential thermal analysis (TG-DTA) results show that no graphitization of diamond grain occurs during sintering. The bonding ability between the vitrified bond and diamond grain, along with the microstructure of vitrified-bond diamond composites, was studied using scanning electron microscopy (SEM). Moreover, the results of energy spectrum analysis (EDS) show that the diffusion and segregation of Na at the interface between the diamond particles and the vitrified bond improve the bonding strength, and the vitrified bond can effectively bond with the diamond particles. Finally, the formation mechanism of the honeycomb structure was elucidated using the surface and interface sintering theory.

Quantitively evaluation of fillers' alignment for targeted manufacturing of functional composite materials

AbstractFiller‐reinforced composite materials are widely used in numerous domains such as energy, optoelectronics, chemistry, and so forth, owing to their versatile microstructures, excellent properties, and low fabrication cost. By finely regulating the distribution and orientation of fillers in the base material, composite materials with fantastic thermal, chemical, and mechanical properties have been demonstrated, which are also known as “metamaterials”. For the anisotropic fillers, the orientation of fillers is crucial for designing and predicting the properties of composite materials. However, accurate and efficient evaluation of fillers' orientation remains a challenge, which severely hinders the microstructural design and topological optimization of composite materials. To solve this problem, a bidirectional pixel‐traversal method which combines with microscopic image processing was developed to evaluate the orientation of fillers in composite materials. Specifically, a vertical orientation maximization algorithm was designed to evaluate the oriented degree and oriented direction of the whole fillers, and a crossing traversal algorithm was designed to evaluate the oriented angle of individual filler. Further, this method was applied to the evaluation of microscopic images from different researches. The evaluated results show a high accuracy (average error is less than 2%) and wide applicability in the evaluation of different types of fillers. This method reveals the underlying relationship between microscopic filler orientation and macroscopic composites properties, which paves a new way for the direct optimization and processing of composite materials.

Nonlinearity of mechanical behavior of 3D-reinforced composites under compression

Modern technological capabilities make it possible to produce 3D spatially-reinforced for polymer composite materials. The tasks of experimental research and analysis of the deformation process of new composite materials for aviation purposes taking into account the nonlinearity of mechanical behavior become actual. The paper presents an experimental study of the mechanical compression behavior of composite material specimens made of 3D woven carbon fiber preforms using the pressure impregnation technology (Resin Transfer Molding method with a pairwise interlayer reinforcement and a longitudinal layer). Compression mechanical tests were carried out on specimens using a universal system of electromechanical testing Instron 5882 and a system of 3D analysis of displacement and strain fields on the surface. Tests were conducted in accordance with ASTM D 3410 recommendations and using specialized tooling. Consideration of nonlinearity parameter during experimental data processing is proposed. The importance of determining the values of critical deformation in compression as a parameter characterizing the moment of the beginning of fracture is noted. Comparison of carbon fiber composite materials made by the same technology from fibers and binders of different manufacturers has been carried out. The experimental diagrams "stress-strain" and their approximating dependences taking into account the nonlinearity function w are obtained. The type of functions w of the studied materials is defined, the linear approximation of dependence of functions w on deformation is substantiated. Values of strength limits, elastic modulus, nonlinearity coefficient and critical damage were obtained, statistical processing of the obtained results and their analysis were carried out.

Effect of the near-surface pore volume evolution on graphite migration of copper-based graphite composite during friction

The discrete element method was used to simulate the friction process of copper-based graphite composite materials in order to analyze the influence of pore structure on the solid lubricants migration in metal-based self-lubricating materials. And the near-surface pore volume evolution was considered in the simulation. The simulation results showed that the graphite particle motion depth and the migration channel increased gradually and tended to stable during friction. The near-surface pore structure has an important influence on the graphite migration and the tribological properties of the composite: the larger the migration channel was, the greater the graphite migration speed was; with the increase in migration channel, the graphite average critical migration depth decreased first then increased, the number of the film-forming particles first increased and then decreased; the greater the migration channel volume was, the more worn particles number were. The numerical simulation was confirmed by experimental analysis on a self-made in-situ observation tribometer, the experimental results were consistent with the numerical simulation results.

