Optimization of Laminates’ Fracture Toughness Using Design of Experiments and Response Surface

Maximization of mode I critical delamination fracture toughness ( G _IC ) in cross ply graphite–epoxy laminates is studied using Design of Experiments and Taguchi arrays. The novel methodology proposed allows continuous and discrete factors to be considered simultaneously. Main and interactive factor effects on G _IC are evaluated. Selection of factors is based on design and material criteria; the ones considered are: width, length, thickness, stacking angle and stacking sequence. A Fractional Factorial experiment is used to reduce the number of tests. Double Cantilever Beam specimens are used for all mode I experiments. Statistically significant factors are culled and a response equation (RE), based on the importance of each factor, is established. The RE is then employed to optimize G _IC within the given set of restrictions. The effect of interfaces on delamination propagation is also investigated.