Influence of high deformation rate, brain region, transverse compression, and specimen size on rat brain shear stress morphology and magnitude
| Autor: | Jenna Gipple, Henry W. Haslach, Lauren N. Leahy |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Materials science
0206 medical engineering Biomedical Engineering 02 engineering and technology Biomaterials 03 medical and health sciences 0302 clinical medicine Shear stress Pressure Animals Composite material Deformation (mechanics) business.industry Brain Extracellular Fluid Structural engineering Organ Size Rat brain 020601 biomedical engineering Biomechanical Phenomena Rats Shear rate Simple shear Transverse plane Shear (geology) Mechanics of Materials Critical resolved shear stress Brain Injuries Stress Mechanical business 030217 neurology & neurosurgery |
| Zdroj: | Journal of the mechanical behavior of biomedical materials. 68 |
| ISSN: | 1878-0180 |
| Popis: | An external mechanical insult to the brain, such as a blast, may create internal stress and deformation waves, which have shear and longitudinal components that can induce combined shear and compression of the brain tissue. To isolate the consequences of such interactions for the shear stress and to investigate the role of the extracellular fluid in the mechanical response, translational shear stretch at 10/s, 60/s, and 100/s translational shear rates under either 0% or 33% fixed transverse compression is applied without preconditioning to rat brain specimens. The specimens from the cerebrum, the cerebellum grey matter, and the brainstem white matter are nearly the full length of their respective regions. The translational shear stress response to translational shear deformation is characterized by the effect that each of four factors, high deformation rate, brain region, transverse compression, and specimen size, have on the shear stress magnitude averaged over ten specimens for each combination of factors. Increasing the deformation rate increases the magnitude of the shear stress at a given translational shear stretch, and as tested by ANOVAs so does applying transverse fixed compression of 33% of the thickness. The stress magnitude differs by the region that is the specimen source: cerebrum, cerebellum or brainstem. The magnitude of the shear stress response at a given deformation rate and stretch depends on the specimen length, called a specimen size effect. Surprisingly, under no compression a shorter length specimen requires more shear stress, but under 33% compression a shorter length specimen requires less shear stress, to meet a required shear deformation rate. The shear specimen size effect calls into question the applicability of the classical shear stress definition to hydrated soft biological tissue. |
| Databáze: | OpenAIRE |
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