A discrete network model to represent the deformation behavior of human amnion

A discrete network model (DNM) to represent the mechanical behavior of the human amnion is proposed. The amnion is modeled as randomly distributed points interconnected with connector elements representing collagen crosslinks and fiber segments, respectively. This DNM is computationally efficient and allows simulations with large domains. A representative set of parameters has been selected to reproduce the uniaxial tension-stretch and kinematic responses of the amnion. Good agreement is found between the predicted and measured equibiaxial tension-stretch curves. Although the model represents the amnion phenomenologically, model parameters are physically motivated and their effect on the tension-stretch and in-plane kinematic responses is discussed. The model is used to investigate the local response in the near field of a circular hole, revealing that the kinematic response at the circular free boundaries leads to compaction and strong alignment of the network at the border of the defect.