IMPACT LOADING ON FIBER METAL LAMINATES

Static indentation and low and high velocity impact tests are conducte d on specimens with a circular clamped test area. Monolithic Al 2024-T 3 and 7075-T6, various grades of Fibre Metal Laminates (FML), and comp osites are tested. The energy to create the first crack for FML with a ramid and carbon fibres is comparable to fibre reinforced composite ma terials and is relatively low compared to Al 2034-T3 and FML with R-gl ass fibres (GLARE). GLARE laminates can show a fibre critical or alumi nium critical failure mode. The dent depth after impact of FML is appr oximately equal to that of the monolithic aluminium alloy. The damage size of FML after impact is considerably smaller than of glass and car bon fibre composite materials. The maximum central deflection during l ow velocity impact loading is approximately equal to the static deflec tion at the same energy (i.e., area under load-deflection curve). This deflection can be modelled using the simplified Von Karman equations neglecting the contribution of the in-plane displacements. For these c alculations the shape: of the specimen under load was measured. This s hape was approximately independent of the central deflection and the t ype of material.