Mechanical Engineering Commons^™

The Role Of Transient Vibration Of The Skull On Concussion, Rodrigo Dalvit Carvalho Da Silva

Electronic Thesis and Dissertation Repository

Concussion is a traumatic brain injury usually caused by a direct or indirect blow to the head that affects brain function. The maximum mechanical impedance of the brain tissue occurs at 450±50 Hz and may be affected by the skull resonant frequencies. After an impact to the head, vibration resonance of the skull damages the underlying cortex. The skull deforms and vibrates, like a bell for 3 to 5 milliseconds, bruising the cortex. Furthermore, the deceleration forces the frontal and temporal cortex against the skull, eliminating a layer of cerebrospinal fluid. When the skull vibrates, the force spreads directly to …

Significance Of The Neck In Concussive Head Impacts – A Computational Approach, Sakib Ul Islam

Electronic Thesis and Dissertation Repository

With the rising concern of concussions in contact sports, it is believed that cervical muscles could play a vital role in attenuating force to the head. However, the biomechanical effect of cervical muscles on head and brain response is not clearly understood. This study adopted a finite element head and neck model to replicate football impacts under various loading conditions to study the effect of neck muscles on head kinematics. Our results indicate that neck muscles have the highest amount of internal energy absorption in early impact, particularly at the time when peak head kinematics develop. Both deep and superficial …

The Effect Of Humeral Short Stem Positioning, Humeral Head Contact, And Head Positioning On Bone Stress Following Total Shoulder Arthroplasty, Amir Tavakoli

Electronic Thesis and Dissertation Repository

Uncemented humeral stems cause stress shielding which result in bone resorption when used in total shoulder arthroplasty (TSA). Shorter length stems show a decrease in stress shielding, however the effect of humeral short stem positioning and humeral head contact and positioning on bone stress is currently not known, hence CT-based tools and Finite Element (FE) methods are used to quantify the effects of the mentioned variables on bone stresses after TSA.

Eight male cadaveric humeri were virtually constructed from computed tomography (CT) data, with a generic short humeral short stem as the implant.

The results of this work show that …

An Investigation On The Influences Of Radial Head Hemiarthroplasty Stem Fixation Techniques On Articular Mechanics, Jakub Szmit

Electronic Thesis and Dissertation Repository

Radial head hemiarthroplasty design has been extensively studied with a focus on utilizing the geometrical characteristics of the native radial dish as a guide of implant placement and design. Although implant design has been studied, optimal radial head implant fixation technique remains unknown. This thesis focused on the effect of stem fit on radiocapitellar contact mechanics, using both finite element and experimental bench-top approaches. Additionally, investigation into the impact of varus/valgus malalignment of the radial head in both the native state and following hemiarthroplasty was conducted. It was found that loose fitting a smooth stem axisymmetric radial head implant through …

Strategies For Ultraprecise Single Point Cutting Of V-Grooves, Delfim A C Joao

Electronic Thesis and Dissertation Repository

V-groove microstructures have found numerous functionalization applications in mechanical, electronic, photonic, biomechanical and optical components. However, despite their wide use, the manufacturing processes associated with their fabrication are limited to axial strategies with a constant depth of cut that do not allow the control of the cutting force and cutting time, and therefore leading to significant micro-burrs as well as an inability to fabricate high aspect ratio grooves. The current thesis addresses this problem with the development of three cutting strategies that make use of a single point cutting process. The study to be detailed herein includes analytical, numerical and …

An In-Silico Assessment Of Stemless Shoulder Arthroplasty: From Ct To Predicted Bone Response, Jacob M. Reeves

Electronic Thesis and Dissertation Repository

Despite the emergence of stemless humeral implants that utilize short fixation features to gain purchase solely in the metaphysis, the literature contains little information regardingthe morphology and mechanical properties of the humerus’ proximal trabecular-canal, and how stemless implants impact bone response. The present work employs in-silicotools, including CT-based and Finite Element (FE) methods, to define parameters that may influence stemless implant design.

The density and morphology of the proximal humerus were assessed using CT-derived point clouds of the trabecular-canal. Bone density was found to diminish 15-20mm beneath the humeral head resection and was greater peripherally. The depth, path and bounding …