Reinforced Epoxy Matrix Research Articles

Mechanical, acoustic and vibration performance of intra‐ply Kevlar/PALF epoxy hybrid composites: Effects of different weaving patterns

AbstractThe influence of different weaving patterns on tensile, acoustic, and vibration behavior of intra‐ply Kevlar and pineapple leaf fiber (PALF) hybrid woven fabric reinforced epoxy matrix composites was investigated. Intra‐ply hybrid Kevlar/PALF woven fabrics were analyzed by three weaves: plain, twill, and basket. Also, epoxy matrix, pure Kevlar, and PALF woven fabric composites were analyzed for comparison purposes. Results revealed that the basket‐type hybrid composites exhibited a higher tensile strength of 77 MPa compared to plain (63 MPa) and twill‐type (73 MPa) hybrid composites. Plain and twill weave hybrid composites presented higher sound transmission loss levels of 28.9 and 30.5 dB, respectively, at higher frequency levels. Free vibration analysis showed that the PALF composites had higher damping and a lower natural frequency whereas the pure Kevlar and hybrid composites (KP1, KP2, and KP3) exhibited lower damping and higher natural frequencies.

Effect of Fiber Mass Fraction on Microstructure and Properties of 2D CF-GO/EP Composite Prepared by VIHPS.

Graphene is often used to improve interlaminar fracture toughness of carbon fiber/epoxy resin (CF/EP) composites. It is still a challenge to improve the toughness while maintaining the in-layer properties. In this study, 2D graphene oxide carbon fiber reinforced epoxy resin matrix (2D CF-GO/EP) composites were prepared by a vacuum infiltration hot-press forming experimental system (VIHPS), and three-point flexural and end notch flexural (ENF) tests were carried out. With the increase of the fiber mass fraction in the composites, the mode II interlaminar fracture toughness (GIIC) layers decrease gradually, and the bond property between the fiber and matrix interface layer becomes worse, because the accumulation of dense fiber bundles reduces the matrix penetration ability of cracks. However, the flexural properties increased first and then decreased, and reached the best flexural properties at 64.9%. When the fiber mass fraction is too high, the interlamellar bonding properties will decrease, and the fiber bundles will compress and affect each other. The delamination phenomenon will occur between the layers of the composites, which affects the overall bearing strength and stress limit of the composites. The results of the study show that the composites prepared by VIHPS have excellent mechanical properties, and the content of carbon fiber plays an important role in the influencing factors of the interlaminar and in-layer properties of composites.

A dual‐scale homogenization method to study the properties of chopped carbon fiber reinforced epoxy resin matrix composites

AbstractIn this work, a dual‐scale homogenization (DSH) procedures including the representative volume element (RVE) and Unit cell (UC) with Halpin–Tsai models in the UC scale and space direction‐sensitive Hotelling expansion (SDSHE) models in RVE scale separately. These two methods are introduced and implemented to predict the response of effective elastic properties in chopped fiber reinforced epoxy matrix structures. A post‐processing scheme of subdomain in UC scale based on Gauss theorem is proposed in SDSHE method, which is used to extract the average strain and stress in UC three‐dimensional structure. In addition, the X‐ray computed tomography was used to determine the fourth order tensor orientation angle and the probability distribution information of chopped fiber length in testing samples. Homogenization properties in RVE scale, and inclusion volume fraction (VF), thickness of interface and orientation tensors are designed in UC scale and compared. The excellent correlations with experiments prove the effectiveness of the proposed models. Furthermore, the algorithm proposed in this paper realizes the homogenization of the two scales in the process of numerical analysis, and it will effectively take into account many problems that cannot be achieved by other algorithms, such as the path strain of the model, the thickness of the interface, and so on.

Hygrothermoelastic response of a finite hollow circular cylinder

In this paper, a hollow circular cylinder of finite length with finite extent occupying the space is considered. Based on the hygrothermoelasticity theory, the transient response of a hollow circular cylinder subjected to the hygrothermal loading at the surface is analyzed. The analytical solution for the coupling and uncoupling effects of temperature, moisture, and thermal stresses is obtained by using the integral transform technique. The numerical results of the transient response of the hygrothermoelasticity field are presented graphically for a graphite fiber–reinforced epoxy matrix composite material (T300/5208).

