Fiber-reinforced epoxy

The results presented below were obtained using a 2 mm thick carbon fiber reinforced epoxy composite laminate with 16 layers. The laminate was quasi isotropic with fiber orientations 0°, 90° and 45°. The laminate had an average porosity content of approximately 1.7%. The object was divided in a training area and an evaluation area. The model parameters were determined by data solely from the training area. Both ultrasound tranducers used in the experiment had a center frequency of 21 MHz and a 6 dB bandwidth of 70%. 

Eig. 10. The variation of the density of carbon-fiber reinforced epoxy resin with the fiber volume fraction, based on the rule of mixtures. 

Fig. 12. (a) The variation of the tensile strength of unidirectional carbon-fiber-reinforced epoxy resin as a function of the fiber volume fraction, (b) The variation of the tensile strength of unidirectional carbon-fiber-reinforced epoxy resin as a function of the fiber volume fraction for low fiber volume... 

Shear-stress-shear-strain curves typical of fiber-reinforced epoxy resins are quite nonlinear, but all other stress-strain curves are essentially linear. Hahn and Tsai [6-48] analyzed lamina behavior with this nonlinear deformation behavior. Hahn [6-49] extended the analysis to laminate behavior. Inelastic effects in micromechanics analyses were examined by Adams [6-50]. Jones and Morgan [6-51] developed an approach to treat nonlinearities in all stress-strain curves for a lamina of a metal-matrix or carbon-carbon composite material. Morgan and Jones extended the lamina analysis to laminate deformation analysis [6-52] and then to buckling of laminated plates [6-53]. 

Fig. 17 presents the variation of the terms E((rf/r)n> and Em(rf/r), i in the mesophase layer for a 65 percent E-glass fiber-reinforced epoxy resin, as they have been derived from Eq. (48). It is wortwhile indicating the smooth transition of the Ermodulus to the Em-modulus at the region r == rf. Similar behaviour present all other compositions. 

Liquid rubbers In order to improve the flexibihty of short glass fiber-reinforced epoxy composites, Kaynak et al. [53] modified the epoxy resin matrix with hydroxyl-terminated polybutadiene (HTPB) liquid mbber. A silane coupling agent was also used to improve the interfacial adhesion between glass fibers and epoxy matrix. However, Humpidge et al. [54] reported some unique processing problems for the resulting pasty mixmres when short textile fibers were incorporated in a hquid mbber medium. 

D. Osborne. The development in the use of FRE (fiber reinforced epoxy) pipe systems for industrial and offshore applications. In Proceedings Volume, number 7, pages 27 5. 10th BHR Group Ltd et al Pipe Protect Int Conf (Amsterdam, Netherlands, 11/10-11/12), 1993. 

Tewarson, A., and Pion, R.F., "Evaluation of the Flammability of a Glass Fiber Reinforced Epoxy Material," 1978, Factory Mutual Research Corporation, Norwood, MA, Technical Report J.I. 

Davies, P. Kausch, H.H., Williams, J.G. and 29 other researchers (1992). Round-robin interlaminar fracture testing of carbon fiber reinforced epoxy and PEEK composites. Composites Sci. Technol. 43, 129-136. 

Ellis C.D. and Harris B. (1973). The effect of specimen and testing variables on the fracture of some fiber reinforced epoxy resins. J. Composite Mater. 7, 76-88. 

Bader M.G., Bailey J.E. and Bell 1. (1973). The effect of fiber-matrix interface strength on the impact and fracture properties of carbon fiber-reinforced epoxy resin composites. J. Phys. D Appi. Phvs. 6, 572-586. 

Jayaraman, K. and Reifsnider, K.L, (1993). The interphase in unidirectional fiber reinforced epoxies effect on residual thermal stresses. Composites. Sci. Technol. 47, 119-129. 

The axial and transverse tensile moduli for a continuous, unidirectional glass-fiber-reinforced epoxy matrix composite as predicted by Eqs. (5.88) and (5.92) are given as a function of volume fraction fiber, E/, in Eigure 5.87. Since Ef E, Eq. (5.92) reduces to the approximate expression ... 

Figure 5.87 Predicted tensile moduli for continuous, unidirectional glass-fiber-reinforced epoxy matrix composite. Reprinted, by permission, from N. G. McCrum, C. P. Buckley, and C. B. Bucknall, Principles of Polymer Engineering, 2nd ed., p. 259. Copyright 1997 by Oxford University Press.

For example, the minimum fiber fraction for a carbon-fiber-reinforced epoxy matrix composite is 0.03. 

Poisson s ratio for the off-axis loaded lamina, v y, can also be derived. The relative tensile modulus, E jEi, shear modulus, Gj jGi2, and Poisson s ratio, v y, are plotted as a function of the angle of rotation, 9, for a glass-fiber-reinforced epoxy lamina and a graphite-fiber-reinforced epoxy lamina in Figures 5.120a and 5.120b, respectively. 

