Browsing by Subject "plastic model"

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An Elasto/Plastic Model of the Ultrasonic Additive Manufacturing
(University of Texas at Austin, 2016) Mao, Q.; Coutris, N.; Fadel, G.M.
Ultrasonic additive manufacturing (UAM) is a solid-state fabrication process that utilizes ultrasonic energy to bond metal foils layer by layer. It has been shown that bond formation is closely related to the plastic deformation of the material at the bonding interface. As a result, a material model is necessary to characterize the elastic and plastic deformation of material under UAM conditions. The existing material models for UAM suffer from the following issues: 1) the models are established based on experimental data of a material different from the material used in UAM. 2) The models have not fully accounted for the influential factors in UAM. Therefore, a new material model is established by modifying the Johnson-Cook model which is known to be simple but effective to capture plasticity at elevated temperature and high strain rate. The model is based on experiments carried out on aluminum 6061-T6 which has been extensively used in the ultrasonic additive manufacturing. Ultrasound-induced effects including strain hardening, strain rate hardening, acoustic softening, and thermal softening are considered in the model. In addition to plasticity, the bond formation/plastic deformation is also profoundly affected by the dynamics of the built feature which has not been considered in combination with plasticity in the existing studies. As a result, a UAM model is established in which both the mechanical and dynamic effects are taken into account. The model is shown to characterize well the plastic deformation at the bonding interface both qualitatively and quantitatively by comparing its predictions with experimental observations.