Prediction and Optimization on Tribological Behaviour of Kenaf/Carbon Fiber Reinforced Epoxy Matrix Hybrid Composites

The awareness on sustainability of the environment among the researchers leads to the exploration of natural fiber composite materials. Hybridization of synthetic fiber and natural fiber is one of the potential strategies to enhance the mechanical properties as well as the degradability of such composite materials. However, less information concerning the optimization of tribological properties of this hybrid composite is available in literature. The aim of this study is to propose a statistical model to predict and optimize wear and coefficient of friction of kenaf/carbon reinforced epoxy composite. The value of parameters; load and sliding velocity ranges from 10 to 30 N and 20.9 to 52.3 m/s, respectively, are used to assess wear and coefficient of friction (COF) of different stacking sequences using the Analysis of Variance (ANOVA). The tribological test was conducted using a pin-on-disc tribometer. Multifactorial design analysis was employed to optimize the test control variables. It was found that, the optimized factors that affects the coefficient of friction and wear is at load 30 N and sliding velocity of 52.36 m/s. The proposed statistical models for wear and COF have 99.5% and 97.6% reliability, respectively. The generated equation models are bounded within the wear test control factors and ranges. The outcome from this study will be very useful for main parameter prediction for an optimized wear and COF.

Development and Mechanical Testing of Carbon Fiber Reinforced Polymer Matrix Composites for Micro Wind Turbine Applications

In this century, composites have been discovered to be the most promising and discriminating material accessible. Composites reinforced with synthetic or natural fibres are becoming more popular as demand for light weight, high strength materials for specialized applications grows are on the rise in the market. In the current work Carbon fiber Reinforced Polymer Matrix Composite material is developed aiming wind turbine blade applications. This research demonstrates the successful development of a carbon fibre reinforced Epoxy matrix composite that can be utilized to make micro wind turbine blades and is very cost effective thanks to the utilization of a simple hand lay-up approach. The peak elongation varies from 12.248 mm to 14.417 mm, and the tensile strength varies from 939.472 N/mm2 to 960.910 N/mm2. It was observed that the Compressive Strength varies from 8.992 N/mm2 to 46.895 N/ mm2 and peak elongation varies from 1.808 mm to 3.462 mm. In three-point bending test, the peak load was found to be 509.96 N. Due to the presence of carbon fibre reinforcement, the bending strength of polyester resin has been greatly increased.

Effect of fiber stacking sequence and orientation on quasi- static indentation properties of sustainable hybrid carbon/ramie fiber epoxy composites

Hybrid polymer composites reinforced with synthetic and natural fibers are gaining more interest in current composite technology in an effort to promote sustainability without sacrificing the performance of synthetic fiber reinforced polymer composites. The goal of this study is to see how the fiber stacking sequence of carbon and ramie fiber, as well as the orientation of ramie fiber, affects the quasi-static indentation behaviour of carbon/ramie fiber reinforced epoxy hybrid composites. The hybrid composite specimens were made using a hand layup approach followed by a hot pressing process. The quasi-static indentation properties of carbon/ramie fiber reinforcements in epoxy matrix were investigated using a hemispherical indenter at varying indenter displacement rates of 10, 20, and 30 ​mm/min for the stated stacking sequence and orientation. The indentation resistance qualities of carbon/ramie fiber reinforced epoxy hybrid composites were evaluated in terms of indentation force, hybrid composite specimen energy absorption capability, and hybrid composite specimen damage caused by hemispherical indenter penetration. The results reveal that a carbon/ramie fiber reinforced epoxy hybrid composite with 5 ramie fiber layers has better energy absorption capabilities, absorbing 114.926 ​J at a 20 ​mm/min indentation rate. Similarly, the indentation force in hybrid composites increases as the number of carbon/ramie fiber layers increases. These results indicate that carbon/ramie fiber reinforced epoxy hybrid composites have a great potential towards low velocity impact applications.

