Fiber Reinforced Plastic Composites Research Articles

Material characterisation of biaxial glass-fibre non-crimp fabrics as a function of ply orientation, stitch pattern, stitch length and stitch tension

Due to their high density-specific stiffnesses and strength, fibre reinforced plastic (FRP) composites are particularly interesting for mobility and transport applications. Warp-knitted non-crimp fabrics (NCF) are one possible way to produce such FRP composites. They are advantageous because of their low production costs and the ability to tailor the properties of the textile to the reinforcement and drape requirements of the application. Based on their specific production parameters, their draping properties can vary significantly. Draping simulations are used to predict the forming behaviour without relying on costly and time consuming trial and error experiments. However, these simulations require a broad material dataset to make accurate predictions. Previous studies have investigated the relationships between production parameters and drape behaviour only in isolation for a limited number of material parameters at a time. In this study, a comprehensive material characterisation is carried out. The influence of ply orientation, stitch pattern, stitch length and stitch tension on the tensile and bending properties and the friction, shear and drape behaviour of NCFs are investigated on a meso and macro scale. Furthermore, the inter-ply sliding phenomena in bias extension tests are analysed and the results of bias extension and picture frame tests are compared.

FEA modelling and environmental assessment of a thin-walled composite drive shaft

Fibre reinforced plastics (FRP) composites have been widely used in the automotive industry with the primary focus on reduced mass. However, there are relatively few reports on their application on power transmission components, such as drive shafts. This paper explores the feasibility of replacing the traditional structural steel by light weight FRP composites in a drive shaft. Three FRP composites are considered against a steel drive shaft; basalt/epoxy, carbon/epoxy, and CNT (carbon nanotubes) reinforced carbon/epoxy composites. The mechanical performance was analysed by finite element analysis (FEA) tool and classical laminate theory (CLT), while the environmental performance was evaluated by life cycle assessment (LCA) method. The study shows that with careful design a composite drive shaft can outperform the mechanical performance of a steel shaft (up to 90% mass saving, and 50% higher Factor of Safety). The study found steel shafts were preferable to FRP shafts based on embodied energy (steel total embodied energy 150MJ, FRP +325MJ). Reductions in carbon footprint from reduced emissions due to weight savings meant a carbon/epoxy shaft was preferable to a steel shaft. Two new material indices were suggested which can be used to select materials based on minimum embodied energy and global warming potential.

Tensile Testing Jig Unit for Foams and Foam-Cored Fiber-Reinforced Plastic Sandwich Composites

Tensile Testing Jig Unit for Foams and Foam-Cored Fiber-Reinforced Plastic Sandwich Composites

Optimization of a New Composite Multicellular Plate Structure in Order to Reduce Weight.

Currently, the most important structural design aims are weight reduction, corrosion resistance, high stiffness and vibration damping in several industrial applications, which can be provided by the application of advanced fiber-reinforced plastic (FRP) composites. The main research aim was to develop novel and innovative multicellular plate structures that utilize the benefits of lightweight advanced FRP and aluminum materials, as well as to combine the advantageous characteristics of cellular plates and sandwich structures. Two new multicellular plate structures were developed for the structural element of a transport vehicle. The first structure consists of carbon-fiber-reinforced plastic (CFRP) face sheets and pultruded glass-fiber-reinforced plastic (GFRP) stiffeners. The second structure consists of carbon-fiber-reinforced plastic face sheets and aluminum (Al) stiffeners. The second main goal of this research was the development of an optimization method of minimal weight for the newly developed all-FRP structure and the CFRP-Al structure, considering seven design constraints. The third main purpose was to confirm in a real case study that lightweight multicellular composite constructions, optimized by the flexible tolerance optimization method, provide significant weight saving (86%) compared to the all-steel structure. The added value of the research is that optimization methods were developed for the constructed new composite structures, which can be applied in applications where weight saving is the primary aim.

