Multi-axial fatigue performance and crack expansion behavior of 2198-T8 aluminum-lithium alloy
The tensile and torsion fatigue crack propagation tests of thin-walled tubular specimens of 2198-T8 aluminum-lithium alloy un-der different loading conditions were conducted.The results show that the multi-axial fatigue life of the specimens increases with the de-crease of equivalent stress amplitude in the crack propagation stage.As the stress amplitude ratio increases,the multi-axial fatigue life de-creases,the axial strain increases,and the torsional strain decreases,and the torsional strain concentration lags behind the axial strain concentration.Combined with the digital image correlation(DIC)technique,the fatigue crack propagation rate model was fitted and two critical plane models were used to predict the crack propagation direction,in which the maximum normal stress plane was the best for pre-dicting the crack propagation direction.With the increase of stress amplitude ratio,the morphology of the crack propagation area changes from wear morphology to the coexistence morphology of wear and fatigue bands,and the crack propagation mode changes from type Ⅱ to type Ⅰ+Ⅱ,and eventually to type Ⅰ dominated.
万方数据
维普