Cutting Parameter Optimization in Milling of Glass Fiber and Carbon Fiber Reinforced Composites to Reduce Cutting Force

Abstract Composite materials are often preferred in many engineering applications because of their lightness and high-strength properties. However, in addition to the advantages of composite materials, processing problems exist. The processing of fiber-reinforced composite materials is more complex than other metal materials. The forces that arise during milling cause undesirable results, such as tool wear and energy loss. In this study, the cutting parameter optimization was made by measuring the force during carbon fiber and glass fiber-reinforced epoxy matrix composites milling. Cutting velocity (90, 120, and 150 m/min) and feed per tooth (0.1, 0.15, and 0.2 mm/tooth) were selected as cutting parameters. Experiments were planned according to the Taguchi method with two parameters and three levels. Optimization of the parameters was evaluated using the signal/noise ratio approach. The effectiveness of parameters on results was determined by analysis of variance (ANOVA). Optimum levels were found as 120 m/min for cutting velocity and 0.1 mm/tooth for feed per tooth both glass fiber-reinforced polymer (GFRP) and carbon fiber-reinforced polymer (CFRP) composites. According to the ANOVA results, the contribution rates of the force parameters were 81.05 % for cutting velocity and 15.03 % for feed per tooth in GFRP composites. The contribution rates of the force parameters were 43.69 % for cutting velocity and 46.18 % for feed per tooth in CFRP composites. The surfaces of the milled samples were examined with an optical microscope to investigate the damage. It was observed that the surfaces of CFRP samples had a better surface quality than GFRP samples.

Resource-efficient manufacturing process of composite materials: Fibrillation of recycled textiles and compounding with thermoplastic polymer

This study aimed to develop a manufacturing process for recycled textile long fiber thermoplastics (RT-LFT) and thereby contribute to circular economy. Three different post-consumer textiles (cotton denim and plain weave, and silk plain weave) were cut into strips and fed directly into a co-rotating twin-screw extruder in which the textile was fibrillated and compounded with polypropylene (PP). The fibrillation of the textile, fiber dispersion, and interaction with the matrix polymer were studied, and the thermal and mechanical properties of the composites were evaluated. For example, cotton denim composites containing 30 wt% fiber content resulted in 26% increase in yield strength and a 72% increase in modulus when compared with that of PP. The RT-LFT process is a straightforward method for transforming used textiles into composites like cups and bottoms, offering advantages such as reduced manufacturing costs, add value for waste material, and lower carbon emissions.

Carbon reduction engineering through value chains intersection, product and process re-design, industrial processes’ scraps de-manufacturing

Composite materials use recently increased, although treatments at their End of Life are inexistent or highly inefficient (from the environmental perspective). Thus, openness to cooperation is needed, supported by methodologies for design for de-manufacturing. The approach proposed in the present work aims at transforming industrial processes’ scraps and off-specification pieces in primary materials, through re-design, without the risk of cannibalisation. It is mainly intended for industrial processes of composite materials; its objective is to find alternative applications to their invaluable final disposal and supports the merging of existing supply chains (Industrial Symbiosis). Nevertheless, it can be easily extended to non-composite and/or non-scraps. Re-design enables the establishment of waste-to-treasure composite scraps’ life cycles and is evaluated through Life Cycle Assessment. The application of the approach involved four Italian companies and results reveal that industrial symbiosis can reduce emissions (from −45% to more than −90%). Guidelines were outlined: involve End of Life operators to know how waste treatments, share information, favour networking and proximity, apply design for disassembly principles, consider simple shapes and modularity during (re)design. Future works will focus on off-the-shelf components and the economic evaluation of the proposed de-manufacturing actions and supply strategies.

A bi-objective decision support tool based on system dynamics and discrete event modelling for sustainable supply chain

Based on the development trend of sustainable concepts and the implement ability of composites combined with Agave Bagasse Fibre (ABF) and Polyethylene Terephthalate (PET). The purpose of this paper is to design a bi-objective decision support tool for supply chain of composite material which combined with ABF and PET. Through the production, processing, recycling, and reprocessing of composite materials, the sustainable supply chain model of four different schemes is designed, and the data results of each scheme model are calculated and analysed. The tool can support supply chain modelling solutions that seek best practices for sustainable supply chains and optimize resource efficiency through cost and carbon dioxide emissions. The sustainable supply chain model was designed, created, and optimized in AnyLogic software using System Dynamics and Discrete Event Simulation modelling methods based on the supply chain model established by previous researchers. According to the analysis results of the model data, the reasonable design of the whole process can effectively reduce the cost and carbon dioxide emissions and achieve the effectiveness and implementation of the sustainable supply chain. The results of this study will provide reference for more sustainable supply chain models in the future. Further research on composite materials can be carried out by combining with practice.

Surface Defect Detection for Automated Tape Laying and Winding Based on Improved YOLOv5.

