Mechanical investigation of inverse FML under mode II loading using acoustic emission and finite element method

Abstract

Fibre metal laminates (FML) are a specific type of material made of both metal and fibre-reinforced composite layers. In this paper, the authors analyse the behaviour of fibre metal laminates with unusual thermoplastic matrices in composite layers under mode II loading. A three-point bending setup was used along with end notched flexural specimen (ENF) to determine behaviour and of the interface between metal and composite layers under shear stress. Due to nonstandard layup configuration, mixed experimental–numerical method is proposed by authors to determine fracture energy. The finite element method is used to analyse conducted tests. A model with cohesive elements is applied to determine damage in the interface layer. For the purpose of understanding the damage process in particular layers, Acoustic Emission analysis was conducted for each specimen and parameters like amplitude, frequency, duration, root-mean-squared level of noise were obtained. As a result of conducted research critical energy in mode II was obtained GIIC=0.05Nmm as well as critical stress value in local shear direction (initiation criterion) tso=10MPa. The result obtained can be used as part of the material model in assessing the mixed-mode state of the researched material.