Composite Manufacturing Processes Research Articles

Multi-level lot-sizing with raw-material perishability, deterioration, and batch ordering: an application of production planning in advanced composite manufacturing

Advanced composite manufacturing processes use polymers and fibers pre-impregnated with thermoplastic or thermoset resins as raw-materials. These highly sensitive materials are considerably perishable, affecting the production process in several ways and requiring special inventory cares. This perishable condition of raw materials in composite manufacturing constitutes the main motivation for this paper. We study a multi-level lot-sizing problem with raw-material perishability and batch-ordering. Several types of perishable raw-material items are procured in batches from suppliers. Once received, two different inventory sub levels are considered: a special storage location where the material can be stored avoiding deterioration, and a secondary location at the shop floor where the material becomes available for production and starts deteriorating. We proposed a mixed-integer programming formulation for the problem and perform computational experiments with sensitivity analyses, demonstrating its potentials for practical applications in planning composite production.

Resin Injection Process in the Manufacture of a Polymer Composite Reinforced with NiTi Ribbons: A CFD Analysis

This work aims to numerically simulating the resin injection manufacturing process of a polymer composite,reinforced with ribbons of NiTishape memory alloy, using the software Ansys CFX®. The multiphase flow mathematical modeling was used to describe the transient and isothermal resin-air flow during the process. Results of the pressure fields, velocity andvolume fractionsof the involved phases are presented. The fluid flow inside the mold was compared withthe flow between parallel flat plates and showed to be consistent. Process parameters, such as resin volumetric flow rate, resin inlet and air outlet positions have a large influence in the mold filling time, volume and position of voids fractions inside de mold and final product quality.

Fabrication of High-Quality Polymer Composite Frame by a New Method of Fiber Winding Process.

Polymer composite frame has been frequently used in the main structural body of vehicles in aerospace, automotive, etc., applications. Manufacturing of complex curved composite frame suffer from the lack of accurate and optimum method of winding process that lead to preparation of uniform fiber arrangement in critical location of the curved frame. This article deals with the fabrication of high-quality polymer composite frame through an optimal winding of textile fibers onto a non-bearing core frame using a fiber-processing head and an industrial robot. The number of winding layers of fibers and their winding angles are determined based on the operational load on the composite structure. Ensuring the correct winding angles and thus also the homogeneity of fibers in each winding layer can be achieved by using an industrial robot and by definition of its suitable off-line trajectory for the production cycle. Determination of an optimal off-line trajectory of the end-effector of a robot (robot-end-effector (REE)) is important especially in the case of complicated 3D shaped frames. The authors developed their own calculation procedure to determine the optimal REE trajectory in the composite manufacturing process. A mathematical model of the winding process, matrix calculus (particularly matrices of rotations and translations) and an optimization differential evolution algorithm are used during calculation of the optimal REE trajectory. Polymer composites with greater resistance to failure damage (especially against physical destruction) can be produced using the above mentioned procedure. The procedure was successfully tested in an experimental composite laboratory. Two practical examples of optimal trajectory calculation are included in the article. The described optimization algorithm of REE trajectory is completely independent of the industrial robot type and robot software tools used and can also be used in other composite manufacturing technologies.

Understanding the impact of fibre wrinkle architectures on composite laminates through tailored gaps and overlaps

Among a variety of defects associated with composite technology, fibre wrinkles are known to be a major source of failure for fibre reinforced plastic and closely associated with the ever popular automated fibre placement technique. In the present work, with the aim to investigate their influence on the failure of carbon fibre reinforced plastics (CFRP), composite laminates containing fibre wrinkles of varying architectures have been designed and prepared utilizing gaps and overlaps based on the understanding of wrinkle formation mechanisms. The effects of these engineered wrinkles with different combination of gaps and overlaps on the mechanical performance of CFRP were systematically investigated. A maximum of 21% and 37% drop in the tensile and compressive strength were recorded for the most severe combination of gaps and overlaps. A simple analytical model was proposed to relate the wrinkle angle to the defect characteristic parameters and a good agreement with experimental results was obtained. Furthermore, numerical simulations were conducted to inform the failure mechanisms where different wrinkle models were generated using previously developed pre-processing tools. Good agreements with experimental observations were obtained in terms of ply waviness, strength and failure modes. These findings provide certain practical insights for controlling defects in composite manufacturing processes.

