Vacuum Bag Research Articles

Determination of the shear characteristics of polymer composite materials

Layered polymer composite materials (LPCM) based on carbon fiber and epoxy are widely used in the construction of commercial aircraft both in manufacturing lightly loaded and main power elements of aircraft airframes. The level of mechanical characteristics for all the composite constructions must be confirmed by experimental data of coupon testing. One of the most important characteristics of a layered composite material is the ability to perceive shear loads. Standard test methods ASTM D5379 and ASTM D7078 are used to determine the shear characteristics. These test methods enable determination of the shear properties of composite materials based on a polymer matrix reinforced with a high-modulus fiber. Comparative tests were carried out according to both methods. The samples were made from the wall and the tehnological zones of the spar to determine the values of destructive stresses and shear modulus. The results showed that the shear stresses in the material obtained by ASTMD7078 significantly (1.8 times) exceed those determined by ASTM D5379. At the same time, the modulus of elasticity differs slightly (by 1.1 times). This is due to the sensitivity of the test results to the method of loading and the quality of the specimens. When stretched according to ASTMD7078, the load is transmitted through the front surfaces of the coupons, which are obtained with sufficiently high quality from the tooling or vacuum bag. When compressed by ASTM D5379, the parallelism of the faces through which the load is distributed becomes critical. Moreover, the thickness of the sample also affected the test results obtained according to ASTM D5379, the greater the thickness, the greater the shear modulus. Proceeding from the results obtained, the recommendations on the choice of the method to be used for determining the shear characteristics of LPCM are formulated.

A novel active hydroforming & curing process to manufacture GLARE laminates: Numerical and experimental investigations

Fiber Metal Laminates (FMLs) are preferable thin-walled structures in several fields for their exceptional mechanical properties. However, how to manufacture thin-walled FMLs structures with complex shapes and guarantee the high mechanical properties is still a challenge. To address these, this paper proposes an innovative hybrid forming method, referred to as active warm hydroforming and curing, to enhance the formability and performance of FMLs in GLARE form by combining the forming and curing process into a single step. The hybrid method was verified on a box-shaped part as a proof-of-concept to assess the feasibility and parameter influence. Online curing was utilized to enhance efficiency and quality. The outcomes revealed that the new method increases the ultimate tensile stress by 12.1 % and reduces curing deformation from 3.1 mm to 1.3 mm compared to the vacuum bagging method. Furthermore, the critical parameters in forming of thin-walled structures, including blank holder force (BHF), pressure rate (PR), maximum pressure (MP), and forming temperature (FT), were identified using experimental, mathematical, and numerical approaches. Four defects in the formed thin-walled structures were observed and successfully eliminated through the control of these parameters. The method and results presented in this paper also provide direct guidance for optimizing the process parameters of FMLs warm hydroforming.

Effects of Graphene Oxide Nanoparticles on Delamination in CFRP and Optimization Using Response Surface Modeling

AbstractCarbon fiber composites recently have captured the attention of many for their wide array of properties surpassing those of traditional metals. Carbon fiber‐reinforced plastic (CFRP) has several excellent properties like a high strength‐to‐weight ratio, better chemical resistance, and other strength characteristics. But one problem affecting the use of CFRP is its delamination. This occurs during drilling holes for various operations. It is a known fact that the aircraft industry is one such industry very much dependent on such drilling operations. Failures such as fiber rupture, surface irregularities, micro‐crack formation, and deformations around drilling regions are commonly encountered during the machining of CFRP composite. This research has studied the effects of graphene oxide nanoparticles on delamination in the drilling of CFRP composite. Carbon fiber is manufactured using a vacuum bag process. The optimum conditions for the drilling process are found by using response surface modeling (RSM) which leads to minimum delamination in CFRP fabricated.

