STRUCTURAL DEFECT MONITORING DEVICE

• US 3,596,269 A
• Filed: 10/25/1968
• Issued: 07/27/1971
• Est. Priority Date: 10/25/1968
• Status: Expired due to Term

• Current Assignee: Richard H. Laska
• Original Assignee: Richard H. Laska
• Inventors: Laska, Richard H.
• Application Number:
  US04/770,531
• Time in Patent Office: 1,005 Days
• US Class Current: 340/518
• CPC Class Codes: B64F 5/60 Testing or inspecting aircraft components or systems
• CPC Class Codes: G01B 7/18 using change in resistance

Abstract

This invention relates to a system for a detecting and monitoring structural defects in mechanical structures such as the skin of an aircraft. The system comprises a group of elongated conductive tapes of known electrical resistance bonded to the aircraft skin but insulated from it at a point which has a history or likelihood of failure. One end of the group of tapes is electrically grounded while the other is electrically connected to a resistance comparing or measuring device, as for example, an ohmmeter. A visual or audible warning device is provided in the form of a light or buzzer including a solenoid holding circuit to hold it on once energized. Thus when a crack or tear occurs in the aircraft skin the warning light or buzzer is energized and a reading of the ohmmeter shows the extent of damage by the degree of resistance change.

Claims

1. A device for detecting and monitoring failure of structure members comprising:

at least two pluralities of elongated electrically conductive members, each of said elongated electrical conductor members being electrically equivalent to each of the other elongated electrical conductors, and each of said elongated electrical conductors being connected to electrical ground at one end thereof and in parallel with the other elongated electrical conductors;

insulating means secured to said elongated electrical conductors for holding said elongated electrical conductors in intimate electrically insulated contact with the structural member; and

an electrical resistance comparing member electrically connected to said plurality of elongated electrical conductors, said electrical resistance comparing member adapted to detect a change in electrical resistance of said plurality of elongated electrical connectors and each of said pluralities of elongated electrical conductors being selectively electrically connected to said electrical resistancE comparing member so that any plurality of elongated electrical conductors may be periodically selectively checked for a change in resistance.

2. The device of claim 1 further characterized by an electrically operated warning device and holding circuit being electrically connected to each plurality of elongated electrical conductors so that if a change in electrical resistance occurs in a plurality of elongated connectors that said electrically operated warning device functions.

3. The device of claim 2 wherein the electrically operating warning device comprise a light and a solenoid holding circuit to keep said light on once energized.

4. The device of claim 2 wherein the electrically operated warning devices comprise a buzzer and a solenoid holding circuit to keep said buzzer sounding once energized.

5. A system for detecting and monitoring structural failure in operating components of a mechanical structural comprising:

at least one group of parallel connected elongated conductors, one end of said group being connected to electrical ground;

said group being secured to and electrically insulated from the mechanical structure; and

an electrical resistance comparing device for measuring the deviation in resistance between a control electrical resistance and that of said group, said electrical comparing device including a visual indicator adapted to reflect the comparative electrical resistances of said control electrical resistance and that of said group.

6. The system of claim 5 further characterized by a plurality of groups of elongated conductors secured to the mechanical structure at various locations and each group being selectively electrically secured to the electrical resistance comparing device so that various locations on the mechanical structure may be periodically selectively examined for structural failure.

7. The system of claim 6 further characterized by the elongated conductors comprising a relatively thin conductive foil and said parallel foils being bonded to and insulated from the mechanical structure so as to follow compound curves in said mechanical structure.

8. The device of claim 7 further characterized by an electrical warning device electrically connected to each group of parallel elongated conductors and including a solenoid holding circuit so that once energized said warning device remains on.

9. The device of claim 8 wherein said warning device is a light.

10. The device of claim 8 wherein said warning device is a buzzer.