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

(a) (b)
Figure 3.12: Out-of-plane deflection from DIC measurements of a panel with H130 core and
a debond diameter of 100 mm (a) prior to propagation and (b) after propagation.
Figure 3.13 shows typical load vs. axial displacement and load vs. out-of-plane displacement
curves for panels with a 100 mm debond and H250, H130 and PMI cores, for additional results
see Apendix B. The out-of-plane deflection refers to the centre of the debond. The debond
opening initially increases very slowly with increasing load until a bifurcation load level
corresponding to the local buckling of the debonded face sheet. After buckling the debond
opening increases rapidly in the postbuckling regime approaching the debond propagation load
level. At the onset of propagation, the load decreases due to the displacement controlled loading
and debond propagation resulting in increased compliance, while the out-of-plane displacement
of the debonded face rapidly increases.
(a) (b)
Figure 3.13: Typical (a) load vs. axial displacement and (b) load vs. out-of-plane displacement
for panels with a debond diameter of 100 mm.
All intact panels with H130 and H250 cores failed by compression failure of a face sheet close to
the wooden inserts, see Figure 3.14 (a). This can be attributed to additional peeling stresses
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