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Prediction of mechanical properties of the cancellous bone tissue of the mandible
Holá, Lucia ; Valášek, Jiří (oponent) ; Thomková, Barbora (vedoucí práce)
The bachelor thesis deals with a problem from the field of biomechanics, specifically to determine mechanical properties of cancellous bone tissue of lower jaw and is focused on Young´s modulus of elasticity and apparent bone density detection. In this thesis a research of studies that were focused on determining a relationship between E and apparent density of trabecular bone is firstly included. Then solution is made using computational modeling using finite element method on the model of lower jaw that was constructed from CT scans. In the SolidWorks software, 12 cubes were made and inserted into the model that was later used in software called ANSYS Workbench, to calculate force reactions and E value using CT number values also calculated in the software. Calculated values of force reactions were then used for Young´s modulus calculation for each axis x,y and z using equations obtained from literature. Next solution was made using the ImageJ program in which values of Hounsfield units were obtained and later recalculated into apparent density values using mathematical relations. Then values of E as a function of CT number and E values obtained from mathematical relation were compared. Lastly the relationships between E and density were determined.
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Comparative analysis of the effect of nonlinearities on the lumbar segment stress/strain of the spine after correction of spondylolisthesis
Holá, Lucia ; Ščerba, Bořek (oponent) ; Vosynek, Petr (vedoucí práce)
This final thesis focuses on the stress-strain analysis of the physiological, postoperative and degenerative state of the lumbar spine segment. The aim of this thesis is to implement nonlinear material characteristics into previously made computational models and to compare these two models. The solution is performed by computational modeling using the finite element method. The geometry model was made by modification of the previous model of geometry. The group of degenerative state models comprises of three different levels of spondylolisthesis, according to Myereding’s classification. Based on the performed analysis, it was found that the increasing severity of spondylolisthesis, as well as the change in material definition plays a huge role in the stress development in the intervertebral discs and in the vertebrae. The total deformation of the spine segment increases with the use of nonlinear material characteristics, as well as with the increasing variability from the physiological state. However, the stress distribution in the intervertebral disc decreases with the use of nonlinear material characteristics and in case of the vertebral stress distribution increases, unlike in the linear material models. The biggest similarity with the physiological state of the lumbar spine segment was found in the postoperative state using the spinal implants.
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Prediction of mechanical properties of the cancellous bone tissue of the mandible
Holá, Lucia ; Valášek, Jiří (oponent) ; Thomková, Barbora (vedoucí práce)
The bachelor thesis deals with a problem from the field of biomechanics, specifically to determine mechanical properties of cancellous bone tissue of lower jaw and is focused on Young´s modulus of elasticity and apparent bone density detection. In this thesis a research of studies that were focused on determining a relationship between E and apparent density of trabecular bone is firstly included. Then solution is made using computational modeling using finite element method on the model of lower jaw that was constructed from CT scans. In the SolidWorks software, 12 cubes were made and inserted into the model that was later used in software called ANSYS Workbench, to calculate force reactions and E value using CT number values also calculated in the software. Calculated values of force reactions were then used for Young´s modulus calculation for each axis x,y and z using equations obtained from literature. Next solution was made using the ImageJ program in which values of Hounsfield units were obtained and later recalculated into apparent density values using mathematical relations. Then values of E as a function of CT number and E values obtained from mathematical relation were compared. Lastly the relationships between E and density were determined.
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