LICENTIATE THESIS - Luleå tekniska universitet

Tensile strength [MPa]
5
4
3
2
1
0
0 2 4 6 8
Strain [‰]
- 9 -
Normailzed stress
1
0.8
0.6
0.4
0.2
0
0 2 4 6 8
Strain [‰]
(a) (b)
Figure 8 Results of the uniaxial tensile tests for series B. (a) Curves showing the
strains of the COD-gauges that were exposed to the highest strain during each
test. (b) The same curves as in (a) but with normalized stress in order to get a
mean curve for the whole test series. The curve that has (+) is the mean curve
used in Figure 10.
Fatigue test
In Figure 9 to Figure 13 some typical results from the fatigue tests are presented.
In Figure 9 the tensile stress versus the strain is displayed for specimen B9. The
specimen failed after 350 load cycles. In Figure 9 the plotted curve is the COD-gauge
that was exposed to the highest strain.
Tensile strength [MPa]
4
3
2
1
0
Load level A: 2.63 MPa
load level B: 3.93 MPa
0 0.2 0.4 0.6 0.8 1
Strain [‰]
Figure 9 Curve showing the tensile strength versus the strain development fro
specimen B9. The specimen failed after 350 load cycles. The two load levels
corresponds to 94% respectively 64% of the average peak load for the uniaxial
tensile tests for the series.
In Figure 10 the total strain versus the number of load cycles is displayed for specimen
B9. In the figure this curve is compared to the average normalized stress-strain curve
for series B.