Mechanical Properties of Brain White Matter under Repetitive Loading Condition: Introducing a Mechanical Damage Function

Repetitive traumatic brain injury (rTBI) is known as one of the common types of brain injuries among infants and amateur and professional athletes. Previous studies have shown that under compressive cyclic loading, with increasing the level of strain, the stress stiffening increases, and for a constant strain, with the repeating load, the stress value decreases. This reduction can be attributed to tissue injury. The current study aimed to introduce a mechanical damage function for brain tissue. For this purpose, samples were extracted from bovine brain tissue and subjected to uniaxial compressive cyclic loading and mechanical properties were calculated using three commonly used hyperelastic models, including neo-Hookean, Mooney-Rivlin, and generalized Rivlin. Using a damage function, the effect of stiffness reduction due to repetitive loading was inserted to the models. The results of the study showed that generalized Rivlin model can display changes in mechanical properties of brain tissue under compressive cyclic loading more precisely than two other models. It is suggested that the damage function proposed in the current study can be used for predicting the mechanical behavior of brain tissue after repetitive loading.

Keywords:

brain tissue , white matter , cyclic loading , repetitive injury , damage function