Woven E-glass Fiber Research Articles

EFFECT OF GLASS FIBER AND SILANE TREATED GLASS FIBER REINFORCEMENT ON IMPACT STRENGTH OF MAXILLARY COMPLETE DENTURE

Background and objectives : The fracture of acrylic maxillary complete dentures is a commonly seen clinical problem which usually occurs due to heavy occlusal forces or accidental damage.The objectives of the study were to measure the impact strength of maxillary complete dentures fabricated with high impact acrylic resin and to evaluate the effect of woven E-glass fiber and silane treated glass fiber reinforcement on the impact strength of the Maxillary complete dentures. Methods :One commercially available heat cured acrylic resin (Trevalon HI) was selected. Preimpregnated woven E-glass fibers (Stick Net) and Silane treated glass fibers were used to reinforce ten maxillary complete dentures each. Ten unreinforced complete dentures served as the control group. The impact strength in Joules of the dentures were measured with a falling-weight impact test. Results : The mean impact strength of the control dentures was 75.22+/- 10.392 J at crack initiation, and 84.62+/- 11.495 J at complete fracture. The mean impact strength of dentures reinforced with preimpregnated woven E-glass fibers was 165.91+/- 12.929 J at crack initiation, and 187.06+/- 17.972 J at complete fracture. The mean impact strength of dentures reinforced with silane treated glass fibers was 112.30+/- 8.709 J at crack initiation, and at complete fracture was 126.43 +/- 8.709 J. Interpretation and Conclusion :The impact strength of maxillary complete dentures fabricated with high impact acrylic resin increased significantly after reinforcement with preimpregnated woven Eglass fibers and silane treated glass fibers. The best improvement, however , was obtained by preimpregnated woven Eglass fibers.

Experimental study of joining thick composites reinforced with non-crimp 3D orthogonal woven E-glass fabrics

A comprehensive experimental study was performed to determine the strength of several co-cured and adhesively bonded joints of composite panels reinforced with non-crimp 3D orthogonal woven E-glass fiber fabrics. Various single-lap and double butt-strap joints were fabricated using co-curing and adhesive bonding and tested in uniaxial in-plane tension. The co-cured joints included special stepped 3D woven preforms, stitched and stapled joints. The joint strength appears to have the lowest values for the co-cured single-lap joints, intermediate values for the co-cured double butt-strap joints and the highest values for the adhesively bonded double butt-strap joints. Stitching and stapling dry preforms resulted in significant increase of the co-cured single-lap joint strength. In the range of strap thicknesses studied for the bonded joints, thinner straps provide a higher joint break force than thicker ones. Tapering strap ends to as small angle as possible was found to be the most effective method of increasing break force of double butt-strap bonded joints.

Effect of thermal shock cycling on the creep behavior of glass-epoxy composites

Abstract The aim of the present work is to investigate the effect of thermal fatigue on the creep and recovery behavior of polymer-matrix composites (ET441 epoxy resin, reinforced with woven E-glass fibers). For this purpose, 3 h creep followed by 3 h recovery tests were performed to specimens, which have previously been subjected to a certain number of thermal cycles (from +50 °C to −27 °C). It was found that the variation of the reduced creep compliance of the materials considered with the number of cycles follows an exponential decay law which was independent on the time period over which the load was applied. In order to better understand such a behavior, a four elements viscoelastic model was applied and the variation of all the four elements with the number of cycles gave a better insight into the observed behavior. In addition, the viscoelastic behavior observed was correlated with the value of the degree of damage and its variation with the number of cycles. It was found that there is a damage threshold corresponding to a certain number of cycles above which damage increases rapidly reaching a plateau where saturation of micro-damage is attained.

A Taguchi Approach for Investigation of Erosion of Glass Fiber — Polyester Composites

Polyester composites reinforced with three different weight fractions of woven E-glass fiber reinforcement are developed. To study the effect of various operational and material parameters on erosive wear behavior of these composites in an interacting environment, erosion test are carried out. For this purpose, an air jet type erosion test rig and the design of experiments approach utilizing Taguchi's orthogonal arrays are used. The findings of the experiments indicate that erodent size, fiber loading, impingement angle and impact velocity are the significant factors in a declining sequence affecting the wear rate. Significance of erosion efficiency in identifying the wear mechanism is highlighted. It is confirmed that the glass-reinforced-polyester composites exhibit mostly semi-ductile erosion response. An optimal parameter combination is determined, which leads to minimization of erosion rate. Analysis of variance (ANOVA) is performed on the measured data and signal to noise (S/N) ratios. A correlation derived from the results of Taguchi experimental design is proposed as a predictive equation for estimation of erosion wear rate of these composites. It is demonstrated that the predicted results obtained using this equation are consistent with experimental observations. Finally, optimal factor settings for minimum wear rate are determined using genetic algorithm.

