United States of America As Represented by the Administrator of Nasa

Edward H Glaessgen

Robert S Piascik

Stephen W Smith

John A Newman

Joel A Alexa

Peter L Messick

Michael R Horne

Terryl A Wallace

Benjamin T Hailer

A composite material includes a structural material and a shape-memory alloy embedded in the structural material. The shape-memory alloy changes crystallographic phase from austenite to martensite in response to a predefined critical macroscopic average strain of the composite material. In a second embodiment, the composite material includes a plurality of particles of a ferromagnetic shape-memory alloy embedded in the structural material. The ferromagnetic shape-memory alloy changes crystallographic phase from austenite to martensite and changes magnetic phase in response to the predefined critical macroscopic average strain of the composite material. A method of forming a composite material for sensing the predefined critical macroscopic average strain includes providing the shape-memory alloy having an austenite crystallographic phase, changing a size and shape of the shape-memory alloy to thereby form a plurality of particles, and combining the structural material and the particles at a temperature of from about 100-700&#xb0; C. to form the composite material.

Strain-detecting composite materials

A first material with a known maximum temperature of operation is coated with a second material on at least one surface of the first material. The coating has a melting temperature that is greater than the maximum temperature of operation of the first material. The coating is heated to its melting temperature until the coating flows into any cracks in the first material's surface.

System for repairing cracks in structures

Method for repairing cracks in structures

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Yorktown, VA, United States of America

Edward H Glaessgen