Composite materials are known to have a poor resistance to through-the-thickness impact loading. There are various methods for improving their impact damage tolerance, such as fiber toughening, matrix toughening, interface toughening, through-the-thickness reinforcements, and selective interlayers and hybrids. Hybrid composites with improved impact resistance are particularly useful in military and commercial civil applications. Hybridizing composites using shape memory alloys (SMA) is one solution since SMA materials can absorb the energy of the impact through superelastic deformation or recovery stress, reducing the effects of the impact on the composite structure. The SMA material may be embedded in the hybrid composites (SMAHC) in many different forms and also the characteristics of the fiber reinforcements may vary, such as SMA wires in woven laminates or SMA foils in unidirectional laminates, only to cite two examples. We will review the state of the art of SMAHC for the purpose of damage suppression. Both the active and passive damage suppression mechanisms will be considered.

Hollow glass fibre reinforced plastics have a structural performance niche in a class of their own. They offer increased flexural rigidity compared to solid glass fibre reinforced plastics, they offset the need for thin sandwich construction which is both difficult and expensive, and they provide an opportunity to develop laminates with improved or tailored characteristics. An experimental hollow glass fibre manufacturing facility is in operation at the University of Bristol. The facility is capable of drawing precision hollow glass fibres of various diameters with varying degrees of hollowness under precise parameter control. Hollow borosilicate glass fibres have been manufactured from tubular preforms with a variety of internal and external diameters, which correspond to a range of hollowness values. In all cases, the resulting hollowness was reduced from that present in the preform state, regardless of drawing rate or furnace temperature. In fact, temperature has been demonstrated to be of paramount importance in controlling fibre hollowness due to the interaction between glass viscosity and surface tension effects. These results suggest that for a given temperature and draw rate there is a single condition where fibre hollowness is maximised and external diameter minimised.

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In this article analytical methods for predicting the mechanical properties of 2D woven composites with different weave patterns and materials are reviewed. These approaches are then evaluated by comparing them to experimental and numerical results.

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