Silent Running – vibro-acoustic metamaterials for the vibration reduction of launcher structures.

VIBRO-ACOUSTIC METAMATERIALS, PASSIVE VIBRATION REDUCTION MEASURES, VIBRATIONS IN LAUNCHER STRUCTURES

Reduced vibrations boost the economic and technical efficiency of launcher structures. (© Fraunhofer LBF)

The aim of the Silent Running project is to integrate innovative vibration-reducing functions into the new generation of fiber composite structures for the aerospace industry. The intention is to reduce the transfer of undesired vibrations using vibro-acoustic metamaterials. Within the scope of the project, a strategy for the design and layout of vibro-acoustic metamaterials is to be developed, experimentally validated and compared with conventional vibration reduction measures.

Vibro-acoustic metamaterials as a passive vibration reduction measure

One of the current research topics at Fraunhofer LBF is the design of vibro-acoustic metamaterials for passive vibration reduction. Metamaterials are artificially manufactured structures which consist of several individual elements. Each individual element is a spring-mass system showing a resonance for a defined frequency. The vibration reduction is enabled through the local resonance effect, with relevant dynamic parameters to be tailored to each other. The mass and rigidity properties are defined by the geometric structure designed for individual elements and the base material used. In the defined frequency ranges, vibration amplitudes can be significantly reduced compared to conventional measures (see Figure 1).

Figure 1: Vibration-reducing effect due to metamaterials compared to the conventional absorbers. (© Fraunhofer LBF)

Metamaterials in and beyond space travel

The launcher structures are exposed to highly diverse vibration burdens depending on the start phase. Structural vibrations occur throughout the start. These vibrations are dangerous for sensitive electronics or the transported load capacity.

The project is intended to investigate the extent to which vibro-acoustic metamaterials can be additionally designed on the load-bearing structure or directly as a load-bearing structure, and the extent to which the vibrations which occur can be reduced. The development of this technology and its use in commercial space travel is carried out in collaboration with MT Aerospace AG. Fraunhofer LBF intends that it be used by means of a technology transfer to other sectors besides space travel.

Design and numerical layout

The work carried out at Fraunhofer LBF focuses on the design, layout and numerical investigation of vibro-acoustic metamaterials. Three strategies were defined in collaboration with MT Aerospace AG. The vibration-reducing effect is to be validated based on experimentally realized demonstrators. Analytic as well as numerical models are assembled to coordinate the dynamic properties of unit cells. The final demonstrator will form a scaled upper stage and show the potential of vibro-acoustic metamaterials.

Sponsors and partners

This project is supported by:

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