Polypyrrole coated carbon fiber/ magnetite/ graphene oxide reinforced hybrid epoxy composites for high strength and electromagnetic interference shielding

Carbon fiber reinforced polymer composites (CFRPs) are in huge demand in the aviation industry for reducing fuel consumption despite their unfavorable electromagnetic interference (EMI) shielding properties. The present work aims to improve the mechanical properties and EMI shielding effectiveness (SE) of polypyrrole (PPy) coated carbon fibers/graphene oxide (GO)/magnetite nanoparticles (MP)/ epoxy hybrid composites. For this purpose, PPy was coated on desized woven carbon fibers (CFs) woven mats via electrophoretic deposition. Graphite oxide and magnetite nanoparticles were synthesized through improved Hummers’ method and modified Massart’s method, respectively. GO was synthesized via ultra-sonication of graphite oxide, with its average thickness determined to be ∼ 1.4 nm as verified by atomic force microscopy (AFM). Solution mixing method and vacuum centrifugal mixing were utilized to disperse GO in epoxy resin. Porosity-free composites were fabricated using the vacuum bag technique. PPy coating, graphite oxide, GO and MP were characterized by scanning electron microscopy (SEM), AFM and Fourier transform infrared spectroscopy (FTIR). The SEM images showed the globular morphology of the deposited PPy on CFs. Hybrid composites containing CFPPy-0.2 wt% GO-0.2 wt% MP showed ∼52%, ∼24%, ∼60% and ∼25% increase in tensile strength, Young’s modulus, toughness, and elongation, respectively, compared to neat CF-epoxy composite. All hybrid composites prepared in this work have SE > 30 dB and could be promising lightweight and high-strength materials for EMI shielding applications in the X-band frequency range.

On the Analyses of Cure Cycle Effects on Peel Strength Characteristics in Carbon High-Tg Epoxy/Plasma-Activated Carbon PEEK Composite Interfaces: A Preliminary Inquiry

In this study, a high-Tg aerospace-grade epoxy composite plate was co-curing welded using a unidirectional PEEK thermoplastic carbon fibre tape to develop advanced composite joints. To account for the surface roughness and the weldability of carbon–epoxy/carbon–PEEK composites, plasma treatments were performed. The co-curing was conducted by the following steps: each treated thermoplastic tape was first placed in the mould, and followed by nine layers of dry-woven carbon fabrics. The mould was sealed using a vacuum bag, and a bi-component thermoset (RTM6) impregnated the preform. To understand the role of curing kinetics, post-curing, curing temperature, and dwell time on the quality of joints, five cure cycles were programmed. The strengths of the welded joints were investigated via the interlayer peeling test. Furthermore, cross-sections of welded zones were assessed using scanning electron microscopy in terms of the morphology of the PEEK/epoxy interphase after co-curing. The preliminary results showed that the cure cycle is an important controlling parameter for crack propagation. A noticeable distinction was evident between the samples cured first at 140 °C for 2 h and then at 180 °C for 2 h, and those cured initially at 150 °C for 2 h followed by 180 °C for 2 h. In other words, the samples subjected to the latter curing conditions exhibited consistently reproducible results with minimal errors compared to different samples. The reduced errors confirmed the reproducibility of these samples, indicating that the adhesion between CF/PEEK and CF/RTM6 tends to be more stable in this curing scenario.

Biocomposite Innovation: Assessing Tensile and Flexural Performance with Maleated Natural Rubber Additives

Fiberglass is the most common reinforcing fiber used in composites, with polymer matrices having high tensile strength and chemical resistance, including an excellent insulating property; however, they are non-degradable. Natural fiber reinforced polymer composites have advantageous properties such as lower density and price, when compared to synthetic composite products. In addition, hybrid composites may be obtained depending on various properties such as the fibers' length, structure, content and orientation, matrix bonding and arrangement. This study was carried out to determine the effect of adding Maleated Natural Rubber (MNR) from natural rubber as a coupling agent, in order to produce the highest tensile and flexural strength. The hand lay-up and vacuum bag methods with the Response Surface Method-Central Composite Design (RSM). -CCD) were used. The composite arrangement pattern was E-glass/OPEFB/E-glass, the volume fraction of OPEFB (oil palm empty fruit bunches):E-glass was 40:60, 50:50 and 60:40, the fraction volume of OPEFB + E-glass:matrix was 40:60, 50: 50, 60: 40 and the coupling agent were added by 9, 10 and 11% of the total epoxy resin used. Furthermore, the composite mold was made of glass with dimensions of 200mm x 50mm x 50mm. The results showed that the composite product obtained from both methods had a tensile strength value, which was influenced by the variable OPEFB fiber and epoxy resin. Meanwhile, the flexural strength was influenced by the OPEFB fiber and the quadratic factor of the epoxy-MNR resin.

