AN ELASTIC NETWORK MODEL-BASED ON THE STRUCTURE OF THE RED-BLOOD-CELLMEMBRANE SKELETON

A finite element network model has been developed to predict the macro scopic elastic shear modulus and the area expansion modulus of the red blood cell (RBC) membrane skeleton on the basis of its microstructure . The topological organization of connections between spectrin molecul es is represented by the edges of a random Delaunay triangulation, and the elasticity of an individual spectrin molecule is represented by t he spring constant, K, for a linear spring element. The model network is subjected to deformations by prescribing nodal displacements on the boundary. The positions of internal nodes are computed by the finite element program. The average response of the network is used to comput e the shear modulus (mu) and area expansion modulus (kappa) for the co rresponding effective continuum. For networks with a moderate degree o f randomness, this model predicts mu/K = 0.45 and kappa/K = 0.90 in Sm all deformations. These results are consistent with previous computati onal models and experimental estimates of the ratio mu/kappa This mode l also predicts that the elastic moduli vary by 20% or more in network s with varying degrees of randomness, In large deformations, mu increa ses as a cubic function of the extension ratio lambda(1), with mu/K = 0.62 when lambda(1) = 1.5.