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Abstract

The invention pertains to a test apparatus and method for assessing thermo-mechanical fatigue related phenomena within a test material wherein a heat source, such as a laser beam is applied to a specimen consisting of a body of the test material, thereby introducing heat to a primary heat introduction zone on the surface of the body to cause local cyclic heating. As part of the cycle, heat is removed through a portion of the specimen surface sufficiently remote from the heat introduction zone to create a substantially spherical temperature gradient within the specimen resembling that of a point source on a semi-infinite body. A stress gradient results from local thermal expansion, thus thermo-mechanically cycling the material. As a result of the thermo-mechanical cycling, phenomena including thermo-mechanically induced creep, residual stress, changes in physical properties, crack initiation and crack growth may be observed within the material, and evaluated for scientific or engineering purposes. An optional background temperature control feature may also be included to raise the background temperature of the specimen during thermal cycling. Among many useful embodiments described herein, the test method may also be configured for non-destructive use on a component, wherein the local damage or crack growth due to thermal cycling is afterwards removed and the surface blended or otherwise reconditioned as required to restore component functionality and structural integrity.

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First Claim