HYBRID LAMINATE COMPOSITE CURVE STRUCTURE AS CYLINDRICAL CONCRETE COLUMN REINFORCEMENT

Composite materials are well known for their lightweight, easy to form, high elastic properties, and relatively low production costs. Laminated composites are composite materials that are widely applied in modern building structures such as aircraft walls, automotive cases, dashboards, press boards, etc. In this study, a curved laminated composite material was used as a reinforcing material surrounding the column structure. This study aims to analyze the mechanical strength of curved laminated composite materials as reinforcement for the cylindrical column concrete structure. Compressive testing of composite materials using the ASTM C39 standard. The materials used are jute fabric, e-glass, epoxy resin, and concrete aggregate. Specimens were molded using a vacuum bagging technique to minimize trapped air in the matrix. The curve shape of the laminated composite was obtained from the shape of the ASTM C39 concrete specimen with a diameter of 50 mm and a length of 150 mm. Based on the results of the study, the compressive strength of the structure increased up to 100% when the jute fabric was given up to 2 layers. Furthermore, the strength of the structure will increase up to 150% in the application of jute e-glass hybrid laminate composite.

Investigation on the effect of multiwalled carbon nanotubes in carbon fiber‐reinforced epoxy composites manufactured using vacuum infusion process and hand layup process followed by vacuum bagging

AbstractEpoxy/carbon fiber (CF) composites are widely used for structural applications owing to their exceptional mechanical and physical characteristics. The main aim of this work is to individually analyze the impact of multiwalled carbon nanotubes (MWCNTs) as nanofillers in epoxy/MWCNTs/CF composites prepared by vacuum infusion process (VIP) and hand layup followed by vacuum bagging technique (HLVB). Optimal Manufacturing Strategies were followed at various stages of manufacturing which include the selection of effective dispersion technique for MWCNTs, identification of optimal weight percentage of MWCNTs in epoxy/MWCNTs nanocomposites and preparation of epoxy/MWCNTs/CF composites. For HLVB samples, tensile and flexural strengths increased from 337.5 to 475 MPa and 615.40 to 677.09 MPa. For VIP samples tensile and flexural strengths increased from 371 to 521 MPa and 714.19 to 769.02 MPa. Thermogravimetric analysis (TGA) indicated improvement in the thermal stability of epoxy with the incorporation of MWCNTs/CF and improved weight percentage retention of 84.7% at 375°C. Fracture analysis of the epoxy/MWCNTs/CF composites prepared using VIP were analyzed by FE‐SEM and revealed that constant fiber rupture caused by better interface and improved bridging mechanism eventually led to enhanced mechanical performance. The predominant immediate fracture mechanism of MWCNTs also indicated this improved interfacial interaction.Highlights Pull‐out fracture mechanism was predominantly seen in high viscous epoxy/MWCNTs composites Immediate fracture mechanism of MWCNTs were predominant in low viscous epoxy/MWCNTs sample Constant fiber rupture of VIP samples indicated improved fiber matrix interface Incorporation of MWCNTs showed improved weight percentage retention 0.5 wt% MWCNTs incorporated VIP epoxy/CF composites showed improved performance

Experimental characterization and modal analysis for woven composite high aspect ratio beam

