Simulating the stress-strain state during laser metal deposition to determine the final warping of products

Additive technologies, including laser powder deposition (a repair technology), enable a sequential deposition of powder layers. This process involves large temperature gradients and technological residual stresses, which can lead to shape violations and change mechanical and operational characteristics of products. To control and prevent residual deformations in the hardfacing body, it makes sense to carry out finite element modeling of the laser powder hardfacing using layer-by-layer activation technology or adding new finite elements to the surface of the hardfacing model. The Element Birth/Death method is the most suitable method for this problem. In this case the elements for the material to be created are deactivated (so not included in the solution area), and then gradually revived and included in the solution area. The material is built up discretely. At each sub-stage of the calculation, corresponding to the revival of the next sub-domain of dead elements, the coupled problem of thermal conductivity and solid mechanics is solved, and thus the result of the solution of the previous sub-stage serves as the initial conditions for the next one. A mathematical model and an algorithm for modeling warping during the deposition are developed, and calculations for the deposition of cylindrical specimens are carried out. During the calculations, the multilinear MISO plasticity model for the sample material and the BISO bilinear plasticity model for the filler powder were used. We verified the model based on the optical control results of changes in the geometry of the experimental samples after the deposition had been carried out. The error in warpage calculation did not exceed 5%.