Glass Fiber Reinforced Polyester Composites Research Articles

Estimation of adhesive wear behavior of the glass fiber reinforced polyester composite materials using ANFIS model

Glass fiber reinforced polyester (GFRP) composite materials are widely used in various applications. The prediction of wear values for composite materials is very complex and nonlinear phenomena. Artificial intelligence methods (AI) and expert systems such as artificial neural networks (ANNs) and fuzzy inference systems (FIS) have a series of properties on modeling nonlinear systems. In some situations, ANNs are insufficient under abrupt changes in input variables. Adaptive Neuro Fuzzy Inference System (ANFIS) is capable of integrating the linguistic expressions of FIS with the adaptation and learning skills of the ANNs. The aim of this study is to determine the optimum material content and working conditions in terms of wear resistance. This study proposes an ANFIS sub-clustering based prediction model for estimation of wear behavior of GFRP composites within various concentrations of materials and under diverse loads and speeds. Proposed ANFIS model extracted optimum concentrations and operating parameters to obtain the minimum wear rate. Due to the wear rate estimation model, optimum wear rate value is reached to 25.0013 (mm3/Nm)*10−6 at CaCO3, polystyrene, glass fiber, glass bead, alumina, load and speed values of 49%, 0%, 11%, 10%, 0.8%, 10 N and 100 rpm respectively. A high estimation capability (R2 = 0.964) has been achieved using ANFIS Model.

Analysis of impacts of thermal shocks on mechanical properties of E-glass fiber reinforced polyester composites

Glass fiber reinforced polyester composites are economic and high-performance composite materialsthat has gained a wide range of applications. Besides the developments in composites design, scientific studies addressing the consequences of thermal changes on the mechanical properties of fiber reinforced polymer composites(FRPCs) are scarce. Therefore, the main aim of the present work is to investigate the physical/mechanical properties of glass fiber reinforced polyester composites under thermal shocks. The effects of thermal cycle duration (2, 5 and 20 hours) on the porosity and mechanical properties (maximum stress, strain, elastic modulus and impact resistance) of polymeric composites reinforced by glass fiber, woven fabric and copper/silica nanoparticles (NPs) were investigated. The results exhibited that the porosity and mechanical properties changed obviously in long duration cycles, i.e., 20 hours. Major reduction trends were observed when the fabric reinforced samples were further reinforced by NPs. It was concluded that although NPs reduce porosity and pose filling effect in composite matrix, can also provide stress concentration locations. The composites reinforced by woven fabric and prepared by RTM method provide better mechanical properties. Moreover, after thermal shocks, the fibers within the composite structure formed curved shapes. Consequently, a reduction occurred at the elastic modulus of fibrous reinforced composites (fiber or fabric) after thermal cycles. Besides theelevated porositywas the predominant factor reducing elastic modulus, fiber deformation was also considered as a hidden factor which has never been discussed in previous research studies. A model of bicomponent structure was used to explain the effects of fiber deformation on elastic modulus of the FRPCs.

Investigation of adhesive wear properties of glass fiber reinforced polyester composites having different chemical compositions

Glass fiber reinforced polyester composite materials are widely used in various areas due to their high specific strength, low weight, excellent elasticity, high corrosion resistance, and high thermal stability. This study aims to investigate the effects of resin materials and various fillers and wear parameters such as different loads and speeds on the tribological properties of glass fiber reinforced polyester composite materials. In this experimental study, various resins (tensile additive orthophthalic polyester and plain orthophthalic polyester), fillers (alumina and glass beads), and reinforcing materials were used during the sample preparation. The samples were subjected to an adhesive wear test at two different speeds ( n = 100 r/min and n = 200 r/min) and different loads ( F = 10 N and F = 20 N) at 150 m sliding distance. The friction coefficient and friction force were measured by the tribometer. The thickness of the wear trace was later measured and the wear rate was calculated. Wear surfaces of samples were visualized with a three-dimensional laser profilometer in order to obtain surface topographies and surface roughness values. The sample surfaces were examined by scanning electron microscopy in order to understand the wear mechanisms and to characterize the morphology of worn surfaces. Experimental results have shown that alumina or glass beads fillers can reduce the average friction coefficient when used in the correct amounts. The use of glass bead filler in orthophthalic polyester resin with tensile additive is more effective than reducing the wear rate compared to alumina filler. The load on the wear behavior of glass fiber reinforced polyester composite materials is more effective than the speed.