High sound absorption of polyester composites / fiber hemp / nanocellulose for automotive interior materials

Human health and environmental comfort are disturbed by the presence of noise, especially in cars, so that effective sound-absorbing materials are currently being developed. To answer the problem of noise in car interiors, polyester composite materials with local hemp fiber and nanocellulose reinforcement were developed. Natural fiber is biodegradable and renewable, and acts as an alternative to the use of synthetic fibers. The method used for the composite material manufacturing process was the casting method. The matrix of the composite material was polyester, while the reinforcement was a combination of local hemp fiber and nanocellulose fiber. Alkalization and non-alkalization processes have been carried out on hemp fiber. The composition of nanocellulose was 0%, 1%, and 3%. The characterization applied in this research were SEM test, FTIR test, sound transmission loss test, and density test. Optimal results were obtained on hemp fiber reinforced polyester composite materials without alkalization and without nanocellulose. Sound transmission loss (STL) was 61.91 dB up to 68.52 dB for the frequency range of 630 Hz to 125 Hz. The standard noise limit on 8-passenger passenger's four-wheeled vehicles is 77-80 dB. Based on the results obtained, the sound absorption is good. The density of this composite material was obtained at 0.989 gram/cm3. This composite material has the potential for developing dashboard material.

Manufacturing high strength aluminum matrix composites by friction stir processing: An innovative approach

Abstract Shape Memory Alloys (SMA), e.g., NiTi (nitinol), are good candidates of reinforcement agents for the improvement of mechanical properties of aluminum alloys. Friction Stir Processing (FSP) has been shown to be an appropriate manufacturing process for particulate Aluminum Matrix Composites (AMCs), due to the mitigation of critical intermetallic formation between particles and matrix. However, AMCs processed by FSP with the matrix material made of high strength alloys, in particular 7xxx series, have systematically shown severe defects, such as clusters and cavities that result from poor material flow. Herein, we present an innovative strategy to manufacture Al7075/NiTi composites via FSP avoiding this unacceptable particle clustering. The strategy involves the addition of 7xxx series Al powder in a groove or multi-holes to be stirred together with the NiTi particles, leading to dissociation of the latter. The X-ray computed tomography acquisitions allow for 3D quantitative assessment of the size and spatial distribution of the embedded reinforcements. It is revealed that the groove filling method results in a more homogenous distribution compared to the multi-holes filling method. Moreover, the distribution is found to be dependent on the particle size, as a higher volume fraction of large particles is observed at the upper part of the FSP stir zone. These new AMCs, with a good Al-NiTi interface, present a potential to tailor the composite mechanical properties by exploiting the shape memory effect of the NiTi reinforcements.

Validation of a smoothed particle hydrodynamics model for a highly aligned discontinuous fibre composites manufacturing process

This work presents a computational model for a discontinuous fibre composite manufacturing process. The alignment mechanism of this novel process, called the High Performance Discontinuous Fibre (HiPerDiF) method, involves highly coupled fluid-structure interactions. Fibres with a length on the order of a few millimetres are placed in a water suspension, sprayed between two parallel plates and deposited on a moving belt to make an aligned discontinuous fibre tape. This technology can be used as part of a composites recycling process to remanufacture reclaimed fibres into valuable recycled composite feedstock by ensuring a high level of alignment. In order to industrialise this process, the throughput must be increased whilst maintaining the high level of alignment. This work aims to assist this development by modelling the alignment mechanism using smoothed particle hydrodynamics (SPH). It is shown through comparison to experiments that SPH models the process well and captures the influences affecting fibre alignment.

