Composite Material That Stops Vibrations and Noise

Vibrations and noise create significant challenges in engineering and construction, as continuous oscillations can cause damage to machinery and buildings, while the resulting noise negatively affects human health and well-being. Traditionally, engineers reduce these problems by using damping materials such as foam, rubber, and mechanical shock absorbers. However, these conventional solutions often make technical applications much bulkier, heavier, and costlier. Moreover, it is extremely difficult to find materials that are rigid, load-bearing, and at the same time capable of providing effective internal damping, since stiffness and damping are generally considered to be opposing properties. In response to this global need, researchers at ETH Zürich have developed a groundbreaking composite material that combines these seemingly incompatible properties.

The foundation of this new composite, developed by researcher Ioanna Tsimouri as part of her doctoral thesis, is based on a highly specific structural composition determined through extensive computer modeling. The material consists of thick, stiff layers made from glass or silicon—of the type used in standard smartphones—bonded together with ultra-thin, rubber-like interlayers made of cross-linked polydimethylsiloxane (PDMS). Theoretical calculations revealed that in order to achieve an ideal balance between stiffness and damping, the rigid glass or silicon must constitute at least 99 percent of the total volume, while the polymer damping layer must make up less than 1 percent. When the polymer layer is too thin, the damping effect disappears, whereas when it is too thick, the composite loses its required structural stiffness. For this reason, the polymer interlayers must be only a few hundred nanometers thick.

The transition from theoretical calculations to laboratory application required the development of a special and highly controlled production process, since the PDMS polymer mixture reacts very quickly once the catalyst is added. Before beginning extensive mechanical testing, Tsimouri had to meticulously verify the thickness of these nanometer-scale layers using scanning electron microscopes. To evaluate the frequency- and temperature-dependent properties of the material, the team conducted three-point bending tests as well as practical drop tests. When the new laminate was dropped from a height of 25 centimeters onto a hard surface, it landed flat and almost silently without bouncing, demonstrating remarkable stability and acoustic damping performance. A piece of pure glass of similar size, on the other hand, fell with a loud noise, bounced back up, and flipped over.

The successful development of this load-bearing, vibration-damping laminate opens the door to a large global market spanning various industrial applications. The material can be integrated into everyday structures such as window glass and machine housings, as well as used in specialized components in the automotive, aerospace, and sensor technology sectors.

Academic Reference / Journal Reference: Tsimouri IC, Caseri W, Hine PJ, Gusev AA. Lightweight silicon and glass composites with submicron viscoelastic interlayers and unconventional combinations of stiffness and damping. Composites Part B 284 (2024) 111717. Doi: external page10.1016/j.compositesb.2024.111717

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