Taguchi method applied to parametric appraisal of erosion behavior of GF-reinforced polyester composites

Polyester composites reinforced with three different weight fractions of woven E-glass fiber reinforcement are developed. To study the effect of various operational and material parameters on erosive wear behavior of these composites in an interacting environment erosion tests are carried out. For this purpose, air jet type erosion test rig and the design of experiments approach utilizing Taguchi's orthogonal arrays are used. The findings of the experiments indicate that the rate of erosion of composites by impact of solid erodent is greatly influenced by the control factors. An optimal parameter combination is determined, which leads to minimization of erosion rate. Analysis of variance (ANOVA) is performed on the measured data and S/N (signal to noise) ratios. A correlation derived from the results of Taguchi experimental design is proposed as a predictive equation for estimation of erosion wear rate of these composites. It is demonstrated that the predicted results obtained using this equation are consistent with experimental observations. Finally, optimal factor settings for minimum wear rate are determined using genetic algorithm.

Mechanisms of Fatigue Damage in Foam Core Sandwich Composites with Unsymmetrical Carbon/Glass Face Sheets

This paper attempts to describe the fatigue response of a foam the core sandwich composite with unsymmetrical carbon/glass face sheets under tension-tension cyclic loading. The laminate is a critical element of the structure of a light full composite airplane which was determined through the stress analyses for numerous load cases. The face sheets, over a PVC foam the core, consist of two similar woven E-glass fibers following unidirectional carbon fibers with epoxy resin. Extensive fatigue data were generated for the S-N diagram of this laminate. Based on the static FEM analyses, two designs for the configuration of foam to solid laminate bonding zone have been investigated. Hence, the effects of using each of these different proposed designs have been determined. The damage events causing final failure were traced during fatigue tests. Four distinct damage events were found. Two of them were initiated and propagated in the foam the core, which could result in lower dispersion in comparison with other composite materials, because of foam the core homogeneity. The first damage event in the core is crack initiation and propagation along thickness, followed by the second damage event, which is crack propagation parallel to the length of the gauge. The parallel crack length is shortened by increasing the load ratio.

Fatigue Notch Sensibility of Thermoplastic Glass Fibre Composites

This paper is concerned with a notch sensibility study of a thermoplastic composite produced from a bi-directional woven E-glass fibres and polypropylene. Experimental tests were performed in three points bending using notched and unotched specimens of polypropylene glass fibres reinforced laminates to evaluate flexural properties and fatigue behaviour. Fatigue results were plotted as the stress range against the number of cycles to failure. The fatigue damage was measured in terms of the stiffness loss. The testes carried out using notched specimens present lower values of both static and fatigue strengths than the unnotched specimens tests.

Effect of cross-sectional design on the modulus of elasticity and toughness of fiber-reinforced composite materials

Many current fabrication protocols for dental fiber-reinforced composites use hand lay-up techniques and technician design input. Little information exists regarding how the manipulation of the cross-sectional design of a prosthesis might affect the modulus of elasticity and toughness. The aim of this study was to determine the effect of simple and complex cross-sectional designs on the modulus of elasticity and toughness of fiber-reinforced composite used for dental prostheses. Two particulate composites (BelleGlass HP and Targis) were reinforced with ultra-high-molecular-weight polyethylene fiber ribbon (Connect), woven E-glass fibers (Vectris Frame), or unidirectional R-glass fibers (Vectris Pontic). A range of fiber positions, orientations, or geometries were incorporated into the rhombic specimens (2 x 2 x 25 mm(3)) to achieve simple and complex experimental cross-sectional designs. The control specimen did not contain fiber reinforcement. Specimens (n=6) were stored 1 week in distilled water at 37 degrees C prior to 3-point load testing to determine the modulus of elasticity (GPa) and toughness (MPa). The data within each main fiber group were subjected to 1-way analysis of variance and a Tukey post hoc test (alpha=.05). Cross-sections of randomly selected test specimens (n=2) were made for scanning electron microscope (SEM) analysis of the fiber distribution. The mean modulus of elasticity varied from 8.7 +/- 2.0 GPa (Targis control) to 21.6 +/- 1.4 GPa (2 unidirectional glass fiber reinforcements, 1 each at the tension side and the compression side). Mean toughness varied from 0.07 +/- 0.02 MPa (unidirectional glass fiber positioned at the compression side) as the lowest mean, to 4.53 +/- 0.89 MPa (unidirectional glass fiber positioned at the tension side) as the highest. Significant differences were identified between specimen groups in each main category (all groups P<.001, except modulus of elasticity of the woven E-glass groups, where P=.003). SEM micrographs showed fiber distribution in the cross section of test specimens to correspond with the intended fiber geometry. The modulus of elasticity of the composite specimens increased when 1 or more glass fiber groups were located at the compression side of the specimen. Toughness was most effectively increased when 1 or more fiber groups were located at the tension side of the specimen.

