Laminated, filament-reinforced epoxy beam specimens were fa tigued in vibratory flexure. The complex modulus of the specimens was measured periodically as fatigue crack damage accumulated. Changes in the real and imaginary parts of the modulus correlated with the amount of crack damage. The imaginary part of the modulus changed substantially. Measurement of these vibration response changes shows promise as a means to nondestructively test the structural integrity of filament-reinforced composite structural mem bers.
Get full access to this article
View all access options for this article.
References
1.
G. Martin, "Nondestructive Testing Techniques for Composites," Paper No. 1 of Reference [4].
2.
A.D. Lucian and M.W. Standart, "The Application of Sonic and Microwave Inspections to Composite Nonmetallic Structures," Paper No. 5 of Reference [4].
3.
Composite Materials Testing and Design, Special Technical Publication 460, American Society for Testing and Materials, Philadelphia, 1969.
4.
NDT of Plastic/Composite Structures, Air Force Materials Laboratory (MAMN), Dayton, 1969.
5.
Proceedings of the Air Force Conference on Fatigue and Fracture of Aircraft Structures and Materials, H. A. Wood, et al, eds., Air Force Flight Dynamics Laboratory TR-70-144, 1970.
6.
M. Schrager , "Fatigue as Monitored by the Torsion Pendulum ," Journal of Polymer Science A-2, Vol. 8 (1970), p. 1999.
7.
J.M. Lifshitz and A. Rotem, "Determination of Reinforcement Unbounding of Composites by a Vibration Technique," Journal of Composite Materials, Vol. 3 ( 1969)' p. 412.
8.
A.T. DiBenedetto, J.V. Gauchel, and R.L. Thomas, "Non-destructive Determination of Damage in Glass-Fiber Reinforced Laminates," Materials Research Laboratory, Washington University , St. Louis, 1971.
9.
A.B. Schultz and S.W. Tsai, "Dynamic Moduli and Damping Ratios in Fiber-Reinforced Composites," Journal of Composite Materials , Vol. 2 (1968), p. 368.
10.
A.B. Schultz and S.W. Tsai, "Measurements of Complex Dynamic Moduli for Laminated Fiber-Reinforced Composites," Journal of Composite Materials, Vol. 3 ( 1969), p. 434.
