Strain sensor
First Claim
1. A strain sensor assembly operable to detect a strain in a structure, comprising:
- a sensor element comprising an elongated, amorphous or nanocrystalline sensing microwire operable to be coupled with said structure so that the sensing microwire is placed in tension when said structure is subjected to strain, said sensing microwire having a positive magnetostriction property, a first remagnetization response when said structure is in an unstrained condition, and a second remagnetization response substantially greater than said first remagnetization response when the structure is in a strained condition and said sensing microwire is placed in tension; and
a detector separate from said structure and including a transmitter unit operable to create an alternating magnetic field of sufficient magnitude to magnetically couple with said sensing microwire in order to interrogate said sensing microwire and induce a sensing microwire remagnetization response, and a remagnetization sensor operable to sense said sensing microwire remagnetization response,whereby when said structure is in a strained condition, said remagnetization sensor will sense said second remagnetization response.
2 Assignments
0 Petitions
Accused Products
Abstract
Improved microwire strain sensor elements (20, 40, 52, 62) and corresponding methods are provided, which permit accurate, wireless strain monitoring of a variety of structures, including composite structures, through use of a remote detector (28). The sensor elements (20, 40, 52, 62) have amorphous or nanocrystalline metallic alloy microwire cores (22, 48), which exhibit substantially reduced remagnetization responses when the sensor elements (20, 40, 52, 62) are coupled with a structure to be strain-monitored, and the structures are in an unstrained condition. When the monitored structure experiences a strain above a pre-selected threshold value, the microwire cores (22, 48) exhibit substantially different remagnetization responses as an indication that the monitored structure has experienced a strain above a strain threshold or over a range of strain. In use, the strain sensor elements (20, 40, 52, 62) are coupled with a structure to be monitored by application of the sensor elements (20, 40, 52, 62) to a surface of the structure, or by imbedding the sensor elements (20, 40, 52, 62) within the structure, and the coupled sensor elements are periodically interrogated by the detector (28). Preferably, the microwire cores (22, 48) are placed in compression in order to suppress the inherent remagnetization responses thereof by means of a surrounding body (26) or surrounding layers (44, 46) formed of synthetic resin material which shrinks upon curing. When the sensor elements (20, 40, 52, 62) are strained as a result of a strain experienced by the monitored structure, the remagnetization responses of the microwire cores (22, 48) are substantially increased.
19 Citations
33 Claims
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1. A strain sensor assembly operable to detect a strain in a structure, comprising:
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a sensor element comprising an elongated, amorphous or nanocrystalline sensing microwire operable to be coupled with said structure so that the sensing microwire is placed in tension when said structure is subjected to strain, said sensing microwire having a positive magnetostriction property, a first remagnetization response when said structure is in an unstrained condition, and a second remagnetization response substantially greater than said first remagnetization response when the structure is in a strained condition and said sensing microwire is placed in tension; and a detector separate from said structure and including a transmitter unit operable to create an alternating magnetic field of sufficient magnitude to magnetically couple with said sensing microwire in order to interrogate said sensing microwire and induce a sensing microwire remagnetization response, and a remagnetization sensor operable to sense said sensing microwire remagnetization response, whereby when said structure is in a strained condition, said remagnetization sensor will sense said second remagnetization response. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of detecting strain in a structure, comprising the steps of:
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coupling a sensor element comprising an elongated, amorphous or nanocrystalline sensing microwire to said structure so that the sensing microwire is placed in tension when said structure is subjected to strain, said sensing microwire having a positive magnetostriction property, a first remagnetization response when said structure is in an unstrained condition, and a second remagnetization response substantially greater than said first remagnetization response when the structure is in a strained condition and the sensing microwire is placed in tension; interrogating said sensor element by creating an alternating magnetic field of sufficient magnitude to magnetically couple with said sensing microwire in order to induce a sensing microwire remagnetization response; and sensing said sensing microwire remagnetization response as an indication of the strain condition of said structure. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A strain sensor comprising:
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a sensor element comprising an elongated, amorphous or nanocrystalline sensing microwire having a positive magnetostriction property and an inherent Barkhausen remagnetization response magnitude; a shape memory material disposed about said sensor element; and a body of material operably engaging said sensing microwire and operable to place the sensing microwire under compression sufficient to substantially reduce said remagnetization response to a first, reduced magnitude. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A strain sensor comprising:
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a sensor element comprising an elongated, amorphous or nanocrystalline sensing microwire having a positive magnetostriction property and an inherent Barkhausen remagnetization response magnitude, and an auxiliary reference wire assembly operably coupled with said sensor element; and a body of material operably engaging said sensing microwire and operable to place the sensing microwire under compression sufficient to substantially reduce said remagnetization response to a first, reduced magnitude. - View Dependent Claims (32, 33)
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Specification