In modern engineering applications such as aerial vehicles, composite structures are widely implemented due to their high structural stiffness and very low weight-to-lift ratio. They also enable designers to control their mechanical properties as well as the manufacturing method and fabrication quality to achieve the required structural performance. However, various manufacturing methods and the fabrication process can be considered production imperfections. In this study, an assessment of the fabrication quality for a typical composite structure is implemented. As considered for airplane wings and helicopter blades, a high aspect ratio structure is implemented as a case study. This structure is composed of laminated woven carbon fiber/epoxy resin fabricated using the vacuum bagging production method. To characterize the mechanical properties of the proposed structure, a mechanical tensile test is carried out. An experimental modal analysis via roving hammer test is implemented to examine the dynamic behavior of the proposed structure. To assess the quality of manufacturing and fabrication quality, the obtained natural frequencies are compared with the ones computed using a numerical technique using the Finite Element Method (FEM). The analytical problem using MATLAB had been established to emphasize the experimental results. Results showed that good manufacturing quality is achieved by using the vacuum bagging production method. Also, the experimental results agree well with both the numerical and theoretical results, Which indicates good manufacturing quality.

ANALISIS UJI EDX PADA MATERIAL BERPENGUAT KARBON KEVLAR DENGAN METODE VACUUM INFUSION DAN VACUUM BAGGING

This study aims to determine the comparison of specific characteristics of bending testing of carbon fiber kevlar material made using two manufacturing methods, namely the vacuum infusion manufacturing method and the vacuum bagging manufacturing method which is then continued with EDX (Energy Dispersive X-Ray) testing to determine the elements contained in the specimen. The results of the analysis of the average bending test results show that the specimen with the vacuum infusion manufacturing method is the method with the best results compared to the vacuum bagging manufacturing method, indicated by the average result of 253.68 MPa for the vacuum infusion method, while for the vacuum bagging method it is shown with an average result of 187.87 MPa. The EDX test results show that the micro-composition of specimens with the vacuum infusion method has a content of O2 and N of 16.83% so that it has a better density because it contains few voids, while for specimens with the vacuum bagging method has a content of O2 and N of 49.78% so that it has a less good density because it contains more voids

PENGARUH CORE HONEYCOMB KOMPOSIT SANDWICH TERHADAP KEKUATAN COMPRESS DENGAN METODE VACUUM BAGGING

Sandwich composites are a combination of two materials with different properties, when combined to form one material that has stronger properties and resistance than its constituent materials. This structure consists of a surface layer (skin) and a core (core). This study used fiberglass woven roving skin, core polylactid acid (PLA), and put together using polyester resin. One of the new technologies used today is 3D printing, which allows the manufacture of products with three-dimensional shapes. The research aims to produce new composite products by creating vertical and horizontally oriented variations of honeycomb cores, combined with PLA cores printed using 3D printing technology. The manufacturing process uses the vacuum bagging method because the process is simpler. The test is performed by flatwise compressive method to evaluate the resistance of the specimen to a given compression load. The test results showed that of the four vertically oriented honeycomb sandwich core composite specimens, the highest maximum compressive strength value was found in vertical honeycomb 3, reaching 61,310 MPa with a maximum load of 46434 N. Meanwhile, in the four horizontally oriented honeycomb sandwich core composite specimens, the highest maximum compressive strength value was found in horizontal honeycomb 2, reaching 15,265 MPa with a maximum load of 13603 N. From the test results It was concluded that the vertically oriented honeycomb sandwich core composite has superior structural strength

Theoretical and experimental validation of critical thermal properties of advanced vacuum bagging for composite manufacturing

The vacuum bagging is a common but critical step of various manufacturing process chains for Carbon/Glass Fibre reinforced polymers (C/GFRP). Whilst developing a new generation of vacuum bagging, significant efforts have been made to deeply understand the relevant physics fields, process variables involved and to provide predictive approaches to support dimensioning and scaling exercises prior to implementation into real production process. Main features of the new bagging system are, (1) the reduction of material diversity through merging of various properties within one single layer and, (2) the suppression of critical folding steps by using thermoforming for pre-shaping purposes. This paper will mainly focus on considerations of heat transfer during the pre-shaping of the film, directly on the CFRP part short before the curing step. For the better risk assessment of the short time exposition of an uncured composite part to the heat flow, a problem of transient coupled field analysis involving heat transfer via conduction, convection and radiation is formulated and solved by using Finite Element Analysis in COMSOL under consideration of realistic process conditions. Further a section dedicated to the comparison of the obtained results with measurements performed on a system including an IR-emitter, the bagging material, a ground plate and in some studies as well a CFRP sample is included. During the study the influence of time, power output of the emitter, distance between emitter and surface as well as irradiation angle has been assessed including a comparison of simulated results and performed measurements.

