Cold spray particle impact simulation using the Preston-Tonks-Wallace plasticity model

In the Cold Spray process, solid powder particles are heated and accelerated to approximately 800 m/s by injecting them into a pressurized gas stream that is expanded through a converging-diverging nozzle. The high velocity particles impact a substrate and undergo severe plastic deformation at very high strain rates. The impact generates a bond between the particles and the substrate, or on particles already deposited on the substrate. The process parameters for each material system are developed experimentally. The most common method of predicting particle deformation was to use a constitutive equation such as the Johnson-Cook material model that is a curve fit of measured high strain rate properties. However, the constant for these types of models have to be determined experimentally for each material of interest and this model does not incorporate important impact events such as rebound of the particle. To better predict particle deformation and to reduce the need for experimental data, a thermodynamics based material model developed by Preston et al. was implemented through a user developed subroutine in finite element analysis. The model was used to predict the deformation of single particles at different impact velocities. The model showed excellent agreement with experimental single particle impact data provided by other universities. No adjustment to the material parameters was required. The development of the model will be explained and model results for deformation will be presented.

Automated summary

In the Cold Spray process, solid powder particles are heated and accelerated to high speeds before impacting the substrate, undergoing plastic deformation and forming a bond. Experimentally determined process parameters are established for each material system. Traditional methods use constitutive equations to predict particle deformation, but require adjustment of parameters based on experimental data and do not account for important impact events.