Polyester Composite Laminates Research Articles

Impact of textile types and their hybrids on the mechanical properties and thermal insulation of mohair-reinforced polyester Composite laminates

Mohair fibres from animals are a great choice for people who care about the environment. They have low toxicity, are abundant in raw materials and don't pose any health risks. However, when compared to synthetic fibres, their mechanical performance is not as good. Mohair fibres are best suited for low to medium load applications, such as car parts, agricultural equipment, sports equipment and household items. Despite their excellent properties, there is still a lot we don't know about mohair textile-reinforced polyester composites. The novelty of this study is testing different mohair fibre textiles to see which one provides the best characteristics. The three most commonly used locally-made mohair fabrics (woven, knitted and pressed mat) were selected as reinforcement in polyester resin. Nine different laminates of similar and hybrid layers were made by hand lay-up in a closed mold at a constant fibre weight fraction (number of layers), mold pressure, curing time and temperature. The results showed that the composite laminate of mat fabric reinforced polyester provides the maximum tensile strength, elongation, flexural strength and thermal insulation of 22 MPa, 2.2 %, 54.6 MPa, 0.27 J and 0.012 m2°C/W, respectively. Meanwhile, the woven laminate exhibited the highest impact strength of 0.27 J and the hybrid laminates of the mat and woven fabrics offer satisfactory strength of 0.25 J.

The effect of fiber stacking sequence on mechanical and morphological behavior of paddy straw/pineapple leaf fiber-reinforced ortho-laminated polyester hybrid composites

The contemporary agricultural natural fiber is effectively used for fabricating composites because of its economical, ample availability, and biodegradability. In this way, the potential material for the reinforcement of hybrid (paddy straw and pineapple leaf) fiber- and ortho-laminated polyester composites was conducted. This research article is focused on the hybridization of untreated, treated, and paddy pulp fiber-reinforced polyester composite laminates. The unidirectional paddy straw fiber and pineapple leaf fiber (PALF) were used in the fabrication process of laminate using a compression molding machine with the mold dimensions of 300 × 300 × 5 mm is used and the investigation of mechanical (tensile, flexural, impact, hardness, shear) behaviors are conducted in the samples as per the standard. Five samples were prepared by varying the fiber content in the matrix in which sample S1 pure polyester plate without any addition of reinforcement. Out of these five samples, sample 4 (S4) produced better tensile, flexural, impact, hardness, and shear values of 28 MPa, 61 MPa, 3.46 Joules, 64 HR L, and 68.7 MPa, respectively. Comparing the laminate samples of S1 and S4 there is a 35.2% increase in the tensile value of S4, similarly, other values also resulted in better hikes. In addition to that, the water absorption properties of the laminate were also evaluated and fiber breakage, fiber pullout, fiber orientation, crack propagation, and voids on the fractured specimens were identified with help of a scanning electron microscope (SEM). Overall, the fabricated hybrid composite laminates were lightweight and has good fiber-matrix bonding with improved mechanical and morphological properties for commercial and home need applications.

Investigation On the Effect of Variation of Drilling Parameters On the Delamination Factor in Waste Tire Rubber Polyester Composite Laminates

Investigation On the Effect of Variation of Drilling Parameters On the Delamination Factor in Waste Tire Rubber Polyester Composite Laminates

Layup Design Optimization for E-glass Woven Roving Fabric Reinforced Polyester Composite Laminates Produced by VARTM

In this study, a satisfactory number of actual test results were used to optimize the stacking sequence design of bidirectional glass-woven fabrics in polyester composite laminates. In optimization, parameters such as glass-woven fabrics with five different areal weights, stacking sequence, number of plies (PLY), and off-axis fiber directions (DEG) were taken as input factors. Values such as tensile strength (UTS) and flexural strength (UFS), mechanical anisotropy factors (AFs), and resin permeability coefficient of stacked glass-fabrics were taken as output responses. In this study, a laboratory-scale vacuum assisted resin transfer molding (VARTM) process was established. Composite laminates with sixteen different stacking and six different number of plies are produced. Mechanical properties such as tensile and three-point flexure have been tested for the composite laminates obtained. In addition, the resin permeability coefficient for each laminate and the AF for tensile and flexural module depending on fiber direction were calculated during production. Many actual test data were obtained versus response to seven factors and five variables. Instead of the experimental designs recommended in response surface methodology (RSM), 64 actual test data were used as responses of the model. In the optimization with the Minitab, the minimum mechanical AF was desired in return to maximum UTS, UFS, and permeability coefficient. Optimum stacking sequence, PLY, DEG, permeability coefficient, and AFs were determined through using RSM. Consequently, the most optimal composite laminate was suggested in real terms in the desirability rate of laminate D=0.6731 with the stacking sequence of [822252]6, six plies, and 0 °/90 ° fiber direction.

