Fatigue crack growth prediction in GLARE hybrid laminates

A mechanistic approach for fatigue crack growth prediction in GLARE laminates is presented. Three-dimensional finite element models are used to obtain the mode I stress intensity factor, KI, in the aluminum layers, and the fatigue crack growth rate of monolithic aluminum expressed as a Paris-type power law is used to predict the crack growth rates in the GLARE laminates. The crack growth rates in three different types of GLARE laminates with center-cracked tension configurations under cyclic loads are predicted and compared with experimental results. Qualitatively, the current approach predicts that the crack growth rate remains approximately constant with crack length, which is consistent with experimental observations. The quantitative correlations with the experimental crack growth rates also show excellent agreement. It is also found that the stress intensity factors in the aluminum layers at different through-thickness locations in the GLARE laminates are not identical. The cause and implications of this discrepancy and the advantages of the current approach to predict crack growth rates in generic hybrid laminates are discussed.