Thermodynamics Commons^™

Static Fracture Behavior Of A Ceramic Matrix Composite At Elevated Temperatures, David M. Agins

Theses and Dissertations

This study investigated systematically the damage initiation damage progression, and failure modes of a ceramic matrix composite, Nicalon/CAS, when loaded in tension at elevated temperatures in the presence of air. A cross-ply lay-up, [0/90]_2s, was studied. The primary means of analysis were stress-strain data taken during monotonic and incremental load tests and crack density assessments. Testing was conducted at room temperature 700°C, and 850°C. The stress-strain response was consistent for monotonic and incremental loading, except for a decrease in failure load at the elevated temperatures. Initial damage progression was also consistent, but the damage leading to failure and …

Experimental Analysis Of Heat Transfer Characteristics And Pressure Drop Through Screen Regenerative Heat Exchangers, Jeffrey L. Wiese

Theses and Dissertations

This study investigated the effect on heat transfer and friction characteristics for screen regenerative heat exchangers with the screen thickness reduced by rolling. The experiments were performed on 250 and 325 mesh, 304 stainless steel screen using helium gas. Reynolds numbers, based on hydraulic radius, Re, were between 10 and 100. Both the Colburn factor, StPr^2/3, and friction factor, f, decreased as the screen thickness was reduced. A correlation was found for predicting friction factor, f. The drag coefficient per screen remained nearly unchanged for thicknesses reduced not more than 30 percent. The decrease in Colburn factor was …

A Nonlinear Three-Dimensional Micromechanics Model For Fiber-Reinforced Laminated Composites, David D. Robertson

Theses and Dissertations

In this study, a three-dimensional micromechanics model is developed. The present capabilities of the model include both unidirectional and laminated composite layups with various types of nonlinear analysis such as a thermoelastic-plastic analysis employing the Prandtl-Reuss flow relations, a thermoviscoplastic analysis using Bodner-Partom unified constitutive theory, and an interfacial damage progression scheme based on a statistical interfacial failure criteria. Such nonlinearities are critical factors during thermomechanical fatigue TMF loading of high temperature composites. Solutions were obtained and extensive comparisons performed with existing micromechanics models, finite element analysis, and experiment with excellent results. In addition, the analysis was developed to require …

Electrostatic Positioning Of Droplets In Turbulent Flows (Lstm 375/Te/93), Nihad E. Daidzic, Adrian Melling

Aviation Department Publications

Report LSTM 375/TE/93, Lehrstuhl fuer Stroemungsmechanik Universitaet Erlangen-Nuernberg Cauerstr. 4, 8520 Erlangen Germany.

Effects Of Radiative Interactions In Molecular Gases Under Local And Nonlocal Thermodynamic Equilibrium Conditions, Manoj Kumar Jha

Mechanical & Aerospace Engineering Theses & Dissertations

Basic formulations, analyses, and numerical procedures are presented to investigate radiative heat interactions in diatomic and polyatomic gases under local and nonlocal thermodynamic equilibrium conditions. Essential governing equations are presented for both gray and nongray gases. Information is provided on absorption models, relaxation times, and transfer equations. Radiative flux equations are developed which are applicable under local and nonlocal thermodynamic equilibrium conditions.

The problem is solved for fully developed laminar incompressible flows between two parallel plates under the boundary condition of a uniform surface heat flux. For specific applications, three diatomic and three polyatomic gases are considered. The results are …