Usage of antimony trioxide, aluminum hydroxide and zinc borate in GRP composite production as fire-retardant additives: An experimental research

In this study, it was aimed to investigate the usability of compounds in inorganic structure and the effect of these compounds used in composites on the mechanical properties of composites in order to give fire retardant properties to glass fiber reinforced polyester composites (CTP). Antimony trioxide (Sb2O3), aluminum hydroxide (Al(OH)3) and zinc borate (2ZnO3.BrO3.3H2O) were added by different proportions (5%, 10%, 15%, 20%, 25%, 30%) to resin blends to improve the non-flammability of the composites. In experimental study, the combustion behavior of the doped CTP composites produced using different inorganic compounds was determined by international combustion standards ASTM D-635, ASTM D-3801 and ASTM D-5048. In addition, thermogravimetric analysis (TGA) was applied in order to determine the thermal behavior of the produced GRP composites due to temperature increase and tensile test were applied according to ASTM 638-14.As a result, when the flame retardant additive ratio is 15% or more in the GRP composites, the hand lay production became difficult due to the increase in viscosity. According to ASTM D-3801, when 30% AH is used, non-combustible material in V1 class can be produced. All FRP composites containing flame retardants were included in the HB - slowly burning material class. Flame retardant use generally reduced the tensile strength of GRP composites, but it was found that 10% increase in AT-doped CTPs.

Effects of toughened polyester on fatigue behavior of glass fiber reinforced polyester composite for wind turbine blade

AbstractCured unsaturated polyester resins are often highly brittle. In this paper, to improve fatigue life of the glass fiber‐reinforced polyester composite (GFRP) used in the wind turbine blade, the unsaturated polyester resin was toughened by 2 wt% liquid carboxyl‐terminated butadiene acrylonitrile (CTBN) copolymer. CTBN liquid rubber has acidic OH of the carboxylic group, which causes incompatibility and poor solubility of CTBN in unsaturated polyester resins. In this study, to increase compatibility and solubility of CTBN liquid rubber in unsaturated polyester resins, 1,4‐Butanediol diglycidyl ether (1,4‐BDGE) was selected to react with carboxylic group of the CTBN liquid rubber which converted to ester functional group. The reactions between epoxy groups of 1,4‐BDGE and carboxyl groups of CTBN were investigated by Fourier‐transform infrared (FTIR) spectroscopy. Four polyester samples were prepared by mixing unsaturated polyester with 0 to 3 wt% of modified CTBN. Tensile tests of polymer samples have been performed to observe the effect of modified CTBN additive. According to the results of the tensile test, the highest tensile strength, elongation‐at‐break, and modulus of toughness were observed in polyester with 2 wt% rubber. Two polyester/glass fiber composite samples with and without 2 wt% rubber were prepared by the vacuum infusion process (VIP) and subjected to fatigue behavior analysis. According to the results of the static tension test, the same value of tensile strength was observed in both composites. The obtained tension‐tension fatigue results (R = 0.1) showed a reduction in maximum stress level enhanced the fatigue life improvement for the samples with 2 wt% rubber due to the increased toughness of the composite matrix. Examining the fracture surfaces of the specimens after fatigue tests, it was revealed that failure of the polyester containing 2 wt% rubber/glass fiber occurred at the interface, while the specimens without rubber showed that failure did not occur at the fiber/matrix interface.

Synthesis of developed rice straw sheets and glass fiber-reinforced polyester composites

In this study, a sheet of random rice straw fiber was developed. These rice straw sheets were used to reinforce polyester matrix. Synthesis of rice straw sheets and glass fibers as synthetic fibers-reinforced polyester composites were investigated. Several new stacking sequences were fabricated with random glass fiber mats with different areal densities (225 g/m2, 300 g/m2, and 450 g/m2) and rice straw sheets. The specific mechanical properties of these natural/synthetic fiber composites were investigated. Scanning electron microscopy was used to study the morphology of the fracture surfaces of the fabricated hybrid composites. Experimental results showed that specific tensile and flexural stiffness of rice straw fiber composite is better those obtained with glass fiber composites. The hybrid natural/synthesis composites with alternating glass fiber mat with areal densities 300 g/m2, and rice straw shows higher specific tensile strength than rice straw and other hybrid composites. Hybrid composites with high areal density on the outer surfaces yield a significant increase in flexural-specific strength and hardness as compared to other fabricated composites.