Digital image correlation (DIC) based damage detection for CFRP laminates by using machine learning based image semantic segmentation

Vision-based damage detection in carbon fiber-reinforced plastic (CFRP) composites can be interfered by such factors as surface texture, stains and lighting. A digital image correlation (DIC) based surface strain monitoring technique, on the other hand, enables to track the change of strain distribution. It is promising to develop a new approach for online structural health monitoring (SHM), in which the DIC strain contours can be scrutinized automatically and the results are no longer substantially subjected to human interference. In this study, a convolutional neural network (CNN) based image semantic segmentation technique is proposed for pixel-level classification of DIC strain field images. A DeepLabv3+ encoder-decoder architecture combined with different feature extraction networks is investigated. The training dataset and validation of the model are obtained through finite element (FE) simulation. The images of quasi-static axial tensile strain field obtained from 2D-DIC are used to test the accuracy and efficiency of the trained CNN model. It is found that use of a pre-trained ResNet-50 CNN model as the backbone network of DeepLabv3+ architecture through a transfer learning algorithm can make the semantic segmentation results reach a mean intersection over union of 0.9236. The prediction accuracy of the semantic segmentation model trained from the FE data is comparable with that of the model trained from the experimental data, which demonstrates that the proposed machine learning approach for DIC measurement is cost-effective.

Research advances in the mechanical joining process for fiber reinforced plastic composites

Fiber reinforced plastic (FRP) composites have received extensive attention in the auto industry and aviation field. For realizing the mechanical joining of fiber reinforced plastic composite, much research has been conducted. In this article, the latest development of the mechanical joining process for fiber reinforced plastic composites was reviewed. The application of numerical analysis methods in the mechanical joining process was also briefly described. Nine diverse mechanical joining processes were discussed, including bolted joining, hole-clinched joining, mechanical clinching, self-piercing riveting, electromagnetic riveting, friction riveting, injection clinching joining, Z-pin joining, and hybrid bond-bolted/riveted joining. The superiorities and drawbacks of diverse mechanical joining techniques were completely summarized. Furthermore, several future research trends for FRP composites were presented, such as establishing a comprehensive numerical analysis model of FRP composites, developing new hybrid joining processes, and developing non-destructive testing technique for defect visualization.

Comparison of Lightweight Structures in Bearing Impact Loads during Ice–Hull Interaction

The current study focuses on the impact loading phase characteristic of thin first year ice in inland waterways. We investigate metal grillages, fibre reinforced plastic (FRP) composites and nature-inspired composites using LS Dyna. The impact mode is modelled as (a) simplified impact model with a rigid-body impactor and (b) an experimentally validated ice model represented by cohesive zone elements. The structural concepts are investigated parametrically for strength and stiffness using the simplified model, and an aluminium alloy grillage is analysed with the ice model. The metal–FRP composite was found to be the most favourable concept that offered impact protection as well as being light weight. By weight, FRP composites with a Bouligand ply arrangement were the most favourable but prone to impact damage. Further, aluminium grillage was found to be a significant contender for a range of ice impact velocities. While the ice model is experimentally validated, a drawback of the simplified model is the lack of experimental data. We overcame this by limiting the scope to low velocity impact and investigating only relative structural performance. By doing so, the study identifies significant parameters and parametric trends along with material differences for all structural concepts. The outcomes result in the creation of a viable pool of lightweight variants that fulfil the impact loading phase. Together with outcomes from quasi-static loading phase, it is possible to develop a lightweight ice-going hull concept.

A Short Review of Recent Progress in Improving the Fracture Toughness of FRP Composites Using Short Fibers

Fiber-reinforced plastic (FRP) composite laminates have excellent mechanical properties, corrosion resistance, and designability and thus are widely used in various engineering fields. However, their interlayer performance is relatively poor due to no fiber reinforcement between the laminate layers. These layers are adhered through resin bonding only, caused during their usage, which results in composite material delamination damage, thus, limiting its performance. In response, researchers have conducted numerous studies on how to improve the interlaminate properties of laminates through component and structural modifications of the composites and interlaminate toughening. Short fiber toughening is a simple and effective way to solve this problem. This paper reviews the latest research progress in short fiber interlaminate toughening and short fiber modified resin toughening, analyzes the mechanisms of short fiber toughening is fiber bridging, fiber debonding, fracture, and the toughening mechanisms specific to different fibers. This review paper also discusses the current problems encountered in short fiber toughening and provides an outlook on the future development direction for short fiber toughening to provide a reference for subsequent research on short fiber toughened composites.