Water absorption studies of pineapple leaf fiber/nano rice husk powder reinforced epoxy matrix hybrid composites

In recent years, various experimental work on reinforced composites natural resources has been successfully carried out. This research focused on water absorption and bio composites from the treatment and untreated Pineapple Leaf Fiber in an epoxy resin matrix that will strengthen nano-rice husk particles. The reinforcement and filler material had different weight percentages for the production of hybrid composite specimens, while the epoxy resin matrix was constant. We employed traditional handmade techniques and effectively produced the same process for hybrid composite boards. For water absorption testing hybrid biocomposite specimens were prepared for experimental results in conformity to the ASTM standards. Epoxy resin matrix hybrid composite specimens, incorporated reinforced nano-rice husk particles, have been absorbed and are comparable to the water absorption of pineapple fibre. Experimental evidence suggests that pineapple leaf fibre samples treated chemically have a higher water absorption performance than untreated pineapple (24 Wt. per cent), which has high levels of composite husk nano-rice (6 Wt. per cent).

Synthesis and characterization of CCTO0.5-BT0.5/epoxy hybrid ceramic polymer composite for electronic applications

In the present paper, calcium copper titanate (CCTO)-barium titanate (BT)/epoxy hybrid composite has been developed using the compression moulding process for electronic applications. Two lead-free piezoelectric ceramics CCTO, and BT, have been incorporated in 50:50 ratios in hybrid filler form into the epoxy polymer matrix to prepare the CCTO0.5-BT0.5/epoxy hybrid composite. Loading a small quantity of CCTO in the epoxy matrix can increase both dielectric constant and loss: whereas BT reinforcement can lower the dielectric loss of the single filler-filled epoxy composite. The electrical propertiesof the prepared CCTO0.5-BT0.5/epoxy hybrid composite are analyzed with varying frequency and temperature. The experimental data of the CCTO0.5-BT0.5/epoxy hybrid composite has shown a significant advancement in dielectric properties compared to the single filler reinforced epoxy composites. So, CCTO-BT/epoxy composite has been evidenced as a potential candidate to replace single filler reinforced epoxy matrix composites for electronic applications.

Mechanical properties of HNT filled carbon fabric epoxy composites

Recent researches are witnessing that nano fillers are significantly contributing the enhancement of strength of solid materials. In the current investigation carbon fabric reinforced epoxy matrix added with halloysite nanotubes (HNT) composites were fabricated using hand layup technique followed by hot pressing. The carbon fabric reinforced epoxy matrix composites (C-E) were fabricated with the addition of 0.1, 0.2, 0.5 and 0.75 wt% halloysite nanotubes (HNT) and tested for its mechanical properties: tensile strength and modulus, flexural strength and modulus using ASTM testing standards. The results revealed that tensile strength and modulus were increased up to 82% and 26.8% respectively and flexural strength and modulus were increased up to 29% and 28.5% respectively as compared to the unfilled carbon fabric-epoxy composites. Failure mechanisms were analysed using SEM photographs.

A review on enhancement of mechanical properties of fiber reinforcement polymer composite under different loading rates

In composites, assessing and evaluating various mechanical properties is critical. Synthetic fibre is utilised as a reinforcing agent in a variety of polymer matrix composites to make mechanical properties better such as stiffness, modulus, and strength in lightweight materials. However, due to issues with synthetic-fibre-based polymer composites like production, recycling, and disposal, it is necessary to develop a composite that is environmentally benign and can be used in a variety of applications such as automobiles, chemicals, and architecture that uses natural fibres. The current study focuses on morphological characterization and mechanical property enhancement of fibre reinforcement polymer composites with varying fibre weight percentages in an epoxy matrix. Mechanical characteristics of natural reinforcement polymer composites such as halloysite nano tube epoxy matrix, alkanized treatment of natural fibres, and synthetic reinforcement polymer composites such as glass fibre carbon fibre and hybrid composite epoxy matrix with different wt percent of reinforcement in epoxy matrix were investigated in this study, as well as how higher loading rates affect mechanical characteristics such as toughness, impact strength, tensile strength, and fracture toughness are compared.

