Method and apparatus for non-destructive testing of composite materials
First Claim
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1. A method for observing potential dimensional stability of plastic composition of thermosetting material comprising the steps of:
- monitoring passive and injected acoustic signals from said composition during formation of a solid state of said composition;
generating a signature over time from said acoustic signals, said signature being uniquely characteristic of said composition; and
analyzing said signature to correlate with known residual stress relief mechanisms and resultant residual stress levels of said composition.
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Abstract
Methods and apparatus are disclosed for monitoring and controlling potential residual stress relief mechanisms in composite epoxy resin materials. Passive and injected, or active, acoustic signals originating in or propagated through a specimen material during the formation process produce signatures identifiable with known residual stress relief mechanisms. Real-time control of material temperature and external pressure during formation in response to acoustic signals measured or observed in relation to desired acoustic signature minimizes formation of undesired material properties.
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Citations
22 Claims
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1. A method for observing potential dimensional stability of plastic composition of thermosetting material comprising the steps of:
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monitoring passive and injected acoustic signals from said composition during formation of a solid state of said composition; generating a signature over time from said acoustic signals, said signature being uniquely characteristic of said composition; and analyzing said signature to correlate with known residual stress relief mechanisms and resultant residual stress levels of said composition. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for observing potential dimensional stability of a plastic composition of thermosetting material comprising the steps of:
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exciting said composition with a pulse train; monitoring passive and injected acoustic signals from said composition during formation of a solid state of said generating a signature from said acoustic signals, said signature being uniquely characteristic of said composition, wherein said signature generating step comprising cross correlating said passive signals and injected signals.
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8. A method for observing potential dimensional stability of a plastic composition of thermosetting material comprising the steps of:
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monitoring acoustic signals from said composition during post-formation conditioning of said composition; generating a signature over time from said acoustic signals, said signature being uniquely characteristic of said composition during said post-formation conditioning; and analyzing said signature to correlate with known residual stress relief mechanisms and resultant residual stress levels of said composition.
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9. An apparatus for testing potential dimensional stability of a plastic composition of thermosetting material:
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means for injecting acoustic signals into said composition; means for monitoring passive acoustic signals and injected acoustic signals emanating from said composition as a result of a process of formation; means for generating a signature of said composition from said passive acoustic signals and from said injected acoustic signals, said signature being uniquely characteristic of said composition; and means for analyzing said signature to correlate with known residual stress relief mechanisms and resultant residual stress levels of said composition, said analyzing means being operative to compare said signature with a template representative of said known mechanisms and stress levels. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. A method for controlling potential dimensional stability of a plastic composition of thermosetting material comprising the steps of:
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injecting a first acoustic signal into said composition; monitoring passive and injected first acoustic signals from said composition during formation of a solid state of said composition; providing a model signature as a function of time representative of second acoustic signals propagated through and emanating from a model composition during formation of a solid state of said model composition; comparing said first acoustic signals with said model signature to develop an error signal during formation of said composition; and modifying at least temperature of said composition during formation of said composition to minimize said error signal. - View Dependent Claims (17, 18, 19, 20, 21, 22)
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Specification