Fiber deformation

Other Fiber Deformations. Deformations such as bending, torsion, shear, and compression are of practical importance in textile apphcations. Bending and twisting of yams, both influential in the development of bulk and stretch in filament yams, are also important in the production of staple yams. Bending characteristics are important in cmsh resistance in carpets. Bending and shear are factors that influence the hand and drape of apparel fabrics, whereas compression influences the recovery of fabrics after such processes as winding. 

However, recent in-situ synchrotron radiation WAXD studies of PTT fiber deformation by Wu et al. [76] showed that the PTT crystal 002 -spacing could be stretched to a length corresponding to a fully trans chain. The increase in the c-axis dimension was accompanied by a decrease in the >-axis length, measured from the 010 reflection (Figure 11.14). When the strain was increased above a... 

Young, R.J., Day. R.J., Zakikhani, M. and Robinson, I.M. (1989). Fiber deformation and residual thermal stresses in carbon fiber reinforced PEEK. Composites Sci. Technol. 34, 243-258. 

Fig. 17. Interaction of a crack with a fiber through fiber deformation and fracture...

FIGURE 16.7 Mechanisms of brush cleaning (a) ideal, (b) fiber deformed, and (c) noncontact mode (from Ref 27). 

Polymer blending also affects the dimensional stability of the HKL-based fibers during the thermostabilization process. The HKL homofibers undergo more than 20% shrinkage during thermostabilization. This fiber deformation affects the utility and the... 

If die hollow fiber is made of glassy polymers, only small fiber deformation is tolerable over the possible operating pressure range to avoid rupture of the fiber wall. Since the selective dense layer ou the outside region of die hollow fiber is normally very thin (less than 1300 A), it is understandable that the shell-feed mode, where the fiber is pressurized externally, is of most commercial interest since the dense layer may be ruptured by dilation if die fiber is pressurized internally. 

The data of Table III (Set A) also demonstrate the high pressure capability of Celgard X-10 hollow fibers. The CO2-N2 mixture separation with aqueous 30% wt/wt 200 ILM-s in Celgard X-10 fibers was studied at applied AP values up to about 550 cm Hg without any significant effect on permeation due to any fiber deformation. 

Mazzoni M.C., Skalak T.C., and Schmid-Schonbein G.W. 1990. The effect of skeletal muscle fiber deformation on lymphatic volume. Am. J. Physiol. 259 H1860. 

When SFCs are stressed, the stresses are transferred to the fibers by shear at the fibers surface, which causes fiber deformation. To estimate the Young s modulus of SFCs, Cox [21] proposed a model that assumes a completely elastic transfer of stresses from the matrix to the fiber. By averaging the stress distribution within the fibers, the theory predicts the Yoimg s modulus for aligned SFCs, in the direction of alignment, to be equal to ... 

In contrast, high-modulus mesophase pitch-based carbon fibers deform by a shear mechanism leading to kink bands at 45° to the fiber axis. 

In order to illustrate the principles, the above examples have been kept simple, in geometry and in types of deformation, but the methods are capable of development to cover other forms of fiber deformation such as bending and twisting, and to treat three-dimensional structures, subject to three axial and three shear modes of deformation. 

When a fiber preform is draped over a tool surface, the orientation of the fibers in the preform will also change. This will change the fiber volume fraction and hence the permeability to resin flow. Depending on the type of fabric and radius of the mold curvature, the deformation and permeability may vary spatially. The designer should consider the effect of permeability variations on the resin propagation when the fabric is placed over a compound curvature surface. Rudd et al. discussed four different mechanisms of fiber deformations ... 

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