Sub- and supercritical D-limonene technology as a green process to recover glass fibres from glass fibre-reinforced polyester composites

Recycling of post-consumed composites based on thermosets reinforced with glass fibre (GF) uses different methods such as mechanical processing, high voltage fragmentation, thermal, and chemical treatments. Chemical treatments are a more interesting methodology because they allow the recovery of cleaner and polymeric matrices free glass fibres. However, depending on the solvent employed, limitations in chemical treatments such as a decrease in mechanical properties and low rate GF recovery are very common. In this paper, an original and green technology is proposed to overcome these limitations. Such technology uses D-limonene at sub- or supercritical conditions (ScD-limonene) in the absence of catalysts or auxiliary molecules, such as supercritical carbon dioxide (ScCO2), making the process more eco-friendly and so contributing to sustainability when compared to other processes that use catalysts or auxiliary molecules. Recovering almost 100% GF and preventing the deterioration or loss of properties, of the recovered GF (RGF) were achieved while the partially degraded resin can be separated and reused as a charge material in new composite formulations. Recycling glass fibre-reinforced polyester resin at composite/solvent (at sub-supercritical conditions) ratios up to 0.15 g mL−1 was possible due to the high solvation power of sub- and supercritical D-limonene. Scanning electron microscopy (SEM) images, X-ray photoelectron spectroscopy (XPS), and tensile strength analyses revealed that RGF exhibits morphological, chemical, and mechanical reinforcing capabilities comparable to virgin GF (VGF). Mass spectrometry of the resin residue (after sub- or supercritical D-limonene treatment) showed predominant fragmentation-patterns inferring the occurrence of partial degradation. The results found in this study, such as short reaction times of 45–60 min, and high recovery efficiencies ≈100%, are highly desirable for practical purposes. Furthermore, the preservation of the mechanical reinforcing properties of RGF at 64–85%, the ease of separation of the products, and solvent reuse, make this technology promising as compared to others. Based on the obtained results, ScD-limonene treatment can be employed as an efficient and eco-friendly strategy to recover GF from waste materials.

Multi response parametric optimisation in machining of marine application based GFRP composite with HSS drill: Application of TOPSIS approach

The article aims at the optimization of the speed, feed and composite laminate thickness of glass fiber reinforced polyester composites. The composite studied is made up of isophthalic polyester resin and chopped E-glass fiber, which is primarily made use in marine applications. The drilling experiments are conducted using the HSS tool of 10 mm diameter, fixed in the computer numerically controlled vertical machining center. The surface integrity and surface morphology issues are considered as the response variables and quantified by delamination factors and surface roughness, respectively. The technique for order of preference by similarity to ideal solution is used for multi response optimization, wherein the performance index is determined as the function of all the selected response variables. The regression model is developed using MINITAB 19 for the performance index, which exhibits an exceptionally high degree of fitness with an average prediction error of 5.72% between the predicted and the experimental values. The selected technique proves to provide better and clear results while considering the correlation between the response variables.

Effect of permeability on GFRP laminate produced by VARTM process

Vacuum assisted resin transfer molding (VARTM) is one of the manufacturing technique that is viable for production of fiber reinforced polymer composite components suitable for aerospace, marine and commercial applications. However the repeatable quality of the product can be achieved by critically fixing the process parameters such as Vacuum Pressure (VP) and permeability of the preform. The present investigation is aimed at studying the effect of permeability for production of Glass Fiber Reinforced Polyester (GFRP) components with consistent quality. The VARTM mould is made with an acrylic transparent top cover to observe and record the resin flow pattern. Six layers of randomly placed glass fiber under five different vacuum pressures VP1 = 0.013, VP2 = 0.026, VP3 = 0.039, VP4 = 0.053 and VP5 = 0.066 MPa were studied. The laminates produced by this process under the above mentioned conditions were characterized with ASTM D procedures so as to study the effect of these process parameters on the quality of the laminate. And as mentioned there is a considerable effect of permeability on the impact strength and the void content in the laminates under different vacuum pressures. SEM analysis of the impact tested fractured GFRP composites showed the bonding of fiber and matrix.

