The UM FEM Module


Click to view enlarged imageThis module lets the user a possibility to introduce into a mechanical system deformable bodies, which are undergone large reference displacement but small deformation. Such an approach makes more exact results in comparison with the multibody simulation. For example the module is useful for the analysis of vibration of car body and bogie frame during the motion of a railway vehicle subject to the influence of railway track irregularities and power generating set. Such models are usually called hybrid.

Flexible bodies are introduced into the UM model with the help of the subsystem technique. Every such a body is presented in the model as a separate subsystem and included into the model on the stage of its description. Flexible bodies can interact with other subsystems of the model including flexible ones by means of joints and force elements of any kind. This approach requires preliminary stage of analysis, which includes modal analysis of a finite-elements model of the body. The module supports import of results of modal analysis from ANSYS, NASTRAN.

Гибридная модель щебнеочистительной машины
Hybrid model of a ballast cleaning vehicle

All kind of tools, which are available for rigid body simulation, are supported by UM core for flexible bodies too. They are online animation during the simulation; coordinates, velocities and acceleration of nodes; reaction forces, etc.

The UM FEM module supports:

Flexible mode of frame of flat platform

Antisymmetric flexible mode

Flat platform in curve

Flexible side frame within a model of a freight car with three-piece bogie
  • visualization of eigenmodes of an flexible body;
  • optional exclusion of some eigenmodes from the final set of modes which presents the flexible body during the simulation of its motion;
  • simulation of the flexible bodies subject to its structural dissipation;
  • optional switching-off flexible properties of bodies and treating the flexible bodies as rigid ones.