In this book, an innovative type of yielding damper is introduced having aluminum panels and stiffened using steel stiffeners. Dampers are the first elements in the structures which respond to seismic forces, prevent from destructive damage to other main elements of structure and reduce the costs related to structural improvement. A comprehensive numerical study is employed in this study. The aluminum panel, its peripheral steel frame, and steel stiffeners are modeled in ABAQUS software. Each of the square and rectangular frames is investigated using six different stiffeners. The panels are considered to be under harmonic load; energy absorption is calculated for every cycle and the results of square and rectangular panels are compared with each other. The best rectangular panel is the panel with two horizontal and vertical stiffeners (RP-3), and the best square panel is the panel with two horizontal and vertical stiffeners (SP-3). Rectangular panels show better behavior than square panels for energy absorbing. Even in some cases, rectangular panels without stiffeners can be used instead of square panels with stiffeners.