Digital Commons Network^™

Design And Development Of A Lubrication Pump For A Horizontally Mounted Air-Conditioning Compressor., Kenneth T. Gilbert

Electronic Theses and Dissertations

Horizontally mounted compressors offer the advantage of reduced height in central air-conditioning units but prove difficult to produce economically due to costs associated with the manufacture of acceptable lubrication systems for the compressors. This study develops an effective, affordable oil pump for use on a horizontal compressor. Concepts are proven through testing of prototype assemblies. Test results drive modifications for future prototypes, and prototypes demonstrating adequate performance are modified for ease of manufacture.

Research in this study proves that the most suitable design results from a modification of a rotating vane pump. The pump’s modifications enable it to pump oil …

On The Generation And Detection Of Ultrasonic Plate Waves In Microporous Polymeric Material, Lin Lin

Electronic Theses and Dissertations

Membranes are among the most important engineering components in use in many process industries. Examples of uses for membranes include water purification, industrial effluent treatment, recovery of volatile organic compounds, protein recovery, bio-separations and many others. Polymeric membranes are the most commonly used membranes. Membranes act as a barrier through which fluids and solutes are selectively transported. Quality assurance is a critical aspect of membrane module fabrication. In other materials, ultrasound has been widely used for materials characterization as well as flaw detection. Recently ultrasonic techniques have been used to detect the presence of defects in membranes. This thesis describes …

Active Vibration Suppression Of Smart Structures Using Piezoelectric Shear Actuators, Brian P. Baillargeon

Electronic Theses and Dissertations

Active vibration damping using piezoelectric materials integrated with structural systems has found widespread use in engineering applications. Current vibration suppression systems usually consist of piezoelectric extension actuators bonded to the surface or embedded within the structure. The use of piezoelectric shear actuators/sensors has been proposed as an alternative, where the electric field is applied perpendicular to the direction of polarization to cause shear deformation of the material. We present an exact analysis and active vibration suppression of laminated composite plates and cylindrical shells with embedded piezoelectric shear actuators and sensors. Suitable displacement and electric potential fknctions are utilized to identically …

Determination Of The Viscoelastic Properties Of General Anisotropic Materials, Anish Sen Senan

Electronic Theses and Dissertations

Elastic properties are rarely sufficient in order to evaluate the condition of a composite material. Knowledge of the viscoelastic properties is very critical for design purposes, for they directly characterize damping. Damping related measurements in the material provides information about the degree of cross-linking and crystallinity of the polymer. For metals, damping may be related to dislocation motion among other characteristics. For composite materials, in general the interphase and the matrix dominate the damping of the material. Ultrasonic measurement of damping gives a non- destructive measure of strength of composite materials. This thesis considers damping characteristics of polymer matrix composites …

Influence Of Stress Relaxation On Watertight Integrity Of Hybrid Bolted Joints, Keith N. Pelletier

Electronic Theses and Dissertations

Stress relaxation and creep are major concerns when loading composite materials. Due to the viscoelactic nature of the matrix material, composite materials tend to lose initial loads at a decreasing rate. This is especially true through the thickness of the material, where the behavior of the material is dominated by the matrix. Of particular interest to the current study presented in this thesis is the investigation of stress relaxation in bolted composite/metal hybrid connections. It is ultimately desired to be able to use bolted composite/metal hybrid connections for naval applications, where it is important to maintain as much of the …

Analysis And Structural Health Monitoring Of Composite Plates With Piezoelectric Sensors And Actuators, Richard C. Mewer

Electronic Theses and Dissertations

Structural vibration suppression and health-monitoring have been the focus of intense research over the past decade, and piezoelectric actuators and sensors are particularly well suited to serve in this application. The first part is an analytical investigation into the cylindrical bending vibrations of piezoelectric composite plates. The second part is a fully experimental investigation into various vibration based structural health-monitoring techniques for bolted composites. The analytical solution consists of Fourier basis functions that satisfy the equations of motion and charge equation. The accuracy of the mechanical displacements, electric potential, and stresses are dependent on the number of terms in the …

Development Of An Frp Reinforced Hardwood Glulam Guardrail, Joshua Keith Botting

Electronic Theses and Dissertations

This study focuses on the development of an aesthetically pleasing, cost effective, timber guardrail system, which utilizes low-grade New England hardwoods such as red maple and beech. This required that several issues be addressed, including structural modeling, rail section design, rail fabrication, evaluation of durability, rail-to-rail field splice connection design, and the evaluation of guardrail system performance under impact loading. The use of glulam beams in infrastructure is increasing rapidly with the reduced availability and increase in cost of high grade solid sawn timber. New techniques allow for increased material usage while maintaining a high strength product. Selective stacking of …