Assessment of the Damage Resulting from Drilling Holes in Waste Tire Rubber Polyester Composite Laminates

In this work, a novel laminated polyester composite that contains waste tire rubber particles and glass fiber is developed. This composite is expected to possess better mechanical and physical properties, than other conventional polyester composites which consist of CaCO3 and glass fiber. This novel composite can be used in car bodies and in the aviation industry. Flat laminated specimens from both composites are prepared by hand layup. Tensile and impact testing are done to evaluate and compare the mechanical properties of these composites. An experiment is done to study the damage that can occur to the novel composite when drilling holes which can be used for joining composite laminates with other parts. Twelve trials were made to reduce the damage by better selection of the drilling conditions. Peel up and push out delamination factors are calculated to investigate the damage. Digital optical microscope is used to investigate the fracture surface of broken specimens and the nature of drilling damage. Comparison between novel and conventional composites shows an improvement by approximately 47% and the density of the new composite decreases by 8%. The optimum drilling cutting speed is approximately 1150 rpm which gives the least delamination factor at the front and back of specimen.

Influence of Fibre Inter-ply Orientation on the Mechanical and Free Vibration Properties of Banana Fibre Reinforced Polyester Composite Laminates

The mechanical properties and vibration damping characteristics of cross-ply laminates ([90°/0°/90°] and [0°/90°/0°]), [0°/45°/0°], four-layered angle ply laminate ([90°/0°]s) and Quasi-isotropic laminates ([0°/90°/45°]s, [0°/45°/90°]s,) containing 50 ± 2 wt% of banana fibres in polyester matrix were investigated. The experimental results indicate that the tensile strength, Young’s modulus, impact strength, and the natural frequency were superior for [0°/90°/0°] laminates. In the case of flexural properties, the Quasi-isotropic laminates displayed better performance than the other configurations. Tensile fractured specimens were examined under a scanning electron microscope (SEM) to understand the difference in failure behavior due to the inter-ply orientation in the laminate.

A Comparative Study on Mechanical Properties of Kenaf Fiber-Reinforced Polyester Composites Prepared by VARI, RTM and CM Techniques

This work aims at comparing the mechanical properties of composite laminate fabricated by three different fabrication processes. Kenaf fiber polyester composite laminates were fabricated by compression moulding technique, Vacuum assisted resin infusion process (VARI) and Resin transfer moulding process (RTM). Vacuum assisted resin infusion (VARI) process bridges the gap between labour intensive compression moulding process and capital intensive Resin transfer moulding (RTM) process. The mechanical properties such as tensile, flexural and impact behaviour were studied. Vacuum assisted resin infusion process showed improved tensile and flexural strength as compared to resin transfer moulding process and compression moulding (CM) process. On the other hand, impact strength of VARI composites is slightly lower than that of RTM and CM composites. From the study, it was found that mechanical properties increase with increase in fiber content and uniform distribution of resin in the matrix. The void content and water absorption properties were evaluated and found to be maximum for the compression moulded composites.

