DAMAGE ACCUMULATION MODELING AND RATE DEPENDENCY OF SPINAL DURA MATER

摘要

As the strongest of the meningeal tissues, the spinal dura mater plays an important role in the overall behavior of the spinal cord-meningeal complex (SCM). It follows that the accumulation of damage affects the dura mater's ability to protect the cord from excessive mechanical loads. Unfortunately, current computational investigations of spinal cord injury etiology typically do not include post-yield behavior. Therefore, a more detailed description of the material behavior of the spinal dura mater, including characterization of damage accumulation, is required to comprehensively study spinal cord injuries. Continuum mechanics-based viscoelastic damage theories have been previously applied to other biological tissues, however the current work is the first to report damage accumulation modeling in a SCM tissue. Longitudinal samples of ovine cervical dura mater were tensioned-to-failure at one of three strain rates (quasi-static, 0.05/sec, and 0.3/sec). The resulting stress-strain data were fit to a hyperelastic continuum damage model to characterize the strain-rate dependent sub-failure and failure behavior. The results show that the damage behavior of the fibrous and matrix components of the dura mater are strain-rate dependent, with distinct behaviors when exposed to strain-rates above that experienced during normal voluntary neck motion suggesting the possible existence of a protective mechanism.