Luna Innovations Inc.

Tennessee Technological University

Osgar John Ohanian, Iii

Matthew Anthony Davis

James Craig Kitchin

Daniel R Vandenberge

Susan Mae Rankin Pope

An apparatus comprises a flexible woven structure including an egress and/or ingress location at an external surface of the flexible woven structure. A fiber optic sensor is embedded in the flexible woven structure to allow the fiber optic sensor to detect one or more of strain, temperature, vibration, acoustics, 3-dimensional shape and/or pressure on the flexible woven structure. The fiber optic sensor extends out of the flexible woven structure at the egress and/or ingress location for connection to a connector or a termination. First thread stitches fasten the fiber optic sensor and any protective coatings, tubing, or conduit to the external surface of the flexible woven structure near the egress and/or ingress location. An optional reinforcement patch may cover the egress and/or ingress location and a portion of fiber optic sensor that extends out of the flexible woven structure at the egress and/or ingress location. Second thread stitches fasten the reinforcement patch to the external surface of the flexible woven structure to protect the fiber optic sensor and reduce bending and stress at the egress/ingress location.

Fiber optic sensor egress/ingress ruggedization for flexible woven structures

An apparatus comprises a flexible filament structure, and a fiber optic sensor with a buffer material that locally bonds the fiber optic sensor to the flexible filament structure to create a bond between the fiber optic sensor and the flexible filament structure to transfer strain from the flexible filament structure to the fiber optic sensor to allow the fiber optic sensor to detect strain on the flexible filament structure while maintaining flexibility in the flexible filament structure. A fiber optic interrogator may be optically coupled to the fiber optic sensor and configured to measure strain. A method comprises embedding a fiber optic sensor with a buffer material in or on a flexible filament structure. Thereafter, the buffer material is activated via heating or curing to locally adhere the fiber optic sensor to the flexible filament structure to create a local bond. The local bond transfers strain from the flexible filament structure to the fiber optic sensor.

One or more fiber optic sensors locally bonded with a flexible filament structure

A system for performing distributed measurements of in-situ stress includes an expandable element with at least one fiber optic sensor. The expandable element can be positioned at various depths in a hole in a substrate. A pressurizing device expands (and contracts) the expandable element when the expandable element is inserted in the hole in the substrate to exert pressure on the hole wall. A pressure sensor provides a sensor output indicative of a pressure applied to the hole wall by the expandable element. The fiber optic sensor and an optical interrogator measure strain along a length of the sensor in a continuous, high spatial resolution manner Based on the measured strain and pressure sensor output, the system determines various properties of the substrate such as, minimum principal stress, maximum principal stress, and/or principal stress direction associated with one or more fractures in the substrate, as well as substrate modulus.

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Blacksburg, VA, United States of America

Osgar John Ohanian, Iii