Structures manufactured in fibre-metal laminates (e.g. Glare) have been designedconsidering ideal mechanical properties determined by the Classical Lamination Theory. Thismeans 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 productionline the complicated manufacturing process becomes difficult to control and the outcome productsmay not meet the quality expected. One of the consequences may be the poor adhesion of metal-prepreg or prepreg-prepreg as the result of porosity.The interlaminar shear strength of fibre-metal laminates decreases considerably, due to porosity, asthe result of insufficient adhesion between layers. Small voids or delaminations lead to stressconcentrations at the interfaces which may trigger delamination-propagation at the aluminium-prepreg and prepreg-prepreg interfaces at load levels significantly lower than what is achievable forperfectly bonded interfaces. Mechanical experiments show a maximum drop of 30% on theinterlaminar shear strength.In the present work, the effects of manufacturing-induced porosity on the interlaminar shear strengthof fibre-metal laminates are studied using a numerical approach. The individual layers are modelledby continuum elements, whereas the interfaces are modelled by cohesive elements which areequipped with a decohesion law to simulate debonding. Porosity is included in the geometry of theinterface by setting some of these elements to a pre-delaminated state.
|Journal||Key Engineering Materials|
|Publication status||Published - 2008|