Stress analysis of lap joints involving natural fibre reinforced interface layers

This paper is concerned with a fatigue study of composite adhesive lap joints. The tests were carried out on specimen joints manufactured using different stacking sequences: solely bi-directional woven E-glass fibres and polypropylene composites; and hybrid stacked composites. The main objective of the work was to improve the fatigue strength using hybrid fibre composites with a polypropylene/hemp natural fibre layer adjacent to the bond interface which was expected to produce more uniform stresses in transient regions. The adhesive used was a Bostik 7452 (Rubber and Plastics Grade) ethyl cyanoacrylate type. The results are presented in the form of curves of stress amplitude versus number of cycles to failure. The failure mechanisms (together with peak stresses in the regions adjacent to the bond obtained by finite elements analysis and experimental values of interlaminar toughness) are discussed in order to explain the lower fatigue strength in hybrid stacked joints than in the original thermoplastic composite joints (contrary what was expected) and the decrease with the natural fibre content.

Effect of fiber position and orientation on fracture load of fiber-reinforced composite

Objectives. The aim of this study was to determine the effect of fiber position and orientation on the initial and final fracture loads of fiber-reinforced composite (FRC). Methods. Test specimens made of two indirect particulate composites (BelleGlass HP, Kerr, Orange, CA) or (Targis, Ivoclar Vivadent, Amherst, NY) were reinforced with ultra high molecular weight polyethylene (UHMWPE) fiber ribbon (Connect, Kerr, Orange, CA), woven E-glass fibers (Vectris Frame, Ivoclar Vivadent, Amherst, NY) or unidirectional R-glass fibers (Vectris Pontic, Ivoclar Vivadent, Amherst, NY). Fibers were placed with different positions, orientations or geometry into the rhombic test specimens (2×2×25 mm 3). Control specimens did not contain fiber reinforcement. The test specimens ( n=6) were stored in distilled water for 1 week at 37 °C before testing in a three-point loading test to determine the initial and final fracture load values. Results. Initial failure loads varied from 22.6 to 172.1 N. The lowest value resulted from one UHMWPE reinforcement fiber located in diagonal orientation and the highest from two unidirectional glass fiber reinforcements, one located on the tension side and the second on the compression side. Significance. Position and fiber orientation influenced the load to initial and final failure, and specimen deflection. Tension side reinforcement was most effective in increasing the load to initial and final fracture.

The effect of reinforcement with woven E-glass fibers on the impact strength of complete dentures fabricated with high-impact acrylic resin

Statement of problem The fracture of acrylic maxillary complete dentures occurs frequently during service through heavy occlusal force or accidental damage. Purpose The purposes of this study were to measure the impact strength of maxillary complete dentures fabricated with high-impact acrylic resin and to evaluate the effect of woven E-glass fiber-reinforcement on the impact strength of the complete dentures. Material and methods Preimpregnated woven E-glass fibers (Stick Net) were used to reinforce 10 complete denture bases fabricated with a heat-polymerized high-impact acrylic resin (Lucitone 199). Ten unreinforced complete dentures served as a control group. All specimens were stored in water at 37°C for 2 months before testing. The impact strengths (J) of the dentures were measured with a falling-weight impact test. The impact strengths of both groups were compared by a repeated measures analysis of variance (α = .05). The Weibull distribution was also applied to calculate the cumulative fracture probability as a function of impact strength. Results The mean impact strength of the control dentures was 90.0±38.1 J at crack initiation, and 95.9±37.7 J at complete fracture, whereas the impact strength of reinforced dentures was 201.7±77.9 J and 277.9±102.5 J, respectively. Statistical analysis showed that impact strength of the high-impact acrylic complete denture was significantly increased by the addition of woven E-glass fiber ( P<.0001). Conclusion The impact strengths of maxillary complete dentures fabricated with high-impact acrylic resin increased by a factor greater than 2 when reinforced with woven E-glass fiber.

Natural fiber composites with plant oil-based resin

Vacuum-assisted resin transfer molding or resin vacuum infusion process was used to make composite panels out of plant oil-based resin [acrylated epoxidized soybean oil (AESO)] and natural fiber mats made of flax, cellulose, pulp and hemp. The composites formed by room temperature cure with natural fiber reinforcement of about 10–50 wt% increased the flexural modulus to a range between 1.5 and 6 GPa depending on the nature of the fiber mat. The AESO resin reinforced with woven E-glass fiber was tested as a reference and gave a flexural modulus of 17 GPa, while a room temperature curing of the neat resin gave a flexural modulus of about 1.1 GPa. Recycled paper was used as a cheap resource of cellulose fiber and found to work well with AESO resin in terms of flow, impregnation, and surface bonding, giving a modulus of over five times that of the neat resin. These low-cost natural composites were found to have mechanical strength and properties suitable for applications in housing construction materials, furniture and automotive parts.

