Characterisation of the Energy Release Rate GIC and GIIC of Fibre Metal Laminates Consisting of GFRP and Permeable Metal PliesThursday (29.09.2016) 09:30 - 09:45 Part of:
One of the big challenges in the field of fibre reinforced polymers (FRP) is to figure out a suitable way to introduce the mechanical load into the structure. In the aerospace industry and for rotor blades of wind turbines this is often realised by using bolted joints. The failure under bearing loading, e.g. delamination, is significant influenced by the ply connection of the composites. The resistance of an interlaminar interface to crack propagation is evaluated by the fracture toughness.
In this work the interlaminar fracture toughness of glass fibre reinforced polymer hybrids with permeable interlayers are deeply investigated. The fibre metal laminates (FML) are manufactured by the vacuum assisted resin transfer moulding. The double cantilever beam and end notched flexure testing methods are employed to measure the energy release rates GIc and GIIc. The results of the FML are compared with a conventional GFRP laminate. The fracture behaviour of the laminates is characterised using fractography and the light microscopy.
The permeable metal plies demonstrate a high potential in designing tough composites for structural applications. The FML show a significant higher fracture toughness GIc and GIIc in comparison to the GFRP laminate. All composites lead to an R-curve behaviour because GIc increases with crack growth due to bridging of the sewing yarn within the GFRP laminate and crack jumping within the hybrids. The fractography demonstrates a higher interfacial bonding between the permeable metal plies and matrix compared to glass fibre/matrix. The permeable metal plies allows the matrix flow through all layers in thickness direction during the injection process and leads to a high inter- and intralaminar matrix wetting with no imperfections (see Figure 1).