Composites Analysis in Aerospace Applications

Computed Tomography for Aerospace

Composite is a very popular material for many different applications, such as Aerospace, Automotive, and Structural constructions. It is usually lighter, stronger, and in most cases less expensive than traditional material. A good example is the Boeing 787 Dreamliner which is the first passenger airplane to use composite materials as the primary material in the construction of its airframe.

The tricky part with composite is the inspection. The structure is so complex – usually Fiber-reinforced polymers, or carbon-fiber reinforced plastic, or glass-reinforced carbon, etc – that it makes it difficult to inspect its internal structures with traditional methods. Even Ultrasonics and Shearography have some limits. Typically composite manufacturers are looking for delamination, porosities, wrinkles, fiber orientation problems, and lack of material.

Computed Tomography can not only nondestructively inspect the inside of the composite structure, but it can also represent a 3D model of the structure with relatively high resolution. 3D is important because the composite material is made of layers, often with fibers distributed in three dimensions. Thus, the properties of the material are anisotropic, because they vary depending on the material orientation.

Composite cone shaped part – nose of a commercial jet plane. Dimensional analysis using VGStudio
Complex Composite fiber part. 3D results obtained with a 1 minute CT scan by NSI.

Using a North Star Imaging CT system (typically the X5000 as it allows for large part inspection and flexible resolution for composite), 3D analysis of composite structure becomes possible. The 3D rendering capabilities of efX-CT, a NSI software, allows for multiple virtual cross sections through the part in multiple axes, and the resolution often allows seeing individual composite fibers that are only a few micrometers in size. Delaminations and wrinkles are detectable. Porosities are quantifiable and measurable.

One of the new trends and a largely unexplored capability of CT is to be able to measure the fiber orientations. Based on the distribution and orientation of fibers, the composite part properties can rapidly change, and most manufacturers and users of composites are interested in quantifying this. Again, CT is a very promising technology, and with the help of powerful third party 3D software, this analysis becomes fast, precise, and automatic.

Fiber orientation analysis of a composite. The colors in the middle picture shows the angle of the fibers and indicate the orientation strength of the part.