Composite Manufacturing Research Articles

Additive manufacturing of geopolymer composites for sustainable construction: critical factors, advancements, challenges, and future directions

Additive manufacturing of geopolymer composites for sustainable construction: critical factors, advancements, challenges, and future directions

High-Precision Printing of Cermets by Collapsable Matrix Assisted Digital Light Processing.

Shaping hard and brittle materials, e.g. cermets, at micrometer resolution has long been known challenging for both mechanical machining and high energy beam based additive manufacturing. Digital light processing (DLP), which features great printing quality and decent precision, unfortunately lacks capability to deal with the popular slurry-typed cermet precursor due to the tremendous optical absorption by its particles. Here, an innovative protocol based on a versatile collapsable matrix is devised to allow high-precision printing of WC-Co cermets on DLP platform. By tuning the external environment, this matrix attenuates composite powders to facilitate photopolymerization at the printing stage, and shrinks to condense green parts prior to thermal sintering. The as-obtained samples by collapsable matrix assisted DLP can reach a relative density of ≈90%, a record-breaking resolution of ≈10µm, and a microhardness of up to 14.5GPa. Complex delicate structures, including school emblem, honeycomb, and micro-drill can be directly fabricated, which has never been achieved before. Impressively, the as-obtained micro-drill is able to be directly used in drilling tasks. The above strategy represents a great progress in DLP by enabling shaping strong light attenuating materials at high resolution. Such advantages are ideal for the next generation ceramic-metal composite additive manufacturing.

Effect of process parameters on mechanical and tribological characteristics of FDM printed glass fiber reinforced PLA composites

PurposeAdditive manufacturing of polymer composites is a transformative technology that leverages the benefits of both composite material and 3D printing to produce highly customizable, lightweight and efficient composites for a wide range of applications.Design/methodology/approachIn this research work, glass fiber-reinforced polylactic acid (PLA) filament is used to print the specimen via fusion deposition modeling process. The process parameters such as infill densities (40%, 50% and 60%) and raster angle/orientations (0°, 45° and 90°) are varied, and the specimens for tensile, flexural, impact, hardness and wear testing are prepared as per their respective ASTM standards.FindingsThe results revealed that with an increase in infill density, the mechanical properties of glass fiber-PLA specimens increase progressively. Optimal tensile properties and flexural properties are obtained at 0° and 90° raster angle orientations and 60% infill density. Minimum wear rate is achieved at 0° raster angle orientation and it increases at 45° and 90° raster angle orientations.Originality/valueUsing SEM, the microscopic analysis of the fractured specimen was analyzed to study the interface between the fibers and matrix and it indicates the presence of good adhesion between the layers at 60% infill density and 0° print orientation.

Enhancing automated fiber placement process monitoring and quality inspection: A hybrid thermal vision based framework

Automated Fiber Placement (AFP) has revolutionized composite manufacturing, yet quality assurance remains challenging due to the significant impact of emerging defects on part quality and the current reliance on time-consuming manual inspection protocols. This paper presents a comprehensive hybrid framework that enhances AFP process monitoring and quality inspection by integrating thermal vision with innovative methodologies. Our framework combines model-based and data-driven algorithms across three modules to address key AFP inspection tasks, including in-situ monitoring, dynamic tow identification, defect detection, segmentation, localization, and quantitative lay-up quality evaluation. The setup-independent spatial–temporal analysis algorithm estimates tow boundaries with sub-pixel accuracy. An optimized SVM classifier, trained on an extensive AFP defect database, achieves a defect detection accuracy of 96.4% and an F1-score of 96.43%, meeting industry standards. The active contours-based segmentation and localization module provides critical qualitative traits such as defect shape, size, and location. Moreover, the novel Defect Area Percentage (DAP) metric enables precise quantitative defect impact evaluation at both the course and tow levels. By consolidating qualitative and quantitative outcomes, the system offers real-time high-level feedback for informed decision-making, significantly improving process performance and reducing machine downtimes. This proactive approach advances AFP process monitoring and quality inspection and positions our framework as a promising solution for next-generation composite manufacturing.

Fabrication and characterization of natural fiber reinforced cowpea resin-based green composites: an approach towards agro-waste valorization.

