Metallic hollow sphere structures - Examples for future noise reduction applications

Recently, structures made of metallic hollow spheres (Metal Hollow Sphere Structures, MHSS) were successfully tested as sound absorbers for the reduction of noise in several applications, e.g. as silencers and enclosures. Advantageous properties of this new absorber material are the high temperature resistance and the high mechanical strength. Self-supporting structures without any additional housing will be possible in future. Furthermore, the high heat resistance of MHSS made of special steels and the gas permeability of the structures will allow the creation multifunctional components such as combined mufflers and diesel soot filters and/or mufflers and catalysts. Thus metal hollow sphere structures will enable engineers to strike new paths in the design of noise reduction components in engineering and vehicle construction. Using an absorber model and measurement data for characteristic values of the structures, an effective acoustic design was carried out. Excellent sound absorbing properties can be expected from MHS for a variety of applications. In this presentation an overview of results for several application areas such as multifunctional mufflers for passenger cars, mufflers for combustion engine driven machines, and enclosures for high speed milling heads will be given