التفاصيل البيبلوغرافية
| العنوان: |
Nonlinear Viscoelastic Wave Propagation in Brain Tissue |
| المؤلفون: |
Laksari, Kaveh |
| المساهمون: |
Darvish, Kurosh, Sadeghipour, Keya, Margulies, Susan, Seibold, Benjamin, Crandall, Jeff R. |
| بيانات النشر: |
Temple University Libraries |
| سنة النشر: |
2013 |
| المجموعة: |
Temple University Digital Collections |
| مصطلحات موضوعية: |
Engineering, Mechanical engineering, Biomechanics, Blast Induced Neurotrauma, Brain Tissue, Discontinuous Galerkin Method, Injury Biomechanics, Nonlinear Viscoelasticity, Wave Propagation |
| الوصف: |
Mechanical Engineering ; Ph.D. ; A combination of theoretical, numerical, and experimental methods were utilized to determine that shock waves can form in brain tissue from smooth boundary conditions. The conditions that lead to the formation of shock waves were determined. The implication of this finding was that the high gradients of stress and strain that could occur at the shock wave front could contribute to mechanism of brain injury in blast loading conditions. The approach consisted of three major steps. In the first step, a viscoelastic constitutive model of bovine brain tissue under finite step-and-hold uniaxial compression with 10 1/s ramp rate and 20 s hold time has been developed. The assumption of quasi-linear viscoelasticity (QLV) was validated for strain levels of up to 35%. A generalized Rivlin model was used for the isochoric part of the deformation and it was shown that at least three terms (C_10, C_01 and C_11) are needed to accurately capture the material behavior. Furthermore, for the volumetric deformation, a linear bulk modulus model was used and the extent of material incompressibility was studied. The hyperelastic material parameters were determined through extracting and fitting to two isochronous curves (0.06 s and 14 s) approximating the instantaneous and steady-state elastic responses. Viscoelastic relaxation was characterized at five decay rates (100, 10, 1, 0.1, 0 1/s) and the results in compression and their extrapolation to tension were compared against previous models. In the next step, a framework for understanding the propagation of stress waves in brain tissue under blast loading was developed. It was shown that tissue nonlinearity and rate dependence are key parameters in predicting the mechanical behavior under such loadings, as they determine whether traveling waves could become steeper and eventually evolve into shock discontinuities. To investigate this phenomenon, the QLV material model developed based on finite compression results mentioned above was extended to blast ... |
| نوع الوثيقة: |
thesis |
| وصف الملف: |
Application/PDF; 10717027 Bytes |
| اللغة: |
English |
| العلاقة: |
TETDEDXLaksari-temple-0225E-11662; http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/242293Test |
| الإتاحة: |
http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/242293Test |
| حقوق: |
The author has granted Temple University a limited, non-exclusive, royalty-free license to reproduce his or her dissertation, in whole or in part, in electronic or paper form and to make it available to the general public at no charge. This permission is granted in addition to rights granted to ProQuest. The author retains all other rights. |
| رقم الانضمام: |
edsbas.ED8B538A |
| قاعدة البيانات: |
BASE |
