Date of Award

12-1995

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Department of Aeronautics and Astronautics

First Advisor

Peter Torvik, PhD

Abstract

Thermal stresses in semi-infinite layered beams heated on the end are calculated using an extension to simple bimetallic thermostat theory. Recently, researchers have used the concept of interfacial compliance to determine interlaminar stresses in a simple thermostat of finite length subjected to a uniform temperature increase. In the present work, the thermostat theory is extended to apply to the beams of interest. A closed-form solution to the problem is obtained. It is not applicable within about one beam thickness (St Venant boundary region) of the end. Various classes of layered materials are analyzed to determine if significant stresses exist outside the boundary region. Thermal stresses of sufficient magnitude to cause failure are confined to the boundary region if all layers of the beam are poor thermal conductors. Significant axial and bending stresses occur outside of the boundary region for layered beams in which one or more layers are relatively good thermal conductors. Very high stresses are found to exist in good conductors bonded to poor conductors of similar stiffness. Significant interlaminar stresses occur only in the boundary region, regardless of the layer thermal conductivities. The applicability of the solution to composite laminates is addressed.

AFIT Designator

AFIT-DS-ENY-95-6

DTIC Accession Number

ADA306532

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