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2730 |
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Thursday, September 29, 2011, Saal B2.1 9:00 AM Modeling & Simulation 3 |
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Development of analytical model to predict cold spray critical velocity from 3D-FEM simulations |
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Ramin Ghelichi* / Politecnico di Milano, Italy Mario Guagliano / politecnico university di milano, Italy Sara Bagheri/ politecnico university di milano, Italy Andrea Trentin/ Associazione Civen, Italy Simone Vezzù/ Associazione Civen, Italy Silvano Rech/ Associazione Civen, Italy |
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The bonding of particles in cold spray coating is due mainly to their kinetic energy upon impact. Experimental investigations reveal that successful bonding is achieved only above a critical particle velocity. The bonding of particles in cold gas spraying is presumed to be the result of extensive plastic deformation and related phenomena at the interface. Generally for a given material, there is a critical velocity in which a transition from erosion of the substrate to deposition occurs. In this study, based on the well recognized hypotheses that the critical velocity is related to adiabatic shear instability induced by high strain rate deformation during the impact, a numerical model of cold spray process is developed using a 3D-FEM-model. Single particles are assumed to impact the substrate in normal direction with given impact velocity and temperature. The MieGruneisen equations of state and JohnsonCook model were used to describe elastic and plastic model of material. The aim of the study is to develop an analytic model able to predict the critical velocity from impact simulations. The problem of detecting the critical velocity using the discrete output of numerical simulation has been solved applying Wavelet transformation and the second derivative of the physical parameters in Sobolev space. Experimental tests are carried out in order to confirm the mathematical model measuring in-flight particle velocities and cold spray deposition efficiency. |