Modal approach based on global stereo-correlation for defects measurement in wire-laser additive manufacturing

Producing Near Net Shape parts with complex geometries using Wire-Laser Additive Manufacturing often requires a mastered and optimized process. Differences between the constructed and nominal geometries of the manufactured entities demand an in-situ defects measurement to complete the production of the entire part successfully. A contactless measuring system is needed to evaluate geometrical deviations without requiring complex post-processing operations. To overcome this challenge and validate a measuring tool that serves the manufacturing purpose, a global stereocorrelation approach is used to measure defects in wire-laser additively manufactured parts. This method relies on the cameras’ self-calibration phase that uses the part substrate’s nominal model. Then, a modal basis is defined to model and evaluate the surface dimensional and shape defects. Hence, an analysis of the texture obtained in additive manufacturing is conducted to assess whether or not it is sufficient for image correlation and defect measurement. Finally, natural and pattern textures are compared to highlight their influence on the measurement results.