The applicability of mechanical spectroscopy as a potential complementary technique to characterize damage and fatigue response of fiber-reinforced laminates was investigated. The interaction between damage induced by cyclic mechanical loads and time-dependent behavior was examined [1,2]. The magnitude and nature of the damage and mechanical response were evaluated.
The effects of fatigue damage on the time, temperature, and frequency response of fiber-reinforced laminates were measured by performing dynamic mechanical analysis (DMA) tests on composite coupons which had been subjected to different amounts of fatigue loading and which exhibit varying degrees of fatigue-induced damage. Creep tests at different temperatures were conducted. Frequency multiplexing was accomplished over a temperature range encompassing the glass transition temperature. The effects of frequency on the temperature transitions of the loss and storage moduli were observed.
The DMA test results were interpreted in light of other conventional measures of fatigue response, such as change in dynamic stiffness and residual strength, and compared to nondestructive evaluation data of the different damage modes present in the laminates.
This paper includes a discussion of the applicability of DMA as a potential test methodology to investigate the effects of fatigue-induced damage on the viscoelastic behavior of fiber-reinforced laminates.