Diagonal tension buckling and post-buckling of fibre-metal laminate beams

As part of a larger ongoing collaborative project between the National Research Council Canada (NRC), Bombardier Aerospace and Carleton University, various GLARE (GLAss REinforced aluminum) web materials were tested to determine their performance while in a state of diagonal tension.{09}Of importance was to evaluate the validity of the methodology developed by the National Advisory Committee for Aeronautics (NACA) for aluminum alloys, when applied to predicting the yielding and failure of GLARE-webs. Each test specimen is an 83 in x 31 in (2.06 m x 0.79 m) flat beam emulation of an aircraft stiffened thin skin. The diagonal tension effect is simulated in the test specimen by applying an in-plane shear load. Under increasing shear stress in the beam, the web material buckles elastically, then forms permanent buckles, and finally suffers a critical failure. The tests were conducted using the Institute for Aerospace Research's Multi-Actuator Test Platform, a new facility for testing large aircraft components and sub-assemblies. Varying thickness of GLARE 3, GLARE 4, and 2024-T3 aluminum were tested. The results have shown that an unmodified NACA-based methodology can be used to predict GLARE web stress/strain reactions up until its yielding point. However, more detailed studies into the plastic buckling behavior of GLARE will have to be conducted to accurately predict critical failures.