Atomistic Simulation of Ultrasonic Welding of Copper

Abstract

Molecular dynamics simulations of ultrasonic welding of two blocks of fcc copper containing asperities under the conditions of a constant clamping pressure and sinusoidal shear displacements were performed. Two different atomistic models of blocks were simulated: Model I with no misorientation between the lattices, and Model II with a special misorientation of 78.46°. Alternating shearing results in a plastic deformation of the interface layers and is accompanied by the emission of partial dislocations. Misorientation between the joined blocks contributes significantly to an interface sliding, interface migration, and pores healing during ultrasonic processing. A significantly larger increase in temperature occurs during shearing in Model II than in Model I. The applied pressure has almost no effect on the interface temperature in both studied models. The temperature increases almost up to maximum values after the first shear cycle, and then practically does not undergo changes in the next four cycles. The temperature at the interface in Model II is significantly higher than that in Model I. The change in the porosity of the interface and its structure are analyzed. The results obtained in the present work contribute to a deeper understanding of the processes occurring at the atomic level during ultrasonic welding of metals.