Enhanced mechanical properties of glass fibre-reinforced polymer composites with addition of AL2O3

ABSTRACT This paper depicts the mechanical behaviour of new class of multi-phase composites consisting of glass fibre-reinforced polyester composite filled with Al2O3 particles, Glass fibre-reinforced polyester composites was prepared by incorporating alumina particle at three different filler contents viz. 1 3 and 6%, and the mechanical properties of these composites are evaluated. The mechanical properties such as impact energy and hardness of the glass fibre-reinforced polyester composite was improved by adding alumina particles but increasing the percentage of filler content could be seen that there was reduction of impact energy, but increasing of hardness value. The macroscopic fracture surfaces of tensile specimens of all types of composites are studied briefly, However, the tensile strength and modulus of the Al2O3-filled glass fibre polyester composite was slightly lower than that of bare glass fibre-reinforced polyester composite, because of the tensile properties are more sensitive for how particles presented as network in the matrix.

Mechanical properties of hybrid woven roving and chopped strand mat glass fabric reinforced polyester composites

In high-performance composites’ manufacturing industries, glass fibers are one of the most important reinforcements with excellent mechanical properties. The aim of the work is to compare the mechanical behavior of two types of glass fiber reinforced polyester composites. Woven roving (W) and chopped strand mat glass fiber (C), for different layers (2, 4, and 6) respectively, were used to fabricate the composites by hand lay-up method. Moreover, the hybrid mixture of the two types of fibers was also fabricated for (2, 4, and 6) layers. The mechanical properties that are included in tensile, impact, and flexural. Also, the morphology properties were used to examine through scanning electronic microscope (SEM). The results show that the mechanical properties of the composites improved by increasing the number of layers of glass fibers. The composites W/UP have better impact strength, while C/UP composites exhibit better flexural behavior than W/UP. However, the hybrid composites WC/UP dominate the best mechanical properties. The morphology analyses supported the mechanical results. From Design of Experements (DOE), it is found that the composites follow the order WC/UP > W/UP > C/UP in terms of tensile strength, and WC/UP > C/UP > W/UP for flexural strength. While the impact strength in the order W/UP > WC/UP > C/UP composites.

Modeling of delamination in drilling of glass fiber-reinforced polyester composite by support vector machine tuned by particle swarm optimization

Surface damage in machining of fiber-reinforced polymer-based composites is almost unavoidable during manufacturing. Most often, machining operation—drilling causes delamination of composite surface that leads to the loss of quality of product. As a consequence, reasonably accurate prediction of delamination factor (Fd) of drilled hole emerges as a prerequisite during the product development stage and freezing the design before final production. However, stochastic nature of the response and heterogeneous material properties make the modeling difficult. In this article, one of the most advanced generalized learning-based technologies, support vector machine (SVM) which could read the underlying unseen effect of input factors on response, is applied for regression model developing of drilling response—Fd on glass fiber-reinforced polyester composite. Gaussian radial basis function and e-insensitive loss function are used as kernel functions and loss function, respectively. Particle swarm optimization (PSO) is modified, and modified PSO is employed to search the optimal combination of internal parameters of SVM for modeling of Fd. Model, thus developed, is validated with follow-up testing data sets. Based on estimated model, optimum input parameters for minimum Fd is further investigated using the procedure of modified particle swarm optimization.

Accuracy Assessment of Ultrasonic C-scan and X-ray Radiography Methods for Impact Damage Detection in Glass Fiber Reinforced Polyester Composites

The present study introduces two quantitative parameters to compare the accuracy of ultrasonic C-scan testing and X-ray radiography methods in the damaged area detection under low-velocity impact in polymer-based composites. For this purpose, the hand lay-up technique of composite processing was employed to prepare the composite specimen. A composite specimen consisting of the glass fiber reinforced with the unsaturated polyester resin was considered for this investigation. The impact tests at different energy levels were carried out to create three damaged areas in this composite specimen. Because the glass/polyester specimen had a transparent surface, a digital scanner was used to obtain an ideal image of specimen representing the region and edge of the impacted areas. Two image quality factors were introduced as quantitative parameters to compare the ultrasonic C-scan and X-ray radiography results with those of an ideal image. The results of this study showed that the ultrasonic C-scan is a more accurate method for inspection of the GFRP specimen.

