Fiber fragment length

The fiber fragment length can be measured using a conventional optical microscope for transparent matrix composites, notably those containing thermoset polymer matrices. The photoelastic technique along with polarized optical microscopy allows the spatial distribution of stresses to be evaluated in the matrix around the fiber and near its broken ends. 

Fig. 3,4. Ln-Ln plot of fiber fragment length as a function of fiber stress (a) for Kevlar 29 fiber-epoxy matrix composite and (b) for a carbon fiber-epoxy matrix composite. Yabin et al. (1991).

Apart from the mechanical properties of the composite constituents that dominate the fiber fragment length, peculiar structural properties of the fiber may... 

Netravali, A.N., Topoleski, L.T.T., Sachse, W.H. and Phoenix, S.L. (1989c). An acoustic emission technique for measuring fiber fragment length distributions in single fiber composite test. Composites Sci. Technol. 35, 13-29. 

Debond length and mean fiber fragment length... 

From Eqs. (4.45) and (4.46), the solutions for the mean fiber fragment length are derived... 

Fig, 4,9, Comparisons of mean fiber fragment length, 2L, as a function of applied stress, (t, between experiments and theory for carbon fiber-epoxy matrix composites with (a) XAl fiber and (b) XAIOO fiber ( ) experiment (---------) prediction (..) debond length. After Zhou ct al. (1995a, b). 

Having satisfied the requirements for full bonding, the mean fiber fragmentation length, 2L, is determined from Eq. (4.72)... 

Fig. 4.12. Varialion of mean fiber fragment length, 2L, versus applied strain, t, in the full bonded interface model (---------) varying ctts(22,) (------------) constant fiber tensile strength ctts- After Kim et al. (1993b).

Finally, the solution for the mean fiber fragmentation length, IL, which is the sum of the debonded and bonded lengths in the partial debond model, is derived from the fiber fragmentation criterion given by Eq. (4.70)... 

Taking the approximate values for the non-dimensional coefficients given in Eq. (4.80), the solution for the mean fiber fragment length, 2L, is given in a closed form equation... 

The mean fiber fragment length, 2L, is plotted as a function of the applied strain, e, in Fig. 4.18. Similar to the results for the fully bonded interface model shown in Fig. 4.12, the full frictional interface model predicts that (2L) decreases sharply with increasing applied strain within a short range of c. A high fiber tensile strength... 

As the load increases, the fibers fail systematically, resulting in a characteristic fiber fragment length. At composite failure, there can be multiple cracks within some fibers. The existence of many fiber fragments is still... 

For the Mileiko18 model of composite creep leading to the steady-state creep rate for fixed fiber length given in Eqn. (63), a rudimentary fiber fragment length model gives... 

Despite the sophisticated statistical techniques used to characterize the fiber fragment length distribution, the shear strength is calculated using an oversimplified representation of the state of stress occurring at the interface... 

Fig. 9. Distribution of axial stress along fiber fragment length [88].

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