Fiber Reinforced Polymer Composite Materials Research Articles

Bond Behavior of Wet-Bonded Carbon Fiber-Reinforced Polymer-Concrete Interface Subjected to Moisture

The use of carbon fiber-reinforced polymer (CFRP) composite materials to strengthen concrete structures has become popular in coastal regions with high humidity levels. However, many concrete structures in these places remain wet as a result of tides and wave-splashing, so they cannot be completely dried before repair. Therefore, it is vital to investigate the effects of moisture on the initial and long-term bond behavior between CFRP and wet concrete. This research assesses the effects of moisture (i) during CFRP application and (ii) throughout the service life. Before CFRP bonding, the concrete blocks are preconditioned with a water content of 4.73% (termed “wet-bonding”). Three different epoxy resins are applied to study the bond performance of the CFRP-concrete interface when subjected to moisture (95% relative humidity). A total of 45 double-lap shear specimens were tested at the beginning of exposure and again after 1, 3, 6, and 12 months. All specimens with normal epoxy resins exhibited adhesive failure. The failure mode of specimens with hydrophobic epoxy resin changed from cohesive failure to mixed cohesive/adhesive failure and to adhesive failure according to the duration of exposure. Under moisture conditioning, the maximum shear stress (τmax) and corresponding slip (smax) of the bond-slip curve first increased and then decreased or fluctuated over time. The same tendency was seen in the ultimate strain transmitted to the CFRP sheet, the interfacial fracture energy (Gf), and the ultimate load (Pu). Analytical models of Gf and Pu for the CFRP-concrete interface under moisture conditioning are presented.

Применение лазерного ультразвука для исследования и диагностики полимерных композиционных материалов, армированных волокнами

Применение лазерного ультразвука для исследования и диагностики полимерных композиционных материалов, армированных волокнами

A multi-pattern compensation method to ensure even temperaturein composite materials during microwave curing process

Microwave curing technologies have many advantages in manufacturing fiber reinforced polymer composite materials used in aerospace products, compared with traditional autoclave curing technologies. However, the uneven electromagnetic field of microwave in the cavity of the curing chamber results in uneven temperature on the surface of composite laminates during curing, which has been a major obstacle in industrial applications worldwide. Existing methods attempted to solve the problem by the random superposition of uneven electromagnetic fields, but the results were still not satisfactory to meet the high quality requirements of aerospace parts. This paper reveals the one-to-one correspondence between heating patterns of composite parts and microwave curing system settings, and reports a new concept to solve this problem by continuously monitoring and compensating the uneven temperature distribution in real-time. Experimental results from both fiber optical fluorescence sensors and infrared thermal imagers showed significant improvement in temperature uniformity compared with existing methods.

A multi-pattern compensation method to ensure even temperature in composite materials during microwave curing process

Microwave curing technologies have many advantages in manufacturing fiber reinforced polymer composite materials used in aerospace products, compared with traditional autoclave curing technologies. However, the uneven electromagnetic field of microwave in the cavity of the curing chamber results in uneven temperature on the surface of composite laminates during curing, which has been a major obstacle in industrial applications worldwide. Existing methods attempted to solve the problem by the random superposition of uneven electromagnetic fields, but the results were still not satisfactory to meet the high quality requirements of aerospace parts. This paper reveals the one-to-one correspondence between heating patterns of composite parts and microwave curing system settings, and reports a new concept to solve this problem by continuously monitoring and compensating the uneven temperature distribution in real-time. Experimental results from both fiber optical fluorescencesensors and infrared thermal imagers showed significant improvement in temperature uniformity compared with existing methods.

Effect of abrasive jet process parameters on machining glass fibre reinforced polymer composite

AbstractAn experimental and theoretical research work on abrasive jet machining of glass fiber reinforced polymer composite materials was conducted using abrasive jet machining setup fabricated in our workshop. The objective of this research work is to machine holes on the glass fiber reinforced polymer composite using an abrasive jet machine under various levels of process parameter. The material removal rate and hole geometry (kerf analysis) were observed as a part of the investigation. Four factors five levels central composite rotatable design matrix was used for optimizing the required number of experiments. The objective of the present investigation is to develop mathematical models using the response surface methodology. The adequacy of the models has been checked using the ANOVA technique. Use of the developed mathematical models, material removal rate and hole geometry of the machined glass fibre reinforced polymer composite helps prediction at 95% confidence level.

Use of Nanoparticles for Enhancing the Interlaminar Properties of Fiber-Reinforced Composites and Adhesively Bonded Joints-A Review.

