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.

Scaling effects in the manufacture and testing of glass fiber-reinforced epoxy grid-stiffened structures have been investigated in this study. Four nominally identical scaled sizes of mold have been manufactured, in which the length, width, height, and internal channel sizes were varied to achieve ¼, ½, ¾ and full-scale stiffened structures. The panels were manufactured on a glass mold using the vacuum-assisted resin transfer molding technique, enabling the flow front to be monitored throughout the filling process. Grid-stiffened beams were removed from the cured panels and tested in flexure on scaled bending fixtures. The vacuum-assisted resin transfer molding manufacturing study on the four scaled sizes indicated that resin infusion incurred more rapidly in the smallest mold, possibly due to difficulties in accurately cutting the glass fabric, which in turn reduced the effective areal density of the fabric, thereby modifying its effective permeability. The flow rates and velocities of the resin fronts in the larger mold sizes were similar, suggesting that an appropriately scaled mold can be used to successfully predict the infusion process in more representative structures. Flexural tests on the grid-stiffened samples highlighted a similar response in the three largest samples, with the smallest sample again offering a modified response. Similar failure mechanisms, including fracture of the grid structure, debonding at the skin-core interface, and flexural failure in the center of the sample, were observed in all of the samples.