The strip yield model from the NASGRO computer software has been applied to predict fatigue crack growth in two different aircraft aluminium alloys under constant amplitude loading and programmed and random variable amplitude load histories. The computation options realized included either of the two different strip yield model implementations available in NASGRO and two types of the input material data description. The model performance has been evaluated based on comparisons between the predicted and observed results. It is concluded that altogether unsatisfactory prediction quality stems from an inadequate constraint factor conception incorporated in the NASGRO models.

Two different principles of TMF-testing were investigated for the wrought aluminium alloy AlCuBiPb (201 I). In the first testing method the specimens are clamped in a stiff load frame. A cyclic temperature load is applied, which leads to an out-of-phase (OP) TMF loading. The local strain is measured within the parallel cross section of the specimen. The second series of OP-TMF tests are conducted using closed loop strain control on a servo-hydraulic TMF testing system, which guarantees a rigid restraint condition within the parallel section of the specimen. To compare these two principles of TMF-testing, additional experiments were conducted with different mechanical strain amplitudes. The two experiments can be compared well, when the local strains are taken into account. Therefore, the method of the rigid clamped specimen can be used to get experimental data in a wide range of strain amplitudes.