Reinforced Polymer Composite Materials Research Articles

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.

Tensile and Bending Analysis of Fabric Reinforced Graded Epoxy Composites

Due their various applications the fabric reinforced polymer composites are subject of a large number of researches especially for aero- and automotive industry. Regarding the last domain there are huge interests in designing and forming composites with controllable strengthens for car bodies able to protect both the driver and passengers inside and pedestrians in case of unfortunate events. In this regard, based on previous studies developed at the Research and Development Centre for Thermoset Matrix Composites, our proposal is to design the bending behaviour of a fabric reinforced materials by means of changing the bending strength of the polymer matrix using a solvent. 1-Methyl, 2- pyrrolidinone is a well-known polymer solvent that had been used in previous studies as vector to transfer various organic agents into epoxy resins. During those studies it had been noticed that the presence of above mentioned solvent is changing the bending behaviour of polymer samples and induces some properties that are belonging to memory-shape materials. The present study is related to mechanical analysis of a multi-layered material (fabric layers) immersed into an epoxy resin having a graded bending strength.

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.

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.

Numerical Simulation and Experimental Validation of E-Glass/epoxy Composite Material under Ballistic Impact of 9 mm Soft Projectile

Fabric reinforced polymer composites have been widely used in automotive industry, aerospace industry and in several defence applications due to their lower density and higher specific strengths comparable to metals. In the present study, experimental and numerical simulations of ballistic impact on E-Glass/epoxy composite when subjected to normal and oblique impact by 9 mm soft lead projectile have been reported. Numerical modelling is used to estimate residual velocity and damage patterns of the composite laminate. The simulations are carried out using Abaqus/Explicit code based on finite element analysis. The findings show that the residual velocity decreases with increase in angle of obliquity and thickness. It is also found that the projectile is stopped by 7 mm thick sample at normal angle where as it is stopped by 5 mm thick sample at 60° angle. Good correlation between numerical simulation and experimental results was achieved, in terms of residual velocity of the projectile and damage of the laminates.

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.

Elasto-plastic response of graphene nanoplatelets reinforced polymer composite materials

In this paper, graphene nanoplatelets GNPs have been used as continuum phases within polymer composite materials. For such a purpose, a multi-scale strategy embedding the constitutive law of each material phase is accounted for to obtain the effective properties. The elasto-plastic response is established in the framework of the J2 plasticity. An expression of the algorithmic tangent operator for each phase is obtained and used as uniform modulus for homogenisation purpose. Using the Mori-Tanaka scheme, the effective non-linear behaviour is predicted for micro-parameters such as the aspect ratio and volume fractions. The results are compared to available experimental data as well as modelling from the literature. They show an enhancement of the equivalent macro stress-strain response with respect to low aspect ratio corresponding to platelet-like inclusions. Also, the volume fraction is seen to improve the composite response.

Elasto-plastic response of graphene nanoplatelets reinforced polymer composite materials

In this paper, graphene nanoplatelets GNPs have been used as continuum phases within polymer composite materials. For such a purpose, a multi-scale strategy embedding the constitutive law of each material phase is accounted for to obtain the effective properties. The elasto-plastic response is established in the framework of the J2 plasticity. An expression of the algorithmic tangent operator for each phase is obtained and used as uniform modulus for homogenisation purpose. Using the Mori-Tanaka scheme, the effective non-linear behaviour is predicted for micro-parameters such as the aspect ratio and volume fractions. The results are compared to available experimental data as well as modelling from the literature. They show an enhancement of the equivalent macro stress-strain response with respect to low aspect ratio corresponding to platelet-like inclusions. Also, the volume fraction is seen to improve the composite response.

Investigation on hole quality of cutting conditions in drilling of CFRP composite

Surface damages and delamination occurred in drilling of the carbon fiber reinforced polymer composite materials, which change depending on their physical and mechanical properties and cutting conditions, and so affect the hole quality. Therefore, it is requires to be selective with regards to drill geometry and drilling parameters during drilling of CFRP. This study investigated the effects of cutting parameters and drill geometry on the hole quality in terms of hole diameter and surface roughness during the drilling of CFRP composite laminate. Drilling experiments were performed with three different levels of drilling parameters that are point angle, cutting speed and feed rate. At the end of the drilling tests, it has determined that if the feed rate increases, the surface roughness value increases while the hole diameter decreases. The feed rate was determined as the most important parameter with a PCR of 78.02% according to analysis of variance. The better hole quality was obtained with 130° drill among the three drill geometry.

