Multibody Dynamics (MBD)

- Simulated product testing, Accelerated learning -

The principle idea in multibody dynamics is to model multiple bodies that are interacting with each other. Bodies are modelled as geometrical entities with inertia. Bodies can be rigid or deformable. In addition, actuators, hydraulic circuits, friction model and external forces are modeled. As a result of dynamic modeling and simulation, reaction forces and moments together with velocities and accelerations are obtained. Modeling and simulation can also be seen as a learning process and that produces understanding about the dynamical behaviour of the system and shortens the development time by reducing the number of physical prototypes.

Multibody dynamic approach can be used to solve loading history of a complicated system or optimize dynamical behaviour of the system. Also, the multibody approach can be used to simulate cases that are difficult or impossible to test in real life. Below is some examples of cases where multibody simulation can be used.

MBD analysis can be used beneficially in following ways:

  • MBD analysis in product delelopment
    Multibody model is a virtul prototype that can be tested early during product development when no physical prototypes exist.

  • MBD analysis in problem solving
    Seeing the dynamic behaviour of the system helps developers to understand complicated causations of the behaviour. Understanding of why the machine behaves as it does is thus improved. Using traditional methods, the detrimental resonances for system function may be left unnoticed. This may prohibit the use of the machinery or in worst case break it.

  • MBD analysis to obtain loading of the structural system
    Forces and moments in the dynamically complicated structural system are obtained using MBD. These forces can be used in subsequent FE analyses.

Typical results of multibody dynamic simulation are stresses, accelerations and velocities in the bodies and forces in actuators and joints.

We use RecurDyn software for our MBD analysis together with different pre- and post-processing software (SpaceClaim, Ansys Workbench etc.).

Jännitystila hammaskontakatissa.

Stress distribution of the boom during the work cycle.

Kutistusliitoksen jännitystila.

Stress distribution of the shrink fit.

Puominosturin jännitystila kesken työkierron.

Stress distribution of the gear contact.

Stressfield Oy, Laserkatu 6, 53850 Lappeenranta, phone +358 5 412 0300, fax. +358 5 412 0949