The influence of low velocity repeated impacts on residual compressive properties of honeycomb sandwich structures

This paper describes the low velocity impact behavior of repeatedly impacted honeycomb sandwich structures which are used in aircraft interiors comprising of unidirectional glass fiber reinforced epoxy composite face sheets and aluminum honeycomb core. Impact energies, maximum loads and the permanent deflection of honeycomb sandwich structures were determined with instrumented drop weight impact test machine to evaluate the repeated impact performance and damage resistance. On the other hand, the preliminary single impact loading tests also performed in order to find the energy levels which were ranged fully elastic energy level to perforation energy level for sandwich composites. Impact test results obtained from repeatedly impacted honeycomb sandwich structures were correlated with a function of force-time, force-deflection and energy-number of impacts curves. This work is also focusing on the residual compressive properties of single and repeatedly impacted honeycomb sandwich structures. Shimadzu AG-X test machine with a load cell of 10 kN was used for compression after impact tests (CAI). The values of residual compressive strength of the single and repeatedly impacted honeycomb samples were compared with the undamaged honeycomb samples according to compressive load-displacement curves.