A paradigm shift towards using bio-resins or bio-derived resins among materials scientists has led to wide exploration of the sector. Polymers such as soy protein isolate, poly(hydroxy alkanoate), poly(lactic acid), and thermoplastic starch are all synthetically modified bio-based resins and are costly. The cowpea-derived resin with the least chemical modification was used in this study as a matrix for the formation of composites with natural fibers at a lesser cost. Fabrication of composites of vetiver and jute with varying weight percentages of fiber (50, 60, and 70%) in the innovative cowpea resin resulted in favorable mechanical properties and degradability. The tensile strength was the highest for the jute-cowpea composite (JCP2) at around 37.49 MPa, which also has a flexural strength of 40.3 MPa. Dynamic mechanical analysis of composites reflects the moderate storage moduli of 1802 MPa for JCP2 and 1351 MPa for vetiver-cowpea (VRCP2) composites. Impact strength studies and thermal stability also show optimistic results. The contact angle, water absorption behavior, and swelling in thickness show the moderate hydrophobicity of the composites. This is also a reason for the improved degradability of the composites in soil-burial and microbial environments. Characterizations such as FE-SEM and FTIR spectroscopy, conducted after the degradation of the samples, showcased the level of deterioration. All these results suggest using the innovative cowpea resin as a good alternative to various other synthetic thermoplastic resins used in the fiber reinforced composite manufacturing field.

Energy-efficient microwelding of copper by continuous-wave green laser: Insights into nanoparticle-assisted absorptivity enhancement

As a highly reflective material, copper has been difficult to weld with IR lasers. Short-wavelength (400–600 nm) lasers offer promising solutions to copper welding due to significant increases in absorptivity (to > 50 %). In this work, we present an experimental study on copper welding by CW green laser. We unveil that nanoparticles redeposited on the copper surface from the vaporized plume can strongly modify the surface condition and result in significant enhancement of the surface absorptivity. The absorptivity can be theoretically enhanced by nanoparticles up to 82 % compared to the polished copper surface. Assisted by this absorptivity enhancement, the threshold power density (critical laser intensity) for copper melting is reduced by more than 50 %, so that continuous and smooth conductive welding tracks can be generated in energy-efficient manner. In situ deposition of nanoparticles generated upon cooling and oxidation of the vapor plume in the vicinity of the melt zone has been identified as the key mechanism of absorptivity enhancement. XPS measurements of the nanoparticles indicated that Cu2O is the dominant species in the redeposited nanoparticles. This study provides novel insights into the fundamental mechanisms in highly-reflective material welding by short-wavelength lasers and offers an opportunity for energy-efficient high-quality welding of highly-reflective material thin films, which can find numerous applications in consumer electronics and electric vehicles, as well as battery industries. Moreover, it enables a new process-material-environment design route for laser additive manufacturing of nanoparticle-reinforced metal matrix composites.

The effect of absorbed moisture and resin pressure on porosity in autoclave cured epoxy resin

AbstractOne of the main issues in epoxy‐based composite manufacturing is the formation of porosity derived from moisture absorption during storage and layup due to the high hydrophilicity of epoxy matrices. During the curing process, the presence of moisture and other volatile compounds can initiate the nucleation and growth of voids. In this study, the effect of both the initial water content absorbed in the uncured resin and the pressure on the porosity development in an epoxy resin was investigated. In particular, Kardos' and Ledru's models, aimed at predicting void formation in polymers, were applied to study the effect of different hydrostatic pressures in an epoxy resin during curing up to the gel point, after conditioning it at two different relative humidity levels, 50% and 95%. Subsequently, the porosity of the cured resin samples was quantified through density measurements. Comparative analysis of the microscopy images of cured samples and the predictions of both models revealed an overestimation of the final void sizes by both models, with the Kardos' model exhibiting a higher deviation. Additionally, a finite element model was employed to investigate the conditions leading to void formation, aiming to understand the factors influencing the porosity development and properly set the process parameters during composite manufacturing.Highlights Evaluation of the conditions leading to void growth in epoxy resin during curing Moisture sorption in uncured epoxy resin Effect of curing pressure on pore development Finite element analysis for void growth during resin curing

