This paper investigates the use of Galfenol (FeGa) composite beams as solid-state, adaptive vibration absorbers that have an electrically-tunable sti ness. The study encompasses the manufacture of these structures by ultrasonic additive manufacturing (UAM) and the formulation of a continuous model for the beams' bending vibrations. The beams' 1st and 3rd resonant frequencies are calculated as a function of base acceleration, Galfenol volume fraction, and DC magnetic eld. The e ects of an axial force, viscoelastic material damping, beam nonuniformity, and Galfenol's nonlinear behavior are incorporated. Autoresonant feedback control is used as a numerical technique to maintain the resonant state under changes in the inputs. The model is validated by comparing (1) calculated and analytical frequency responses and (2) calculated and measured resonant frequencies and modes shapes of a Galfenol/Al 6061 composite beam that was manufactured using UAM. The modeling results show that by varying the DC magnetic eld, the resonant frequency can be tuned between 3 % and 51 % for Galfenol/Al 6061 composites containing from 10 % to 100 % Galfenol by volume, respectively. The magnitude of this change will increase for composites that have a softer matrix. The axial force was found to have only a small e ect on the maximum resonant frequency tunability, but, for high Galfenol volume fractions, was also found to broaden the region over which tuning can occur.