Fiber-matrix bonding

Composite 1 with the higher fiber/matrix bonding shows a linear-elastic behavior up to = 160 MPa, which is clearly higher than that of composite 2. The following nonlinear region is small, resulting in an elongation at fracture of 0.32 %. 

Fig. 6. Tensile stress versus strain for two 2D-SiC/SiC composites with different fiber matrix bonding (bonding 1 stronger than 2)...

Fig. 10. Stress-strain curves of 2D-C/SiC with optimized fiber/matrix bonding...

Fiber glass-reinforced plastic tanks, 24 299 Fiber grating, 11 150-151 Fiber length (FL), 18 148 Fiber manufacture, sodium bisulfite in, 23 673 Fiber-matrix bonding, 26 771-772 Fiber modification, chemical, 16 14 Fibernodes, 11 595 Fiber-optic probes, 16 524 Fiber optics, 11 128-162, 15 469 attenuation in, 11 132-133 dispersion in, 11 134-135 fiber drawing in, 11 141-145 fiber strength in, 11 141-145 history of, 11 128-131 inside processes for, 11 136-140 near-infrared, 23 141 optical amplifiers with, 11 145-146 optical fiber fabrication for,... 

Grande, D.H., Mandell, J.F. and Hong, K.C.C. (1988). Fiber-matrix bond strength studies of glass and metal matrix eomposites. J. Mater. Sci. 23, 311 328. 

Mandell, J.F., Chen, J.H. and McGarry, F.J. (1980). A microdebonding test for in situ assessment of fiber/matrix bond strength in composite materials. Int. J. Adhesion Adhesives 1, 40-44. 

When these specimens are stressed in tension, the fibers fracture first. If the fiber-matrix bond is weak, the resulting stress is relieved by debonding on either side of the break. These debonded fibers slide back into their holes in the resin, against considerable friction, and the load is built up again in the fibers. 

Critical fiber length = [Ultimate or tensile strength times fiber diameter/2] times the fiber-matrix bond strength or the shear yield strength of the matrix— whichever is smaller... 

The method adopted for the comparison of silane treatment effects on fiber-matrix bond strength was the determination of interfacial shear strength (IFSS) in single-filament composite (SFC) specimens [13, 14], which we have used extensively in investigating fiber-matrix interactions. The conditions of silane treatment of single fibers as well as the corresponding effects on IFSS could thus be carefully controlled, measured, and compared. 

The improvements in fiber-matrix bonding brought about by the application of silane coupling agents should be reflected in the results of IFSS measurement using the SFC specimen. The relative merits of the three silanes studied here can thus be compared through the IFSS values obtained under optimal conditions of silane application in each case. These results are presented in Figs 6 and 7. 

The effect of the HRH system on adhesion is further illustrated by the micrographs (Figures 7-11) of the same rayon-natural rubber composite with and without HRH. Figures 7-9 show a thin section of the composite without HRH stretched to various elongations with the force applied parallel to the direction of orientation. Many voids form as the strain is increased owing to fiber-matrix bond failures. Both the number and size of voids increase with increasing strain. 

In comparing the acido-basicity of the untreated and electrochemically (or anodically) treated fibers in Table 11, it is observed that the amine-treatments increase significantly the basicity of the fibers (Samples II and III), while commercial oxidation increases the acidity (IV), as expected. This behavior is probably explained in terms of the presence of any physisorbed species (such as, amine and oxygen functional groups for the fiber surfaces amined and oxidized, respectively). This can improve the degree of adhesion at interfaces of the composites for fiber surfaces incorporated with epoxy matrix for playing an important role in forming the fiber-matrix bond. 

F. Abbe and J.-L. Chermant, Fiber-Matrix Bond Strength Characterization of Silicon Carbide-Silicon Carbide Materials, J. Am. Ceram. Soc., 73[8], 2573-2575 (1990). 

First, the carpet waste must be disassembled into short fibers of appropriate length. By optimizing the fiber length and fiber/matrix bond properties, improved toughening effect can be achieved [8, 9], This generally means that the... 

R.A. Lowden, D.P. Stinton, The influence of the fiber - matrix bond on the mechanical behavior of Nicalon/SiC composite, ORNL/TM-10667, December 1987. 

Dibasic ammonium phosphate, (NH4)2HP04, was included in all composites, acting both to improve fiber-matrix bonding and to reduce the friction and wear of the graphite fibers at elevated temperature, as reported by Lancaster (11). 

This extensive matrix spalling was not observed for the other composites, implying relatively weak fiber-matrix bonding in the LlWl specimens. Weak bonding was possibly due to poor impregnation of the fibers by the matrix during fabrication, or a deficiency of the phosphate fiber-matrix binder in the near surface region of the composite. 

Although the presence of the reinforcing fibers enhances the strength and modulus properties of the base material, they also cause a complex distribution of stress in the materials. For example, even under simple tensile loading, a triaxial stress system is set up since the presence of the fiber restricts the lateral contraction of the matrix This system increases the possibility of brittle failure in the material. The type of fracture which occurs depends on the loading conditions and fiber matrix bonding. 

Ceramic matrix composites require a fiber interface coating to prevent fiber-matrix bonding and to produce crack deflection and fibrous fracture in the composite. Work at the... 

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