The RecurDyn/RFlex toolkit allows RecurDyn to include mode-based Reduced Flex (RFlex) flexible bodies in RecurDyn models. RFlex bodies are a very low-computational-cost method for including flexibility in a model.

RFlex bodies represent the deformation of the body using component mode synthesis (CMS), in which the deformation of the body is represented by a linear combination of vibration mode shapes and static correction modes. RecurDyn/RFlex is useful for modeling flexible bodies in which the total deformation is small and can be well-represented by vibration modes, but in which the body can experience arbitrarily large translation and rotation.

Because the user manually chooses which modes to use to represent the deformation of the body, the number of degrees of freedom of an RFlex body can be very small, and yet represent deformation very accurately.

The modes for an RFlex body can be generated from an FFlex mesh directly in RecurDyn using RecurDyn’s built-in modal eigensolver RFlexGen. RecurDyn/RFlex also allows for importing the modal data to define an RFlex body from third-party modal analysis software (NX/Nastran, ANSYS, ANSYS/DesignSpace, Ideas, MSC/Nastran, Altair OptiStruct, Technostar TSV and Autodesk Simulation Mechanical)

Stress and strain analysis can be performed on RFlex bodies. The stresses, strains, and displacements can be graphed or displayed in contour plots. Fatigue analysis can also be performed on the results directly in RecurDyn using the RecurDyn/Durability toolkit (a separate purchase is required), or the output can be exported for fatigue analysis in FEMFAT.



  •  Efficiently include flexible components within your RecurDyn full-system model.
  • Investigate effects due to the flexibility in the system, including enhanced vibration analysis.
  • Calculate more accurate loads in systems with path-dependent structures, for use in fracture or fatigue calculations.


  • Extracts modal results (FEA linear dynamics) from various FEA software:
    • ANSYS
    • Siemens NX Nastran
    • MSC/Nastran
  • Supports constraint (static correction) modes, due to unit displacement of boundary nodes, created by FEA software
  • Supports attachment (dynamic correction) modes
    • Reduces errors identified during the simulation.
    • Dynamic mode created by RecurDyn
  • These additional modes can overcome the limitations of the modal approach.
  • Saves data in a neutral file that can be archived and reused.




For a technical question please feel free to contact us. Our team will do its best to help you as fast as possible.

Phone: +49 (0)89-322-098-22
Mobile Phone: +49 (0)151-546-171-74


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