Metal Foams: A Design Guide

Characterization methods 37
40 40 40 40 ∆ε
0.05
30 30 30 30
0.04
0.03
0.02
20 20 20 20 0.01
0.00
10 10 10 10
0
0 10 20 30
0
0 10 20 30
0
0 10 20 30
0
0 10 20 30
3 4: ∆ε= 0.2% 4 5: ∆ε= 0.35% 5 6: ∆ε = 0.65% 6 7: ∆ε= 1.0%
A B
∆ε
40
30
20
10
40
30
20
10
40
30
20
10
40
30
20
10
0.10
0.09
0.08
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0.00
0
0 10 A 20 30
0
0 10 B 20 30
0
0 10 20 30
0
0 10 20 30
3: σ/σo = 0.46 5: σ/σo = 0.75 6: σ/σo = 0.86 7: σ/σo = 1.0
A
40 40 40
40
∆ε
0.05
30 30 30 30
0.04
0.03
0.02
20 20 20 20 0.01
0.00
10 10 10 10
0 0 0 0
0 10 A 20 30 0 10 20 30 0 10 20 30 0 10 20 30
3−U: σ/σ o = 0.46 5−U: σ/σ o = 0.75 6−U: σ/σ o = 0.86 8−U: σ/σ o = 1.0
Figure 3.9 Distortional strain maps for incremental loading : Top row:
incremental distortion at various load levels. Middle row: maps of
accumulated distortion at various load levels along the deformation history.
Bottom row: incremental distortion at various unloading levels
an order of magnitude larger than the applied strain. Outside the bands, the
average strains are small and within the elastic range. The principal strains
reveal that the flow vectors are primarily in the loading direction, normal to
the band plane, indicative of a crushing mode of deformation. The cumulative
distortions exhibit similar effects over the same strain range.