This review paper aims at reporting some of the notable works carried out concerning the use of nanoparticles (NPs) as a means of improving the resistance of fiber-reinforced polymer composite materials (FRPs) and adhesively bonded joints (ABJs) to delamination initiation and propagation. Applications of various nanoparticles, such as carbon-based, ceramic-based and mineral-based are discussed. The main properties that have been considered for improving the delamination and fatigue resistance of FRPs are the interlaminar shear strength, fracture toughness, and fracture energy. On the other hand, cohesive and interfacial strengths have been the focused parameters in the works that considered enhancement of ABJs. The reported results indicate that inclusion of NPs in polymeric matrices leads to improvement of various material properties, even though some discrepancies in the results have been noted. Notwithstanding, additional research is required to address some of the issues that have not yet been tackled, some of which will be identified throughout this review article.

Charpy impact response of glass fiber reinforced composite with nano graphene enhanced epoxy

Fiber reinforced polymer composite materials show several superior properties over conventional engineering materials; on the other hand, most of composite materials also have some drawbacks such as brittle behavior of matrix. This study is aimed to improve the impact response of composite material by adding nano particle into epoxy matrix. For this purpose; an experimental study was conducted to investigate the effect of graphene nano particles inclusion in epoxy resin with glass fiber reinforced composite plate on the Charpy impact response. Glass fiber reinforced (GFR) epoxy composite plates were produced with various graphene nano platelets content such 0, 0.1, 0.25 and 0.5 wt%. Low velocity impact response was investigated by using Charpy impact test method. Impact energy and impact damage results presented in detail.

Investigation on the effect of drilling parameters on the tool wear and delamination of glass fibre-reinforced polymer composite using vibration signal analysis

Glass fibre-reinforced polymer composite materials are widely used in industrial, aerospace and automotive sector. It has excellent properties such as high strength to weight ratio, higher fatigue limit, high stiffness to weight ratio, corrosion resistance and design flexibility. The strength of the composite highly depends upon orientation of the fibre material. Drilling is one of the major machining operations that are carried out on Glass fibre-reinforced polymer composite materials to the need for components assembly. There are many problems encountered while drilling glass fibre-reinforced polymer composites. The major problems are excessive tool wear and delamination of the composite during drilling, which reduce the strength of the composite during application. In the present study, the experimental investigations are carried out to analyse the effect of various machining parameters, i.e. cutting speed and feed rate on the tool wear and delamination. The time and frequency domain analysis of vibration signals measured using sound sensor is also used to predict the effect of machining parameters on delamination as well as to develop the tool replacement strategy.

Characteristics of the shear mechanical properties and the influence mechanism of short basalt fiber reinforced polymer composite materials

To increase the engineering applications of basalt fiber, the characteristics of the shear mechanical properties and the influence mechanisms of the fiber length ( Lf) and volume fraction ( Vf) for short basalt fiber reinforced epoxy resin polymer composites were investigated. The following results were obtained: (1) The first critical loads on all the shear load–displacement curves are close to the same value due to having the same interface bonding of the fiber–matrix; (2) the shear strength, deformation, and energy dissipation capacity all increase with increasing Vf; however, when Lf is 6 or 9 mm, these increases are slower, whereas when Lf is 3 mm, these values increase at an approximately constant rate; and (3) the shear elastic modulus of the samples reaches its maximum value when Lf is 3 mm and Vf is 25%; however, it increases more quickly when Lf is 6 or 9 mm. The failure mode of the samples with the larger Lf values is mainly debonding between the fiber and matrix; when Vf is high, the fibers can easily bundle, which reduces the adhesion between the fibers and matrix. In addition, the main failure mode of the 3-mm-long fiber samples is fiber pull-out; when Vf is high, the short fibers that are not pulled out significantly increase the deformation ability.

FRP-Needles as Discrete Reinforcement in Concrete

AbstractThis paper presents a new type of discrete reinforcing element for concrete produced from either waste or new pultruded fiber-reinforced polymer (FRP) composite materials. These elements, r...

HybridRTM - Quality Controlled Manufacturing of Hybrid Material Composites through Resin Transfer Moulding

HybridRTM terms a publicly funded project, which aims at the development of a processing technique for manufacturing of light weight structural components from hybrid materials. In particular, components involving metal as well as fibre-reinforced polymer composite materials are manufactured in a single processing step by means of the resin transfer moulding (RTM) technique. Project activities include material development and characterization, modelling of thermally induced residual stresses, process simulation, mould development as well as model-based process control in order to ensure consistently high component quality. This paper outlines the fundamental idea of the project and summarizes the most important results gained during the first two years of project activities.

