Optimization of the acoustic performance of Polyimide foams

摘要

Due to their low weight, high fire resistance and good mechanical strength, SOLIMIDE®rnPolyimide foams are good candidates for sound packages in aerospace sound transmissionrnapplications. However, their high resistance to airflow limits the sound absorptionrnefficiency inside a double wall structure and thus the sound transmission loss of thernstructure. The paper discusses two concepts to improve the transmission efficiency of suchrnmaterials for double wall applications: (i) improving its sound absorption behavior byrnremoving mechanically or chemically the cell membranes and thus decreasing both thernflow resistance and tortuosity, (ii) coupling the Polyimide foams to screens (porous orrnimpervious) to improve the transmission loss in targeted frequency bands.