β-Cyclodextrin-allyl isothiocyanate complex as a natural preservative for strand-based wood composites

Environmental concerns over chemicals used for protecting wood and wood products from biological degradation have prompted the development of natural wood preservatives with lower health risks and prolonged efficacy. In this study, an effective and environmentally friendly method is demonstrated to substantially improve the durability of a strand-based wood composite product by incorporating a natural wood preservative system. Specifically, allyl isothiocyanate (AITC), a mustard oil-based natural biocide, was encapsulated into the cavity of β-cyclodextrin (βCD) and the as-prepared βCD-AITC complex was applied in the strand-based composite manufacturing process to produce a natural-preservative-treated engineered wood panel. The formation of the βCD-AITC complex was qualitatively confirmed by attenuated total reflection-Fourier transform infrared spectroscopy, and the inclusion yield of AITC was estimated to be 71% by thermogravimetric analysis. The preservative complex was blended with southern pine strands at 0%, 5%, and 10% prior to the application of polymeric methylene diphenyl diisocyanate resin and hot-pressing. The application of the preservative system significantly improved decay resistance against brown-rot fungi, Gloeophyllum trabeum and Postia placenta, by keeping the average mass losses of the treated panels below 7%. The internal bond strengths of the treated panels were maintained above the required level for structural OSB for use in humid conditions specified in the European OSB product standard. This study suggests the βCD-AITC complex to be a promising alternative to conventional preservatives for the protection of wood composite products.

Effect of Material and Process Variables on Characteristics of Nitridation-Induced Self-Formed Aluminum Matrix Composites-Part 1: Effect of Reinforcement Volume Fraction, Size, and Processing Temperatures.

This paper investigates the effect of the size and volume fraction of SiC, along with that of the processing temperature, upon the nitridation behavior of aluminum powder during the nitridation-induced self-formed aluminum composite (NISFAC) process. In this new composite manufacturing process, aluminum powder and ceramic reinforcement mixtures are heated in nitrogen gas, thus allowing the exothermic nitridation reaction to partially melt the aluminum powder in order to assist the composite densification and improve the wetting between the aluminum and the ceramic. The formation of a sufficient amount of molten aluminum is key to producing sound, pore-free aluminum matrix composites (AMCs); hence, the degree of nitridation is a key factor. It was demonstrated that the degree of nitridation increases with decreasing SiC particle size and increasing SiC volume fraction, thus suggesting that the SiC surface may act as an effective pathway for nitrogen gas diffusion. Furthermore, it was found that effective nitridation occurs only at an optimal processing temperature. When the degree of nitridation is insufficient, molten Al is unable to fill the voids in the powder bed, leading to the formation of low-quality composites with high porosities. However, excessive nitridation is found to rapidly consume the nitrogen gas, leading to a rapid drop in the pressure in the crucible and exposing the remaining aluminum powder in the upper part of the powder bed. The nitridation behavior is not affected by these variables acting independently; therefore, a systematic study is needed in order to examine the concerted effect of these variables so as to determine the optimal conditions to produce AMCs with desirable properties for target applications.

Prototyping of Bi-stable Polyurethane-Based Composite Booms

This paper deals with the design and prototyping of an ultrathin deployable tubular structure, made of composite material, which is expandable to a minimum length of 10 m in the deployed configuration. This structure has a small volume (2000 cm3) in the folded configuration, facilitating the transport and storage operations. Once deployed, the structure is able to support instrumentations with a weight of few kilograms, such as small antennas, cameras, sensors, and solar panels. We performed buckling analysis using the finite element method (FEM) by way of the commercial software ABAQUS 6.12. This numerical investigation was performed both to select the optimal geometrical configuration of cross section and to evaluate the critical load that leads to instability of the structure. Moreover, the effect of unavoidable geometrical variations of the thickness due to the composite manufacturing process was evaluated in non-linear buckling investigation. Fabrication process was deeply investigated to find suitable technological solutions to realize a 10-m boom component. Prototypes of 2 m and 4 m length have been produced and tested by loading the top end of both structures.

Integration of rCF in resin transfer pressing process

A new composite manufacturing process, resin transfer pressing, is introduced in this paper. In this process, nonwoven fabrics made of recycled carbon fibers are oversaturated with thermoset resin, i.e. they contain excess resin. The oversaturated nonwoven fabrics are prefabricated and used as resin carrier in a press process, where they are placed in a heated mold together with a dry textile-based preform. During pressing, the resin is pressed out and transferred from the nonwoven into the non-impregnated preform and hence impregnates the whole reinforcement. This study examines the oversaturation of nonwoven fabrics, the resin transfer pressing laminate manufacturing and the surface quality of the laminates. The ability of a nonwoven fabric to be oversaturated with resin is defined by the saturation degree, which was determined as up to 12 for glass fiber nonwoven fabrics and up to 60 for recycled carbon fiber nonwoven fabrics. Different laminates are manufactured by resin transfer pressing, and the impregnation quality is evaluated. With an optimized stacking sequence, a pore content <1% was achieved. The use of recycled carbon fiber nonwovens in the resin transfer pressing process leads to a less wavy surface compared to a wet compression molding manufactured laminate, showing a decrease of waviness Wz25 of 11% minimum.