To address the issues of low detection accuracy, slow detection speed, high missed detection rate, and high false detection rate in the detection of surface defects on pre-impregnated composite materials during the automated tape laying and winding process, an improved YOLOv5 (You Only Look Once version 5) algorithm model was proposed to achieve the high-precision, real-time detection of surface defects. By leveraging this improvement, the necessity for frequent manual interventions, inspection interventions, and subsequent rework during the automated lay-up process of composite materials can be significantly reduced. Firstly, to improve the detection accuracy, an attention mechanism called "CA (coordinate attention)" was introduced to enhance the feature extraction ability, and a Separate CA structure was used to improve the detection speed. Secondly, we used an improved loss function "SIoU (SCYLLA-Intersection over Union) loss" to replace the original "CIoU (Complete-Intersection over Union) loss", which introduced an angle loss as a penalty term to consider the directional factor and improve the stability of the target box regression. Finally, Soft-SIoU-NMS was used to replace the original NMS (non-maximum suppression) of YOLOv5 to improve the detection of overlapping defects. The results showed that the improved model had a good detection performance for surface defects on pre-impregnated composite materials during the automated tape laying and winding process. The FPS (frames per second) increased from 66.7 to 72.1, and the mAP (mean average precision) of the test set increased from 92.6% to 97.2%. These improvements ensured that the detection accuracy, as measured by the mAP, surpassed 95%, while maintaining a detection speed of over 70 FPS, thereby meeting the requirements for real-time online detection.

Unveiling Sustainable Potential: A Life Cycle Assessment of Plant-Fiber Composite Microcellular Foam Molded Automotive Components.

The development and utilization of new plant-fiber composite materials and microcellular foam molding processes for the manufacturing of automotive components are effective approaches when achieving the lightweight, low-carbon, and sustainable development of automobiles. However, current research in this field has mainly focused on component performance development and functional exploration, with a limited assessment of environmental performance, which fails to meet the requirements of the current green and sustainable development agenda. In this study, based on a life cycle assessment, the resource, and environmental impacts of plant-fiber composite material automotive components and microcellular foam molding processes were investigated. Furthermore, a combined approach to digital twinning and life cycle evaluation was proposed to conduct resource and environmental assessments and analysis. The research results indicate that under current technological conditions, resource and environmental issues associated with plant-fiber composite material automotive components are significantly higher than those of traditional material components, mainly due to differences in their early-stage processes and the consumption of electrical energy and chemical raw materials. It is noteworthy that electricity consumption is the largest influencing factor that causes environmental issues throughout the life cycle, especially accounting for more than 42% of indicators such as ozone depletion, fossil resource consumption, and carbon dioxide emissions. Additionally, the microcellular foam molding process can effectively reduce the environmental impact of products by approximately 15% and exhibits better overall environmental performance compared to chemical foaming. In future development, optimizing the forming process of plant-fiber composite materials, increasing the proportion of clean energy use, and promoting the adoption of microcellular foam injection molding processes could be crucial for the green and sustainable development of automotive components.

Research on selective laser sintering process of ternary composite materials (PP/MCMB/CNT)

The composite material composed of polypropylene and conductive filler has good corrosion resistance, light weight and good conductivity, and is one of the preferred materials for fuel cell bipolar plates. The formation of ternary composite materials composed of polypropylene, mesocarbon microbeads and carbon nanotubes is realized by selective laser sintering. The influences of laser power, scanning speed, scanning spacing and defocus amount on forming quality are studied. The formability of mixed powders with different composition proportions as well as the conductivity, bending strength and hydrophobicity of the formed samples are investigated. The results show that when the input energy density is insufficient, it is easy to form defects such as spheroidized particles and worm-like structures. The parameters with good forming quality are in the following range: defocus amount is + 3 mm; line energy density is 2.94–3.85 J/mm2; peak power density is 1.13 × 104-1.48 × 104 W/mm2 and scanning spacing is 0.1–0.14 mm. The conductive filler in composite material is beneficial to improving the conductivity, but it will reduce the formability of the mixed powders and reduce the bending strength and hydrophobicity of the sample. The effect of mesocarbon microbeads on improving conductivity or on reducing hydrophobicity is smaller than that of carbon nanotubes.