Mechanical and machinability study on discontinuously reinforced sisal fibre polyester composite laminates

Due to the advancement in the field of bio composites the role of plant fiber reinforced composites has increased over the last few years. Now, these materials are used for both serviceable and non-serviceable applications. The components to be manufactured by natural fiber reinforced composites can be created using simple manufacturing techniques. However, joining of these manufactured parts has been the major difficulty faced by manufacturers. Extensive research has been carried out in drilling of polymer matrix composites and metal matrix composites, however the studies on behavior of natural fiber reinforced composites are limited. Hence an attempt has been made to study the mechanical characterization, machinability and microstructural study of Discontinuously Reinforced Sisal Fiber Polyester (DRSFP) composite laminates. From the experimental results it is observed that Moisture absorption was 1.4% for 40 h’ time period due to porosity content, the lumen and fiber matrix adhesion, at higher load frictional thrust increases and resulted in increased debonding and fracture, main effects plot for three body abrasive wear indicates the selection of less Load (4 kg) and less speed (100 rpm) results in the best combination to get minimum abrasive wear value, selection of Spindle speed (1500 rpm), Feed rate (10 mm min−1) and Point angle (90°) resulted in the best combination to get better surface roughness and minimum delamination. From the SEM micrographs of the drilled hole of DRSFP composites it is observed that the hole drilled at point angle 118° has severely damaged surface compared to point angle 90° and 104° due to more fiber pull-out, surface and subsurface cracks (radial direction), de-bonding of fiber-matrix.

Tensile, flexural, impact, and hardness properties of alkaline-treated Sunnhemp fiber reinforced polyester composites

ABSTRACTThe natural fibers and their specific properties attracted researchers in the recent years for the development of new polymer composites. In this way, the Crotalaria juncea L. (Sunnhemp) fiber was identified as a potential material for reinforcement and the preparation of polyester-based polymer matrix composites was carried out. The present investigation was focused on fabrication of untreated and alkaline-treated C. juncea L. (Sunnhemp)–polyester composite laminates and the evaluation of tensile, flexural, impact, and hardness properties as per ASTM. The different kinds of fiber orientations such as random, continuous, biaxial, and triaxial were considered and the properties were evaluated.

The post-impact response of flax/UP composite laminates under low velocity impact loading

Flax fibre-reinforced unsaturated polyester composite laminates were fabricated by vacuum bagging process and their impact and post-impact responses were investigated through experimental testing and finite element simulations. Samples of 60 mm × 60 mm × 6.2 mm were cut from the composite laminates and were subjected to a low-velocity impact loading to near perforation using hemispherical steel impactor at three different energy levels, 25, 27 and 29 Joules. Post-impact was employed to obtain full penetration. The impacted composite plates were modelled with various lay-ups using finite element software LS-DYNA (LS-DYNA User’s Manual 1997) to provide a validated finite element model for the future investigation in the field. The effects of impact and post-impact on the failure mechanisms were evaluated using scanning electron microscopy. Parameters measured were load bearing capability, energy absorption and damage modes. The results indicate that both peak load and the energy absorption were reduced significantly after the post-impact events. Consequently, it was observed from the visual images of the damages sites that the extent of damage increased with increased incident energy and post-impact events.

Fatigue resistance of randomly oriented short glass fiber reinforced polyester composite materials immersed in seawater environment

Randomly oriented short fiber mat reinforced polyester composite laminates immersed in natural seawater for various periods were tested in static and cyclic fatigue loading under three-point bending conditions. Water absorption increased the weight of the specimen while the extraction of soluble compounds induces a weak weight loss. Wohler curves carried out from repetitive fatigue tests were drawn for the different periods of immersion time. These curves, which are characterized by an important and a significant scatter in their lifetime, were modeled by straight lines. These glass-polyester laminates deteriorate in fatigue tests at a constant rate by cycle decade. This rate increases with increasing immersion time in seawater at a constant speed. A comparison between different mathematical models of endurance curves shows that Wohler's equation gives a good representation of the average part of the curve.

