Guided wave-based system for cure monitoring of composites using piezoelectric discs and fiber Bragg gratings/phase-shifted Bragg gratings
AssigneeUnited States of America as represented by the Administrator of NASA
InventorsTyler B. Hudson, Fuh-Gwo Yuan, Nicolas Auwaijan, Frank L. Palmieri
Life of this patent
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Abstract
System and method for in-process cure monitoring of a material utilizes one or more sensors such as fiber Bragg gratings (FBGs) or phase-shifted FBGs (PS-FBGs) and at least one optical line fiber connected to the sensor(s). The sensor(s) and the optical line may be embedded in the material prior to curing the material may comprise a fiber reinforced polymer. Waves are excited into the material during curing thereof to form guided waves that propagate through the material. At least one wave metric of the guided waves is measured utilizing the sensor(s).
Claims20
A method of in-process cure monitoring of a material, the method comprising;
- embedding at least one sensor selected from the group consisting of fiber Bragg gratings (FBGS) and phase-shifted FBGS (PS-FBGS) at a first location, and at least one optical line that is operatively connected to the sensor, into the material to be cured;
- exciting waves into the material during curing of the material at a second location that is spaced apart from the first location to form guided waves that propagate through the material from the second location to the first location;
- causing light to propagate through the optical line to the sensor;
- and
- measuring at least one wave metric of the guided waves at the first location by utilizing the sensor receiving the propagated light, including measuring a wavelength spectrum oscillation to determine local strain resulting from the guided waves at the first location induced by the guided waves propagating through the material;
- and
- measuring chemical cure shrinkage strain by utilizing the sensor, wherein the chemical cure shrinkage strain is induced by curing of the material.
A method of in-process cure monitoring of a material, the method comprising
- operatively connecting at least one optical sensor to a fiber reinforced composite material at a first location, wherein the optical sensor is a phase-shifted fiber Bragg grating that reflects predefined wavelengths of light and transmits all other wavelengths of light;
- operatively connecting at least one optical line to the optical sensor;
- exciting waves into the fiber reinforced composite material during curing of the composite material at a second location that is spaced apart from the first location to form guided waves that propagate through the composite material from the second location to the first location;
- causing light to propagate through the optical line to the sensor;
- and
- measuring at least one wave metric of the guided waves at the first location utilizing the optical sensor receiving the propagated light, including measuring a wavelength spectrum oscillation to determine local strain resulting from the guided waves at the first location line induced by the guided waves propagating through the material;
- and
- measuring chemical cure shrinkage strain by utilizing the sensor, wherein the chemical cure shrinkage strain is induced by curing of the material.
Dependencies are inferred from the claim text.