Mechanical damping and dynamic modulus measurements in alumina and tungsten fibre-reinforced aluminium composites

Modeling of the Effect of Temperature, Frequency, and Phase Transformations on the Viscoelastic Properties of AA 7075-T6 and AA 2024-T3 Aluminum Alloys

“…[28] The experimental dynamic elastic moduli of AA 2024-T3 and pure Al at RT compare well to the elastic modulus data available in the literature (Figure 3), as expected since the contribution of the loss modulus is very small and frequency has very little effect at low temperatures. The latter data series exhibits similar slopes with temperature in the vicinity of RT, except from Wolfenden and Wolla's [33] for which the slope is steeper by a factor of 2. The larger decrease of the storage modulus with temperature at low frequencies rather than at high frequencies is typically explained by the Arrhenius-type behavior of the relaxation rate, which means that the mechanical relaxation time diminishes as the temperature increases.…”

“…The initial decrease (as early as at RT) of the storage modulus with temperature for both AA 7075 and AA 2024 is explained by the dependence of the elastic moduli (i.e., the elastic stiffness constants) on temperature, which is a wellknown phenomenon for metals, and particularly for aluminum. [29][30][31][32][33] This decrease of the storage modulus has also been observed in AA 6061 and AA 6061-T6. [28] The experimental dynamic elastic moduli of AA 2024-T3 and pure Al at RT compare well to the elastic modulus data available in the literature (Figure 3), as expected since the contribution of the loss modulus is very small and frequency has very little effect at low temperatures.…”

“…[1,3,9,12,15,20,24,[29][30][31][32][33]46,47] Figure 7 shows the computed storage modulus compared to the experimental data for a test series on AA 2024-T3 at excitation frequencies of 100, 30, 10, 3, and 1 Hz. Figure 7 shows also the evolution of GPZ and h¢/S¢ concentration with temperature.…”

“…Deviations from this linear behavior were reported close to the absolute zero and above 573 K (300°C), far from the region of applicability of this model. Also, Wolfenden and Wolla [33] observed a highly linear decrease of the dynamic elastic modulus with temperature from RT to 748 K (475°C), measured at a high frequency (80 kHz), for pure Al and for AA 6061 reinforced with alumina (Al 2 O 3 ). Finally, the dynamic elastic modulus that we obtained with the DMA for AA 2024-T3 and pure Al compare well to the static and dynamic elastic modulus data available in the literature (Figure 3).…”

“…3-Elastic modulus E (static and dynamic) vs temperature T. Static elastic modulus data were obtained from the literature for pure Al [29,30,32] and for AA 2024. [31] Dynamic elastic modulus was obtained from the literature for pure Al at 80 kHz [33] and from DMA tests for AA 2024-T3 and pure Al at 1 Hz. All data are experimental, except those from Varshni's models.…”