Intumescent fire‐retardant performance and small‐scale reaction mechanism on banana/bio‐epoxy composites

AbstractThe present work deals with the thermal degradation, the physical characterization, and kinetic mechanisms of green epoxy resin‐based biocomposites (BC) reinforced by banana leaf fiber (BLF). The two main samples have been manufactured using the vacuum bag resin transfer molding method. The first, BLF‐based BC, is used as a control sample, while the second sample is coated with 6% wt. of intumescent fire retardant (IFR), which contains APP and boric acid. The effect of IFR coating has been investigated using thermogravimetric analysis (TGA) under inert and oxidative atmospheres and kinetic studies of model‐free and model‐based approaches have been applied for predicting the kinetic parameters of thermal degradation reactions. The TGA results show that the IFR coating delays the thermal degradation around 13–20 K of BLF‐based BC materials, which leads to an increase of 8% in the char residue under inert atmosphere. In addition, the sample has been characterized by SEM, EDS, and FTIR analysis (before and after the TGA test). The effectiveness of the IFR protective role is displayed on the SEM micrographs by showing the hole of the char enclosed and built the foam layer. The kinetic parameters from model‐free and model‐based curve fitting of BLF‐based BC and BLF‐based BC‐coated IFR are obtained, while the effect of IFR on the kinetic parameter increased the activation energy (model‐free and model‐based) under inert atmosphere. The fitting methods and optimization procedure gave excellent results for kinetic parameters, showing a particularly good correspondence with the TGA experimental data.

An investigation of the mechanical characteristics of natural particle‐reinforced glass and epoxy composites after immersion in acidic and basic aging solutions

AbstractThis study aimed to ascertain the alterations in aging responses of fiber‐reinforced composites, as well as the effects of their natural particle reinforcement, through exposure to acidic and alkaline solutions. Specimens were produced with 0 wt. % (neat), 1 wt. %, 2 wt. % and 3 wt. % particle ratios from acorn and pinecone particles. A particle content of 2 wt. % was determined to yield the best mechanical properties in all mechanical tests conducted for pinecone reinforcement. The highest improvement in strength, observed in 3 wt. % pinecone‐reinforced composites, reached 22.5% at flexural strength. HCl and NaOH diluted in water were chosen as aging solutions. Mechanical tests were repeated at different stages of aging. According to the findings, 1 wt. % particle‐reinforced composites showed better resilience to the mechanical property reduction effect of aging compared to the 2 wt. % and 3 wt. % particle‐reinforced composites. At a particle ratio of 2 wt. %, the acorn‐reinforced specimens exhibit their highest maximum penetration force, which is 5% higher than that of the 0 wt. % composite, consistent with the results of tensile and compressive tests.Highlights Composite material was manufactured by hand lay‐up and vacuum bagging method. Specimens were aged using acid and base solutions. Tensile, compressive, and bending results were obtained depending on particle type and ratio. Tensile, compressive, and bending strengths of composites were compared according to various aging times.

