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Experimental geometry.

In the initial configuration the director is vertical. Uniform displacements in direction 2 on the two faces with normal e₂ (thicker lines) are then prescribed. The rest of the boundary is free, and the out-of-plane component of the displacement is free for the entire sample. The stretch s is defined as the ratio between the deformed and the original length of the sample in direction 2.

This stretching procedure influences the director. Its orientation is vertical in the initial state, and horizontal in the final, highly stretched state. In the intermediate states the orientation is not uniform throughout the sample, but exhibits a characteristic layered texture, which corresponds to the lamination construction used to compute the quasicoinvex envelope of the energy.

Experimental observation by Kundler and Finkelmann of stripes in the central region of the sample at moderate stretches. The light and dark areas correspond to transparent and opaque regions under polarized light transmission, and have different director orientation. Picture: Courtesy of I. Kundler and H. Finkelmann, Institut für Makromolekulare Chemie, Freiburg. The entire sample is around 10 millimeters long, and 0.3 millimeter thick. The width of the domains is about 1 to 10 micrometers.

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