What is Multi-Flexible-body Dynamics (MFBD)?

MFBD (Multi Flexible Body Dynamics) in RecurDyn is a technology to analyze the dynamic behavior of systems which include both rigid bodies and flexible bodies. It is the combination of MBD (Multi-Body Dynamics) analyzing the rigid body motion and the Finite Element Method (FEM) to analyze the motion, stresses, and deformation within flexible bodies. RecurDyn’s solver combines with these two components into a single solver. RecurDyn is much faster and more robust than a co-simulation approach.

Two flexible body formulations are supported in MFBD in RecurDyn. One is modal superposition, in which the deformation of a body is represented by a set of linear mode shapes obtained from an eigen analysis of the flexible body. The other is the nodal (or mesh-based) method, in which all nodal degrees of freedom are considered. The nodal method supports both nonlinear geometric deformation as well as nonlinear material formulations, such as plastic strain and large-strain rubber-like hyperelastic materials. RecurDyn’s powerful analysis environment combines both the modal and the nodal methods into the same solver, giving RecurDyn an incredibly robust, fast, and reliable solver.

Flexible body meshes can be either imported from externally created FE meshes, or the meshes can be conveniently created directly inside of RecurDyn using its built-in mesh engine. RecurDyn is the first Multi-Body Dynamics analysis software to incorporate a mesher, allowing the user flexibility and convenience in MFBD modeling and analysis.

MFBD modeling and analysis highlights

  • FFlex and RFLex can be used at the same time.
  • Mesh-Pre-Solve-Post (one-stop process) within RecurDyn
  • Convenient conversion of Body type (Rigid↔Flexible)
  • Existing Joint, Force and Contact connections are preserved when the body type is converted.

Modeling and Analysis Process in MFBD

Differentiators of MFBD

Other features of MFBD • 2D and 3D contacts

  • Boundary conditions can be defined for individual nodes.
  • Support for various rigid body elements (Rigid, Interpolation)
  • Support for various elements (Beam, Shell, Solid, Rigid)
  • Fast analysis using SMP support
  • The results can be output in the FEMFAT format.
  • Nodal flexible bodies can be created by importing mesh data generated externally (ANSYS, Nastran, Design Space formats are supported).
  • Modal flexible body can be created by importing modal analysis results generated by external FEA software (ANSYS, Nastran, IDEAS, RADIOSS/OptiStruct and Simulation Mechanical are supported).

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