Detection of early fatigue damage in composite materials by nondestructive inspection (NDI) techniques has been demonstrated for ±45° Glass/Epoxy, and ±45°/0° Graphite/Glass/Epoxy. Dynamic axial modulus and temperature were monitored continuously with a correlation between temperature rise and modulus decrease observed. The modulus decrease and temperature rise are indicative of irreversible damage in these materials.
Torsional modulus measurements and coin tap tests were performed at 0, 106, 5 × 106, and 107 cycles, on all fatigue specimens. Other NDI procedures including holographic interferometry, ultrasonics, penetrant, and X-Ray radiography were performed on two specimens of each material to evaluate their effectiveness in detecting fatigue damage. Ultrasonics and holography proved to be effective; however, at this time, no clear quantitative correlation beween structural properties and NDI measurements has been determined.
Get full access to this article
View all access options for this article.
References
1.
M.J. Salkind, "Fatigue of Composites," Composite Materials: Testing and Design (2nd Conference), STP497, ASTM, Phila., 1972, p. 143.
2.
L.J. Broutman and S. Sahu, "Progressive Damage of Glass Reinforced Plastics During Fatigue," Proc. 24th SPI Conference, February 1969, 11-D.
3.
L.J. Broutman and S. Sahu, "A New Theory to Predict Cumulative Fatigue Damage in Fiberglass Reinforced Plastics," Composite Materials: Testing and Design (Second Conference), STP497, ASTM, Phila., 1972, p. 170.
4.
K.L. Reifsnider, W.W. Stinchcomb, R. Williams, and L.A. Marcus, "Heat Generation in Composite Materials During Fatigue Loading," VPI, AFOSR-TR-73-1961, May 1973 .
5.
L.C. Cessna, J.A. Levens, and J.B. Thomson, "Flexural Fatigue of Glass Reinforced Thermoplastics" Proceedings 24th SPI Conference, February 1969, 1-C.
6.
K.L. Reifsnider, W.W. Stinchcomb, R. Williams, and H.M. Turgay, "Frequency Effects on Composite Fatigue Reliability," to be published in STP580, ASTM, Phila., 1975.
7.
W.W. Stinchcomb, K.L. Reifsnider, L.A. Marcus, and R.S. Williams, "The Effects of Frequency on the Mechanical Response of Two Composite Materials to Fatigue Loads," Fatigue of Composites, STP569, ASTM, Phila., 1975, p. 115.
8.
W.W. Stinchcomb, K.L. Reifsnider, L.A. Marcus, and R. Williams, "Effects of Cyclic Frequency on the Mechanical Properties of Composite Materials," VPI, AFOSR-TR-73-1907, July 1973.
9.
M.G. Ulitchny and J.J. Lucas, "Evaluation of Graphite Composite Materials for Bearing-less Helicopter Rotor Applications," Sikorsky Aircraft, NASA CR-132414, January 1974.
10.
K.H. Boller , "Fatigue Fundamentals for Composite Materials," Composite Materials: Testing and Design, STP460, ASTM, Phila., 1969, p. 117.
11.
J.B. Sturgeon , "Fatigue and Creep Testing of Unidirectional Carbon Fibre Reinforced Plastics," Proc. 28th SPI Conference, February 1973, 12-B.
12.
R.A. Heller , G.N. Swift, W.W. Stinchcomb, A.B. Thacker, and J.C. Liu, "Time and Temperature Dependence of Boron Epoxy and Graphite-Epoxy Laminates," VPI, AFML TR-73-261, November 1973.
13.
G. Epstein, "Nondestructive Test Methods for Reinforced Plastic/Composite Materials ," Aerospace Corporation, Report No. SAM SO-TR-69-78, September 1972.
14.
G. Martin and J.F. Moore, "Research and Development on NDI Techniques for Composites," North American Rockwell, AFML-TR-68-202, June 1968.
15.
J.R. Zurbrick , "Development of Nondestructive Test Methods for the Quantitative Evaluation of Glass Reinforced Plastics," AVCO Corporation, AFML-TR-66-269, March 1969.
16.
C.N. Owston and E.A. Jaffe, "Nondestructive Testing and Inspection Applied to Composite Materials and Structures," AGARD Report No. 590, 1971, p. 3.
17.
J.L. Rose, J.M. Carson, and D.J. Leidel, "Ultrasonic Procedures for Inspecting Composite Tubes," Analysis of the Test Methods for High Modulus Fibers and Composites, STP521, ASTM, Phila., 1973, p. 311.
18.
G. Martin and J.F. Moore, "Research and Development on NDT Techniques for Composites," North American Aviation, AFML-TR-67-166, November 1967.
19.
G. Martin and J.F. Moore, "Research and Development on NDT Techniques for Composites," North American Aviation, AFML-TR-66-270, February 1967.
20.
R.T. Anderson and T.J. DeLacy, "Nondestructive Testing of Composites ," Metal Progress, Vol. 102, No. 2 (1972), p. 88.
21.
J.L. Cook, W.W. Rienhardt and J.E. Zimmer, "Development of NDT Techniques for Multidirectional Fiber Reinforced Resin Matrix Composites," McDonnell Douglas, AFML-TR-71-187, October 1971.
22.
O.J. Burchett and John L. Irwin, "Laser Holography of Carbon Composite Structures ," Carbon Composite Technology, Proceedings of the 10th Annual Conference, ASME, 1970 , p. 237.
23.
W.A. McCaughey , R.M. Grant, and G.M. Brown, "Holographic Nondestructive Testing of Aircraft Materials," Proc. 15th National SAMPE Symposium and Exhibition, SAMPE Publication Vol. 15, p. 913.
24.
H. Aas, R. Erf, and J. Waters, "Investigation to Determine the Feasibility of Employing Laser Beam Holography for the Detection and Characterization of Bond Defects in Composite Material Structures," United Aircraft Research Labs, NASA CR-111836, February 1971.
25.
J. Fritz-Randolph , D.C. Phillips, P.W.R. Beaumont, and A.S. Tetelman, "Acoustic Emission Studies of Boron-Epoxy Composites," J. of Comp. Mat. , Vol. 5 (1971), p. 542.
26.
R.S. Williams and K.L. Reifsnider, "Investigation of Acoustic Emission During Fatigue Loading of Composite Specimens," J. of Comp. Mat., Vol. 8 (1974), p. 340.
27.
A.D. Lucian and M.J. Standart, "The Application of Sonic and Microwave Inspections to Composite Nonmetallic Structures," Proceedings of Aerospace-AFML Conference on NDT of Plastic Composite Structures, March 1969, Dayton, Ohio.
28.
M.J. Salkind , "Fiber Composite Structures," Proceedings of the International Conference on Composite Materials , AIME, N.Y., to be published.
