In arc welding based additive manufacturing, the surface topographies of deposited layer are more complex than conventional welding, therefore, the distribution of the electromagnetic force in molten pool, arc pressure, plasma shear stress and heat flux on molten pool surface are not the same as the conventional welding. A three-dimensional weak coupling modeling method of the arc and metal transport is developed to simulate the arc, molten pool dynamic and droplet impingement in arc welding based additive manufacturing. In the arc model, the molten pool is simplified to be solid state on the ...