Basic mechanical properties of balloon-type TEEK-L polyimide-foam and TEEK-L filled aramid-honeycomb core materials for sandwich structures

The objectives of this study are to investigate the basic mechanical properties of TEEK-L polyimide-foam of a balloon type and TEEK-L filled aramid-honeycomb core-materials for sandwich structures and to compare their mechanical properties with those of AIREX R82 and ROHACELL WF foam core-materials. Compression, tension, and plate-shear tests provided their stress-strain relationships, elastic modulus, and strength. The test results are compared and discussed. The major results obtained are: (1) Filling the aramid honeycomb cells with TEEK-L can improve the basic mechanical properties of an aramid-honeycomb core-material, in particular making them higher than the values expected from the principle of superposition for compression tests and equal to the values expected from superposition for plate-shear tests. (2) The basic mechanical properties of the TEEK-L filled aramid honeycomb are superior to those of AIREX R82 110 and equivalent to those of ROHACELL WF 110, where the three materials have equal densities. (3) The basic mechanical properties of TEEK-L are inferior to those of AIREX R82 60 and ROHACELL WF 51, when materials with equivalent densities are compared. (4) TEEK-L filled aramid honeycomb has high potential as 3 new core material for aerospace sandwich structures.