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US4538462A Expired / Lapsed US ⏱️ 0.0 years remaining

Adhesive bond integrity evaluation method

Assignee: Lockheed Martin Corp
•
Filing: 1983-12-12
•
Granted: 1985-09-03
•
Expires: 2003-12-12
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Abstract

Abstract The invention is a method of determining whether an adhesively bonded joint between two structural elements meets established strength requirements. The method comprises the following steps: (1) Determining by test the levels of acoustic energy to be directed and/or focused by a transducer 12 on a minute area of the adhesively bonded joint 14 and further the application times thereof. The combinations of directed and/or focused acoustic energy and application time are selected to macroscopically stress and/or strain-to-failure the minute area of the adhesively bonded joints having minimum acceptable bond strength or less; (2) Directing and/or focusing by means of a transducer 12 acoustic energy on the minute area of the adhesively bonded joint to be tested and steadily increasing the directed and/or focused acoustic energy/time up to the selected combination which would macroscopically stress and/or strain-to-failure the minute area of the adhesively bonded joint 14 were it of less than minimum acceptable bond strength, and (3) Monitoring by means of one or more focused and/or unfocused acoustic receiver 24 the interaction of the directed and/or focused acoustic energy with the minute area of the adhesively bonded joint 14 and/or the acoustic emission therefrom, a sudden change in the monitored acoustic interaction and/or emission, while the directed and/or focused acoustic energy/time is being steadily increased, indicating bond unacceptability.

Inventors

  • 👤 Jan J. Hartog
  • 👤 Jack L. Bellin
  • 👤 Gilbert C. Knollman
  • 👤 Arthur D. Jonath

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-11-02 19:53
CPC Classifications
G; G01; G01N; G01N19/00; G01N19/04; G01N29/00; G01N29/04; G01N29/045

Claims Analysis

Total Claims: 12
Claim 1
Independent Claim 172 words
A method of determining whether adhesively bonded joints between two structural elements have acceptable strength levels comprising the steps of: determining by test the levels of acoustic energy to be directed to a minute area of the adhesively bonded joint and the application times of said directed acoustic energy, said combinations of directed acoustic energy and application time selected to macroscopically stress and/or strain-to-failure said minute area of the adhesively bonded joints having minimum acceptable bond strength or less; directing said acoustic energy on said minute area of the adhesively bonded joint and steadily increasing said directed acoustic energy/time up to the selected combination which would macroscopically stress and/or strain-to-failure said minute area of the adhesively bonded joint were it of less than minimum acceptable bond strength; monitoring the interaction of said directed acoustic energy with said minute area of the adhesively bonded joint and/or the acoustic emission therefrom, a sudden change in said monitored acoustic interaction and/or emission, while the said directed acoustic energy is being steadily increased, indicating bond unacceptability.
Claim 2
Independent Claim 172 words
A method of determining whether adhesively bonded joints between two structural elements have acceptable strength levels comprising the steps of: determining by test the levels of acoustic energy to be directed to a minute area of the adhesively bonded joint and the application times of said directed acoustic energy, said combinations of directed acoustic energy and application time selected to macroscopically stress and/or strain-to-failure said minute area of the adhesively bonded joints having minimum acceptable bond strength or less; directing said acoustic energy on said minute area of the adhesively bonded joint and steadily increasing said directed acoustic energy/time up to the selected combination which would macroscopically stress and/or strain-to-failure said minute area of the adhesively bonded joint were it of less than minimum acceptable bond strength; monitoring the interaction of said directed acoustic energy with said minute area of the adhesively bonded joint and/or the acoustic emission therefrom, a sudden change in said monitored acoustic interaction and/or emission, while the said directed acoustic energy is being steadily increased, indicating bond unacceptability.
Claim 3
Dependent Claim 16 words
The method of claim 1 wherein said acoustic energy is also focused on said minute area.
Claim 4
Dependent Claim 18 words
The method as set forth in claim 1 wherein said acoustic energy is provided by a piezoelectric transducer.
Claim 5
Dependent Claim 24 words
The method as set forth in claim 3 including the step of providing a coupling agent between said transducer and the adhesively bonded structure.
Claim 6
Dependent Claim 24 words
The method as set forth in claim 4 wherein said coupling agent is a fluid selected from the group consisting of water and oil.
Claim 7
Dependent Claim 16 words
The method as set forth in claim 5 wherein said monitoring is accomplished by said transducer.
Claim 8
Dependent Claim 21 words
The method as set forth in claim 5 wherein said monitoring is accomplished by means of at least one acoustic receiver.
Claim 9
Dependent Claim 25 words
The method as set forth in claim 6 wherein said acoustic receiver is mounted on the side of the adhesively bonded joint opposite said transducer.
Claim 10
Dependent Claim 21 words
The method as set forth in claim 6 wherein said acoustic receiver is mounted on the same side as said transducer.
Claim 11
Dependent Claim 20 words
The method as set forth in claim 6 or 7 or 8 or 9 wherein said acoustic energy is pulsed.
Claim 12
Dependent Claim 24 words
The method as set forth in claim 6 or 7 or 8 or 9 wherein said acoustic energy is delivered in a continuous fashion.

References Cited (Backward Citations)

US3529465A Cited
US3911734A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1988-09-02 1989-03-04 1989-09-03 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1992-09-02 1993-03-04 1993-09-03 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1996-09-02 1997-03-04 1997-09-03 $7700.00 Window Closed / Lapsed

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