Investigation of Metal Wire Mesh as Support Material for Dieless Forming of Woven Reinforcement Textiles

Within the rapidly growing market for fiber-reinforced plastics (FRPs), conventional production processes involving molds are not cost-efficient for prototype and small series production. Therefore, new flexible forming techniques are increasingly being researched, many of which have been inspired by incremental sheet metal forming (ISF). Due to the different deformation mechanisms of woven reinforcement fibers and metal sheets, ISF is not directly applicable to FRP. Instead, shear and bending of the fibers need to be realized. Therefore, a new dieless forming process for the production of FRP supported by metal wire mesh as an auxiliary material is proposed. Two standard tools, such as hemispherical punches, are used to locally bend a reversible layup of metal wire mesh and woven reinforcement fiber fabric enclosed in a vacuum bag. Therefore, the mesh aids in introducing shear into the material due to its ability to transmit compressive in-plane forces, and it ensures that the otherwise flexible fabric maintains the intended deformation until the part is cured or solidified. Basic experiments are conducted using thermoset prepreg, woven commingled yarn fabric, and thermoplastic organo sheets, proving the feasibility of the approach.

High performance shape-adjustable structural lithium-ion battery based on hybrid fiber reinforced epoxy composite

High performance shape-adjustable structural batteries with both excellent electrochemical performances and mechanical properties, and compatible with conventional batteries and composite processing techniques, are highly attractive for next generation electrical vehicles and electrical aircrafts. Herein, a high-performance structural lithium-ion battery composite (SLBC) is developed by encapsulating commercial-available battery core materials with hybrid fiber reinforced epoxy composite laminate shells, which can be assembled into desired irregular shapes with the conventional vacuum bagging technique. Firstly, the laminate shell layout with the combination of glass fiber woven fabric (GFWF) and carbon fiber woven fabric (CFWF) is designed and optimized. Meanwhile, a PET film is employed to wrap the battery core materials, which enables processing of the SLBC with liquid electrolyte in ambient condition. The SLBC obtained demonstrates both prominent mechanical (flexural strength of 211.7 MPa and flexural modulus of 7.7 GPa) and electrochemical properties (an initial discharge capacity of 98.5 mAh/g at 0.2C, a high energy density of 314.5 Wh kg−1, and a good cycling performance) owing to the hybrid design of CFWF and GFWF as well as a sealed environment to guarantee the battery operate well. Impressively, the in-situ mechano-electrochemical measurements are assessed under the out-of-plane compressive stress and the flexural stress conditions. These results show that the SLBC under loading can maintain stable electrochemical performance even at a high out-of-plane compressive stress of 20 MPa and a high flexural stress of 150 MPa. Furthermore, the SLBC can also maintain the excellent discharge capacity when subjected to a high impact energy, which is promising in next generation electrical vehicles. Finally, the wave-like SLBC fabricated demonstrates the effectiveness in withstanding loads and driving electric fan simultaneously, which is promising in next generation electrical vehicles..

The effect of hexagonal boron nitride nanopowders addition on the mechanical behaviors of basalt fabric reinforced composites

Purpose The purpose of this paper is to investigate the effect of doping element on the structural, thermal properties, mechanical performance and the failure mechanism of hexagonal nano boron nitride (h-BN)-reinforced basalt fabric (BF)/epoxy composites produced by hand lay-up and vacuum bagging technique. h-BN particles doped to composite materials increased the tensile, bending and impact strength of the composite at certain rates while 1 Wt. % h- BN addition shows the highest tensile and flexural strength. Design/methodology/approach The epoxy resin was doped with h-BN nanopowder at the certain rates (0, 1, 2 and 4 Wt.%) and the epoxy: hardener ratios used in the study were selected as 80%: 20% by weight. Then, with the aid of a roller by hand lay-up method, a mixture of epoxy + hardeners containing nanoparticles and nanoparticle-free were fed onto BFs, 12 layers of each dimension 30 cm × 30 cm. The surplus epoxy resin was moved away from the composite sheets using the vacuum bagging process and left to cure at room temperature for 24 h. ASTM D3039 for tensile, D7264 for three-point bending and D256 for Izod impact test were performed for the mechanical tests. After the tensile test, the morphologies of the fracture surface were examined with a stereomicroscope and various failure mechanisms are highlighted. Findings In this study, a series of basalt/epoxy composites with h-BN nanopowders have been prepared to identify the effect of filler ratio on mechanical properties. It has been known from the results of mechanical experiments that the addition of h-BN improves the mechanical performance of materials at a certain rate. The tensile and flexural strengths of h-BN doped composites, increase for concentrations of 1 Wt.% h-BN, but decrease with the increasing content of it. The basalt/epoxy resin composite with higher mechanical properties could be a potential material in the automotive and aerospace industries. Originality/value The aim of this study is to contribute to literature within the context of this new combination of composites and their mechanical properties, failure mechanisms. It presents detailed characterization of each composite by using X-ray differaction (XRD), differential scanning calorimetry (DSC), fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy.

