Page 117 - 3D Fibre Reinforced Polymer Composites

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on elastic foundation with an initial deflection as shown in Figure 4.23b. The initial
deflection is introduced to model the filler yarn waviness, which can be experimentally
measured from a micrograph of the cross-section. The cross-sectional micrographs (see
Figure 4.15) show that the yam waviness can be approximated by a sine function.
Possible failure mode range and loci were then predicted using the model. A good
agreement between the measured and predicted failure load ranges and the observed
failure loci was reported. This will be discussed in details in Section 5.3.1.
Emehel and Shivakumar (1997) proposed a tow collapse model for predicting
compressive strength of multiaxial laminates and textile composites. In this model, the
unidirectional composite compressive strength model based on microbuckling of fibres
embedded in a rigid-plastic matrix was employed to develop a resulting expression in
terms of the matrix yield strength under the fibre constraint, fibre tow inclination angle,
fibre volume fraction, and the area fractions of various sets of inclined tows. The
predicted strengths agree reasonably well with those measured in the experimental tests.