Production and Characterization of Porous Materials with Customized Acoustic and Mechanical Properties

An overriding objective of the CRC 880 was to reduce noise of future civil aircraft. It was shown that the usage of porous materials can effectively reduce aircraft noise. They are used at the trailing edge replacing a section of the solid wing surface. In order to improve the acoustic properties of these materials, a rolling process was established which allows grading of the material. Initially, it was unclear how well the technique could be applied to porous materials and what effects it would have onto their structure and properties. A porous aluminum as well as a sintered fiber felt was investigated, which showed good results in the acoustic wind tunnel (AWB at DLR Braunschweig) in the unrolled state. In this article it is shown that the rolling process is very well suited to change porosity and thus properties of porous materials in a targeted manner without negatively affecting the mechanical stability. Both, the influence of cold rolling on the porous structure and the mechanical properties were investigated.