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Graph showing delamination area versus number of cycles for 14 CFRP cantilever specimens. 52 An Experimental Investigation into Damage Propagation Measurements taken for each specimen at each of the ten fatigue cycle increments showed noticeable reductions in static stiffness with increasing strain levels (see Fig. 6). Such changes are obviously linked to the size of the damage area within the specimen. In order to assess the relationship between static stiffness and damage area, correlation coefficients were calculated separately for autoclaved and pressed specimens, using the following relationship: where x = static stiffness and y = damage area.

Under low velocity impacts, the major forms of damage consist of matrix cracking and delamination. Delamination is the more critical, as it may cause significant reduction in compressive strength. Thus, to improve the impact resistance property of a composite laminate, the interfaces of the laminate must be toughened. One method being considered for interface toughening is the use of adhesive layers. By placing tough adhesive films along the interfaces of the laminae, Chan et aU demonstrated that edge delamination in coupon laminate specimens subjected to in-plane tension could be suppressed.

Variation of specific energy absorption with diameter for 8 mm thick cones. 38 The Crush Performance of Composite Structures with 0 = 11 0, and those with 0 = 22° triggered by internal chamfers had crush zone morphologies similar to those of axisymmetric tubes (Fig. 2), however the internal debris fronds were wider than the external fronds. In cones with 0 = 22° triggered by an external chamfer and all 0 = 45° cones, all the debris passed to the inside of the specimen as can be seen from Fig. 6.