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

(a)
Debonded face sheet
Figure 3.16: Finite element model of a panel with a debond diameter of 100 mm. (a)
Submodel min. element length 0.02mm (b) global mode min. element length 0.25 mm.
Figure 3.17 shows load vs. out-of-plane deflection of the centre of the dobond for panels with
200 mm debond and PMI, H130 and H250 cores determined from experiments and finite
element analysis. In Figure 3.17 the point where the crack starts to propagate in the tested panels
is marked with an open circle (“”). The load reduction at the onset of propagation is shown only
for the experimental results, as only initiation of debond propagation is modelled numerically (no
crack propagation algorithms are implemented in the finite element model).
(a) (b) (c)
3.17: Finite element and experimental results for out-of-plane displacement vs. load diagram
for panels with 200 mm debond and (a) H130 (b) H250 and (c) PMI core.
Experimental buckling load of the debonded panels and numerical buckling loads determined by
linear eigenbuckling analysis as well as non-linear finite element analysis are given in Table 3.6.
It is seen that the buckling loads of the panels with 100 mm debond diameter increase
significantly with increasing core stiffness, but for the larger debonds the increase is smaller. The
numerical and experimental buckling loads show fair agreement.
54
200
200
200
200
(b)