Investigation of Novel Flax Fiber/Epoxy Composites with Increased Biobased Content.

Currently, biobased epoxy resins derived from plant oils and natural fibers are available on the market and are a promising substitute for fossil-based products. The purpose of this work is to investigate novel lightweight thermoset fiber-reinforced composites with extremely high biobased content. Paying attention to the biobased content, following a cascade pathway, many trials were carried out with different types of resins and hardeners to select the best ones. The most promising formulations were then used to produce flax fiber reinforced composites by vacuum bagging process. The main biocomposite properties such as tensile, bending, and impact properties as well as the individuation of their glass transition temperatures (by DSC) were assessed. Three biocomposite systems were investigated with biobased content ranging from 60 to 91%, obtaining an elastic modulus that varied from 2.7 to 6.3 GPa, a flexural strength from 23 to 108.5 MPa, and Charpy impact strength from 11.9 to 12.2 kJ/m2. The properties reached by the new biocomposites are very encouraging; in fact, their stiffness vs. lightweight (calculated by the E/ρ3 ratio) is comparable to some typical epoxy-glass composites.

Compressive and Shear Strength of Kevlar based Nano Composites

The Fibre Reinforced Composite (FRC) material consists of building materials in macroscopic level by having fibres and resin as reinforcement and matrix material respectively. It has different physical and chemical properties that were bonded together in order to get new material with different required characteristics from individual components. The properties of the composites are largely depending on the matrix and reinforcement materials. The matrix strengthening process by introduction of fine nano particles in composite laminate was done in this work. In order to study the effect of nano particles, the composite consists of Kevlar- 49 (K49) fibre in woven form with epoxy resin as matrix was considered. All the test specimens have been prepared with 12 layers of K49 to build 3mm thickness using vacuum bag moulding method. The K49 fibre in form of plain-woven type were chosen as reinforcement material. The nano fillers such as Titanium dioxide (TiO2), Calcium Carbonate (CaCO3) and Graphite powder (Gr) were used as nanomaterial added in the matrix and was compared with pure K49 reinforced composites for better performance. The TiO2, CaCO3 and GR nano fillers were constituted on various weight ratios in FRC. The structural properties like compression and shear strengths were determined as per ASTM standards. The fracture behaviour for all the categories of laminate has been detailed and reported using scanning electron microscope.

Design and Fabrication of a Customized and Fully‐Recyclable Carbon Fibers/Epoxy Composites Prostheses via a Functional Additive Manufacturing Approach

AbstractThis study presents an innovative approach based on the combination of two different techniques for fiber‐reinforced epoxy composites manufacturing, i.e., additive manufacturing (AM) and hand lay‐up‐assisted vacuum bagging. It represents a proof of concepts for the manufacturing of a customized and lightweight lower‐limb prostheses having built‐in functional elements, such as sensors. In particular, a soluble tool for fabricating a complex‐shaped carbon reinforced epoxy composite is produced by AM. The 3D printed model is properly designed to integrate a functional element, in a customized way, within the composite structure itself. Moreover, a fully‐recyclable epoxy resin system is used as matrix for the fabricated composite part to recover the expensive functional part and carbon fibers as soon as the prostheses has reached the end of its life (EoL). The prostheses recycle is carried out through a chemical recycling process that relies on the presence of acid‐cleavable groups within the epoxy‐cured network that allows for the cleavage of the crosslink under certain conditions. A similar approach is proposed in the state of art, but by using the traditional autoclave prepreg process and without considering the handling of the part at its EoL.