RBSDYN

The RBSDYN software is a sizing and analyse tool for bearings (2 and 4 contact spot balls, cylindrical or tapered rollers). The code calculates the load distribution between each rolling element, the origin of the load being either mechanical or thermal, or even the fittings between the rings in their housing and onto the shaft. The load distribution is calculated taking into account the features of the assembly (rigid or elastic preload, external forces, mounting conditions) and the stiffness of the rotor, housing and bearings. The software uses a 2D-axisymmetric finite element (FE) code coupled with a calculation code dedicated to the bearing. This combination makes it possible to take into account the non-linearity of the bearing's stiffness and to use it notably in the dynamic calculation in time step integration.

The loads can be of a mechanical origin (at nodes, by gravity, static acceleration fields, harmonic vibrations, random spectrum and shocks) or of thermal origin specified by a user temperature mapping. The code can also calculate the thermal resistance (in K/W) of each row of balls in the bearing regarding its mounting conditions and the model thermal environment. This feature is particularly useful to get the bearing thermal coupling and use it in the mechanism's thermal model.

RBSDYN uses business models resulting from the CNES' acquired expertise to represent the behavior of links between rotor or stator nodes such as spacers and hoops. The software allows the importation of mass, stiffness and damping matrices defined by the user or condensed on a given number of nodes following the super-elements technique . It also models specific elements such as flexible membranes and infinitely rigid bodies.

RBSDYN calculates the stiffness of the bearings and of the complete model. The software performs the modal analysis of the model from the linearised model according to the current static equilibrium state. This step allows to optimize the bearing definition with respect to the external loads (regarding the amplification on the eigen frequencies) and the targeted bearing endurance (regarding the limited Hertz's pressure).

RBSDYN calculates the displacement field either in linear resolution or by integrating it numerically by time steps. As an output, the software provides the results of bearing parameters such as Hertz pressure at each contact spot, ball crushing or gapping and the contact ellipse truncation.

It is also possible to specify parameters' value ranges on which the code makes a series of calculations to analyse the sensitivity of each one over the main results. All results can be exported in a spreadsheet format.