Integrated Carbon-Fiber-Reinforced Plastic Microstrip Patch Antennas

A carbon fiber microstrip patch antenna is presented, constructed entirely from fiber-reinforced plastic materials, and fabricated directly into carbon-fiber-reinforced plastic (CFRP) composites as part of the composite manufacturing process. Fabrication of antennas as part of the composite manufacturing process provides numerous benefits, such as conformation to complex curvatures, reduced weight, and reduced aerodynamic impact. Modification of the localized conductivity of the carbon fiber using materials such as copper meshes is shown to improve the gain of the antenna by as much as 5 dB, while also improving the interlaminar shear strength of the composite by 22%.

Development of a continuous manufacturing process for self-reinforced composites using multi-step highly drawn polypropylene tapes

Despite the benefits of recycling, impact resistance, and lightweightness, polypropylene (PP) self-reinforced composites (SRCs) still suffer from a lack of research, especially in continuous manufacturing processes. Herein we report a comprehensive study, from the four-step high-ratio drawing of PP-tapes to the continuous manufacturing of SRCs. The mechanical properties of the PP-tape depend strongly on the final draw ratio with the intermediate drawing history having a negligible effect. Mechanical improvements accompany increases in melting temperature and crystallinity, and a decrease in density. PP-SRC was manufactured by continuous double-belt pressing, with optimum performance attained when processed with a 87-148-80 (°C) temperature profile. Structural integrity was not attained at lower temperatures due to poor impregnation, whereas higher temperatures degraded the mechanical properties of the PP-SRC by relaxing the highly drawn PP-tapes. Finally, an analytical approach based on micro-computed tomography, PP-tape relaxation, and rule-of-mixture calculations led to accurate predictions of experimental moduli.

The effect of thermal mismatch on the thermal conductance of Al/SiC and Cu/diamond composites

Thermal mismatch at the interface is inevitable in the manufacturing process of metal matrix composites. The relationship between strain and thermal conductivity of metal is obtained. The plastic strain region caused by thermal mismatch and its effect on thermal conductance of Al/SiC and Cu/diamond are acquired and discussed using the finite element method. It is found that the average strain is independent of particle size and proportional to the ratio of particle radius to distance. The strain will affect the thermal conductivity of composites in two ways. One is to decrease the effective thermal conductivity of matrix, which is more significant for the Al/SiC system than the Cu/diamond system, but it has a relatively small impact on the thermal conductivity of composites. The other is to reduce the interfacial thermal conductance (ITC) by weakening interfacial bonding and scattering phonon transport, making the effective thermal conductivity of reinforcement and thermal conductivity of composites decrease, which has a bigger impact on composites with high thermal conductance reinforcements. The results also show that there is an increase of thermal conductivity of composites with ITC in a specific region determined by particle size, and the composite reinforced with large particles has a higher thermal conductivity at low ITC because of the low density of interface. Our work is important for understanding the effect of thermal mismatch on thermal conductance of metal matrix composites and provides a way to bridge the relationship between mechanical behavior and physical properties.

Tensile Strength of Carbon Fiber/Epoxy Composite Manufactured by the Bladder Compression Molding Method at Variable Pressure Levels

Composite materials uses have been increasingly ubiquitous due to their advantages, for example, in being strong, lightweight, and rust-resistant. Various composite manufacturing processes are designed to obtain composite products of better quality, including minimizing the number of pores or voids trapped within and increasing the fiber volume fraction until an optimal value is achieved. The method employed in this research was the bladder compression molding method, and the materials used were woven carbon fabric and epoxy matrix. According to previous research which used this method, the higher the pressure in the bladder, the better the product quality generated. The aim of this research was to investigate the effect of changes in the pressure level in the bladder (1, 2, 3, 4, 5, 6, 7, and 8 bar) on the mechanical properties of the composite produced. The test specimen was gained by cutting the composite product with a CNC router machine. The tensile test results indicate that the ultimate testing tensile strength was 604 MPa and that the optimal pressure in the bladder was 7 KPa. The conclusion of this research is that the composite product quality would increase with the progressive increase in the bladder pressure to the point of optimal pressure.

