Dynamic Mechanical Properties of Fiber-Metal Laminates

Fiber-metal laminated cantilever beams, made of glass-fiber reinforced GLARE and aramid-fiber reinforced ARALL laminates interlaced with aluminum layers, were first excited by a shaker at various frequencies surrounding resonances. Dynamic Young’s moduli and damping ratios were then evaluated using both free-vibration (resonance) and forced-vibration (non-resonance) schemes. Results from both schemes are in good agreement. Compared to aluminum alloys, the dynamic Young’s moduli of fiber-metal laminates are relatively lower. For all types of fiber-metal laminates tested in this study, their values are almost constant within an excitation frequency range up to 5,000 Hz whereas the damping ratios oscillate within a narrow range of 0 to 0.02. The obtained dynamic moduli are in excellent agreement with their static counterparts. Better results were obtained when using a strain gage near the clamped end, as compared to a piezoelectric accelerometer at the tip.