## Theory

A multibody system consists of rigid and flexible bodies. These bodies can be connected to each other by constraints or force elements. Once the system is set up, either a static or dynamic solver is used to calculate the states of the system.

## Relevance of multibody simulation

Regarding the increasing complexity of technical systems in modern engineering and science, simulations have become inevitable. Virtual experiments for simulating machines, engines or robots are an essential tool in applied sciences for the design and optimization of structures and machines. The actual physical or mechanical system is replaced by an equivalent system modelled by rigid or deformable bodies, which can undergo large translations and large rotations as well. Therefore, the so-called multibody system consists of interconnected bodies with different material and functional properties. Multibody systems allow the modelling of entire systems of rigid and flexible bodies connected by joints and driven by forces and actuators. The equations of motion for such complex systems are highly nonlinear. Therefore, a numerical solution for the dynamic equations has to be found instead of an analytical solution.

In order to compute deformations or vibrations of flexible bodies, as well as motions of entire multibody systems, computer-aided methods have to be used. Many software tools have originated from academic research from different groups leading to different strategies concerning problem setup and solving the obtained system equations. Many of the commercial software tools offer additional packages, which often originate from application-driven research, regarding e.g. control systems.