Jack S Bellin

US Patent:

45384622, Sep 3, 1985

Filed:

Dec 12, 1983

Appl. No.:

6/560639

Inventors:

Jan J. Hartog - Palo Alto CA
Jack L. Bellin - Palo Alto CA
Gilbert C. Knollman - Palo Alto CA
Arthur D. Jonath - Palo Alto CA

Assignee:

Lockheed Corporation - Burbank CA

International Classification:

G01N 2900

US Classification:

73577

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.