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Kambara, HajimeThe rheological properties of aluminum borate whisker filled resins
Doctor of Philosophy, Case Western Reserve University, 1994, Macromolecular Science
The purpose of this work is to investigate the rheological properties of epoxy resin filled with high concentrations of aluminum borate (9Al2O3-2B2O3) whiskers. Rheological measurements are performed with parallel plate rheometer. The rheology exhibits nonlinear viscoelasticity from low strain region through entire range studied. The presence of an effective network of whiskers comprising an internal structure is proposed. The thesis is consisted of three parts. The first is the conformation of the internal structure of whisker network and its deformation. By applying the external shearing force, both steady and dynamic, to the whisker suspension, the responses of the rheological properties have been monitored. The data is interpreted and quantitative analyses are carried out. The second is the reformation behavior of the deformed internal structure. No major study is done about reformation behavior of the internal structure of short fiber suspension. In this part, the condition of deformed internal structure is analyzed and then reformation behavior under zero shearing force is studied. The third is the phenomenological similarity of rheological properties between the whisker suspension and the liquid crystal polymer. This phenomenon is observed f or only whisker suspension not for ordinary glass fiber suspension due to whiskers' small dimension. The fourth is the investigation about effects of whisker/whisker interaction and whisker/resin interaction on the rheological behavior. From these studies, the change of rheological status upon the external force such as processing procedure has been clarified.

Committee:

Hatsuo Ishida (Advisor)

Keywords:

rheological properties; aluminum borate; whisker filled resins

Rinehart, Aidan WalkerA Characterization of Seal Whisker Morphology and the Effects of Angle of Incidence on Wake Structure
Master of Science in Mechanical Engineering, Cleveland State University, 2016, Washkewicz College of Engineering
Seal whiskers have been found to produce unique wake flow structures that minimize self-induced vibration and reduce drag. The cause of these wake features are due to the peculiar three-dimensional morphology of the whisker surface. The whisker morphology can be described as an elliptical cross section with variation of diameter in the major and minor axis along the length and, angle of incidence, rotation of the elliptical plane with respect to the whisker axis, α at the peak and β at the trough. This research provided a more complete morphology characterization accomplished through CT scanning and analysis of 27 harbor and elephant seal whisker samples. The results of this study confirmed previously reported values and added a characterization of the angle of incidence finding that the majority of angles observed fall within ±5° and exhibit a random variation in magnitude and direction along the whisker length. While the wake effects of several parameters of the whisker morphology have been studied, the effect of the angle of incidence has not been well understood. This research examined the influence of the angle of incidence on the wake flow structure through series of water channel studies. Four models of whisker-like geometries based on the morphology study were tested which isolate the angle of incidence as the only variation between models. The model variations in angle of incidence selected provided a baseline case (α = β = 0°), captured the range of angles observed in nature (α = β = -5°, and α = β = -15°), and investigated the influence of direction of angle of incidence (α = -5°, β = -5°). The wake structure for each seal whisker model was measured through particle image velocimetry (PIV). Angle of incidence was found to influence the wake structure through reorganization of velocity field patterns, reduction of recovery length and modification of magnitude of Tu. The results of this research helped provide a more complete understanding of the seal whisker morphology relationship to wake structure and can provide insight into design practices for application of whisker-like geometry to various engineering problems.

Committee:

Wei Zhang, PhD (Advisor); Ibrahim Mounir, PhD (Committee Member); Shyam Vikram, PhD (Committee Member)

Subjects:

Aerospace Engineering; Aquatic Sciences; Engineering; Fluid Dynamics; Mechanical Engineering

Keywords:

seal; whisker; PIV; biomimicry; fluid dynamics; particle image velocimetry; bio-engineering; engineering; mechanical engineering; aerospace engineering; experimental fluid dynamics;

Bebek, OzkanROBOTIC-ASSISTED BEATING HEART SURGERY
Doctor of Philosophy, Case Western Reserve University, 2008, Systems and Control Engineering

Coronary heart disease is a leading cause of death in the USA. A promising treatment option for this disease is off-pump coronary artery bypass graft (CABG) surgery as the artery grafting is done without stopping the heart. In the robotic assisted-surgery concept the surgeon views the surgical scene on a video display and operates on the heart as if it were stationary while the robotic system actively compensates for the motion of the heart. With the proposed system concept, the CABG surgery will be possible without using passive stabilizers, and the hospitalization time and cost of the operation will be decreased.

In this dissertation intelligent robotic tools for assisting off-pump (beating heart) CABG surgery are presented. Most important aspects of such a robotic system are accurately measuring and predicting the heart motion as they are instrumental in canceling the relative motion between the heart surface and surgical tools attached to the robotic manipulators. The proposed control algorithm contributes to the field by using biological signals in the estimation of heart's future motion for active relative motion canceling. Also a novel contact position sensor is developed to measure the position of the beating heart and a preliminary noise characterization for the future sensor system implementation is presented.

Committee:

Murat Cavusoglu (Advisor)

Keywords:

bypass surgery; flexible structures; medical robotics; motion canceling; motion sensing; real time tracking; sensor fusion; whisker-like.