Remote self-powered structure monitor
First Claim
1. A method for determining the growth of a fatigue crack in a remote metal rotating structural member, comprising the following steps:
- detecting the acoustic sound transmitted by a remote metal rotating structural member in response to a transient load using a sensor having a power storage device positioned to provide a signal enhancing inertial load from said sensor;
analyzing the detected sound waveform shape including determining the amplitudes of the fundamental, harmonic and non-harmonic frequencies;
providing a waveform library having a plurality of defined waveform shapes corresponding to the acoustic sound transmitted by the remote metal rotating structural member in response to a transient load which exceeds the elastic load limit of the remote metal rotating structure'"'"'s material;
subjecting the remote metal rotating structural member to an unknown transient load, each transient load being applied for a different duration, within a range of durations;
detecting the waveform shape of the remote metal rotating structural member in response to the unknown transient force (i.e. strain) applied to the structure of interest by the load, including the determined peak amplitude of the acoustic signature, the duration of the signature, and the determined amplitudes of the fundamental, the distribution of frequency content, and the harmonic and non-harmonic frequencies of acoustic signature;
determining the type of structural acoustic signature by selecting from the waveform shape library the waveform of a remote metal rotating structural member;
comparing the acoustic signature events detected in the remote metal rotating structure monitor;
determining crack growth by comparing an equivalent FFT representation of acoustic signature with a plurality of threshold acoustic signatures converted into equivalent frequencies; and
performing pattern recognition for classifying the acoustic signature for structural health assessment.
1 Assignment
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Accused Products
Abstract
An acoustic rotor monitor that is an autonomous self-powered measurement instrument which can detect embedded and hidden fatigue cracks in remotely inaccessible devices such as helicopter rotor system components. A predictive maintenance-related problem for rotor craft is the detection of fatigue cracks as a continuous real-time monitoring process under dynamic rotor system loading conditions. The rotor monitor focuses on the embedding an acoustic emission-based smart sensor directly into the rotor system to measure the high frequency stress waves indicating that a structural crack has propagated as a “self-powered” measurement without reducing structural integrity.
66 Citations
12 Claims
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1. A method for determining the growth of a fatigue crack in a remote metal rotating structural member, comprising the following steps:
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detecting the acoustic sound transmitted by a remote metal rotating structural member in response to a transient load using a sensor having a power storage device positioned to provide a signal enhancing inertial load from said sensor;
analyzing the detected sound waveform shape including determining the amplitudes of the fundamental, harmonic and non-harmonic frequencies;
providing a waveform library having a plurality of defined waveform shapes corresponding to the acoustic sound transmitted by the remote metal rotating structural member in response to a transient load which exceeds the elastic load limit of the remote metal rotating structure'"'"'s material;
subjecting the remote metal rotating structural member to an unknown transient load, each transient load being applied for a different duration, within a range of durations;
detecting the waveform shape of the remote metal rotating structural member in response to the unknown transient force (i.e. strain) applied to the structure of interest by the load, including the determined peak amplitude of the acoustic signature, the duration of the signature, and the determined amplitudes of the fundamental, the distribution of frequency content, and the harmonic and non-harmonic frequencies of acoustic signature;
determining the type of structural acoustic signature by selecting from the waveform shape library the waveform of a remote metal rotating structural member;
comparing the acoustic signature events detected in the remote metal rotating structure monitor;
determining crack growth by comparing an equivalent FFT representation of acoustic signature with a plurality of threshold acoustic signatures converted into equivalent frequencies; and
performing pattern recognition for classifying the acoustic signature for structural health assessment. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for determining the growth of a fatigue crack in a remote metal rotating structural member, comprising the following steps:
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detecting the acoustic sound transmitted by a remote metal rotating structural member in response to a transient load using a sensor having a power storage device positioned to provide a signal enhancing inertial load from said sensor;
analyzing the detected sound waveform shape including determining the amplitudes of the fundamental, harmonic and non-harmonic frequencies;
providing a waveform library having a plurality of defined waveform shapes corresponding to the acoustic sound transmitted by the remote rotating metal structural member in response to a transient load which exceeds the elastic load limit of the structure'"'"'s material;
subjecting the remote metal rotating structural member to an unknown transient load, each transient load being applied for a different duration, within a range of durations;
detecting the waveform shape of the remote metal rotating structural member in response to the unknown transient force (i.e. strain) applied to the structure of interest by the load, including the determined peak amplitude of the acoustic signature, the duration of the signature, and the determined amplitudes of the fundamental, the distribution of frequency content, and the harmonic and non-harmonic frequencies of acoustic signature;
determining the type of structural acoustic signature by selecting from the waveform shape library the waveform of a remote metal rotating structural member;
comparing the acoustic signature events detected in the remote structure monitor;
determining crack growth by comparing an equivalent FFT representation of acoustic signature with a plurality of threshold acoustic signatures converted into equivalent frequencies; and
performing pattern recognition for classifying the acoustic signature for structural health assessment. - View Dependent Claims (8, 9, 10, 11, 12)
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Specification