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Techniques to measure strain development and failure in a fabric

  • US 8,240,200 B2
  • Filed: 08/27/2009
  • Issued: 08/14/2012
  • Est. Priority Date: 08/27/2009
  • Status: Active Grant
First Claim
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1. A system for characterizing an impact in a fabric, said system comprising:

  • a fabric comprising a plurality of individual yarns that have been woven into a plurality of layers wherein said fabric includes a sensing element woven in each of said layers to provide a plurality of sensing elements;

    wherein a parameter of said plurality of sensing elements depends on a strain in said sensing element in each of said fabric layers;

    a transducer coupled to each of said sensing element wherein said transducer is configured to generate an output voltage versus time including an initial linear slope region based on said parameter of said sensing, wherein said initial linear slope region is related to said strain according to the equation ε

    =kwα

    /2cfab, where ε

    is said strain, kw is a wire constant associated with said sensing element, α

    is said linear slope and cfab is the speed of sound in said fabric, and wherein said strain is a local strain such that said local strain is uniform over a portion of said sensing element; and

    a controller coupled to said transducer, said controller configured to receive said output of said transducer, to determine a strain in said sensing element based, at least in part, on a change in said output voltage versus time of said transducer for each of said fabric layers, and to characterize said impact in said fabric based on said strain in said sensing element by determination of the location of said impact and failure of a layer indicated by a deviation from the linearity of said initial linear region of said voltage versus time slope.

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