The group Machine Dynamics and Vibration Technology develops and applies methods and procedures for the dynamic design and optimization of mechanical systems. A holistic approach consisting of adequate modelling, realistic excitation processes and validation by means of measurements and test bench tests is pursued. These methods can be used to solve a variety of technical problems in different industries. Application-oriented questions are worked on in cooperation with manufacturers and users.
The technical and economic demands on machines are constantly increasing. Rising energy costs and the associated economic significance of energy consumption have led to an increased use of the design principles of lightweight construction in conjunction with the calculation concept of operational stability. A prerequisite for a light, energy-saving and at the same time safe design is that the load collectives used for the operational stability calculation correspond to operational loads.
Modern simulation tools such as multi-body simulation (MBS) and the finite element method (FEM) enable the simulation-assisted design of dynamic systems. The system behaviour during operation and the resulting loads on the components can be calculated using MBS. Sufficiently accurate models and representative application scenarios are required for this. The FEM can be used to determine the stresses in the components. The IGMR researches how the simulation scenarios have to be designed in order to calculate representative loads and strains with the least possible simulation effort.
The design of gear units with non-uniform transmission ratios usually takes place with regard to the movement task to be performed. The necessary lengths and distances of the mechanism are determined in such a way that it can fulfil the movement task. In dynamic synthesis, dynamic aspects are considered in addition to fulfilling the movement task. Aside from length and distance, the mass and inertia of the links are also adapted. In addition to fulfilling the movement task, other objectives can be pursued as early as the design stage: These can be the reduction of vibration excitation, the forces acting on the frame or joints or the reduction of energy consumption. The last aspect in particular is the focus of current research at the IGMR: For example, a process is currently being developed for the synthesis of particularly energy-efficient mechanism-servomotor combinations.
In processing machines, such as textile or packaging machines, complex movement tasks often have to be implemented. In many cases, non-uniform mechanisms are used. The subsequent increase in the operating speed of such machines, usually with the aim of increasing productivity, often leads to vibration problems. These can manifest themselves in vibrations of the entire machine, the drive train, individual components, or in the overload of the drive. With the help of the measurement technology available at the IGMR, problems at the machine can be analyzed, causes identified and countermeasures derived. The IGMR can rely on many years of experience in the design implementation of countermeasures, such as the reconstruction of vibration-prone components or the mass or power compensation of mechanisms.
Due to rising energy prices, the energy efficiency of industrial robots is gaining in significance. A promising approach to reducing the energy consumption of repetitive movements, such as those found in the packaging industry, is the targeted use of the dynamic properties of the robot. For this purpose, elastic elements are introduced into the robot structure, which are tuned in such a way that the proper movement of the system corresponds to the desired trajectory. However, this method allows only a specific movement between fixed start and end points to be generated. In order to apply this concept in practice, real-time capable path planning algorithms are required, which allow the dynamic properties of the system to be used at any start and end points.
The four-unit crank gear is a basic kinematic structure that forms the basis of the kinematic structure of numerous mechanisms. Crank gears are used, for example, as a guide gear to guide a tool on a certain path or as a transmission gear to create a fixed connection between the drive position and the output position.
Non-uniform transmissions in combination with controlled drives are used, for example, for motion tasks in which the temporal course of the output motion along the path curve is changed. In the case of fast-running transmissions with uneven transmissions and, in particular, those designed in a lightweight design to reduce drive power, the flexibility of individual components results in undesired vibration movement.
An uneven pattern of wear occurs in an existing tire testing machine, which essentially serves to examine the wear behaviour during constant speed driving in the speed range of 80 to 120 km/h with adjustable camber, track, wheel load and torque. This leads to the conclusion that vibrations occur in the drive train of the tire testing machine.
Two-drum winders are used for cutting and winding a wide variety of papers. Figure 1 shows the schematic structure of a two-drum winder. A web tension is created between unwinding and support rollers in the paper web to guide the paper web through the cutting section without defects and creases, where the paper web is cut lengthwise. In order to counteract the formation of wrinkles before the cutting section, the paper web is stretched crosswise to the paper running direction and then rolled up continuously on individual cores.
In the past, the technical and economic demands placed on rail vehicles have grown steadily. The increased energy costs and the associated economic significance of energy consumption in vehicle operation have led to an increased use of the design principles of lightweight construction in conjunction with the calculation concept of operational stability. A prerequisite for a light, energy-saving and at the same time safe design is that the load spectra used for calculating the fatigue strength correspond to the loads that arise in subsequent use of the vehicle.