An integrated approach of CCD-TOPSIS-RSM for optimizing the marine grade GFRP drilling process parameters

Abstract This article aims to optimize the drilling process parameters using an integrated approach of the central composite design (CCD), the technique for order of preference by similarity to ideal solution (TOPSIS) and response surface method (RSM) to reduce delamination in the marine grade glass fiber reinforced polyester (GFRP) drilling. Marine grade GFRP composite laminates of 6, 8 and 10 mm thickness were made using E-glass fiber and isophthalic resins. Drilling experiments were conducted using 10 mm high-speed steel (HSS) drills on the specimen as per the central composite design framework with a face center value of unity. The process parameters speed (600, 1050 and 1500 rpm) and feed (0.1, 0.3 and 0.5 mm/rev) were considered as the control variables along with the material thickness. TOPSIS technique is used to optimize the process control parameters: speed, feed and material thickness based on four output performance characteristics: thrust force, torque, entry delamination and exit delamination. Analysis of variance (ANOVA) with a 99% confidence interval is used to determine the significant main and interaction effects with the corresponding percentage contribution of the drilling parameters. The experimental results indicate feed to be the most influential factor in the drilling of marine grade glass fiber reinforced polyester composites contributing 70.38% to the variation in the overall performance index, represented by the TOPSIS grade (TG).

Dynamic mechanical analysis of banana, pineapple leaf and glass fibre reinforced hybrid polyester composites

Abstract Over many years, for the reinforcement of polymers natural fibres are being used. In present work, the DMA of banana, pineapple leaf and glass fibre reinforced polyester composites i.e., storage modulus (E′), loss modulus (E″), damping (Tanδ) and glass transition temperature (Tg) were carried out with the effect of fibre content, frequency and temperature i.e., 30%, 20%, and 10% natural fibre loading with the frequencies of 1 Hz, 2 Hz, 5 Hz, 7 Hz and 10 Hz are considered on hybrid fibre reinforced polyester composites and the temperature ranging from room temperature to 130 °C at a heating range of 5 °C/min.

Experimental investigation of mechanical and machining parameters of hybrid nanoclay glass fiber-reinforced polyester composites

In this work, the effect of nanoclay addition to glass fiber-reinforced polyester composites is studied. The pristine glass fiber-reinforced polyester composites (i.e., staking sequence, kind of fabric used, etc.) and hybrid nanoclay in varying weight fraction (0, 1, 2, 3, 4 and 5 wt%) and glass fiber-reinforced polyester composite is prepared by vacuum-assisted resin infusion technique. Fracture toughness studies are done to analyze the critical stress intensity factor and critical strain energy release rate. The optimum mechanical properties are obtained for hybrid nanoclay glass fiber-reinforced polyester composites with clay content of 3 wt%. This paper also deals with the study of optimizing the cutting parameters (Cutting speed and feed rate) to obtain maximum mechanical properties in hybrid nanoclay glass fiber-reinforced polyester composites during drilling process. It has been found that the torque is unaffected with increase in cutting speed. On contrast with increase in feed and nanoclay weight fraction, the torque increases. The drilled samples are further subjected to mechanical testing. Tensile studies confirms that better mechanical properties are obtained for optimum machining parameter of (0.045 mm/rev, 210 rpm) for 3 wt% nanoclay and glass fiber-reinforced polyester nanocomposites. The hybrid clay and glass fiber-reinforced nanocomposites generally posses better mechanical properties compared with pristine glass fiber-reinforced polyester composites.

Nanoparticles in Glass Fiber‐Reinforced Polyester Composites: Comparing Toughening Effects of Modified Graphene Oxide and Core‐Shell Rubber

The role of nanoparticles in the fracture toughness of glass fiber‐reinforced polyester composites (GFRPs) was investigated. An unsaturated polyester resin (UPR) and a vinyl ester resin (VER) were toughened by two distinct methods: (1) incorporating a very low loading (0.04 wt%) of alkyl or vinyl modified graphene oxide (mGO); or (2) adding core‐shell rubber (CSR, 1 and 5 wt%). For unreinforced resins, results from compact tension tests revealed that adding 0.04 wt% of mGO increased the fracture toughness (GIC_Resin) of UPR and VER by as much as 49 and 35%, respectively, without lowering the modulus and glass transition temperature (Tg); however, the mode I interlaminar fracture toughness (GIC_Comp) of GFRPs was not improved. On the other hand, CSR is a more effective toughener, though at much higher loadings. 1 wt% had little effect, but 5 wt% of CSR enhanced GIC_Resin of UPR and VER by 280 and 600%, respectively, with a significant decrease in flexural modulus and flexural strength. 5 wt% of CSR was not able to increase the GIC_Comp of UPR laminates either; however, CSR did increase the initiation GIC_Comp and propagation GIC_Comp of VER laminates by 50 and 33%, respectively. Scanning electron microscopy of the fractured specimens revealed weak fiber–matrix bonding for all GFRPs. This work suggests that enhancing fiber–matrix bonding is critical to gain the benefit of adding nanoparticles to GFRPs. POLYM. COMPOS., 40:E1512–E1524, 2019. © 2018 Society of Plastics Engineers

