Multi Flexible Body Dynamics (MFBD) 글 편집
Multi Flexible Body Dynamics (= Flexible Multi Body Dynamics)
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 combines with MBD (Multi-Body Dynamics) to analyze the motion of rigid bodies and FEM (Finite Element Method) to analyze the motion, stresses, and deformation of flexible bodies. RecurDyn’s solver combines with these two components into a single solver. This provides RecurDyn with a much faster and much more robust solver than could be achieved through co-simulation.
Two flexible body formulations are supported in MFBD in RecurDyn. One is the method of modal synthesis, 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 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 and large-strain rubber-like hyperelastic materials. RecurDyn’s powerful multi body dynamics analysis environment combines both the modal and the nodal methods into the same solver, giving RecurDyn an incredibly robust, fast, and reliable solver.
Furthermore, 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 code to incorporate a mesher, allowing the user great flexibility and convenience in MFBD modeling and analysis.
The guideline to choose FFlex and RFlex
MFBD (Multi Flexible Body Dynamics) modeling and analysis highlights
- Flex 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.
1-hour webinar to explain what Multi Flexible Body Dynamics (MFBD) is and how to use MFBD with RecurDyn
This webinar about MFBD introduces how Flexible Bodies can be used in Multi Body Dynamics.
Please don't miss this if your system includes deformations or vibrations with flexible bodies in motion.
After you watch this webinar, you can understand how to use Multi Flexible Body Dynamics.
MBD (Multi-Body Dynamics) Analysis
A Multi-Body Dynamics analysis is the analysis of the motion over time of a system of rigid bodies interconnected by joints and acted on by forces, and possibly driven by user-defined motions of specific bodies in the system. The forces acting on the bodies can be inter-body forces, like springs or contact, or externally applied forces, such as gravity or a driving force. RecurDyn provides an intuitive, easy-to-use environment for modeling and analyzing Multi Body Dynamics.
Features of MBD (Multi-Body Dynamics) Analysis in RecurDyn
- Simple and easy to model a specified motion, force, joint, or contact.
- Intuitive modeling and composition of mechanism elements and configurations of mechanical systems.
Example of a Multi Body Dynamics Model (MBD model of Clutch)
If you are unable to watch this video, click the link below.
(Watch youku video)
MFBD (Multi Flexible Body Dynamics) Analysis
Features of MFBD (Multi Flexible Body Dynamics) Analysis in RecurDyn
- Rigid and flexible bodies can be easily connected together in the same model.
- The number of bodies to be treated as flexible can be adjusted, as well as the flexible body formulation between the modal and nodal methods. This allows for simulation time to be optimized based on the needs for fidelity in the results.
- Boundary conditions and forces applied to the flexible parts are controlled much more naturally and much more accurately than they are using rigid bodies to estimate the forces to be applied to isolated parts in finite element analysis afterward.
- Connections, joints, and force elements are preserved when converting a rigid body to a flexible one.
- A rigid body in a RecurDyn model can be easily replaced with a mesh from other FE software.
Example of a Multi Flexible Body Dynamics Model (MFBD model of Clutch)
If you are unable to watch this MFBD video, click the link below.
Note:
Multi Flexible Body Dynamics (MFBD) is also called:
Flexible multibody dynamics (FMBD) or Flexible Multi Body Dynamics
Sometimes, it is referred to as FEA-MBD coupling or FEA-MBD coupled simulation.
Features & Advantages
Differentiators 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 are supported.)
- Support for noise source analysis using ERP in Acoustics toolkit
Features & Advantages
Joint Connections & Contact
- The same Joint connection element can be used for Rigid-to-Rigid, Rigid-to-Flexible or Flexible-to-Flexible bodies when performing an MFBD simulation.
- The contact can be defined between Rigid-to-Rigid, Rigid-to-Flexible, or Flexible-to-Flexible bodies.
Self Contact
- Self-Contact can be defined within one flexible body. The results of stress, strain, and deformation of the flexible body caused by the contact due to the dynamic behavior can be checked through dynamic simulation.
Nonlinear Flexibility
- It is possible to perform a simulation of a flexible body with large deformation caused by the force transmitted from the dynamic behavior. You can also check not only animation but also quantitative results (Contour, Plot).
Accurate Loading Conditions
- Dynamics simulation can be performed by transmitting external complex forces such as joints, forces, and contact generated by dynamic behavior to one flexible body. As a result, you can check the results of stress, strain, and deformation acting on a specific flexible body belonging to the mechanical system by the dynamic behavior of the entire mechanical system to be analyzed.
Mesher
- RecurDyn is the first dynamics software to have its own mesh engine, providing a more convenient MFBD environment. Through the AutoMesh function tin the mesh engine, the process of converting a rigid body to a flexible body in order to extend from MBD to MFBD can be performed easily and quickly with justone click.