Innovative polymer‐based composite materials in additive manufacturing: A review of methods, materials, and applications

AbstractThis review paper delves into the manufacturing methods, material properties, and applications of polymer‐based composites in the field of advanced manufacturing, offering a detailed explanation of their production through various additive manufacturing (AM) techniques and their diverse applications across multiple industries. Polymer‐based composite materials have emerged as crucial elements in AM due to their enhanced properties and design versatility, enabling the creation of components with unprecedented performance characteristics. The paper comprehensively covers the major AM methods employed for composite materials, including fused filament fabrication, Digital Light Processing/Stereolithography, Direct Ink Writing, and Selective Laser Sintering. Each of these methods is explored in terms of its mechanism, suitability for different composite materials, and the resulting material properties. The review also provides an insightful analysis of how these AM techniques are revolutionizing industries such as soft robotics, mechanical, electrical, and biomedical fields. The paper concludes by discussing the current challenges in this domain and projecting future trends in the development and application of composite materials in advanced manufacturing. This review aims to offer a comprehensive resource for researchers and practitioners in the field, highlighting the transformative impact of polymer‐based composites in AM and their growing significance across various sectors.Highlights Comprehensive review and classification of novelties in printing method for polymer based composite material manufacturing. Introduces innovative techniques to create and enhance material properties of composites. Explores interdisciplinary applications in biomedical, electronics, and sensors, demonstrating material versatility. Provides a systematic correlation between manufacturing method, material properties, and applications of novel polymer‐based composites.

Development and Manufacturing of a Fibre Reinforced Thermoplastic Composite Spar Produced by Oven Vacuum Bagging.

The limited recyclability of fibre-reinforced thermoset composites has fostered the development of alternative thermoplastic-based composites and their manufacturing processes. The most common thermoplastic-based composites are often costly due to their availability in the form of prepreg materials and to the high pressure and temperatures required for their manufacturing. Yet, the manufacturing of economic and recyclable composites, made of semi-preg composite materials using traditional composite manufacturing technologies, has only been proved at a laboratory scale through the manufacturing of flat plates. This work reports the manufacturing of a real structural part, a wing spar section with complex geometry, made of commingled polyamide 12 (PA12) fibres and carbon fibres (CFs) semi-preg and by oven vacuum bagging (OVB). The composite layup was studied using finite element analysis, and processing simulation assisted in the determination of the PA12/CF preform for OVB. Processing of two forms of semi-preg materials was first evaluated and optimised. The material selection for part manufacturing was mainly defined by the materials' processability. The spar section was manufactured in two OVB stages and was then mechanically tested. The mechanical test showed a linear strain response of the prototype up to the maximum load and validated the optimised layup configuration of the composite structure.

Analysis and Testing of a Launch-Vehicle-Like Composite Conical–Cylindrical Shell

Launch-vehicle shell structures, which can be composed of both cylindrical and conical sections, are known to be susceptible to buckling due to their large radius-to-thickness ratios. Advancements in composite manufacturing and numerical methods have enabled designers to consider more nontraditional shapes, such as connecting the conical and cylindrical sections with a toroidal transition to create a single-piece conical–cylindrical shell. This single-piece construction eliminates the need for a stiff, heavy interface ring between sections and has the potential to reduce mass. To better understand the buckling behavior of a composite conical–cylindrical shell, a laboratory-scale article was designed, fabricated, and tested. Before the test, a finite element model that included thickness variations and radial imperfections was created. The test article buckled elastically at 251.8 kN, approximately 8.8% higher than the predicted buckling load of 231.4 kN. Because the test article buckled elastically, the buckling test was repeated. The buckling load measured from the second test was within 1% of that from the first test. Continued research on conical–cylindrical structures has the potential to expand the design space for launch-vehicle structures and lead to improved designs and reduced mass.

