Figure 4.

Pressurized thin membrane: Regional variation of growth under isotropic and anisotropic conditions. As the membrane is inflated, it locally grows up to ϑ^g = 1.05 corresponding to 5% area growth, while other regions deform elastically at ϑ^g = 1.0 and do not grow. The isotropic membrane shows significant area growth and develops spherical protrusions, top row. Under the same pressure, the anisotropic membranes with vertical fibers, middle row, and with horizontal fibers, bottom row, develop anisotropic protrusions.