Residual Strength and Fatigue Lifetime of ... - Solid Mechanics

(a) (b)
Figure 4.6: Deflection of the face sheet at the point of loading (Y deflection) vs. number of
cycles for (a) control parameter qG=q= 0.05 and (b) qG=q= 0.2.
More cycles are needed in the simulation with smaller control parameters qG=q=0.05 as
expected, but the calculated deflections agree well with the reference analysis. When the control
parameters are increased to qG=q=0.2 fewer simulation cycles are needed, but as it is seen from
Figure 4.6 (b), the deflection of the debonded face sheet in the simulation using the cycle jump
method is lower than in the reference simulation, which shows the inaccuracy of the simulation.
Figure 4.7 presents G vs. number of cycles. Even though G has a highly non-linear behaviour,
the cycle jump method is able to capture this behaviour by conducting small or no jumps. In the
simulation with the control parameters qG=q=0.05 there is fair agreement between the reference
analysis and the cycle jump simulation, see Figure 4.7 (a). However, the results from the
simulation with the control parameters qG=q=0.2 show some inaccuracies, see Figure 4.7 (b).
(a)
(b)
Figure 4.7:G at the crack tip vs. cycles for (a) control parameters qG=q= 0.05 and (b)
qG=q= 0.2.
Crack length vs. cycle diagrams for the two control parameters qG=q=0.05 and qG=q=0.2 are
shown in Figure 4.8. In the initial cycles (up to 200 cycles) the crack growth rate is large due to a
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