Effect of Mechanical Properties on Various Surface Treatment Processes of Banana/Cotton Woven Fabric Vinyl Ester Composite

Natural fibers have been used to reinforce materials in many composite structures. Many types of natural fibers have been investigated including flax, hemp, ramie, sisal, abaca, banana etc., due to the advantage that they are light weight, renewable resources and have marketing appeal. These agricultural wastes can also be used to prepare fiber reinforced polymer hybrid composites in various combinations for commercial use. Application of composite materials in structural applications has presented the need for the engineering analysis. The present work focuses on the fabrication of polymer matrix composites by using natural fibers like banana and cotton which are abundant in nature and analysing the effect of mechanical properties of the composites on different surface treatments on the fabric. The effect of various surface treatments (NaOH, SLS, KMnO4) on the mechanical properties namely tensile, flexural and impact was analyzed and are discussed in this project. Analysing the material characteristics of the compression moulded composites; their results were measured on sections of the material to make use of the natural fiber reinforced polymer composite material for automotive seat shell manufacturing.

The Comparison on Mechanical Bonding Properties of Untreated Coconut Fiber towards Synthetic Fiber for Fiberglass Boat Building

The development of high performance materials made from natural resources is increasing worldwide. The interest in natural fiber reinforced polymer composite materials is rapidly growing both in terms of their industrial applications and fundamental research. They are renewable, cheap, completely or partially recyclable, and biodegradable. The coconut fiber can be a potential candidate to replace the industrial core and foam which its application are worldwide and it is used to increase the thickness of the fiberglass boat. In this research, three types of testing panel are constructed by using 10 mm of Coconut Fiber, 3D Core Foam and Infusion Grooved PVC Foam as the sandwich core. The resin infusion method which is produce quality final products have been used. The findings be obtained by conducting two testing methods, for the Flatwise Tensile Strength testing, the specimens taken from Coconut Fiber product yielded a higher value of strength which is 3.005 MPa compared to the specimens taken from Infusion Grooved PVC Foam and 3D Core Foam which is 2.963 MPa and 1.264 MPa respectively. For the Flatwise Compressive Strength testing, the specimens taken from the Coconut Fiber product had higher value of compressive stress compared to the value of specimens taken from Infusion Grooved PVC Foam and 3D Core Foam which is 29.66 MPa, 2.58 MPa and 4.68 MPa respectively. This research has proved that the Coconut Fiber is quite suitable to become as one of the laminating schedule for the construction of the fiberglass boat hull.

Reduced order multiscale modeling of fiber reinforced polymer composites including plasticity and damage

A multiscale procedure based on asymptotic expansion homogenization (AEH) technique is formulated to study the inelastic deformations and damage of fiber reinforced polymer composite materials (FRP). FRPs show significant inelastic deformation and local phase damage before the ultimate failure point and capturing these accurately using AEH is an active research area. The complex implementation and high computational cost of AEH when used in multiscaling can be alleviated by the reduced order techniques proposed by Oskay and Fish (2007). In the present work, the reduced order AEH formulation is extended to capture the plasticity and damage in the matrix. The initial studies are performed for representative volume element (RVE) which show the behavior as expected. This new formulation is applied to study the low velocity impact of composites. The results (force-time curves and extent of damage) are validated with experiments. The model is successfully able to capture the deflection at various points on the laminate plate and permanent indentation on the surface.

Experimental Investigation of Mechanical and Morphological Properties of Flax-Glass Fiber Reinforced Hybrid Composite using Finite Element Analysis

The use of cellulosic fibers as reinforcing materials in polymer composites has gained popularity due to an increasing trend for developing sustainable materials. In the present experimental study, flax and glass fiber reinforced partially eco-friendly hybrid composites are fabricated with two different fiber orientations of 0° and 90°. The mechanical properties of these composites such as tensile, flexural and impact strengths have been evaluated. From the experiments, it has been observed that the composites with the 0° fiber orientation can hold the maximum tensile strength of 82.71 MPa, flexural strength of 143.99 MPa, and impact strength of 4 kJ/m2. Whereas the composites with 90° fiber orientation can withstand the maximum tensile strength of 75.64 MPa, flexural strength of 134.86 MPa, and impact strength of 3.99 kJ/m2. Morphological analysis is carried out to analyze fiber matrix interfaces and the structure of the fractured surfaces by using scanning electron microscopy (SEM). The finite element analysis (FEA) has been carried out to predict the resulting important mechanical properties by using ANSYS 12.0. From the results it is found that the experimental results are very close to the results predicted from FEA model values. It is suggested that these hybrid composites can be used as alternate materials for pure synthetic fiber reinforced polymer composite materials.