Combined effect of multiwalled carbon nanotubes, graphene nanoplatelets, and aluminum trihydride on the thermal stability of epoxy composites

AbstractGlass fiber reinforced epoxy matrix is modified with a hybrid combination of fillers, and composites were fabricated using the advanced pultrusion technique. The focus of the investigation was to comprehensively understand the synergy between the carbon nanofillers and the role of aluminum trihydride on the thermal characteristics. A ratio of 2 wt% of multiwalled carbon nanotubes and 3 wt% of graphene is established by prior optimization technique for improved thermal properties. Using X‐ray diffraction analysis, the presence of the two carbon fillers was confirmed. Aluminum trihydrate was incorporated in the epoxy matrix with the objective of improving the thermal properties. By thermogravimetric analysis and differential scanning calorimetry, assessment of the thermal properties of the composites has been undertaken. The use of the two carbon fillers leads to enhancement of the thermal properties and contrary to expectations, the composites with hybrid fillers undergo minimal degradation due to pyrolysis. Uniform dispersion of the nanoparticles and good interfacial bonding of fillers with the epoxy are observed to be critical for the enhancement of thermal properties. The ratio of the two carbon fillers used helps in their preferential alignment and hence significant improvements in thermal properties are observed. Glass transition temperature reveals a 13°C increase increases due to the inclusion of carbon nanofillers and aluminum trihydride.

Thermomechanical properties of epoxy resin/basalt fiber/hydrotalcite composites and influence of hydrotalcite particle size on their properties

AbstractNatural fibers (NFs) and inorganic particles have been successfully grown in the polymer to enhance its properties. The basalt fiber (BF) and modified hydrotalcite (LDHs) reinforced epoxy resin matrix composites were prepared, and the effects of fiber and modified hydrotalcite (G‐LDHs) on the microstructural characteristics of composites were investigated. Fourier transform infrared spectroscopy and X‐ray diffraction were respectively used to analyze the structure of modified BF and G‐LDHs, and thermogravimetric analysis was performed to study thermal stability. The mechanical properties of composites, including dynamic thermomechanical and tensile and flexural properties, were respectively studied by dynamic mechanical analysis (DMA) and universal testing machine. Experimental results show the successful synthesis of high‐performance epoxy copolymers. The impact strength, tensile strength, and elastic modulus of EP/BF/G‐LDHs respectively reached 7.07 kJ/m2, 20.52 MPa, and 2595 MPa when the content ratio of BF to hydrotalcite in the additive was 3:3. The DMA test showed that the glass transition temperature (Tg) value increased by 18.3°C, and the thermal stability of composite materials was improved. The storage modulus E′ value increased by 268.04 MPa, and the stiffness of the epoxy material and the mechanical properties were also elevated. The TGA and DTG curves indicate that the cured composites also exhibit excellent thermal stability. The effect of g‐LDHS particle size on the properties of composites was also discussed. Overall, the synergistic and complementary enhancement effect of the two materials is the best when the diameter of hydrotalcite is similar to that of BF, and the performance of the composite material is considerably improved.

Mode-I interlaminar fracture of aramid and carbon fibers reinforced epoxy matrix composites at various SiC particle contents

Abstract The Mode-I interlaminar fracture characteristics of aramid fabric andcarbon fabric reinforced epoxy composites along with the influence of SiC particle content were explored. Double cantilever beam (DCB) tests were performed in accordance with ASTM D 5528 for the purpose of examining the behavior of Mode-I delamination. The results showed that, the adhesion strength of an SiC particle within an aramid/ epoxy composite system was better than that within a carbon/epoxy composite system. The highest values of Mode-I fracture toughness of an aramid fabric/epoxy specimen and a carbon fabric/epoxy specimen were 1391 J × m-2 and 701 J × m-2 with SiC particle contents of 10 wt.-% and 5 wt.-%, respectively. The micrographs from optical and scanning electron microscopes verified the enhancements of Mode-I interlaminar fracture toughness behavior.

