SPH modeling and investigation of cold spray additive manufacturing with multi-layer multi-track powders

Abstract

Cold spray (CS), as a new solid-state additive manufacturing technique, involves complex phenomena like high-speed impacting of micro-powders, large material deformations, phase change and jet generation. The CS process is difficult to be accurately simulated, and the underlying coating mechanisms, especially for multi-powders CS, have not been well understood. As a Lagrangian and particle method, the smoothed particle hydrodynamics (SPH) method has natural advantages in treating large deformations and capturing moving interfaces. In this work, we present an improved SPH approach to implement three-dimensional particle modeling and study of the multi-layer multi-track CS problem. The kernel gradient correction (KGC), adaptive smoothing length and the constitutive model are integrated in the improved SPH. The contour profile and width thickness ratio of the deformed powder obtained by the present simulation are very close to the experimental results. The bonding behaviors in a single powder CS with different materials are first explained where the critical velocities for different materials are obtained. Furthermore, coating behaviors in CS with different layers and tracks of powders are comprehensively analyzed. Some typical deformation parameters of the powders track with regard to an increasing impacting velocity are attained. With the present numerical model, a larger scale multi-layer multi-track CS is promising to be reproduced with some parameter windows predicted, which is greatly helpful to CS operations.