Investigation of delamination and surface quality of machined holes in drilling of multiwalled carbon nanotube doped epoxy/carbon fiber reinforced polymer nanocomposite

In the drilling of carbon fiber reinforced polymer composite materials, drilling-induced delamination and surface roughness of machined holes are causes of major concern, particularly, when components, made of carbon fiber reinforced polymer, are used in the aerospace industry. In order to minimize these drawbacks, an innovative technique has been developed by adding multiwalled carbon nanotube in the polymer matrix to improve interlaminar shear strength and flexural strength of the laminates. Experimental results indicate that with this process, flexural strength and interlaminar shear strength get enhanced by almost 24% and 28%, respectively, when compared to neat epoxy carbon fiber reinforced polymer composite. The image process results reveal that delamination factor gets decreased by 21% and 28.60% at the entrance and the exit side, respectively. This, in turn, not only reduces the delamination factor during the process but also facilitates the process to be carried out more smoothly. During this investigation, scanning acoustic microscope was used to study ply-by-ply damage followed by ultrasonic C-scan on both sides of the laminates, which showed good agreement with the experimental results. Measurement of surface roughness of the machined hole showed the maximum Ra value of 5.03 µm in neat epoxy carbon fiber reinforced polymer composite. However, a sample with 1.5 wt% of multiwalled carbon nanotube showed a decline in Ra value (1.18 µm). Thus, addition of multiwalled carbon nanotube to the polymer matrix could reduce the drilling-induced delamination as well as the surface roughness of machined hole simultaneously.

Signal Quality Improvement Using a New TMSSE Algorithm: Application in Delamination Detection in Composite Materials

This paper introduces a novel method to improve the quality of ultrasonic phased array signals for localizing with accuracy delamination defects. The improvement is achieved by the introduction of a new threshold for the Shannon energy. In first, we have applied the threshold modified S-transform algorithm (TMST) in the case of ultrasound B-scan. Thereafter, we have adapted and applied the S-transform Shannon energy (SSE) algorithm in the field of ultrasonic testing. At last, we have proposed a novel algorithm based on threshold modified S-transform and Shannon energy (TMSSE) to increase the improvement of the ultrasound B-scan. A simulation study has been carried out simulating a composite material containing three defects in different positions in order to highlight the phenomenon of delamination. Experimental tests were performed on a sample of carbon fiber reinforced polymer composite material (CFRP) with a delamination defect close to the front face. Both experimental and simulated results show that the proposed method can improve the quality of ultrasound B-scan which enhances the localization of delamination defects.

Rehabilitation and strengthening of high-strength rectangular CFST beams using a partial wrapping scheme of CFRP sheets: Experimental and numerical study

Recently, concrete-filled steel tubular (CFST) members are becoming highly recommended by engineers for use in composite structures. Lately, carbon fiber-reinforced polymer (CFRP) composite materials have been used for strengthening steel and CFST flexural members. Both experimental and numerical studies are adopted in this research to further investigate the behavior of various sections of rectangular CFST beams strengthened and/or repaired with unidirectional CFRP sheets. The effects of the U-shaped wrapping scheme using multiple CFRP layers applied at various beam lengths was studied. In general, the results demonstrated that the moment capacity of strengthened CFST beams increased significantly with increasing CFRP layers; for example, it increased by approximately 40% and 55% for beams with compact and slender sections, respectively, when wrapped with 4 CFRP layers. The capacity of damaged CFST beams has improved over 65% when repaired with 2 CFRP layers. Moreover, the effects of wrapping the beam along 75% of its length achieved a similar enhancement ratio and behavior as that of the beam with wrapping along 100% of its length for the same CFRP layers.

Sound insulation analysis and optimization of anti-symmetrical carbon fiber reinforced polymer composite materials

Due to the advantages of high strength and low density, carbon fiber reinforced polymer (CFRP) composite material has become more and more attractive given the increasing demand of lightweight design requirement in the automobile industry. However, as density reduces, the sound insulation ability of CFRP panels is usually inferior compared with traditional metal materials such as steel and aluminum, which may lead to deteriorated noise insulation performance inside the vehicle cabin when the CFRP material is used as body panels. For the sake of investigating the sound insulation ability of CFRP, two optimization methods are proposed, and the optimal ply angles that lead to the largest sound transmission loss in two different frequency ranges are obtained accordingly. On the basis of optimization, the sound insulation capability of CFRP and two metal materials are thoroughly compared. It is found that, when optimally designed, the CFRP panel can achieve a transmission loss level comparable to its metal counterparts at low frequencies (e.g., <300Hz) with substantially less weight.

Taguchi’s orthogonal array approach to evaluate drilling of GFRP particulate composites

The influence of filler material on drilling of glass fiber reinforced polymer composite materials which is used in aerospace and electronic industry has been studied. Drilling test were performed under the operational condition of varying in feed, speed and drill tool diameter using radial drilling machine. Drill tool dynamometer is used to find the thrust and torque force for all specimens. L9 orthogonal array is adopted to conduct the experiments. Taguchi method and analysis of variance are used to analyze the experimental values. Multiple linear regressions are used to develop a model. This model gives the correlation between process parameters with the thrust and torque and compared with the experimental results. Result shows that speed and feed are the most sensitive parameters for thrust and torque force.