Niklas Thoma
M.Sc. Niklas Thoma
Mehrkörperdynamik (IWTM)
Current projects
ABSORBED - Acoustic Black holeS fOR viBration rEDuction
Duration: 01.12.2024 to 31.08.2027
Increasing demands are being placed on dynamically loaded systems in terms of durability and comfort. This is particularly evident regarding the NVH (noise, vibration and harshness) behavior of the machines that leads to noise pollution, which can cause mental and physical problems. A general goal research in this field is to effectively avoid vibrations with minimal use of materials, low additional mass and low space requirements.
Conventional vibration reduction methods generally use various stiffening and damping concepts to reduce broadband excitations, whereby a high additional mass often has to be introduced for low frequency ranges in order to achieve sufficient amplitude reduction. If economic aspects and the reliability of vibration damping systems are also taken into account, conventional, established damping concepts reach their limits.
As part of the planned project, the theoretical concept of structure calming with acoustic black holes, which has been tested on a laboratory scale, is to be implemented in practice and made applicable.
The term “acoustic black hole” (ASL) describes a passive method of vibration damping. The starting point is a thin-walled structure in which the thickness of the plate decreases consistently according to a power law as a function of the plate length. This local decrease in stiffness leads to a uniform reduction in shaft velocity. When considering an ideal ASL system with a structure whose thickness tends towards zero, the wave velocity also reaches zero at the end point, thus avoiding reflection. As a result, energy accumulates at this point and can be effectively dissipated by damping effects.
The use of acoustic black holes can be a significant disadvantage as they affect the basic structure by reducing the thickness of the material. This reduction in thickness can in turn significantly limit the protective functions of structures such as enclosures. The static properties of the components are strongly influenced, which represents a major challenge for the design. Consequently, the integration of acoustic black holes has a significant impact on the design of components, which often need to undergo extensive redesign to ensure the required structural integrity and safety.
In order to meet the aforementioned challenges, it makes sense not to integrate the ASL directly into the basic structure of the components, but to apply them as ASL damping elements to the surface of the structure. This approach makes it possible to achieve the desired damping effects without reducing the material thickness of the basic structure and thus restricting potential protective functions.