Damage assessment system for composite plastic structures using fiber optics

• US 4,581,527 A
• Filed: 07/29/1983
• Issued: 04/08/1986
• Est. Priority Date: 07/29/1983
• Status: Expired due to Fees

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Crane, Roger M., Macander, Aleksander B.
• Primary Examiner(s): Nelms, David C.
• Application Number:
  US06/518,715
• Time in Patent Office: 984 Days
• Field of Search: 250/227, 250/221, 250/222.1, 340/550, 340/555, 340/556, 340/557, 350/96.1, 350/96.34, 350/96.15
• US Class Current: 250/227.14
• CPC Class Codes: G01M 11/086 Details about the embedment of the optical fiber within the DUT

Abstract

A damage assessment system consisting of a three-dimensional grid of opti fibers for locating and assessing damage in plastic composite structures. A optical fiber grid system is implanted in a composite structure during its fabrication and becomes integrated with it. The optical fiber grid experiences an identical load/damage condition as the structure itself. Using a system of interrogation based on optoelectronics, passage or continuity of light throughout the system can be monitored for light attenuation or interruption. Highly stressed fibers would attenuate light while broken fibers would interrupt or hinder light transmission. By monitoring a number of optical fiber ends, the extent of damage in three dimensions can be determined.

Claims

1. A damage assessment system for fiber reinforced composite material comprising:

a plurality of layers of optical fiber grids, said layers being placed at various depths within said material, so that when damage occurs to said material, said optical fibers are affected, each of said layers including two orthogonal series of optical fibers arranged in a gridwork pattern;

at least one input device for producing light and transmitting said light into one end of said optical fibers,

at least one output device for receiving light transmitted by said optical fibers from said input device;

a viewing device connected to said output device for observing which optical fibers transmit light;

whereby damage to said material affects the ability of said optical fibers to transmit light from said input device to said output device so that the extent of damage to said material in each layer may be observed in said viewing device to determine in three dimensions the severity of damage.

2. A damage assessment system according to claim 1, wherein said output device is an optoelectronic device.

3. A damage assessment system according to claim 2, wherein said input device includes a light emitting diode.

4. A damage assessment system according to claim 3, wherein the optical fibers in each series are regularly spaced.

5. A damage assessment system according to claim 1, further comprising an interrogation device for sequentially examining each of said fibers and transmitting the results to said viewing device individually.