Energy absorption in aluminium honeycomb cores reinforced with carbon fibre reinforced plastic tubes

The energy-absorbing behaviour of an aluminium honeycomb core reinforced with unidirectional and woven carbon fibre reinforced plastic composite tubes has been investigated experimentally at quasi-static rates of strain. Small diameter carbon fibre reinforced plastic tubes, with chamfered ends, were inserted into the cells of an aluminium honeycomb in order to yield a lightweight energy-absorbing material. The resulting data are compared with crushing tests on arrays of free-standing composite tubes, supported on a specially designed compression test fixture. The study continues with an investigation into size effects in the energy-absorbing response of these cellular materials, where compression tests are undertaken on four scaled sizes of reinforced honeycomb core. Crushing tests on the multi-tube arrays have shown that woven carbon fibre reinforced plastic tubes absorb significantly greater levels of energy than their unidirectional counterparts. Here, the specific energy absorption did not vary with the number of tubes in the array, with values for the woven tubes averaging 110 kJ/kg and those for the unidirectional tubes averaging 75 kJ/kg. Inserting composite tubes into aluminium honeycomb served to increase the measured specific energy absorption of the core, resulting in values of specific energy absorption of up to 100 kJ/kg being recorded in the woven-based system. Tests on four scaled sizes of core have shown that the measured SEA does not vary with specimen size, indicating that data generated on small samples can be used to represent the energy-absorbing response of larger, more representative components.