DAMAGE TOLERANCE OF NON-CONVENTIONAL LAMINATES WITH DISPERSED STACKING SEQUENCES

摘要

The optimisation of composite laminate designs towards a better impact tolerance is often overlooked in favour of efficient in-plane, statically loaded designs. This means that the response to impact damage is, in general, not accounted for in the design phase but evaluated for those designs that meet the static load requirements.rnThere is often margin to improve the impact response of a laminate previously designed to withstand in-plane loads in an optimal way. Using optimisation tools based on genetic algorithms, it is possible to design alternative laminates to the ones using 0°, 90°, and ±45° plies, that still keep the same in-plane and bending stiffness properties. In these non-conventional laminates the plies are dispersed through the 0-90° range at intervals of 5°. In the construction of such stacking sequences, the layers at 0° can be dispersed, for example. Manufacturing of such laminates is practical nowadays as the industry switches from hand laying processes to accurate automated fibre-placement technology. By dispersing the laminate stacking sequence, crack propagation between plies of the same orientation may be prevented. Additionally, part of the impact load carried by the matrix in traditional laminates may be transferred to the fibres which have much higher failure threshold values. These factors may help improve the damage tolerance of a given laminate without sacrificing its stiffness.rnThis paper reports the design and testing (low-velocity impact and compression-after-impact) of non-conventional carbon-fibre laminates and comparisons to the performance of traditional configurations.