Figure 5.120 Elastic constants for unidirectional (a) glass fiber reinforced epoxy and (b) graphite fiber-reinforced epoxy laminae. Reprinled, by permission, from P. C. Powell and A. J. I. Housz, Engineering with Polymers, pp. 222, 223. Copyrighl 1998 by Stanley Thorned Publishers.

Some electrical properties of reinforcing fibers, composite resins, and the resulting composites are given in Tables 6.12, 6.13, and 6.14, respectively. These values should be taken as approximate only, especially for the composites, since fiber orientation, content, and field strengfh have an enormous impacf on fhe dielecfric properties of these materials. Some of the most widespread electrical applications for glass-fiber-reinforced epoxy systems are in printed circuit boards and electrical housing such as junction boxes. 

The relevant properties of these materials for the torsional-mechanical analysis are listed in Table 8.11. On the basis of specific elastic modulus and specific shear modulus, the best materials are the graphite-fiber-reinforced epoxy resin, followed by either of the alloys, then the Kevlar fiber-reinforced epoxy. The chopped glass sheet molding compound is obviously not a good choice. 

Ultrahigh-modulus graphite-fiber-reinforced epoxy resin 303 7 0.25 0.006 6 1688 18.30 0.36... 

Use the data below for the erosive wear for alnmina particles impacting on a graphite-fiber-reinforced epoxy resin composite material to determine the four parameters Uf,Us,vi, and Vp in Eq. (P8.1). You may need to look up some additional data and make appropriate assumptions to solve this problem. You may also find a spreadsheet helpful for solving the fom equations with four unknowns. 

The composite system chosen was basalt fiber-reinforced epoxy resin. The study of basalt fibers as reinforcement for polymers has been a topic of continuing interest from our early investigations [ 10-12]. 

You are to pultrude a thin fiber reinforced epoxy plate at arate of lcm/s. Assume kinetic properties given in the last two problems and that the material is best represented with the autocatalytic second order reaction kinetic model of the previous problem. You are asked to design the die and the process to manufacture this product. 

Kandola, B.K., Horrocks, A.R., and Rashid, M.R. 2006. Effect of reinforcing element on burning behavior of fiber-reinforced epoxy composites. In Recent Advances of Flame Retardancy of Polymeric Materials, Lewin, M. (Ed.), Proceedings of the 17th Conference, BCC, Stamford, CT. 

Fig. 7. Comparison of stress-strain curves for carbon-fiber-reinforced epoxy composites of different thermal histories. Error rectangles were drawn to indicate a 95% confidence level for both stress and strain...

In order to study the effect of physical aging on the carbon-fiber reinforced epoxy, the freshly quenched materials were then sub-Tg annealed at 140 °C. After annealing for only 10 minutes at that temperature, the toughness of the composite was restored to a level comparable to that of the postcured material (see Fig. 7). It is likely that residual thermal stresses resulted from the quenching were annealed away during this 10 minutes thermal aging at 140 °C. 

Fig. 9. Effect of sub-Tg annealing on the ultimate mechanical properties of carbon-fiber-reinforced epoxies...

Substrates used included fiber-reinforced epoxy base polymer [FRP], nylon 66, polytetrafluoroethylene [Teflon], poly(ethylene terephthalate) [PET], phenolic resin, and thermoplastic polyimide [ULTEM, GE]. FRPs were the primary substrates used. Initially, they were cleaned with detergent in an ultrasonic bath followed by rinsing with deionized water and alcohol. For further cleaning, they were treated with oxygen plasma (1.33 seem, 60 W, 5 min) followed by a hydrogen plasma treatment (3 seem, 60 W, 5 min). 

Calculate (a) the modulus of elasticity, (b) the tensile strength, and (c) the fraction of the load carried by the fibers for a continuous glass fiber-reinforced epoxy resin, with 60% by volume E-glass fiber, stressed under isostrain conditions. The tensile strength and modulus of the fibers are 1800 MPa and 76 GPa, respectively, and the values of these quantities for the matrix are 60 MPa and 2.4 GPa, respectively. 

Glass-fiber-reinforced epoxy resins are also used for chemical plants but are more expensive than the polyester resins. In general they are resistant to the same range of chemicals as the polyesters but are more resistant to alkalis. 

In a recent study, the interphases for different fiber/polymer matrix systems were investigated. By using phase imaging the differences in local mechanical property variation in the interphase of glass fiber reinforced epoxy resin (EP) and glass fiber reinforced polypropylene matrix (PP) composites could be unraveled. As shown in Fig. 3.68, the glass fiber, the interphase and the PP matrix can be differentiated based on their surface mechanical properties as assessed qualitatively by TM phase imaging. 

Epoxy resins are by far the most widely used polymer matrices for advanced structural composites and, if carbon, glass, and aramid fiber reinforced epoxies... 

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