Low-velocity impact responses of Napier fibre/polyester composites

The low-velocity impact response of Napier grass fibre/polyester composites was investigated. Napier grass fibre was used as the reinforcing material in polyester composite laminates. Napier/polyester composites specimens of 10%, 15%, 20%, 25% and 30% fibre volume fraction were produced using a compression moulding machine. The specimens of the mentioned fractions were impacted with a 5 J energy level using an instrumented drop weight impact tester (IMATEK IM10). The fracture damage of the impacted specimen was analysed using a field-emission scanning electron microscope (FESEM). The experimental result shows the relationship between the volume fraction percentage of Napier fibres and the impact force, energy absorbed and stiffness of the composites. Pure polyester specimens displayed brittle behaviour with a lower peak force, lower energy absorption and less time to failure compared to Napier reinforced composites. The impacted Napier/polyester composites with fibre loading of 30% show higher absorbed energy, peak force and longer time to failure. Furthermore, the experiments on each fibre volume fraction revealed increasing load-bearing capability and energy absorption with an increase in the volume fraction of Napier fibre. The FESEM observation exhibits various failure mechanisms such as fibre breakage, fibre pull-out, matrix cracking and fibre splitting.

Tensile and Flexural Strength of Untreated Napier Grass Fibre/Polyester Composites

This paper describes the experimental investigation of the tensile and flexural strength of untreated Napier grass fibre reinforced polyester composites. Napier grass fibres were extracted trough conventional water retting process and used as reinforcing materials in the polyester composite laminates. Tensile tests were then conducted for the composite specimens from the laminates at 25% fibre loading using the electronic extensometer setup to obtain the tensile properties. The results show significant differences in tensile strength between random short fibres laminates and random long fibrelaminates with the long fibres yield over 30 % higher in strength.Both the short and long fibre composites exhibits similar strength with short fibres having slightly higher flexural strength to long fibres The laminate also shows higher maximum strength compared to other commonly available natural fibre composites with almost 75 % improved in the maximum strength compared to the short kenaf fibre reinforced composites.

Tensile Strength of Untreated Napier Grass Fibre Reinforced Unsaturated Polyester Composites

This paper describes the experimental investigation of the tensile strength of untreated Napier grass fibre reinforced polyester composites. Napier grass fibres were extracted trough conventional water retting process and used as reinforcing materials in the polyester composite laminates. Tensile tests were then conducted for the composite specimens from the laminates at 25% fibre loading using the electronic extensometer setup to obtain the tensile properties. The results show significant differences in tensile strength between random short fibres laminates and random long fibre laminates with the long fibres yield almost 45 % higher in the strength. The laminates also show higher maximum strength compared to other commonly available natural fibre composites with over 70 % increase in the maximum strength compared to the short kenaf fibre reinforced composites.

Effects of processing conditions on the mechanical and water absorption properties of resin transfer moulded kenaf fibre reinforced polyester composite laminates

This paper focuses on the mechanical and water absorption properties of kenaf fibre reinforced polyester laminates manufactured by resin transfer moulding. Varying processing conditions were considered as alternatives to fibre treatments, thereby potentially avoiding additional cost and complexity in the manufacturing process. Laminates were produced by altering fibre moisture content, mould temperature and mould pressure following injection. Tensile, flexural, impact and water absorption tests were conducted. Processing conditions were found to have little effect on properties except for pressurisation which increased tensile and flexural strength and decreased water absorption at low fibre volume fractions. Examinations using a scanning electron microscope showed that all the laminates failed by fibre pull-out.

Notched Strength and Effective Crack Growth in Woven Fabric Composite Laminates with Circular Holes

The effective crack growth model (ECGM) is extended to evaluate the residual strength of woven fabric composite laminates with circular holes. It is assumed that when the local normal stress reaches the tensile strength of the unnotched laminate, damage initiates and propagates with increase of the applied load. The damage is then modelled by a fictitious crack with cohesive stress acting on the crack surfaces. The damage growth is simulated by extension of the fictitious crack step by step and reduction of the cohesive stress with crack opening. The apparent fracture energy (G*) is used to define the relationship between the unnotched strength and the critical crack opening. Based on the equilibrium condition, an iterative technique is applied to evaluate the applied load required to produce the damage growth. The residual strength of notched composite laminates is defined by the unstable point of the applied load with damage growth. The residual strength of notched woven fibric carbon/epoxy, glass/epoxy and glass/ polyester composite laminates were evaluated with various hole diameters and specimen widths. Effect of specimen geometry on the critical damage zone size was discussed. The simulations from the effective crack growth model correlate well with the experimental data in open literature.