Embodiments provide methods and systems for modeling mechanical features of a structural dynamic system. A method according to an embodiment provides, in computer memory, a finite element model representing a structural dynamic system. Next, in a processor coupled to the computer memory, a system of equations with a first term representing a linear combination of a mass, a stiffness, and a damping of the finite element model and a second term representing modal damping is solved. According to such an embodiment, the system of equations is solved using the Sherman-Morrison-Woodbury formula or a preconditioned iterative method. In turn, an improved 3D model of a real world object based on the finite element model is formed utilizing results of the solved system of equations with the finite element model and modal damping to model mechanical features of the represented structural dynamic system.