Fibre-axis diagram

This done, consider the other layer lines on the photograph. A reciprocal lattice rotation diagram is prepared as before from the and f values of all the spots. If row lines are exhibited, then the remaining axis of the reciprocal lattice is normal to the zero-level not, as in Fig. 89 in other words, the crystals are monoclinic with their b axes parallel to the fibre axis. It is again necessary to remember that one or both reciprocal axes of the zero-level net may have to he halved to account for all the points on other levels. 

As pointed out in section 2.5.1, where the reciprocal lattice is defined, it is possible to determine the shape and dimensions of any real lattice from the corresponding information about the reciprocal lattice. The spots on the /th layer line correspond to reciprocal-lattice points lying on the reciprocal-lattice plane containing all points hkl) for different h and k. The fibre diagram is in fact similar to what would be obtained if the following imaginary experiment were performed. Place the origin of a suitably scaled version of the reciprocal-lattice at the point where the incident X-ray beam would strike the film, with the normal to the planes of constant / parallel to the fibre axis and therefore to the meridian of the fibre pattern. Rotate the reciprocal lattice around the meridian and mark a point on the film every time a lattice point intersects it. To understand the difference between this pattern and a real fibre pattern it is useful to consider fig. 4.13. 

Fig. 3. Isochronous modulus-strain data for specimens cut at various angles, 6, to the fibre axis of cold-drawn LDPE, draw ratio 4-2. In all diagrams, except where explicitly stated otherwise, test temperature was 20 C. (After Darlington and...

Fig. 5. Smectic x-ray diagram from sample C-6 of Fig. 4(b) with fibre axis parallel to the x-ray beam.

Figure 17.51 Schematic diagram of 10° off-axis shear test. Source Reprinted from Chamis CC, Sinclair JM, Ten-degree off-axis test for shear properties in fibre composites, Exp Mech, 17, 339-346,1977.

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