FLEXIBLE MULTIBODY SYSTEMS MODELING FOR A DYNAMIC ANALYSIS WITH GEOMETRIC NONLINEARITY

Simulation tools are an open and active research field for analysis of multibody systems, as it permits time and cost reduction in the design process of mechanical systems. During the last years, the authors have developed a method for the analysis of rigid-flexible multibody systems. The flexible bodies are modeled by means of the floating frame of reference formulation. This group of methods works with two kind of coordinates, elastic and reference coordinates, which allow us to consider separately the movement of large and small amplitude. It is the most widely used group of methods in the computer simulation of flexible multibody systems and they are accurate considering small deformation hypothesis behavior of the components. With large flexible components rotating to high speed, the small deformation hypothesis behavior are no longer admissible and the second order effects are determinant in the movement prediction. This work investigates the geometric stiffness phenomena modeling in the analysis of flexible multibody systems with a double objective, the accurate determination of the stress field and the achievement of real-time performance on conventional PC platforms. A system where this geometric nonlinearity is relevant is analyzed. Two proposals are explored, incrementing the number of axial deformation modes and considering the foreshortening effect, respectively, in order to improve the accuracy and the efficiency of the current formulations.