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Detection apparatus for structural failure in aircraft employing piezoelectric transducers

  • US 3,956,731 A
  • Filed: 09/27/1974
  • Issued: 05/11/1976
  • Est. Priority Date: 09/27/1974
  • Status: Expired due to Term
First Claim
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1. An apparatus for the detection of structural failures in aircraft comprising:

  • at least one pair of piezoelectric transducers adapted to be secured to a component of the aircraft in a predetermined area, each of said transducers being sized for a specific resonance and adapted to convert said resonance into electrical energy of a predetermined frequency;

    a first electrical circuit connected to each transducer and including a filter and a differential amplifier to pass only signals of a selected frequency, a voltage level detector to receive said selected frequency signals and preset to pass only signals of a predetermined voltage, a switch responsive to said predetermined voltage signals and an indicator actuated by the operation of said switch; and

    a second electrical circuit connected to each transducer and including a power line with an on-off control, an oscillator activated by said control when operative to generate electrical signals in the associated second circuit at the predetermined frequency aforesaid and a transformer to amplify the voltage of said generated signals to a level sufficient to pass the voltage level detector aforesaid, said on-off control including a circuit maker and breaker in said first circuit and being operative to alternately connect either one of said circuits.

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