ABSTRACT
This chapter shows that the intrinsic deformation of surface material elements can be represented by a sequence of geometric alterations: a dilation or condensation of surface area followed by extension of the surface element at constant area. Similarly, the rate of deformation of the surface can be decomposed into the fractional rate of area change and the fractional rate of extension at constant area. Experimentally, the determination of material properties of biological membranes involves applying prescribed forces and observing the resulting change in shape of the membrane and the time rate of change of membrane conformation. Both deformation and rate of deformation are quantitatively analyzed in terms of alterations in the surface geometry of the encapsulating membrane. The relative displacement in time of the material points in each small element specifies the intrinsic deformation of the surface, and the time rate of change specifies the rate of deformation.
