Vibrations With Adaptronics Take The Swing

The container ship slowly leaves the quay. The diesel two-stroke engines boom inside. 60,000 kW of power make everything vibrate: the connections on the engine, the high-pressure lines for fuel and lubricating oil, the drive train, stairs, steps, floors and ceilings made of steel - simply everything. The vibrations are transmitted to the entire hull. "A massive problem: The vibrations not only interfere, they also damage important components of the ship," says Dipl.-Ing. Heiko Atzrodt, scientist at Fraunhofer LBF in Darmstadt. However, this problem does not only exist with ships - unwanted vibrations also lead to costly failures in machines and systems, for example, when components can no longer withstand the loads.

Simulate vibration reduction on the computer

This can be remedied by adaptronic systems: they help to reduce vibrations. Fraunhofer LBF has programmed simulation software that can be used to efficiently develop these systems: the Mechanical Simulation Toolbox. “For the first time, simulation software for adaptronic systems is available. To date, there has been no continuous development process for such systems. Corresponding software has so far only been available as stand-alone solutions,”said Atzrodt.

The software can be used to simulate passive and adaptronic systems for reducing vibrations on the computer. No additional electrical energy is introduced in passive systems. They work through their structure alone. Springs and additional masses, for example, reduce the vibrations of bridges, engine or gearbox bearings by modifying the transmission paths. "However, there are limits to these systems, especially for mobile applications, since they cannot be as big and heavy as they want," explains Atzrodt. Then adaptronic systems come into play.

Three toolboxes complement Matlab / Simulink

These components convert supplied electrical energy into mechanical energy and thus actively counteract the vibrations. As a result, they are more efficient despite their lower weight and smaller size. The Fraunhofer LBF toolbox simulates the vibrating and the required adaptronic system. Starting with the simple model, the virtual system can later be complexly constructed.

A total of three toolboxes are available, which were written for Matlab / Simulink and are intended to sensibly expand these programs. This means that all options of Matlab / Simulink are available to the user, as well as the blocks and functions of the Mechanical Simulation Toolbox. According to Atzrodt, the combination offers a good opportunity to implement the simulation strategy for the design of passive and active measures, because adaptronic systems can be designed step by step on the computer. “This saves time and money for expensive prototypes. Systems can be optimally designed right from the start,”Atzrodt mentions as advantages. The simulation environment is not limited to shipping. “It can be used wherever vibrations occur,” says Atzrodt.

The software consists of three packages:

• Structure and Vibration: The Structure and Vibration Toolbox was created for the design and analysis of passive measures to reduce vibrations. In combination with the Smart Structure toolbox, semi-active and active systems can be mapped.
• Ansys-Matlab Interface: The Ansys-Matlab Interface Toolbox links the possibilities of the FE tool Ansys with Matlab / Simulink. With the toolbox, Ansys models can be reduced and co-simulations implemented in different ways.
• Smart Structures: With the Smart Structures Toolbox, the Structure and Vibration Toolbox is supplemented by the possibility of simulating semi-active and active systems. The toolbox will appear in the next few months.