Engineering Commons^™

Machine Tool Accuracy Characterization, Error Modeling And Compensation Using Telescopic Ballbar And Laser Interferometer, Yalcin M. Ertekin

Doctoral Dissertations

"This dissertation presents the results of the research investigation on the machine tool accuracy characterization, error modeling and error compensation using telescopic ballbar and laser interferometer. Increasing demand for both higher machine tool accuracy and machining tolerances has resulted in a great need to measure and characterize the accuracy of NC machine tools and minimize machine tool induced errors on machined components before manufacturing parts, instead of inferring it from parts already machined. Using a telescopic magnetic ballbar, the results of the accuracy assessment of an old Bridgeport Series I CNC 2 1/2 axes vertical machining center are presented in …

Displacement-Based Analysis And Design Of Rigid Retaining Walls During Earthquakes, Yingwei Wu

Doctoral Dissertations

"This research focused on the analysis and design of rigid retaining walls subjected to earthquakes and considered nonlinear foundation soil properties. The simultaneous sliding and rocking movements of retaining walls were considered. Seven field conditions, including moist, submerged, perched and saturated backfill with a sloping drain, were specified by design codes. A computer program capable of computing displacement using real time history records or equivalent sinusoidal motions was developed. Finally, a dynamic design procedure was proposed for practicing engineers.

The study revealed that maximum shear modulus in foundation soil, maximum ground acceleration, and soil nonlinearity had significant effect on the …

The Hygrothermal Response And Physical Aging Of Polymer Matrix Textile Composites, Natalie L. Dixon

Masters Theses

"Woven graphite/epoxy composite laminate is one type of composite currently being investigated for use in aircraft engine components. However, polymers tend to become brittle with age, especially when exposed to elevated temperature. It is necessary to understand the physical changes in a material during the aging process in order to predict the long-term behavior.

In addition to aging, materials used in aircraft will be exposed to a wide variety of temperatures and relative humidity levels. Variations in temperature and moisture content affect both the physical and the mechanical properties of composites.

Experimental methods are described for hygrothermal testing of a …