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Since it also supports various elements as follows, it enables fast and accurate MFBD simulations by effectively meshing complex geometries.
- 2-node beam (Beam2)
- 3-node tri shell (Shell3)
- 4-node quad shell (Shell4)
- 4-node tetra (Solid4)
- 5-node pyramid (Solid5)
- 6-node wedge (Solid6)
- 8-node hexa (Solid8)
- 10-node tetra (Solid10)
Applications
Parking Brake
- Toolkit Used : FFlex, Professional
- Objective : Improve the design of a highly stressed part in an automobile parking brake system to increase its durability.
- Modeling Methodology : The parts that have relatively high stiffness and low fatigue are modeled as rigid bodies and the highly stressed part is modeled as flexible body. Contact is used to model the connection between the flexible body and a rigid body where the most significant fatigue occurs.
If you are unable to watch this video, click the link below.
Landing Gear
- Toolkit Used : FFlex, Professional
- Objective : Estimate the fatigue and reliability of aircraft landing gear by analyzing its dynamic behavior as the airplane lands.
- Modeling Methodology :The interaction of the landing gear strut and the support arms is modeled using kinematic joints, and the interaction of the inner and outer struts of the landing gear, which are both flexible bodies, is modeled using flexible-to-flexible body contact.
If you are unable to watch this video, click the link below.
Double Valve Spring
- Toolkit Used : FFlex, Professional
- Objective : Verify the dynamic behavior, stress, strain, and deformation of double valve spring experiencing contact between a cam and the valve assembly, which contains a double value spring.
- Modeling Methodology : The spring is modeled as a flexible body, and self-contact is used in the double value spring to capture the interaction of the spring windings when the spring is compressed.
If you are unable to watch this video, click the link below.
Manufacturing Robot
- Toolkit Used : FFlex, RFlex, Professional, CoLink
- Objective : Examine the relationship between the driving torques applied at the joints of the robot arm and the contact forces between the gripper and the object.
- Modeling Methodology : The driving torque was desired that maintained an acceptable level of contact forces acting on the object. FFlex (the nodal method) was used to model the parts in contact to capture the effect of the acceleration of the arm on the contact with the object.
If you are unable to watch this video, click the link below.
Printer
- Toolkit Used : FFlex, RFlex, Belt, MTT3D, Professional, CoLink
- Objective : Verify the vibration of the ribbon cable and case of an inkjet printer while printing a page when the carriage is moved by a belt drive system.
- Modeling Methodology : The flexibility of the printer case is important to the objective, but it experiences relatively little deformation. Therefore, it is modeled using RFlex (the modal method). The ribbon cable experiences very large nonlinear geometric deformation. Therefore, it is modeled using FFlex (the nodal method). Also, the carriage drive belt is modeled as an FFlex flexible body using a shell belt and the paper is modeled as an FFlex flexible body using MTT3D.
If you are unable to watch this video, click the link below.
Paper
- Toolkit Used : MTT3D
- Objective : A simulation is used to predict the stacking behavior of paper as it passes through the rollers of a printer, while including the effect of air resistance on the dynamic behavior of the paper at a high feed rate (60 pages per minute) in a laser printer.
- Modeling Methodology : The shape of the rollers is specifically designed to bend the paper laterally as the paper passes through them. This increases the longitudinal stiffness of the paper as well as increases the effect of air resistance, both of which are important to the stacking of the paper as it leaves the printer. MTT3D’s sheet shell paper elements, which are modeled using the nodal method, can accurately capture the stiffening response of the paper due to the bending imparted by the rollers.
If you are unable to watch this video, click the link below.
Wind Turbine
- Toolkit Used : FFlex, RFlex, Professional, Gear, Bearing
- Objective : The stresses in the blades of a windmill for wind power generation are estimated through a dynamic simulation of a windmill complete with transmission and generator assembly.
- Modeling Methodology : The blades experience small deformation, so accurate stresses and deformation can be predicted using RFlex (the modal method). The bearings and the gears are modeled as rigid bodies, while the planet gear carrier is modeled as a FFlex body to capture the effect of the complex loading conditions it experiences.
If you are unable to watch this video, click the link below.
Note:
Multi Flexible Body Dynamics (MFBD) is also called:
Flexible multibody dynamics (FMBD) or Flexible Multi Body Dynamics
MFBD Solution
RecurDyn’s MFBD solution allows convenient and easy modeling of MFBD and its effective analysis. An MBD model can be easily converted to an MFBD model through the use of the RecurDyn’s Auto Mesher. Durability analyses can be easily performed using the results of an MFBD simulation. MFBD has been directly embedded into various other toolkits as well, such as RecurDyn/MTT3D and RecurDyn/Belt.
(MFBD = FMBD (Flexible Multibody Dynamics))
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Modeling and Analysis Process in MFBD
