Blade materials, testing methods and structural design - Wind Power Generation and Wind Turbine Design - page 454

Figure 25: Comparison of failure loads for the compressive buckling of fl at and
curved laminates as a function of through-thickness position for 15
and 25 mm 2 delamination in square plates (width 40 mm) [74].
failure load was dependent on the size and through-thickness position of the
delamination. The curved laminates exhibited an asymmetry of failure load with
the through-thickness position of the delamination; when both delaminations were
at the same depth, it was observed that a delamination located near the outer radius
gave a greater strength reduction than a delamination near the inner radius.
Damage resulting from impacts may consist of multiple delaminations. As
would be expected, depending upon size, multiple delaminations cause greater
strength reduction than a single delamination. To determine structural integrity, is
therefore of interest to understand how the geometric distribution in multiple delam-
inations affects strength reduction in laminates. Wang et al . [ 75 ] studied fl at glass
fi ber reinforced plastic specimens containing a single or two embedded delamina-
tions. With reference to Fig. 26, they found that that the maximum reduction in