A beam to 3D model switch in transient dynamic analysis

Abstract

International audienceTransient structural dynamic analyses often exhibit different phases, which enable one to use an adaptive modeling. Thus, a 3D model is required for a better understanding of local or non-linear effects, whereas a simplified beam model is sufficient for simulating the linear phenomena occurring for a long period of time. This paper proposes a method which enables one to switch from a beam to a 3D model during a transient dynamic analysis, and thus, allows one to reduce the computational cost while preserving a good accuracy. The method is validated through comparisons with a 3D reference solutioncomputed during all the simulation

Assessment of 3D modeling for rotor–stator contact simulations

“…One can use an explicit scheme. Another way to reduce the computational time consists in using a strategy which enables us to switch from the 1D model to the 3D model when contacts occur, as proposed by the authors in Tannous et al [35]. This enables us to combine the advantages of 1D and 3D models.…”

“…This may well be due to the somehow high computational cost engendered by such models. To reduce this computational cost, the 1D and 3D dynamical model coupling was the main concern in Tannous et al [35] but no 3D contact modeling was addressed at that time.…”

A beam to 3D model switch for rotor dynamics applications

“…. A projector matrix P, introduced in Tannous et al [36] and recalled in Appendix A, can be defined to transform the beam displacement vector into a 3D rigid body displacement per beam section P . Since the beam and the 3D solution are expressed in different frames, the beam solution is first transformed to the rotating frame by Eq.…”

“…At a consequence, they initiate, at the switch instant, a transient stage with high frequency oscillations, mostly on the accelerations of the 3D solution. To stabilize the solution after switching, and as proposed in Tannous et al [36], one can filter these high frequency oscillations by introducing a numerical damping in the time integration scheme (HHT integration scheme Hilber et al [42] for example), or make velocities and accelerations corrections (triple static switch procedure also discussed in Tannous et al [36]). This later method, proved to be efficient, eliminates completely the transient stage and provides a stable 3D switch solution.…”

“…Narasimhan and useful to model non-linearities restricted in space. This approach has been proposed in Tannous et al [36,37] for transient dynamic applications excluding overall rotations, based on the PhD of Tannous [38].…”