Fatigue and tensile behaviors of fiber-reinforced thermosetting composites embedded with nanoparticles

The development of studying nanocomposites has grown up rapidly in the last decade. The objective of the current research is to study the influence of incorporating cellulose nanocrystals on the mechanical properties of polyester resins, as well as to develop continuous filament e-glass fiber-reinforced polyester nanocomposites, which combine traditional composites with the added advantages of nanocomposites. Cellulose nanocrystals were uniformly dispersed into the polyester resin by an ultrasonic processor. The incorporation and dispersion of cellulose nanocrystals were a state-of-the-art method aimed at overcoming poor dispersion problems at low weight fractions of nanoparticles. Three weight percentages of cellulose nanocrystals were prepared, which were 2%, 4% and 6%. Fatigue and tensile specimens were manufactured by resin transfer molding process. Cellulose nanocrystals were fully characterized by using X-ray diffraction, transmission electron microscopy, Fourier-transform infrared spectroscopy and zeta-sizer analysis. The optimum incorporation percentage of cellulose nanocrystals was used to prepare glass fiber-reinforced polyester specimens containing cellulose nanocrystals. Tensile and fatigue behaviors of glass fiber-reinforced polyester composites were evaluated by means of universal testing machine and rotating bending fatigue machine. A series of testing specimens for each property was examined in accordance with the corresponding ASTM and JIS standards. The experimental results showed that the addition of 4% cellulose nanocrystals to polyester matrix lead to the optimum tensile and fatigue properties. Mechanical properties were improved through the enhanced material design and proper selection of compatible nanoparticles, and adding cellulose nanocrystals in a weight fraction that does not affect the mechanical properties of glass fiber-reinforced polyester nanocomposites negatively. The presented design of material and geometry have shown promising results for wide range of applications, particularly in biomedical industry, energy and electronics.

Comparative Study on Flame Retardancy, Thermal, and Mechanical Properties of Glass Fiber Reinforced Polyester Composites with Ammonium Polyphosphate, Expandable Graphite, and Aluminum Tri-hydroxide

The aim of this study is to enhance the flame retardant property of the glass fiber reinforced polyester composites by using intumescent flame retardants such as ammonium polyphosphate (APP) and/or expandable graphite (EG) in addition to aluminum tri-hydroxide (ATH). Flame retardant properties of the composites were tested by limiting oxygen index and UL-94 tests. Chemical characterization of the materials was done using Fourier transform infrared spectroscopy. Mechanical properties were evaluated by tensile test, and surface morphology analysis was performed by using stereomicroscope and scanning electron microscope. Thermal properties of the composites were characterized by thermogravimetry/differential thermal analyzer. The results showed that the flame retardancy of the composites was significantly improved by the addition of intumescent flame retardants with no considerable adverse effect on the mechanical properties. Thermal analysis data revealed that intumescent flame retardants increased the char yields of the composites. Also, the APP containing formulations yielded lower weight loss rates. To our knowledge, this is the first study investigating the flame retardancy, thermal, and mechanical properties of glass fiber reinforced polyester composite comprising ATH, APP, and EG in dual- or triple-flame retardant formulations.

Vibration and damping characteristics of sisal and glass fiber reinforced polyester composite

This study aims to evaluate the result of experimental investigation carried out on free vibration characteristics and damping factors of short sisal & glass fiber polyester composite. Composites specimen is fabricated in random fiber orientation using to hand lay-up method by Influence of fiber length (10mm) and weight percentage (5, 10, 15, 20 wt. %) . Studies revealed that increase in the fiber content will in-crease the natural frequency (Hz) and decrease the damping factor is given by the composites having a fiber loading of 20 wt. percentage ranges. The properties were compared with neat polyester. In this work, increasing fiber content increases the natural frequency (Hz) and decrease the damping factors of the composite.