Sub-Fiber Scale Precision Dicing of Aramid Fiber-Reinforced Plastic Composites

Aramid fiber-reinforced plastic (AFRP) composites are widely used in aerospace, rail transit, marine and military industries, due to their high specific strength, high impact resistance, fatigue resistance and excellent designable properties. In order to meet different application requirements, cutting processes need to be carried out, such as window opening, edge cutting and slit cutting. However, the characteristics of high tensile strength and toughness, low interlaminar strength, non-uniformity and anisotropy make AFRP composites a difficult-to-machine material. They are prone to produce rough cutting surfaces and cutting damages including burr, wire drawing, delamination, resin burn, material flanging, etc. To solve this problem, the ultra-thin diamond dicing blade was used for high-speed cutting of AFRP composites in sub-fiber scale in this research. The influence of process parameters on cutting force, cutting temperature, maximum spindle current, tool wear and cutting surface quality were investigated by establishing the cutting force model, L16(45) orthogonal experiment, single factor experiment, range analysis and variance analysis. The theoretical and experimental results show that cutting AFRP composites with ultra-thin diamond dicing blade can obtain smooth surfaces without common cutting damages. When the cutting speed is 91.11 m/s (spindle speed n = 30,000 r/min), the cutting depth is 0.2 mm and the feed speed is 5 mm/s, the surface roughness Ra can be as low as 32 nm, which realize the precision cutting of AFRP composites.

Development of a method and technology for the production of 3D knitted reinforcement grids

Abstract The use of fibre-reinforced plastic composites (FRP) for lightweight construction solutions is becoming increasingly important. The processing of 2D scrims into complete 3D FRP components has been carried out with the help of complex manual assembly steps. The disadvantages of this procedure are distortions in the textile and, thus, deviations in the fibre alignments from the calculated load path. This paper presents a newly developed basic technology for the production of 3D reinforcing grids with variable warp and weft yarn section lengths based on multiaxial warp knitting technology. For this purpose, a new type of machine module and associated control technology for the production of weft yarn reserves on a multiaxial warp knitting machine was developed. In combination with technology from previous research work on the production of warp yarn lengths suitable for component contours, a basis was created for the production of 3D reinforcing grids.

Optimization of HNT nanoparticle distribution based on EPD process in epoxy–CFRP composites

There are numerous methods for reinforcing laminate composites using nanoadditives. However, the random dispersion of nanoparticles in polymer resins leads to critical defects owing to excessive dispersion. This study investigated a method of depositing halloysite nanotubes (HNTs) on a carbon fabric surface via electrophoresis deposition (EPD) for reinforcing the through-thickness strength of carbon fiber-reinforced plastic (CFRP) composites. The voltage during the EPD process was set as 6–12 V, which is the working range for nanoparticles during EPD. In addition, CFRPs were fabricated from modified carbon fabrics using vacuum-assisted resin transfer molding. The optimum voltage was determined as 6 V. At higher voltages, the mechanical properties deteriorated owing to the distribution of HNTs and damage to the fibers. The performance of the EPD-modified CFRPs was better than that of neat CFRPs. The highest strength was observed at 0.7 wt.% HNTs and 6 V, which indicated the feasibility of the EPD process and a well-dispersed morphology. The strong interaction of HNTs with carbon fabric influences the through-thickness mechanical properties of CFRP composites.

Corrosion Behavior and Internal Pressure Capacity of a Composite System Used to Connect Metallic Pipes

This research aims over how different kinds of fiber-reinforced plastic (FRP) may change the internal pressure capacity and corrosion behavior of linked metal pipes. Hence, aluminum pipes have been fabricated for further usage in wrapping with various FRP and welding. Used FRP materials include carbon fiber/epoxy (CFRP) and kevlar fiber/epoxy (KFRP) (CFRP). These fibers have been slit into narrow strips for use in the fabric-winding technique of connecting. Four-layer KFRP pipes and eight-layer KFRP-CFRP pipes are also viable options that have been investigated. On the other hand, comparisons have been made using pipes that have two different kinds of welding. The findings demonstrated an increase in the internal pressure capacity of the pipe compared to welding. The corrosion test was finally performed. The findings demonstrated that FRP connecting methods outperformed both welded and unjoined pipes in terms of corrosion resistance. These findings indicate that FRP composites have a bright future for use in pipe joining.

Environmental affected mechanical performance of additively manufactured carbon fiber–reinforced plastic composites

Due to their attractive strength-to-weight ratios, stiffness-to-weight ratios, thermal expansion, corrosion resistance, and vibration resistance properties, carbon fiber reinforced plastic (CFRP) composites have been widely used in applications ranging from aerospace to sporting goods. Considering some of the advantages of additive manufacturing (AM) over traditional subtractive methods, AM is being used to fabricate CFRP composites. For the fabrication method, several investigations have been conducted on materials and processing effects on the mechanical performance of the composites. However, no studies have investigated the effects of environmental conditions on mechanical performance. This study reports the environmental (temperature and relative humidity) affected mechanical performance of AM fabricated CFRP composites exposed to three different environmental conditions: warm–wet, warm–dry, and cold–dry, compared to samples tested immediately after fabrication under normal ambient conditions. The result was that the warm temperatures have insignificant effects on the mechanical performance of the composites, while near-zero degree cold temperatures have significant effects after the 96 h and 250 h short-term exposure periods. The result also showed the temperature to have more significant effects on mechanical properties than relative humidity. Under the warm conditions, the dry humidity resulted in a slight increase in material mechanical properties over the nominal ambient condition, while the wet humidity showed an insignificant reduction in material mechanical properties.