Moisture Absorption Studies of COIR and Sisal Short Fiber Reinforced Polymer Composites

Abstract: Easy availability of natural fibre, low cost and ease of manufacturing have urged the attention of researchers towards the possibility of reinforcement of natural fiber to improve their mechanical properties and study the extent to which they satisfy the required specifications of good reinforced polymer composite for industrial and structural applications. Polymer composites made of natural fiber is susceptible for moisture. Moisture absorption in such composites mainly because of hydrophilic nature of natural fibers. Water uptake of natural fiber reinforced composites has an effect on different. Lot of researchers prepared the natural fiber reinforced composites without conducting water absorption tests; hence it is the potential area to investigate the behavior of the composites with different moisture absorption. In this research the experimental sequence and the materials are used for the study of coir and Sisal short fiber reinforced epoxy matrix composites. The coir and Sisal short fibers are made into the short fibers with 10 mm x 10 mm x 5 mm size. The Epoxy Resin-LY556(Di glycidyl ether of bi phenol) and Hardner-HYD951 (Tetra mine), the water absorption behaviors are analyzed in the coir and Sisal short fibers reinforced epoxy composites. The water absorption behaviors of the epoxy composites reinforced with the coir and sisal short fibers with 25, 30 and 35wt% were analyzed at three different water environments, such as sea water, distilled water, and tap water for 12 days at room temperature. It was observed that the composites show the high level of the water absorption percentage at sea water immersion as compared to the other water environments. Due to the water absorption, the mechanical properties of macro particle/epoxy composites were decreased at all weight percentages. Keywords: Natural fibre, Moisture absorption, Coir and sisal short fibre, Reinforced polymer composites, Water absorption behaviour Polymer matrix composite (Epoxy resin) using Coir and sisal short fibre and to study its moisture absorption behaviour

Effects of recovered brown alumina filler loading on mechanical, hygrothermal and thermal properties of glass fiber–reinforced epoxy polymer composite

This study investigates the efficiency of recovered brown alumina (RBA) particles filled in epoxy glass-fiber composites. The RBA particles were obtained from grinding wheel rejects with the help of the mechanical crushing process. Recovered particles finer than 120 grit were used as particulate filler for composite preparation. Composites were processed through a hand-layup technique by varying RBA filler loading percentages (0, 5, 10, 15, and 20 wt.%) in a glass fiber–reinforced epoxy matrix. Physical, mechanical, water absorption, and thermal properties of the composites were tested experimentally. By suitable addition of RBA, it is possible to tailor the shore-D hardness, tensile modulus, flexural strength, flexural modulus, and maximum degradation temperature. The 20%-filled RBA composite shows the maximum flexural strength of 382 MPa, and the shore-D hardness value was 85. The fracture surface shows a failure mechanism dominated by matrix cracking and debonding of fiber/particles from the interface. Hygrothermal testing of the RBA20-filled composite reveals 9% and 4% reduction in tensile and flexural properties. The thermal stability of the glass fiber–reinforced composite improves as the filler percentage increases. Maximum thermal stability of 435°C was observed in 20%-filled RBA polymer composite.

Effect of filler loading and orientation on alkali-treated cornhusk film reinforced epoxy laminate composites

Cornhusk film (CHF) has been used as reinforcement in epoxy matrix to develop CHF-epoxy laminate composites (CHFEC). Subsequently, the influence of CHF loading by weight (3%, 6% and 9%) as well as the angle of orientation (00, 450 and 900) of its ridges on the dynamic mechanical properties of the composites has been studied. Alkali-treated CHF results in better CHF/epoxy interphase and shows improvement in composite performance. Strength-to-weight ratio (SWR) of alkali-treated CHF is increased by 7.2% as compared to that of untreated one. Dynamic mechanical analysis shows best results for 6wt% CHF loaded composites with 372 MPa storage modulus as compared to that with 212 MPa for neat epoxy. The positive shift in tan δ peak of around 8.2 °C for the composites validates the effectiveness of CHF as a reinforcing agent in epoxy matrix. The maximum increase in storage modulus is found up to 75.47%, and it retains 4 times its value in rubbery zone as compared to neat epoxy. The CHF-epoxy composites retain their homogeneity, which is further improved at higher angle of orientation of CHF. The predicted viscoelastic properties of composites from the theoretical expressions are in line with the actual results. Results of statistical analysis show that CHF loading and its orientation in the laminate are significantly affecting the overall properties of the composites. The maximum moisture absorption is found ~ 1.024%, which is much lower than the permissible standards for wood-polymer composites. CHF based epoxy laminate composite structures can be used for developing partitioning panels, decking and similar applications.

