A methodology for CT based non-destructive geometrical evaluations of lattice structures by holistic strut measurement approach

The presence of lattice structures is increasing in the manufacturing domain especially in the air/spacecraft and biomedical applications due to their advantages of high strength-to-weight ratios, energy absorption, acoustic and vibrational damping, etc. Dimensional accuracy of a lattice structure is one of the most important requirements to meet the desired functionality as there could be significant deviations in the asproduced part from the designed one. Evidently, an approach (non-destructive) to evaluate the dimensional accuracy of all the elements and eventually the lattice quality is of great significance. X-ray computed tomography (CT) has emerged as a promising solution in the field of industrial quality control over the last few years due to its non-destructive approach. In this work, we propose a methodology for geometrical evaluations of a lattice structure by measuring the deviation in the shape and size of its strut elements holistically. The acquired CT data of the complete lattice is extracted in the form of a point cloud and then segmented and stored as a single strut element with unique identification so that measurements can be performed on the strut individually. As demonstrated with a metallic BCCz type lattice structure, the methodology helps in critical evaluation of its quality and the correlation with spatial position of the individual struts; e.g. the lattice exhibits large variations of shape among the inclined struts while the vertical struts possess consistency in their shape.