Investigation of Quality of Drilled Holes by Guiding the Drill Bit Using Permanent Magnet on a Glass Fibre Reinforced Polymer Composite Material

The use of glass fibre reinforced polymer composite materials (GFRP) increases due to its superior properties that draw the attention of the other researches focusing on relevant aspects concerning the machining of such materials. In conventional machining for hole creation, drilling is the most frequently employed machining process for hole generation in fibre reinforced materials. Due to the laminated structure of the composite materials, several types of damages and other surface irregularities are introduced during drilling processes. These defects in the holes lead to about 60% of the rejections in assembly plant. Surface roughness has been identified to be the main contribution for defects in holes machined in composites. These defects would create reduction in structural stiffness, which may lead to variation of dynamic performance of the whole structure. Hence, achieving the desired hole quality is of great importance for the functional behaviour of the mechanical parts. In the present work, the effect of permanent magnet on the quality of drilled holes on GFRP composite is presented. Experiments are performed under different magnetic drilling conditions of spindle speed, feed rate and drill diameter on CNC drilling machine using three levels of factors. A procedure has been adopted to assess and optimize the chosen factors by the use of Box Behnken design to analyse the effects of different parameters. From the experimental results, it has been observed that the technique used is convenient to predict the main effects and their interaction effects of different influential combinations of machining parameters on surface roughness. It has been found that effect of permanent magnetic on the guiding mechanism of the drill bit which lead to get improved surface roughness with better circularity compared to normal drilling processes. A mathematical model has been developed for the prediction of surface roughness using permanent magnet and normal drilling processes.

Modelling of thermomechanical behaviour of fibrous polymeric composite materials subject to relaxation transition in the matrix

Abstract Background Fiber–reinforced polymer composite materials are widely used in different branches of industry due to their distinctive features such as high specific strength and stiffness and due to as considerable opportunity to formulate materials with controllable variation of properties in response to the action of external factors (smart-materials). A distinguishing feature of products made of composite materials is that the processes of product and material fabrication are inseparable. Therefore the estimation of composite properties based on the composite architecture and properties of the reinforcing fibers and matrix is a very actual task. Methods The model of polymer behavior at glass transition recently developed by the authors was generalized to the case of fiber-reinforced polymer matrix composites using two approaches: one is base on the concept of free specific energy, the other – on the growth of matrix stiffness. For homogeneous materials these two approaches are of equal worth, whereas for composite materials they give different results under deformation in the transverse direction. The stiffness growth approach is more accurate, but is very expensive computationally and, is highly sensitive to the experimental data errors. Results Using the finite element method and averaging technique the thermoelastic constants of composites containing different types of fibers in the glassy and high-elastic states were calculated based on the fiber and matrix properties. Softening of the matrix has an insignificant effect on the longitudinal modulus of a composite but leads to a considerable decrease of the transverse and shear moduli. The coefficient of thermal expansion in the transverse direction is much higher than the coefficient of thermal expansion in the longitudinal direction, especially when the composite is in the high-elastic state. Conclusion The model of polymer behavior at glass transition recently developed by the authors can be generalized to the case of fiber-reinforced polymer matrix composites. The thermoelastic constants of composites containing different types of fibers can be calculated from the fiber and matrix properties using the finite element method and averaging technique.

Residual Stresses Introduced to Composite Structures due to the Cure Regime: Effect of Environment Temperature and Moisture

Material behaviour of structural components is very important to understand. In fibre reinforced polymer composite materials, this is more difficult in comparison to isotropic materials as they are made up of two constituents: the fibre and the matrix. For aerospace composite materials, the matrix is usually an epoxy resin that cures at a high temperature. This curing regime is known to introduce residual stresses to the composite material as it cools from the high cure temperature. However, how to consider these residual stresses in a structural analysis is still widely debated. In this paper, the authors investigated the offset of thermal residual strains introduced by the cure regime by the swelling of the composite when exposed to moisture.