Investigations on structure and properties of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) reinforced by diss fibers: Effect of various surface treatments

The paper reports some experimental results on the effect of different chemical modifications of Diss fibers on the properties of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) biocomposites involving alkaline, combined alkaline/peroxide and combined alkaline/silane treatments. The biocomposite samples loaded at 20 wt% were prepared by melt compounding. Scanning Electron Microscopy (SEM) showed a better fiber-matrix interaction between Diss fiber and matrix after surface fiber treatment. Differential Scanning Calorimetry (DSC) and X-ray Diffraction (XRD) results indicated an increase in crystallinity index of the biocomposites. In addition, the incorporation of Diss fibers treated with alkali-silane resulted in an improvement in Heat Deflection Temperature (HDT) and shore D hardness from 141.1 °C and 75.1–145.7°C and 86.2, respectively, in comparison with the neat matrix. This also agreed with the flexural properties results, which showed a significant increase in flexural modulus by almost 30 % compared to the neat PHBV. The same trend was observed for water absorption. Overall, combined alkali-silane treatment was found to be most efficient surface treatment method to develop strong interfacial adhesion between PHBV and Diss fiber, increasing the scope of application in manufacturing of light weight green composites.

Surface engineering of carbon nanotube-carbon fiber networks for enhanced strength in additive manufacturing of nylon composites

This work quantifies the impact of chemical functionalization of carbon nanotubes and carbon fibres on the interfacial shear strength, tensile and interlaminar shear strength properties of additively manufactured nylon composites. The surface chemistry of functionalized carbon materials was evaluated through infrared spectroscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. Single carbon fibre was dip-coated in a suspension of nanotubes and embedded into a nylon matrix. The fibres were pulled out to measure the interfacial shear strength, and the fibres with attached neat, carboxylated, and silanized nanotubes increased it by up to 67 %, 112 %, and 216 %, respectively. Composite samples were manufactured using a novel hybrid additive manufacturing method, which was able to deposit nylon layers and a suspension containing carbon reinforcement. The use of chemically functionalized nanotubes in the suspension led to carbon layers that improved tensile strength by 49 % and tensile modulus by 126 % over neat nylon. Functionalization of carbon reinforcement increased the interlaminar shear strength by up to 63 %. Overall, this paper demonstrates the importance of chemical modification in composite materials containing a large interface area of carbon materials.

Thermophysical Characterization of Materials for Energy-Efficient Double Diaphragm Preforming

The Double Diaphragm Preforming (DDPF) process uses vacuum pressure and heat to pre-shape dry carbon fabric reinforcements between flexible diaphragms in liquid composite molding (LCM). Accurate modeling of heat transfer within DDPF requires knowledge of the thermophysical properties of the constituent materials under processing conditions. This study investigates the thermal conductivity of silicone diaphragms and carbon fabrics with embedded thermoplastic binder webs, utilizing transient plane source (TPS) and modified transient plane source (MTPS) methods, respectively. Additionally, the specific heat of silicone, carbon fibers (both chopped and powdered), and binder were measured using differential scanning calorimetry (DSC). Mixed samples comprising chopped fibers with 1.8 wt% binder and powdered fibers with 3.6 wt% binder was also analyzed with DSC. This study also examined the influence of reheating cycles on the specific heat of carbon fiber—3.6 wt% binder samples—and the effect of compaction and vacuum on the thermal conductivity of carbon fabrics with an embedded binder. While silicone exhibited linear-specific heat behavior, the thermoplastic binder showed non-linearity due to phase change. The combined carbon fiber-binder samples demonstrated slight non-linear specific heat variations depending on reheating cycles. The thermal conductivity of the fabric preforms decreased with the addition of thermoplastic binder and under vacuum-compaction conditions. The established temperature-dependent specific heat relationships and thermal conductivity provide valuable data for optimizing DDPF preforming parameters and enhancing energy efficiency in composite manufacturing.

A Mechanism-Based Reaction-Diffusion Model for Accelerated Discovery of Thermoset Resins Frontally Polymerized by Olefin Metathesis.