Investigation of the mechanical and ballistic properties of hybrid carbon/ aramid woven laminates

High-performance ballistic fibers, such as aramid fiber and ultra-high-molecular-weight polyethylene (UHMWPE), are commonly used in anti-ballistic structures due to their low density, high tensile strength and high specific modulus. However, their low modulus in the thickness direction and insufficient shear strength limits their application in certain ballistic structure. In contrast, carbon fiber reinforced epoxy resin matrix composites (CFRP) have the characteristics of high modulus in the thickness direction and high shear resistance. However, carbon fibers are rarely used and applied for protection purposes. A hybridization with aramid fiber reinforced epoxy resin matrix composites (AFRP) and CFRP has the potential to improve the stiffness and the ballistic property of the typical ballistic fiber composites. The hybrid effects on the flexural property and ballistic performance of the hybrid CFRP/AFRP laminates were investigated. Through conducting mechanical property tests and ballistic tests, two sets of reliable simulation parameters for AFRP and CFRP were established using LS-DYNA software, respectively. The experimental results suggested that by increasing the content of CFRP that the flexural properties of hybrid CFRP/AFRP laminates were enhanced. The ballistic tests’ results and the simulation illustrated that the specific energy absorption by the perforation method of CFRP achieved 77.7% of AFRP. When CFRP was on the striking face, the shear resistance of the laminates and the resistance force to the projectiles was promoted at the initial penetration stage. The proportion of fiber tensile failures in the AFRP layers was also enhanced with the addition of CFRP during the penetration process. These improvements resulted in the ballistic performance of hybrid CFRP/AFRP laminates was better than AFRP when the CFRP content was 20 wt% and 30 wt%.

Thermal stability and gamma ray shielding properties of tungsten borides/epoxy micro-composites

Particle reinforced epoxy matrix composites have recently been intensively prepared and investigated in numerous publications as a promising alternative gamma ray shielding materials. In this work, a DDM (4,4′-diaminodiphenylmethene) hardener modified by AA (acrylic acid) was used to cure the epoxy resin (E51) at room temperature. To obtain high performance epoxy composites, 30% by weight of tungsten borides WB and WB2 microparticles treated with a KH-560 silane coupling agent were incorporated into the epoxy matrix (EP0) and the composites were coded as EP30WB and EP30WB2, respectively. SEM (scanning electron microscopy) analysis confirmed the good dispersion of these fillers within the polymeric matrix. The structure of the synthesized epoxy matrix and its related composites were characterized using the FTIR (Fourier transform infrared) analysis. According to the FTIR spectra, the epoxy matrix as well as the micro-composites were effectively cured in less than 4 h. This rapid curing process can be justified by the reaction of the epoxy and acrylamide groups as well as the strong reactivity of DDM with AA. The thermal stability of the samples was evaluated by DSC (differential scanning calorimetry) and TGA (thermal gravimetric analysis). DSC analysis revealed that EP30WB2 has a high exothermic peak (166.68 °C) compared to EP30WB (154.48 °C). In addition, the TGA analysis showed that T5% (temperature of 5% weight loss) increased from 207.01 °C for EP0 to 339.65 °C for EP30WB and 346.92 °C for EP30WB2. Meanwhile, the char yield (Yc) at 800 °C has increased from 23.85% for EP0 to 40.36% for EP30WB and 45.99% for EP30WB2, respectively. Moreover, using a Cs-137 radioactive source, the linear and mass attenuation coefficients (μ, μm), half-value layer (HVL), ten-value layer (TVL) and radiation protection efficiency (RPE) for the epoxy matrix EP0, EP30WB and EP30WB2 micro-composites were experimentally determined. The shielding efficiency for EP0 was 17% and it was improved to 32% and 35% by filling EP0 matrix with WB and WB2, respectively.

Low velocity impact behaviour of surface treated glass fibre reinforced epoxy matrix hybrid composites

This task is intended to perform impact tests with a low-speed test on the specimen. The tests are carried out to improve their tolerance of impact so that they can be used for realistic applications in the real world. The specimen is treated with acid and a base for one day. By the hand-laying method, the specimen shall be prepared. Microscopy of the electron scanning is carried out in order to receive data on the surface topography of the affected specimen. Various low speed experiments have been evaluated in this paper.