Research on curing kinetics of multiaxial warp‐knitted composites

AbstractIn this paper, the differential scanning calorimetry (DSC) was used to test the crosslinking reaction system between epoxy resin and curing agent, and the curing kinetic model of the resin system was established by means of phenomenal model. The optimal curing process was obtained based on DSC curve. The quadriaxial warp‐knitted composite specimens were prepared by vacuum‐assisted resin infusion (VARI). The effects of curing process on mechanism properties and failure mechanism of the composite specimens were studied experimentally. Results show that the cross‐linking reaction between epoxy resin and curing agent agrees with the autocatalytic reaction model and the curing kinetics model could be used to characterize the curing process of the matrix. The optimum curing process could be used to improve the interface properties between the matrix and the fiber, and the crack progress will be inhibited as the specimen bearing the external force, and the mechanical properties of the specimen is also improved significantly. Result could provide a theoretical basis for the study of curing kinetics of epoxy resin, the exploration of curing process of composite materials and improve the strength of composits.

Dynamic Modeling and Performance Evaluation of a 5-DOF Hybrid Robot for Composite Material Machining

Dynamic performance is an important performance of robots used for machine processing. This paper studies the dynamic modeling and evaluation method of a 5-DOF (Degree of Freedom) hybrid robot used in aerospace composite material processing. With the consideration of the dynamics of the serial part, the complete dynamic model of the hybrid robot is established based on the virtual work principle. In addition to the widely considered acceleration term, a dynamic performance evaluation index that comprehensively considers the acceleration term, velocity term and gravity term in the dynamic model is proposed. Using the dynamic performance index, the effect of the placement direction of the robot and the arrangement of the double symmetric limbs on robot dynamics are investigated. The results indicate that the vertical placement is beneficial to the dynamics of the hybrid robot, and the arrangement of double symmetric limbs has different effects on different limbs.

The drilling process impact on the parameters of the polymer composite materials processing quality

The paper examines the influence of the drilling process on the strength characteristics of fibrous polymer composite materials. Experimental studies of the polymer composite materials processing with spiral drills and cutting edges of P18 and VK8 with a diameter of 5 mm were conducted in cutting modes in accordance with the technological recommendations of TI 36-39-89 (SE "Antonov"). To analyze the temperature factor influence on the strength indicators of carbon fiber ELUR-P-01 and fiberglass T-10-14 in the drilling process, experiments were conducted in accordance with the ASTM-D5766 standard (USA). Temperature measurements during drilling were carried out with a non-contact infrared pyrometer DT-8865. Research on the ultimate strength of samples with holes was performed on the INSTROM - 5582 installation. It was established that the polymer composite materials strength of bolted joints working under compression is higher when processed with carbide drills with cutting edges with VK8, which can be explained by the fact that the tool made of carbide material promotes more intensive heat removal from the cutting zone and reduces the force load due to cutting edges of the drill.

A probabilistic constant amplitude life diagram modeling method for composite materials considering spatial mapping relation

AbstractConventional constant amplitude life diagrams (CLDs) model cannot reasonably describe mean stress effect and stochastic uncertainty present in the fatigue failure process of composite materials. To address this problem, taking the spatial mapping relationship between probabilistic S‐N curves and probabilistic CLD model as an entry point, a probabilistic CLD modeling method is proposed under the assumption of linear equations and the assumption of equiprobable quantile point between static strength distributions and fatigue life distributions. The p‐S‐N curve is established using fatigue test data from different load zones divided by different stress ratios.Subsequently, the p‐CLD model is derived through the spatial mapping relationship of the p‐S‐N curve. The method is validated by fatigue test data of glass fiber/polyester resin composites. The results indicate that the proposed method can offer an accurate description of the probabilistic behavior of composite materials.

Changing the approach to sustainable constructions: An adaptive mix-design calibration process for earth composite materials

One major drawback of excavation earth-based composite construction materials is the variability in excavation earth characteristics from site to site. This variability can affect certain physical properties, and, in turn, the design models used to create a structure. To solve this problem, a methodology has been developed to predict the physical properties of earth-based composites for any mix-design variation, which enables a robust structural design process.This new methodology has been tested for Shot-earth, a new class of earth-based composite material made using high rates of excavation earth, aggregates, and a low rate of stabilization if needed. Shot-earth is placed using a high-speed dry-mix process.The methodology was tested by preparing small, inexpensive specimens through a process that simulates the dry-process used to fabricate Shot-earth in the field. An adaptive technique, used in conjunction with the experimental methodology, allows for the identification of the variant of possible Shot-earth mix-designs that provides optimal physical properties for a specific project. This technique is potentially applicable to any type of earth-based composite. The proposed methodology's reliability enables a fast and cost-effective detailing of Shot-earth constructions.