A proposed multiplexed fiber-optic sensor system capable of analyzing a composite material during its curing cycle and over its service lifetime is presented. The sensor is composed of two independent sensing schemes that will ultimately be multiplexed onto a specialized single-mode/multimode optical fiber. The first sensing scheme is a fiber-optic viscosity and temperature sensor used for composite cure analyses. This sensor is based on (1) the laser-induced viscosity-dependent fluorescence phenomena observed in epoxy-based composite materials and (2) the temperature-dependent decay-time fluorescence phenomena observed in thermographic phosphors. The second sensor is based on a low-finesse, single-mode fiber-optic Fabry-Perot interferometer and is used as a strain/vibration sensor for lifetime nondestructive evaluations on composites. Experimental results have determined that these sensor concepts are feasible alternatives to cure-analysis monitors and conventional strain-analysis techniques.

Topics
Fabry-Perot interferometers, Fiber optic devices, Optical fibers, Optical materials, Composite materials
1.
Micromet Instruments, Inc.
,
21 Erie St. Cambridge, MA 02139
.
2.
Day
,
D. R.
 (
1988
).
Thermoset Cure Process Control for Utilizing Microdielectric Feedback
, pp.
594
–
602
, in
Proceedings of the 33rd Int. SAMPE Symposium and Exhibition on Materials - Pathways to the Future
, held in
Anaheim, California
,
March 7-10, 1988
.
3.
Kranbuehl
,
D. E.
 et al (
1987
).
Monitoring Processing Properties of High-Performance Thermoplastics Using Frequency-Dependent Electromagnetic Sensing
, pp.
338
–
348
, in
Proceedings of the 32nd Int. SAMPE Symposium and Exhibition on Advanced Materials Technology ’87
, held in
Anaheim, California
,
April 6-9, 1987
.
4.
Ciriscioli
,
P. R.
 and
Springer
,
G. S.
 (May/June
1989
).
Dielectric Cure Monitoring: A Critical Review
,
SAMPE J.
(
3
):
35
–
42
.
Google Scholar
 
5.
Levy
,
R. L.
 and
Schwab
,
S. D.
 (
1986
).
Fluorescence Optrode Cure Sensor
,
McDonnell Douglas Research Laboratories
,
St. Louis, Missouri
.
Google Scholar
 
6.
Schwab
,
S. D.
 and
Levy
,
R. L.
 (
1988
).
Advances in the Development of the Fluorescence Optrode Cure Sensor (FOCS)
, Vol.
59
, pp.
591
–
595
, in
Proceedings of the ACS Division of Polymeric Materials: Science and Engineering
, Fall Meeting,
Los Angeles, California
.
7.
Afromowitz
,
M. A.
 (October
1988
).
Fiber Optic Polymer Cure Sensor
,
J. of Lightwave Technology
,
6
(
10
):
1591
–
1594
.
Google Scholar
 
8.
Uruti
,
E. H.
,
Bawk
,
R. M.
, and
Blaszyk
,
P. E.
 (
1988
).
Optical Fibers for Structural Sensing Applications
,
Corning Glass Works
,
Sullivan Road, Corning, New York
.
Google Scholar
 
9.
Hofer
,
B.
 (September
1987
).
Fiber Optic Damage Detection in Composite Structures
,
Composites
18
(
4
):
309
–
316
.
https://doi.org/10.1016/0010-4361(87)90294-1
Google Scholar
Crossref
Search ADS
 
10.
Waite
,
S.R.
,
Tatam
,
R. P.
, and
Jackson
,
A.
 (November
1988
).
Use of Optical Fiber for Damage and Strain Detection in Composite Materials
Composites
19
(
6
):
435
–
442
.
https://doi.org/10.1016/0010-4361(88)90700-8
Google Scholar
Crossref
Search ADS
 
11.
Murphy
,
K.
 and
Duke
,
J. C.
, Jr. (Spring
1988
).
A Rugged Optical Fiber Interferometer for Strain Measurements Inside a Composite Material Laminate
,
J. Composites Technology & Research
10
(
1
):
11
–
15
.
https://doi.org/10.1520/CTR10269J
Google Scholar
Crossref
Search ADS
 
12.
Cates
,
M. R.
 et al (
1985
).
Laser-Induced Fluorescence of Europium-Doped Yttrium Oxide for Remote High-Temperature Thermometry
, K/TS-11,776,
Martin Marietta Energy Systems, Inc.
,
Oak Ridge Gaseous Diffusion Plant
.
Google Scholar
Crossref
Search ADS
 
13.
Cates
,
M. R.
 et al (
1984
).
Applications of Pulsed-Laser Techniques and Thermographic Phosphors to Dynamic Thermometry of Rotating Surfaces
, K/TS-11,504,
Martin Marietta Energy Systems, Inc.
,
Oak Ridge Gaseous Diffusion Plant
.
Google Scholar
Crossref
Search ADS
 
14.
Beshears
,
D. L.
 et al (
1986
).
Evaluation of Commercially Available Coating Techniques for Application of Thermographic Phosphors to Nickel-Based Alloys
, K/TS-11,801,
Martin Marietta Energy Systems, Inc.
,
Oak Ridge Gaseous Diffusion Plant
.
Google Scholar
 
15.
Butler
,
C. D.
 and
Hocker
,
G. B.
 (
1978
).
Fiber Optics Strain Gauge
,
Applied Optics Technology
17
(
18
):
1867
–
1869
.
Google Scholar
 
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1989
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