Numerical modelling of abdominal wall mechanics: The role of muscular contraction and intra-abdominal pressure

Abstract The biomechanics of the abdominal wall depends on muscular activation, tissue mechanical behavior and Intra-Abdominal Pressure (IAP). In this work, a numerical model of a human abdomen is presented, based on abdominal wall geometry from medical images. Specific constitutive formulations describe tissues mechanical behavior. Connective tissues are modelled as hyperelastic fiber-reinforced materials, while muscular tissues are described by means of a three-element Hill's model. The abdominal cavity is represented by a volume region interacting with the abdominal wall. Numerical analyses are developed by applying a muscular contraction, inducing a volume reduction of the abdominal cavity and a simultaneous IAP increase. Numerical results of abdomen displacement at IAP corresponding to an abdominal crunch are compared with experimental results acquired via 3D laser scanning on healthy subjects. Numerical and experimental results are mutually consistent and show that muscular activation induces a raising in the region adjacent to linea alba along the posterior-anterior direction and a lowering along lateral-medial direction of the abdominal wall sides. The numerical model developed in this work allows a coherent representation of the abdominal wall mechanics.