Ineffective fiber length

In [148] it was shown that the strength of the composite depends on the fiber strength at the so-called ineffective length, so that only a few percent of the total amount of the ineffective fiber lengths in the composite become broken before the specimen fails completely. The authors of [148] proposed to express the relationship between the average fiber strength [Pg.19]

The significance of Rosen s work lies in the attempt of quantifying the efficiency of stress transfer across the interface with respect to the fiber length, by introducing the concept of ineffective length . The ineffective fiber length, (2L), was defined by specifying some fraction, (f>, of the undisturbed stress value below which the fiber shall be considered ineffective. (2i) normalized with fiber diameter, 2a, is derived as... 

Fig. 4.5. Normalized ineffective fiber length, (2i),/2a, as a function of modulus ratio, E jEms for varying fiber volume fraction, Vf. After Rosen (1964).

Darby et al [42] investigated the effect of broken or cut plies in a 6k XAS reinforced PES matrix. To calculate the stress distribution of a break in a single carbon fiber under tension, the shear lag method of Cox [43] was used and the ineffective length of a single broken fiber... 

In the last five sections we have shown how a lens, on the one hand can increase source efficiency for collimated beam illumination of a fiber, while, on the other hand, it is ineffective at increasing the efficiency of the diffuse source. If we couple these facts with the description of the diffuse source as a superposition of collimated beams, it is evident that the efficiency of a partially diffuse source can be increased by a lens. The situation is illustrated in Fig. 4—8. We assume the step-profile fiber is weakly guiding so that 9 1, and the focal length satisfies... 

The tubular current source was described in Section 21-6, where we showed that it is ineffective in exciting bound modes unless either of the resonance conditions of Eq. (21-15) is satisfied. A similar conclusion holds for the radiation fields. If the tube length 2L is large compared to the spatial period 2n/Sl, where 2 is the frequency in Eq. (21-13), it is intuitive that power will be radiated essentially at a fixed angle to the fiber axis. This is also a consequence of Floquets theorem [7]. However, unlike the current dipole, radiation now depends on the orientation of the currents on the tube. 

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