7.6 Computed tomography of composites

X-ray computed tomography (CT) can provide high spatial resolution 3D images of composite materials. Further, as a non-destructive technique it can also track the evolution of damage over time as a function of loading or environment in situ. Here the basic principles of the method and some of the current limitations when applied to composite materials and components are discussed. The capability of the technique is then illustrated, firstly for 3D imaging of the current state of the composite, whether that be as-manufactured, or after some form of service loading, providing detailed quantitative information about the composite architecture, fibre misalignments, manufacturing defects and in-service damage modes. In addition the use of such 3D information to create realistic image-based numerical models is discussed. Secondly, the increasing use of in situ environments is opening up a wide range of time-lapse studies enabling the evolution of microstructure, either during the manufacturing process, or in operando. Tension, compression, torsion, impact and fatigue loading are considered. Finally, the prospects for further development of the technique are discussed, particularly with respect to high speed imaging.