Frontal ring-opening metathesis polymerization (FROMP) involves a self-perpetuating exothermic reaction, which enables the rapid and energy-efficient manufacturing of thermoset polymers and composites. Current state-of-the-art reaction-diffusion FROMP models rely on a phenomenological description of the olefin metathesis kinetics, limiting their ability to model the governing thermo-chemical FROMP processes. Furthermore, the existing models are unable to predict the variations in FROMP kinetics with changes in the resin composition and as a result are of limited utility toward accelerated discovery of new resin formulations. In this work, we formulate a chemically meaningful model grounded in the established mechanism of ring-opening metathesis polymerization (ROMP). Our study aims to validate the hypothesis that the ROMP mechanism, applicable to monomer-initiator solutions below 100 °C, remains valid under the nonideal conditions encountered in FROMP, including ambient to >200 °C temperatures, sharp temperature gradients, and neat monomer environments. Through extensive simulations, we demonstrate that our mechanism-based model accurately predicts the FROMP behavior across various resin compositions, including polymerization front velocities and thermal characteristics (e.g., Tmax). Additionally, we introduce a semi-inverse workflow that predicts FROMP behavior from a single experimental data point. Notably, the physiochemical parameters utilized in our model can be obtained through DFT calculations and minimal experiments, highlighting the model's potential for rapid screening of new FROMP chemistries in pursuit of thermoset polymers with superior thermo-chemo-mechanical properties.

A feasibility study of oil palm empty fruit bunch pulp as a substitution for radiata pine pulp for autoclave fibre cement composite production

The main objective of this study was to investigate the feasibility of using unbleached pulp from oil palm empty fruit bunches, produced via the Ethanolamine pulping process, to replace Radiata Pine pulp in autoclave fibre cement composite (AFCC) manufacturing. The Ethanolamine pulping process was chosen for its silica retention capability on empty fruit bunch surfaces. The research involves three key phases: an initial characterization of RPP and EFBP properties, including kappa numbers and pulp aspect ratios; subsequent AFCC production with varying RPP content levels (0%–13%) and different cement-to-silica (C/S) ratios (0.2–1.0); and the introduction of EFBP as a partial or complete substitute for RPP at a fixed C/S ratio. Results reveal RPP excels in fibre quality attributes like length, coarseness, fineness, width, and wet/dry zero span, while EFBP offers advantages in fibre count and macro fibrillation index. X-ray diffraction confirms silica presence on EFBP. The highest modulus of rupture (MOR), at 15.5 MPa, is achieved with 9% RPP and a C/S ratio of 1.0. Subsequent analysis, with 1% EFBP interval substitutions to total 13% pulp content, yields the highest MOR values under dry (16.7 MPa) and wet (9.9 MPa) conditions using recipes with 6% RPP and 3% EFBP. XRD confirms the presence of silica on EFBP, forming a crystalline flake layer post-autoclaving. Thus, EFBP proves suitable as a partial AFCC substitute.

Smart Industrial Internet of Things Framework for Composites Manufacturing.

Composite materials are increasingly important in making high-performance products. However, contemporary composites manufacturing processes still encounter significant challenges that range from inherent material stochasticity to manufacturing process variabilities. This paper proposes a novel smart Industrial Internet of Things framework, which is also referred to as an Artificial Intelligence of Things (AIoT) framework for composites manufacturing. This framework improves production performance through real-time process monitoring and AI-based forecasting. It comprises three main components: (i) an array of temperature, heat flux, dielectric, and flow sensors for data acquisition from production machines and products being made, (ii) an IoT-based platform for instantaneous sensor data integration and visualisation, and (iii) an AI-based model for production process forecasting. Via these components, the framework performs real-time production process monitoring, visualisation, and prediction of future process states. This paper also presents a proof-of-concept implementation of the framework and a real-world composites manufacturing case study that showcases its benefits.

Polyester and Hymenaea Courbaril Residue for Sustainable Composite Manufacturing

Objective: To evaluate the mechanical behavior of polymer composites reinforced by wood residue known as Játobá (Hymenaea Courbaril), in powder form. It aims to reduce impacts to the environment through the use of waste. Theoretical Framework: Composites are generated from the union of materials, aiming to obtain specific properties arising from their components. Usually these are divided into two phases, matrix. The possibility of using materials less harmful to the environment in composite has gained prominence in research in the area. Method: To obtain the properties of the composites, standardized specimens were manufactured according to ASTM D638. The matrix selected was terephthalic polyester resin and the reinforcement was Játobá wood residue, in the form of powder. The results were obtained by tensile strength tests. Results and Discussion: The average value of tensile strength obtained was 11.76 (±1.70) MPa. The comparison of the results of this study with other literature revealed the superiority of the tensile strength of the composite of the present work in relation to others with different reinforcements of wood residues. Research Implications: The use of wood waste in composites is beneficial for reducing the irregular disposal of matter in the environment. Also, it aims to generate added value to a useless material. Originality/Value: The use of natural and renewable materials as reinforcement in composites is of great relevance, aiming to reduce the use of synthetic raw material. In addition, there is the manufacture of composites of low cost and weight and feasibility of manufacture.

