Mechanical investigation on interlaminar behaviour of inverse FML using acoustic emission and finite element method

Fibre metal laminates (FML) are a group of materials consisting of layers of both metals and fibre reinforced composites. In this paper, the authors analyse the behaviour of fibre metal laminates with unusual thermoplastic matrices in composite layers under flexural loading. A three-point bending test is used to determine the flexural behaviour and interlaminar shear stress (ILSS). Two configurations of a specimen are taken into account – with fibre parallel to the specimen (A) and with fibre perpendicular to it (B). Numerical simulations using the finite element method are carried out. A model with cohesive elements is applied to model damage and a model with a continuum shell is used to determine ILSS. Both approaches can be successfully used for specimens group A. This proves that obtained previously material data is proper to use in the analysis of more complicated structures. In the case of group B, other causes than only interface damage need to be included. To investigate this, analysis of the acoustic signals is used to describe phenomenon occurring during bending for group A and B specimens. Conclusions based on AE support the hypothesis based on the optical remarks and results from numerical modelling.