Multibody Simulation
This page provides an overview of current research projects in the field of multi-body simulation.
Joint project “Intelligent press for automated cold plastic forming (IPakU)”
Sub-project “Adaptive path control with active load-sway damping - IPakU-Reg”
The aim of the “IPakU” research and development project between the project partners Ostseestaal GmbH & Co. KG, the Fraunhofer Institute for Large Structures in Production Engineering IGP and the University of Rostock/LTMD is to further develop the functional model for the automated cold plastic forming of sheet metal, for example for shipbuilding and aircraft construction, which was created as part of the previous joint project “HakU”.
In the predecessor project “HakU”, the Chair of Technical Mechanics/Dynamics at the University of Rostock developed a path control system for the multi-chain crane system based on a mathematical design model. Under idealized conditions, the path control system guides the sheet metal almost exactly along a desired trajectory. If the idealized conditions are not given, e.g. due to external disturbances, parameter and structural errors in the design models or initial conditions that are not consistent with the target trajectory, path deviations occur.
The aim of the “IPakU-Reg” sub-project is to implement a path control system that automatically compensates for these path deviations by means of suitable movements of the crane drives. For this purpose, the movement variables of the sheet metal are continuously measured during the travel movement or estimated using model-based algorithms in order to calculate the required drive movements of the crane system.
The starting point for the control design is a design model of the mechanical controlled system, which describes the kinematic and dynamic properties of the crane system and the payload that are essential for path control.
Joint project “Handling system for automated cold plastic forming”
Sub-project “HakU - Inv: Inverse feedforward control”
The joint project “HakU - Handling system for automated cold plastic forming” between Ostseestaal GmbH & Co. KG, the Fraunhofer IGP and the Chair of Technical Mechanics/Dynamics deals with the development of an automated handling system for a currently purely manually controlled forming process. At Ostseestaal, cold plastic forming in the form of bending is realized using a shipbuilding press with a blade and die. The manual control of this cold plastic forming process results in a number of problems with regard to accuracy and economic efficiency.
The sub-project “HakU - Inv” deals with a mathematical model for inverse feedforward control of the handling system. Two relevant problems arise from the chair's experience with CABLEV and from the analysis of the existing forming system:
- The position of the plate mounted on four chain hoists is not completely geometrically defined (kinematically indeterminate load guidance), resulting in undesirable pendulum oscillations due to the mass inertia of the plate.
- As a result of its own weight forces, elastic deflection of the plate mounted on the four chain hoists occurs. The automated drive control system must therefore take the elastic deflection into account during positioning by adjusting the chain lengths.
Wind turbines are generally designed for a service life of 20 to 25 years. The mechanical structure is designed for this reference service life on a site-specific basis. However, the sites are only roughly classified by the certification guidelines with regard to the loads to be expected there. As a result, the actual loads on the turbines may be lower than assumed during planning. For this reason, many wind turbines have structural reserves even after the end of their reference service life. This means that dismantling the turbines after the end of the reference service life makes neither economic nor ecological sense. At present, wind turbines are being dismantled which, under certain circumstances, could have remained standing and generating electricity for a few more years.
The aim of the project is to determine the individual service life of the mechanical structures of a wind turbine. To do this, it is first necessary to record the actual stress history of the wind turbine support structure during operation. Direct measurement of the stresses on a wind turbine during operation is only possible at accessible points and requires an extremely high level of metrological effort. In this context, it makes more sense to indirectly derive the cyclic stresses from movement variables of the wind turbine that are relatively easy to measure. The functional relationship between the measured variables and the stresses must be determined using suitable numerical structural models. The cyclic stresses determined during the operating time of the wind turbine can be used to derive service life predictions adapted to the respective stress history. The difference between the individual service life prediction and the reference service life then results in the service life reserve that can be used beyond the reference service life.
