Date of Award

Spring 2001

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Electrical & Computer Engineering

Program/Concentration

Electrical Engineering

Committee Director

Ravindra P. Joshi

Committee Member

Linda Vahala

Committee Member

Frederic McKenzie

Abstract

Nondestructive material testing and diagnostics play an important role in reliability analysis, component wear-out testing, life-cycle estimates, and safety inspections. Of the several techniques available for nondestructive inspections, thermal analysis has been chosen to be the focus of this thesis research. An equivalence between the system of equations for the heat flow problem, and the variables of circuit theory suggests that an electrical model can be constructed to represent the actual thermal system. This electrical model is constructed based upon a finite difference discretization of the heat flow equation. Using these associations a basic one-dimensional electrical model has been constructed and linked with a circuit simulator (such as SPICE) to simulate the transient, steady state and ac heating scenarios of a sample thermal system. The basic model has been proven to accurately represent the thermal system. It has then been expanded to include temperature dependence of the conductivity parameter (with the aid of voltage controlled resistors) and multidimensional heat flow by extending the one-dimensional circuit along various directions. Finally, this SPICE-based model has been applied for thermal analysis of samples containing surface material defects such as cracks. It is shown that the model can adequately locate such cracks based upon the electro-thermal relationships between time delay and voltage (temperature) magnitudes. It would thus be a useful simulation tool in the analysis of defects and for investigating non-intrusive thermal diagnostic response.

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DOI

10.25777/xphr-5a82

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