Table 1

Nominal chemical composition of the 6061 aluminum alloy (%)"

Fig. 1

Evolution of the maximum stress versus the cycle number during the LCF testing at Δε=±1.2% and ambient temperature (25℃)"

Table 2

Fatigue life characteristics of the 6061-T6 alloy under LCF loading at ambient temperature"

Fig. 2

SEM fractographs of the 6061 alloy after the LCF failure at Δε=±1.2%: (a) overall fracture surface morphology with the crack initiation site (red box) and predominant crack propagation direction (red arrow); (b) high-magnification view revealing the morphology of micro-voids and dimples (color online)"

Fig. 3

RVE model of the polycrystalline 6061 alloy containing 200 grains with random crystallographic orientations, where the specific grains are selected for the local analysis (color online)"

Table 3

Calibrated constitutive parameters for the 6061-T6 alloy"

Fig. 4

Comparison between the CPFE predictions (solid-line curves) and experimental measurements (discrete points) for the volume-averaged stress-strain response at Δε=±1.2%: (a) 1st loading cycle and (b) 8th loading cycle"

Fig. 5

Validation of cyclic stress-strain responses at multiple total strain amplitudes: (a)–(c) hysteresis loops at Δε=±0.8% for the 1st, 10th, and 36th cycles; (d)–(f) hysteresis loops at Δε=±1.0% for the 1st, 10th, and 14th cycles, where symbols represent the experimental data while solid lines denote the CPFE predictions"

Fig. 6

Predicted evolution of the dislocation density with the number of cycles in the 6061 alloy during the strain-controlled LCF testing at various total strain amplitudes (color online)"

Fig. 7

Spatial distribution within the polycrystalline RVE after eight cycles at Δε=±1.2%: (a) equivalent stress and (b) total dislocation density (color online)"

Fig. 8

Comparison of the local cyclic stress-strain responses for selected grains with different crystallographic orientations after eight cycles at Δε=±1.2% (color online)"

Fig. 9

Strain localization after eight cycles at Δε=±1.2%, visualized by the distribution of accumulated equivalent plastic strain (color online)"

Fig. 10

Distribution of the accumulated equivalent plastic strain in the polycrystalline RVE after ten loading cycles at (a) Δε=±0.8% and (b) Δε=±1.0% (color online)"

Fig. 11

Comparison between the predicted and experimental fatigue lives for the 6061-T6 alloy under strain-controlled cyclic loading at ambient temperature (color online)"

Fig. 12

Equivalent stress distribution in the single-crystal aluminum matrix after eight loading cycles at Δε=±1.2%, highlighting the stress concentration adjacent to the coarse particles of (a) needle-shaped and (b) platelet-shaped (color online)"

Fig. 13

Accumulated equivalent plastic strain field in the single-crystal matrix following eight cycles at Δε=±1.2%, demonstrating the heterogeneous plastic deformation surrounding the coarse particles of (a) needle-shaped and (b) platelet-shaped, where the insets show the corresponding contour maps of dislocation density around the intermetallic phases (color online)"

Fig. A1

Stress-strain responses for the RVEs with different grain numbers at Δε=±1.2%: (a) 1st loading cycle and (b) 8th loading cycle (color online)"

Fig. A2

Distribution of the accumulated equivalent plastic strain after eight cycles at Δε=±1.2%: (a) 150 grains and (b) 250 grains (color online)"