Papers by Keyword: Fibre Metal Laminates

Abstract: Although Fibre Metal Laminates (FMLs) show many advantages compared to other composite materials, their layered structure, a result of bonding dissimilar materials, makes FMLs prone to delamination. Conventional solutions to toughen the metal-composite interface have already reached their limit. For further improvement to the metal-composite interfacial bonding properties, a multiscale approach involving micro/nanotoughening mechanisms needs to be implemented. However, the fabrication of FMLs with controlled toughening at different length scales is complicated. This paper introduces a new methodology to manufacture FMLs having micro-and nanosized features using a 3D interconnected silver nanowire interleave at the metal-composite interface. The effects of processing parameters on the extent and effectiveness of the multiscale toughening mechanisms are presented.

Abstract: Kenaf natural fibre has become the subject of interest for a wide range of engineering sectors due to its biodegradable and outstanding mechanical properties. In this study, the effect of loading rate on the indentation behaviour of fibre metal laminates (FMLs) based on kenaf/epoxy subjected to static indentation loading was investigated. The fibre metal laminates were made of chopped strand mat (CSM) kenaf fibre with epoxy resin composite and 0.6 mm thickness of 1100-O aluminium alloy sheet by using vacuum infusion process (VIP) and hydraulic pressing technique. The experiments were conducted by using a universal testing machine with loading rate of 1 mm/min, 10 mm/min and 100 mm/min. The results of indentation resistance, energy absorption and corresponding indentation failure mechanisms were compared and discussed in this study. For 2/1 FMLs, the maximum contact force increased when the loading rate increased. The loading rate did not affect the indentation failure mechanisms of the 2/1 FMLs. However, for 3/2 FMLs, delamination occurred when the specimens were indented with loading rate of 10 mm/min.

Abstract: Multiple-site Damage (MSD) is a dangerous scenario for aircraft structures due to the interaction of adjacent cracks in one structural element. Despite their excellent fatigue crack growth resistance, Fibre Metal Laminates (FMLs) may also encounter this damage scenario. However, only few studies on fatigue crack growth in presence of MSD in FMLs has been reported. An overview of the relevant methods for predicting the crack propagation properties of MSD in FMLs is given and discussed in this paper. The fatigue crack growth of MSD in FMLs was experimentally studied and is reported in this paper. A new analytical methodology, based on the superposition principle and displacement compatibility method, is proposed.

Abstract: Structures manufactured in fibre-metal laminates (e.g. Glare) have been designed considering ideal mechanical properties determined by the Classical Lamination Theory. This means that among other assumptions, perfect bonding conditions between layers are assumed. However, more than often, perfect interfaces are not achieved or their quality is not guaranteed. When in laboratory, high-quality fibre-metal laminates are easily fabricated, but in the production line the complicated manufacturing process becomes difficult to control and the outcome products may not meet the quality expected. One of the consequences may be the poor adhesion of metalprepreg or prepreg-prepreg as the result of porosity. The interlaminar shear strength of fibre-metal laminates decreases considerably, due to porosity, as the result of insufficient adhesion between layers. Small voids or delaminations lead to stress concentrations at the interfaces which may trigger delamination-propagation at the aluminiumprepreg and prepreg-prepreg interfaces at load levels significantly lower than what is achievable for perfectly bonded interfaces. Mechanical experiments show a maximum drop of 30% on the interlaminar shear strength. In the present work, the effects of manufacturing-induced porosity on the interlaminar shear strength of fibre-metal laminates are studied using a numerical approach. The individual layers are modelled by continuum elements, whereas the interfaces are modelled by cohesive elements which are equipped with a decohesion law to simulate debonding. Porosity is included in the geometry of the interface by setting some of these elements to a pre-delaminated state.

Abstract: The quality of stamp formed parts depends on a number of variables. Numerical studies based on finite element analysis can provide evolution of strain during forming and correlate with different failures of the formed parts. This study presents a methodology of capturing the evolution of strain during forming through a photogrammetric method. An open die was used to monitor the strain evolution of domed parts. The forming characteristic of a fibre-metal laminate system was compared to a monolithic aluminum alloy to elucidate the differences in the strain evolution during forming. It was found that the two materials exhibited different strain evolution during forming and this affected the failure behavior of the formed parts.