Material damage system and method for determining same
AssigneeUnited States of America as represented by the Administrator of NASA
InventorRobert Okojie
Life of this patent
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Abstract
A system and method for determining a change in a thickness and temperature of a surface of a material are disclosed herein. The system and the method are usable in a thermal protection system of a space vehicle, such as an aeroshell of a space vehicle. The system and method may incorporate micro electric sensors arranged in a ladder network and capacitor strip sensors. Corrosion or ablation causes a change in an electrical property of the sensors. An amount of or rate of the corrosion or the ablation and a temperature of the material is determined based on the change of the electrical property of the sensors.
Claims19
A system comprising:
- a material susceptible to corrosion or ablation and having a thickness defined between a first end and a second end;
- a first sensor and a second sensor on the material and extending along the thickness adjacent the first end and toward the second end, the first sensor having an electrical component that changes an electrical property of the sensor as temperature of the material changes, and wherein the second sensor has an electrical property that is constant with respect to changes in temperature of the material,
- an electrical circuit coupled to the first sensor and the second sensor to determine the change in the electrical property of each of the first sensor and the second sensor;
- and
- a processor determining a thickness and a temperature of the material based on the change of the electrical property of the first sensor and the second sensor;
- wherein the second sensor has a capacitance configured to change as a length of the second sensor changes.
A method comprising the steps of:
- positioning a first micro electric sensor and a second micro electric sensor within a susceptible material;
- applying a current or voltage to the first micro electric sensor and the second micro electric sensor;
- exposing the susceptible material to a substance causing a change in a temperature and thickness of the susceptible material;
- determining the temperature of the susceptible material from an electrical property of the first micro electric sensor;
- and
- determining the thickness of the susceptible material from an electrical property of the second micro electric sensor, wherein the electrical property of the first micro electric sensor changes more with temperature than the second micro electric sensor;
- wherein the second micro electric sensor has a capacitance configured to change as a length of the second micro electric sensor changes.
A method comprising the steps of:
- embedding a plurality of sensors within a material, the plurality of sensors comprising at least a first ladder sensor, a second ladder sensor, and a capacitor strip, the second ladder sensor having more rungs than the first ladder sensor, wherein the second ladder sensor having electrical components that are less temperature sensitive than electrical components of the first ladder sensor;
- applying a current or voltage to each of the plurality of sensors;
- exposing the material to a change in temperature causing a change in an electrical property of at least the second ladder sensor;
- ablating a portion of the material to change an electrical property of at least the first ladder sensor and the capacitor strip;
- determining a temperature of the material based on the change in the electrical property of the first ladder sensor and the second ladder sensor;
- and
- determining a thickness of the material based on the change of the electrical property of the capacitor strip and the change of the electrical property of the second ladder sensor;
- wherein the second ladder sensor has a capacitance configured to change as a length of the second ladder sensor changes.
Dependencies are inferred from the claim text.