A theory for distortion studies of lung parenchyma based on alveolar membrane properties

A finite element model reprensenting the microscopic structure of the lungs is presented. Analysis of the model yields information on the mechanical properties of the lung parenchyma. The micro-properties upon which the model is based are computed by extrapolating uniaxial data calculated from experimentally obtained pressure-volume relationships of excised lungs. Macro-properties are subsequently found by assembling the micro-elements into a parenchymal structure of the lung, and analyzing its responses to non-uniformly applied forces. Experimental information regarding the mechanical properties of lungs is lacking and this mathematical model which is based on the known pressure-volume relationships can fill a need in mechanical studies of the lungs. In particular, it provides the complete information for the element stiffness relationship in finite element analysis. Comparison of the model properties with recently conducted macro-level distortion experiments indicates very good correlation.