Manufacturing of Single-Polymer Composite Materials Based on Ultra-High Molecular Weight Polyethylene Fibers by Hot Compaction

This paper describes the manufacturing process and properties of single-polymer composites based on ultra-high molecular weight polyethylene fibers produced by hot compaction. The hot compaction results in partial surface melting of the initial fibers, and melted part after cooling forms a matrix of the self-reinforced composites. Using high pressure during hot compaction allows to increase the fibers’ melting point and allows to avoid relaxation processes. Moreover, the fiber-to-matrix ratio may be changed using this approach by varying pressure and temperature. The flexural test was carried out to determine the mechanical properties. Samples obtained at 160 °C and 50 MPa have optimum properties (flexural strength and Young’s modulus were equal to 116.5 MPa and 15.3 GPa, respectively). It was found that mechanical properties of the obtained composites depend on both matrix amount and preservation of oriented fibers structure. The small amount of melted fibers does not allow to form matrix for load transferring. But the excessive melting of the fibers can result in a significant decrease in the fibers’ mechanical properties.

Digital twin of composite assembly manufacturing process

Industry is facing the management of geometrical deviations along the entire lifecycle of the product. It is helped by digital twin tools that may minimise the geometrical deviations from nominal of products. The new digital twin tools allow to manage geometrical variations through a set of steps fully related by modern information and communication technologies that establish a continuous and unambiguous flow of information among the different steps of this digital process along the whole product lifecycle. They are based on data coming from manufacturing, assembly and inspection. The available large data sets from manufacturing and inspection allow to develop new and more accurate simulation models that realistically consider form deviations and process signature, i.e. the pattern left by the manufacturing process on the produced part surfaces. The present work introduces a digital twin tool to support the lightweight design of assemblies in composite material. It establishes a continuous and unambiguous flow of variation information from the part design to assembly, passing through manufacturing by considering the manufacturing signature. It was applied to a case study and the obtained results agree with the experimental ones.

Composite technologies to the fore at K

Alongside the many mainstream plastics technologies on show at the triennial K 2019 show gathering in Düsseldorf, Germany, a number of new composite manufacturing processes and materials were presented. Reinforced Plastics highlights some examples.

Effects of geometry constraints and fiber orientation in field assisted extrusion-based processing

Composite manufacturing processes adapted for assisted-additive manufacturing (AM) have recently been proposed. Extrusion-based AM utilizes shear-driven alignment in producing printed structures where polymers and fibers naturally align parallel to the material flow. Convergent flow geometries become the dominant processing route for thermoplastic-melts and thermoset polymer extrusions. For rotational fibers, the phenomenon known as Jeffrey orbits poses issues during extrusion through a convergent channel, resulting in a randomized fiber architecture. Methods of minimizing Jeffrey orbits include the application of an additional external force such as a magnetic field to arrest or counteract the rotation. This work explores a combination of magnetic forces in conjunction with adjusted channel geometries using theory and experimental observations. The findings suggest the ability to alter fiber orientation in flow in a 300 cP viscosity matrix by modifying the extrusion channel geometry.

Optimization of manufacturing copper-graphite composite for electrical contact applications using grey relational analysis

Copper-graphite composite is one of the most important copper based composites, which is used, widely in electrical applications due to its excellent conductivity and high wear resistant. In this work, an attempt has been made to improve the multi-performance characteristics of copper graphite composite prepared by powder metallurgy and increase its expected life by optimizing the manufacturing process of this composite using statistical method. The experiments were carried out under various conditions of compacting pressure, sintering temperature and graphite content based on L9 orthogonal array. The experimental results indicated that multi-performance characteristics of the prepared composite such as electrical conductivity, densification and wear rate are influenced significantly by the studied parameters and the optimal process parameters level for optimum multi-performance characteristics was obtained in a compaction pressure of 750 MPa, sintering temperature of 950 °C and 10 Vol.-% of graphite content.