J. M. Wells, JMW Associates, Mashpee, MA

Summary:

Of the many industrial nondestructive modalities, X-ray computed tomography, XCT appears to be the most powerful for the direct imaging and 3D visualization of both internal and external features of engineering interest. Substantial improvements in the image processing and visualization capabilities with modern XCT, have become available with continuing developments in both advanced hardware and voxel diagnostic and visualization software. While relatively small, the industrial XCT community has benefited significantly from leveraging the capabilities of the extensive medical imaging field. Micro-tomography allows the resolution of features to < 20 microns, but has sample volumetric limitations (~ <10 cm³), too restrictive for many engineering applications without destructive sectioning. Meso-scale tomography, however, allows for the resolution of features to > 250 microns (0.25 mm) in considerably larger structures. Depending on the capability of the XCT facility utilized, low to medium density sample volumes of ~ 10⁶ cm³ can be interrogated in detail.

The capture of the location, orientation, meso-scale size and 3D shape of design and/or damage features allows for the accurate visualization of 2-D and reconstructed 3-D solid object virtual imaging. Defects with significant density or x-ray absorption coefficients differences are discriminated, isolated and analyzed in situ apart from the surrounding sample host material. Image reconstruction, damage quantification and analysis, and visualization techniques are employed and discussed along with the software packages utilized. Engineering examples are discussed relating to impact damage in metal and ceramic materials.