Fracture Behavior of Woven Composites Containing Various Cracks Geometry

Recently, polymeric composite materials are widely used in automotive applications for reducing structural weight, saving fuel, and improving performance. Accidentalimpact damage is an important issue in the use of these composite materials as body components. The damages or cracks in the present work were represented by notched specimens. The test specimens were fabricated from polyester resin reinforced by woven E-glass fiber. A series of tests were conducted to measure the notched strength of composite laminates with various types of through-the-thickness cracks such as central normal notch (CNN), center inclined notch (CIN), single edge notch (SEN) and double edge notch (DEN). A Modified Point Stress Criterion (MPSC) was proposed for predicting the tensile strength of composite laminates with various aspect ratio (a/w), that is, notch length to specimen width ratio. The results show that the load–elongation diagrams of notched and unnotched glass fiber reinforced polyester (GFRP) specimens have a nonlinear behavior, with clear “Knee”, associated with audible noises. For the same notch length, the notched strength of GFRP specimens with symmetric cracks (CNN, CIN and DEN) is quite consistent. The lowest notched strength is for SEN specimens. An excellent agreement is found between the experimentalresults of centralnotched specimens (CNN and CIN) and the predicted values using the MPSC than the reviewed published theories. The critical stress intensity factor ( KIC) was determined from the centralnotched specimens and used to predict the notched strength of edge notched specimens (SEN and DEN). The type of the central notch (inclined or normal) insignificantly affects the values of the stress intensity factor, KIC.

Fatigue behaviour of composite adhesive lap joints

This paper is concerned with a fatigue study of composite adhesive lap joints produced from a bi-directional woven E-glass fibres and polypropylene. The adhesive used was a Bostik 7452 (Rubber & Plastics Grade) ethyl cyanoacrylate type. The effects of layer orientation, lap joint length and water immersion on the fatigue behaviour were studied. The specimens were immersed in water during periods until ninety days for controlled temperatures of 20, 40 and 70 °C. The results are presented in the form of curves of stress amplitude versus number of cycles to failure and also in the form of number of cycles to failure against time to exposure in water for fixed stress amplitudes. The fatigue damage and failure mechanisms were analysed and discussed. The joint shows that creep deformation within the temperature range of this study was probably the mainly cause of the dynamic stiffness reduction observed.

Interlaminar fracture behaviour of sandwich structures

The experimental determination of mode I interlaminar fracture toughness ( G IC) values within the composite material core of sandwich structures, by using double cantilever beam (DCB) specimens, is strongly affected by—amongst other factors—the strain rate applied to the specimen. On the other hand, phenomena such as fibre bridging and crack-tip splitting are closely related to the applied strain rate, so that experimentally determined G IC values are expected to be rate-dependent. Another difficulty for G IC evaluation is the unknown difference between the real and measured crack length. Thus, although a number of different data reduction methods have been developed in the literature for the determination of G IC values, a great discrepancy between predicted G IC values has emerged. In the present paper, sandwich structures consisting of two aluminium skins bonded together with an epoxy-based adhesive reinforced with woven E-glass fibres were tested in the form of DCB specimens for the determination of their G IC values. Due to the non-linear and inelastic behaviour of the system, both the classical simple beam theory as well as the usual 5% compliance approach failed to predict G IC. The results are in good agreement experimental observation is suggested here for the determination of G IC. The results are in good agreement with those derived by applying a model developed by Bishop and Drucker, further developed by Devitt et al. and recently completed and presented in its final form by Williams and Freeman. Moreover, a strong effect of the applied strain rate on the G IC values was observed.

Effects of Seawater Immersion on the Impact Resistance of Glass Fiber Reinforced Epoxy Composites

Little, if any, information regarding the effects of seawater immersion on the impact resistance of composite materials has been published to date. In the present study, instrumented impact tests were used to characterize such effects for two glass fiber reinforced epoxy composites. One material consisted of continuous nonwoven E-glass fibers in a conventional epoxy resin and the other consisted of woven E-glass fibers in a rubber toughened epoxy resin formulated specifically for marine applications. In the conventional epoxy system, the energy for incipient damage increased significantly follow ing seawater immersion due to plasticization of the matrix by the absorbed moisture. Both glass/epoxy systems experienced substantial reductions in peak load and energy absorbed at peak load as a result of moisture-induced degradation of the fibers and fiber/matrix interface. Energy after peak load decreased in the conventional epoxy system follow ing immersion. Total energy absorbed was reduced significantly for both glass/epoxy systems following seawater immersion. These results indicate that moisture-induced degradation can significantly reduce the impact resistance of glass fiber reinforced epoxy composites.