Non-Smooth Dynamics Method Research Articles

Modelling rotational friction damping devices using the Non-Smooth Dynamics method

The dynamic response of frames equipped with an anti-seismic rotational friction damper is studied. The algorithm of the Non-Smooth Dynamics method (NSD), specifically designed for the numerical simulation of non-smooth dynamical systems, was programmed to efficiently deal with the non-smooth character of the friction law. An extensive campaign of numerical computations was carried out to study different frames, either submitted to a harmonic excitation force or to the ground acceleration history of the El Centro earthquake. Each friction damper has two prestressed bracing bars; the cases of axially rigid and axially compliant bracing bars were considered. Performance criteria enabled to conclude on the optimal range for the maximum moment at the frictional hinge of the damper. For the analyzed frames of one, three and five floors and for both rigid and deformable bracing bars, under the action of the El Centro earthquake, it was concluded that the optimal range for the frictional moment is wide and approximately independent of the number of floors. An important reduction of the relative displacements and absolute accelerations of the floors of the frames with friction dampers was observed with respect to the situation of absent frictional damping.

Modeling and simulation of planar multibody systems with revolute clearance joints considering stiction based on an LCP method

The main objective of this study is to present a general modeling and simulation methodology for planar rigid multibody systems with revolute clearance joints considering the effect of stiction. The normal and tangential contact forces acting at the contact points between the components of the clearance joints are described by a Hertzian-based contact force model and the Coulomb dry friction model, respectively. The equations of motion of the systems are derived on the basis of Lagrange equations of the first kind and the Baumgarte stabilization method. Based on the non-smooth dynamics method, the determination of stick-slip transitions and the calculation of static frictional forces of the contact points are transformed as a linear complementarity problem (LCP), which is solved with an event-driven scheme. Finally, two numerical examples are given as demonstrative applications. The results show that the stiction in the revolute clearance joints influences the dynamic response of the multibody systems.