Modeling blast failure of fibre metal laminates

Fibre metal laminates (FMLs) are multi-layered materials based on stacked arrangements of aluminium alloy and fibre-reinforced composite materials. Currently, FMLs such as GLARE (glass fibre/aluminium) and CALL (carbon fibre/aluminium) are attracting the interest of a number of aircraft manufacturers. For example, GLARE is being used in the manufacture of the upper fuselage of the A380, an aircraft that is capable of carrying up to 700 passengers. However, with such composite materials being more widely used, an on-going concern is the effect of foreign object impacts and blast on their mechanical properties. An example of impact is that of an aircraft underbelly or wing impacted at high velocity during take-off and landing by stones and other small debris from the runway. In addition blast can also occur in aircraft due to accident or terrorist attack. Composites undergo either impact or blast likely suffer both internal and external damages. In this paper, 3-D nonlinear finite element models were then developed to simulate blast failure of FMLs. Here, the effort was concentrated on modelling woven glass fibre reinforced composites, as simulation of aluminium alloys is relatively simple. In the current work, a damage evolution law is incorporated into the composite constitutive behaviour to obtain the blast response of FML panels. The implementation of the composite failure model into Abaqus/Explicit through a user-defined subroutine is discussed and validated. Also, the approximation of the blast impulse expressed by a surface pressure function is discussed and the limitations of this approximation are specified. The model is validated against the experimental results. Finally, summary remarks are drawn to highlight the major outcomes.