From virtual to actual assisted tape placement − application of the Frenet frame to robotic steering trajectories

A novel computational tool is presented that integrates the design and manufacturing of variable-angle tow composites for automated tape placement, facilitating the creation of tow-steered trajectories for cut-outs. Steering movements of the robot are planned and executed within a MATLAB virtual environment via short paths and linear commands. Leveraging piecewise-continuous clothoid splines and the Frenet frame, the tool furnishes crucial details on trajectory vectors, steering angles, and curvatures. Via four integrated modules, the user can define input parameters such as the robot’s actuators and structural geometry, allowing for the subsequent visualisation of the steered trajectories as well as the generation of the manufacturing code. Finally, to assess the potential and limitations of this methodology, the file containing all details is integrated into the Kuka KR L240-2 robot model to continuously steer a carbon fibre/PEEK tape around an elliptical cut-out in a composite panel using laser-assisted tape placement, representative of an access hole in an aircraft wing.

Manufacturing and cold spraying of hybrid composites — A path for metallizing thermoset matrix composites

This study aims to realize and metallize the hybrid thermoset-thermoplastic fiber reinforced composites for aerospace applications. Two variations in the manufacturing route including cocuring and hybrid interlayer were adopted for realizing the RTM6-PEI-CF composite. Low pressure cold spray metallization technique is applied by varying the processing parameters stand-off distance and traverse speed. Microstructural analysis and mechanical tests (roughness check, nanoindentation tests) were performed on sprayed composites. Overall, manufacturing routes affected the inherent structure of the composite and subsequent coating quality. Mechanical interlocking induced close contact of PEI-aluminum (Al) particles characterized into uniform coating with surface morphology variation shown in cocured composites. Coating adhesion strength increment up to 18 MPa was noted by using the PEI-carbon fiber (CF) semi-preg in manufacturing. The tomography scan highlighted the structural integrity of the manufactured and coated composites, revealing coating-thermoplastic contact, interphase, and porosity in the inter-tow fiber region. An increase in the traverse speed to 2 mm/s reduced the electrical conductivity and adhesion strength of the coating with the hybrid composite. Within the limits of this investigation, opting for lower stand-off distance and traverse speed (here, 10 mm and 1 mm/s) reflected in improved adhesion and approximately 1.5 mm coating thickness.

Sintesis dan Karakterisasi Pupuk Multinutrien Calcium-Ammonium-Phosphate (CAP) Berbahan Cangkang Kupang Merah

Fertilisers and composites are two types of materials that can be used to improve soil fertility. However, these two materials have some differences. One of them is in the manufacturing process, fertilisers can be made in various ways, while the composite manufacturing process can only be done by biological processes. The objectives of this paper are (1) To determine the effect of acidity degree (pH) on the formation of Calcium-Ammonium-Phosphate particles, (2) To determine the optimisation of Calcium Ammonium Phosphate from red mussel shells by precipitation method, and (3) To determine the characteristics of Calcium-Ammonium-Phosphate produced using SEM-EDX and XRF analysis. The type of research used uses experimental research. The results and conclusions drawn are (1) The solubility of CaHPO4 decreases with increasing pH so that the weight of the resulting product increases in the precipitation method, (2) The best condition for making calcium ammonium phosphate fertiliser with red shell material is in the condition of red shell weight of 30 grams and pH 7, (3) The chemical composition contained in the CAP product with the condition of 20 grams of shell weight at pH 5 is Ca content of 74.76%, and phosphorus content of 23.5%, (4) The particle size at pH 3 weight of 20 grams ranges from 830 nm - 1970 nm and the particle size at pH 3 weight of 30 grams ranges from 1980 nm - 5220 nm. Therefore the fertiliser product does not include nano particles, (5) The CAP fertiliser product meets the SNI standards for NPK fertiliser and dolomite fertiliser.