Influence of nozzle design and process parameters on surface roughness of CFRP machined by abrasive jet

ABSTRACTCarbon fiber reinforced polymer composites find extensive applications in the areas of automotive, aircraft and aerospace, medical sciences, and electronics. Their usage in automated engineering industry needs good quality in components and excellent surface finish. The aim of this research work is to make holes on carbon fiber reinforced polymer composite material using a newly designed nozzle with and without internal thread. Surface roughness (Ra) was calculated across the depth of the machined hole. The effect of air and abrasive mixture pressure (P), stand-off distance (L), nozzle diameter (D), and abrasive size (S) on surface roughness was carried out for two different nozzles. The experimental result showed offer of good surface finish on CFRP materials from the newly designed nozzle with internal thread.

Strengthening in flexure–shear of RC beams with hybrid FRP systems: Experiments and numerical modeling

This paper presents an experimental and numerical investigation of reinforced concrete beams strengthening by means of different combinations of externally bonded hybrid fabrics-reinforced polymer composite: Carbon and glass fabric–reinforced polymer composite and another fabric-reinforced polymer composite based on vegetable fiber it is the jute fiber. The objective of this study is the conjugation of the properties of each type of fiber fabric to increase the load capacity, rigidity, and ductility of reinforced concrete beams and obtaining a typical model of reinforcement beams, which provides both these three desired mechanical properties. Three control beams and 27 beams strengthened in flexural–shear with Carbon, glass, and jute fabric–reinforced polymer composite and hybrid fiber fabrics were conducted and tested under three points bending. The load–deflection response, ductility, and associated failure modes of the tested specimens have been recorded and analyzed. In addition to the experimental investigations, numerical simulation using ABAQUS was developed to predict the load–deflection response and the failure modes, the results were compared with the corresponding experimental results, a good correlation was obtained.

Structural Damage Assessment of FRP Strengthened Reinforced Concrete Beams under Cyclic Loads

Worldwide, the need for structural retrofit is on the rise and the use of Fibre Reinforced Polymer (FRP) composite material systems is becoming an accepted method for repairs, rehabilitations, and strengthening of deficient structures. The great qualities of the FRP materials, certified in the laboratories and confirmed in the fields have all contributed to propel the material as a very promising one, though more works need to be done to certify the fatigue resistance and durability criteria. This research looked at the experimental investigations of Reinforced Concrete (RC) beams strengthened flexurally with externally-epoxy bonded FRP laminates under four point cyclic loads. Dynamic tests are used to assess damages in the FRP-strengthened RC beams under cyclic loads. 6 RC beams of 150 x 200 mm cross-section and length of 2.20m and were reinforced with four 12mm ribbed longitudinal steel bars. Three types of FRP laminates made of high modulus carbon fibre, high strength carbon fibre and glass fibre were adopted. The results confirm that dynamic-based method is an efficient way of assessing damage evolution in RC beams strengthened with FRP laminates under cyclic loads. The results offered a criterion that can be adopted for quick assessment of the efficiency of FRP composite systems before applying them to civil applications.

High-performance fire-resistant polymeric nanocomposite for aerospace applications

This investigation essentially highlights development of novel high-performance fire-resistant polymeric nanocomposite with respect to its orientation towards future generation aviation. Therefore, an attempt has been made to increase thermal stability and fire resistivity of phenolic/cotton fabric reinforced polymer composite, which is desirable for aircraft interiors. There is considerable increase in adhesion characteristics of phenolic fabric reinforced polymer composite due to atmospheric pressure plasma treatment. The phenolic fabric reinforced polymer is subsequently coated with nanosized calcium silicate reinforced polybenzimidazole composite in order to increase thermal stability and fire resistance property. Thermogravimetric analysis reveals that polybenzimidazole-coated fabric reinforced polymer shows significantly better thermal stability than the uncoated phenolic fabric reinforced polymer. There is a significant increase in the limiting oxygen index characteristics of polybenzimidazole-coated fabric reinforced polymer when compared to the uncoated phenolic composite resulting in considerable improvement in fire resistivity of the polymers.