In-situ observation and numerical simulation on the transient strain and distortion prediction during additive manufacturing

Additively manufactured parts are easily distorted during manufacturing process, which seriously affects their dimensional accuracy and even leads to failure in severe cases. Currently, there is a great challenge to perform directly and in-situ study on the dynamic evolution of the part distortion. In this study, the transient strain and distortion evolution of a typical Ti-6Al-4V thin wall during additive manufacturing were successfully revealed through digital image correlation (DIC) method and numerical simulation, and these two approaches demonstrated good agreement in strain distribution. The results indicated that the strains magnitude and evolution behavior varied with the location of the thin wall, especially at the center and side edges. The non-uniform distribution of longitudinal and vertical strains caused the thin wall to distort during the manufacturing process. The distortion of the thin wall was predicted by the numerical method, which exhibits an inward contraction at side edges and a downward contraction at the center of the upper area. The predicted final distortion of the thin wall was consistent with that of thin wall in many experimental studies. This study lays a foundation for future use of DIC and numerical simulation to predict and control part distortion during the additive manufacturing process.