Mechanical Properties of Passive and Active Diaphragm Muscle: Theoretical Framework and Experimental Validation

Abstract

A comprehensive constitutive theory is developed for the diaphragm. The theory can describe the mechanical properties of the diaphragm muscle in its passive and active states in a unified manner. It also describes the mechanical properties of the diaphragm under mechanical loads in arbitrary directions. The theoretical model involves seven material constants that represent the nonlinear elastic moduli and activation strains of the diaphragm muscle. The values of these material constants are determined by using in vitro experimental data, including that from shear loading experiments which are documented in this work for the first time.

Keywords: Diaphragm mechanics, Muscle activation, Anisotropy, Constitutive function, Experiments