Damping factors were determined for cantilever beams made of cross- plied epoxy fiberglass laminates as they were vibrated at different strain levels in first and second mode bending simultaneously. It was found that the damping factor could be calculated from the crack density and the strain volume function at maximum previous strain and was almost inde pendent of the current strain distribution. It was also found that the damp ing factor was almost the same in both first and second modes and that, unlike metals, there was very little interactive effect.
Get full access to this article
View all access options for this article.
References
1.
A.B. Schultz and D.N. Warwick, "Vibration Response: Fatigue Crack Damage in Filament-Reinforced Composites,"J. Comp. Mat., 5, July 1971, pp. 394-404.
2.
R.F. Gibson and R. Plunkett, "Dynamic Mechanical Behavior of Fiber-Reinforced Composites : Measurement and Analysis,"J. Comp. Mat., 10, Oct. 1976, 325-341.
3.
K.L. Reifsnider and J.E. Masters, "Investigation of Characteristic Damage States in Composite Laminates," 78 WA/AERO-4, ASME1978.
4.
A. Pervize and J.E. Bailey, "On Multiple Transverse Cracking in Glass Fiber Epoxy Cross Ply Laminates,"J. Mat. Sci., 13, 1978, pp. 2131-2136.
5.
R. Plunkett and M. Sax, "Nonlinear Material Damping for Non-sinusoidal Strain,"J. Appl. Mech., 45, 4, 1978, pp. 883-888.
6.
R.F. Gibson and R. Plunkett, "Forced-Vibration Technique for Measurement of Material Damping,"Experimental Mechanics , 17, 8, Aug. 1977, 297-302.
7.
R.D. Blevins , "Formulas for Natural Frequency and Mode Shape,"Van Nostrand, 1979, Table 8-1.
8.
R. Plunkett and C.T. Lee, "Length Optimization for Constrained Viscoelastic Layer Damping,"J.A.S.A., 48, 1 (Pt 2), 1970, 150-161.
9.
B.J. Lazan, "Damping Properties of Materials," Applied Mechanics Surveys," H. N. Abramson et al, eds. Sparton Books, 1966 pp. 703-715.
