What Is Multi Flexible Body Dynamics (MFBD)?

Before we can talk about Multi Flexible Body Dynamics, we need to explain what Multi Body Dynamics is.

Many products such as automobiles, heavy machinery, office equipment, space structures, robots and other types of machines have mechanical and structural systems that consist of multiple, interconnected components.

The dynamic behavior of these multi body systems is often highly nonlinear.  This presents a problem for the engineers designing and  optimizing these systems.  In most cases, these complex problems can only be solved by using sophisticated computer software.


Because of its versatility in analyzing a broad range of applications, multi body dynamics simulation software has grown over the past two decades to be an important tool for the design, virtual prototyping and analysis of complex articulated mechanical systems.

What Is Multi Flexible Body Dynamics?

Traditional multi body dynamics (MBD) approaches have difficulty dealing with the complexity of many current applications. In particular, the need for accurate, realistic results requires that MBD software takes into account that components are not rigid but have a certain flexibility.

Until now, Multi Body Dynamics software solutions have not been capable of handling the large number of degrees-of-freedom (DOFs) typical of FEA models. Consequently, it has been standard practice to reduce the number of Nodal-DOFs through a reduced set of Modal-DOFs: so called “modal reduction.”

However, Modal Reduction is limited to linear analysis of the flexible component.  It is also difficult to simulate contact interactions or impact conditions between flexible bodies.

Stress recovery, based on dynamic deformations, has also been a problem. This has made fatigue analysis difficult to accomplish in the modal approach to multi body analysis.


Fully Integrated FEA

Function Bay has successfully developed a fast Multi-Flexible Body Dynamics (MFBD) solver that integrates Multi Body Dynamics and FEA into one simulation tool.

With RecurDyn you can import complete linear as well as non-linear FEA components into the multi body model. The integrated model is solved as one; co-simulation is no longer needed. RecurDyn calculates the non-linear deformations of the flexible FE components during the MFBD simulation, eliminating all limitations of the Modal Reduction approach.

Stress recovery is performed in one step during post-processing for fatigue analysis. And the full integrated FEA solver enables efficient analysis of contact between both flexible and rigid components.

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