Effect of surface topography on injection joining Ti alloy for improved bonding strength of metal-polymer

Titanium matrix fiber-reinforced plastic composites had attracted increasing interest in marine and other fields because of their excellent mechanical and corrosion resistance. However, the interfacial bonding strength between the titanium matrix and the plastic is an important factor limiting its wide application. In this paper, the surface of titanium alloy TC4 (Ti-6Al-4V) was anodized to form an oxide layer with a 1–2 μm crack structure on the surface of titanium alloy. Then the titanium alloy was combined with plastic polyphenylene sulfide (PPS) by direct injection molding. The results show that different oxide layer structures on the surface of titanium alloy, which can be obtained by different anodizing times and anodizing temperatures, can obtain TC4-PPS composites with different bond strengths. The maximum bond strength of TC4-PPS composites was 16.8 MPa when the anodizing temperature was 90 °C and the oxidation time was 30 min. We also discussed the effect of titanium alloy oxide layer surface morphology, wettability, roughness, composition, failure mode, and glass fiber on the bonding strength, which is important for expanding the application of titanium alloy and plastic composite.

A review of fatigue behavior of FRP composites

The Fiber Reinforced Plastic (FRP) composite may be defined as a combination of two or more materials that individually might lack but together shows desirable properties. FRP composites are lightweight, corrosion-resistant, impact-resistant, electrically insulated, low-maintenance, less expensive, resistant to moisture, termites, fungus, and bacterial development and services for extended periods of time. Public works (federal, state, and municipal parks), automobiles, aerospace, wood replacement, benches, boardwalks, decks, fences, playgrounds, ramps, military, construction, flooring, siding, roofing, and restrooms are just a few of its applications. The fatigue behaviour test is the crucial test that traditional material and composite materials must pass through. It is the method of assessing materials for their cyclic behaviour usually at a constant rate, thus a material's endurance limit can only be discovered through fatigue testing. FRP composite manufactured through different processes into various final products were evaluated under a cyclic load till they reached their failure or till they reached a percentage of overall stiffness loss to determine its fatigue behaviour. This review paper sums up the changes in the fatigue behaviour obtained on FRP composites of the various composition prepared through different operations in different matrices and fillers.

Significantly improving mechanical properties of epoxy resin-based carbon fiber-reinforced plastic composites via introducing oxazolidinone segments

Herein, the oxazolidinone (OX) segments have been successfully introduced into carbon fiber-reinforced plastic (CFRP) composites via the bulk polymerization of the isocyanate and epoxy (EP) groups to significantly promote the mechanical properties. Through the bulk polymerization, the OX segments in epoxy resin (OX epoxy resin) have been formed, verified via the Fourier transform infrared (FT-IR) spectroscopy. Afterward, in order to obtain the cured OX epoxies, the as-prepared OX epoxy resin has been mixed with the pure EP resin for further curing. Thermogravimetric analysis (TGA) and dynamic mechanical thermal analysis (DMTA) have shown that the cured OX epoxies have exhibited improved thermal resistance and higher Tg than the cured neat epoxies. After introducing OX segments, the flexural strength, flexural modulus, and impact strength of the cured OX epoxies have been promoted by 30.1%, 12.1%, and 82.9%, respectively. Moreover, the mechanical properties of CFRP composites, fabricated from OX epoxy resin and T1100 carbon fibers, have been improved as well and in particular, the flexural strength, flexural modulus, impact strength, interlaminar shear strength, and compressive strength after the impact of the composites have been improved by 25.9%, 8.4%, 23.6%, 35.5%, and 23.8%, respectively. Furthermore, the impact damage of the composite laminates has been analyzed via Ultrasonic C-scan.

