Biomechanical Response of the Bovine Pia-Arachnoid Complex to Normal Traction Loading at Varying Strain Rates

The pia-arachnoid complex (PAC) covering the brain plays an important role in the mechanical response of the brain due to impact or inertial loading. The mechanical properties of the bovine PAC under tensile loading have been characterized previously. However, the transverse properties of this structure, such as shear and normal traction which are equally important to understanding the skull/brain interaction under traumatic loading, have not been investigated. These material properties are essential information needed to adequately define the material model of the PAC in a finite element (FE) model of human brain.

The purpose of this study was to determine, experimentally, the material properties of the PAC under normal traction loading. PAC specimens were obtained from freshly slaughtered bovine subjects from various locations. Quasi-static and dynamic tests along the radial direction were performed at four different strain rates (0.36, 2.0, 20.5, and 116.3 s-¹) to investigate the rate and regional effects. Results suggest that the PAC under traction loading is stiffer than brain tissue, rate dependent, and can be characterized as linearly elastic until failure. However, no regional difference was observed.