The influence of the addition position of cellulose nanofibers on the crystalline and mechanical properties of carbon fiber-reinforced polypropylene composites

ABSTRACT The introduction of nanofillers into conventional microsized fiber-reinforced plastic composites has great potential to improve the fracture toughness and crystalline properties of composites, especially for semicrystalline thermoplastic polymers. Although the selective reinforcement is possible by nanofiller addition, the influence of the addition position of nanofillers on the mechanical properties and crystalline properties still has not been revealed. In this work, the cellulose nanofibers (CNFs) as the secondary filler were added (i) into a polypropylene (PP) matrix by a melt-mixing process and (ii) onto a carbon fiber (CF) surface by a dip-coating process in a CF-reinforced PP composite. By focusing on the transcrystals surrounding CFs, which enable improvement of the interfacial strength, the crystalline properties and mechanical properties were investigated through polarized optical microscopy, differential scanning calorimetry, X-ray diffraction, and 3-point bending tests in this study. We revealed that (i) CNF addition into the PP matrix disturbed the transcrystallization surrounding CFs and that the mechanical properties slightly decreased. Conversely, (ii) CNF addition onto the CF surface promoted transcrystallization surrounding the CF, and the flexural yield strength and modulus significantly improved by a maximum of 30% and 63%, respectively.

The Effect of Carbon Fiber Types on Tool Wear During Edge Trimming of 0 deg, 45 deg, 90 deg, and 135 deg Carbon Fiber-Reinforced Plastic Laminates

Abstract Carbon fiber-reinforced plastics (CFRP) composites are difficult-to-machine materials due to extensive tool wear. This article investigates the impact of carbon fiber types on tool wear in edge-trimming CFRPs, each with the ply angle of 0 deg, 45 deg, 90 deg, or 135 deg, using uncoated tungsten carbide endmills at the high spindle speed of 6000 rpm and the constant feed of 0.0508 mm/rev. Three distinct types of carbon fiber tows, including T300 as standard modulus (SM), IM-7 as intermediate modulus (IM), and K13312 as high modulus (HM), have been vacuum infused into CFRP laminates and edge trimmed to investigate wear characteristics. Three wear criteria measured are flank wear, edge rounding radii, and worn area. The results show that tool wear is influenced by carbon fiber properties, such as fiber tensile strength, tensile modulus, and fiber microstructure. Overall, IM carbon fibers with the highest tensile strength produced the most extensive tool wear due to the abrasive carbon fibers. Of four fiber directions, the largest tool wear was obtained from the 45 deg angle, while the lowest tool wear occurred in the 0 deg angle.

Biomimetic approaches towards lightweight composite structures for car interior parts

Due to good density specific mechanical properties and low carbon footprint, natural fibre-reinforced plastic composites made from fleeces and felts are frequently used as automotive interior parts. The industry targets further mass reduction. Following a biomimetic technology-pull approach, natural fibre-reinforced polypropylene plates with improved lightweight potential were produced using compression moulding. Best results were obtained for a sandwich structure with thin, unidirectional flax fibre layers surrounding a needle felt based core. It was inspired by the carapace structure of the red-eared slider Trachemys scripta elegans. The lay-up performed well, not only with a high density specific flexural stiffness of 2.33GPa1/3 cm3/g, strength of 9.46 MPa1/2 cm3/g, and energy dissipation but also through less abrupt failure due to an asymmetric orientation of unidirectional fibres in the two face sheets. Combined with a mass-reduced needle felt as a core, this concept displays a promising and unconventional approach for further mass reduced, sustainable interior panels used as non-visible and visible design elements in the vehicle.

Thermal barrier coating for carbon fiber-reinforced composite materials

Carbon fiber-reinforced plastic (CFRP) composites are widely employed in lightweight and high performance applications including supercars, aero-vehicles, and space components. However, although carbon fibers are thermally stable, the low thermal endurance of the matrix materials remains a critical problem in terms of the performance of the material. In this study, we proposed a new, Al 2 O 3 -based thermal barrier coating (TBC) for the CFRP composites. The TBC comprised α-phase Al 2 O 3 particles with a mean diameter of 9.27 μm. The strong adhesion between the TBC and the CFRP substrate was evaluated using a three-point bending test. When the CFRP substrate was subjected to a 500–700 °C flame, the 1.45-mm thick TBC protected the CFRP substrate remarkably by reducing the surface temperature to 188–228 °C. The thermo-mechanical responses of this TBC/CFRP composite were analyzed after thermal shock tests. Surprisingly, 50% of the pristine flexural strength of the TBC/CFRP composite was preserved, whereas that of neat CFRP was reduced significantly by 95%.