To validate the low cycle fatigue(LCF)life of laminated composite fan blade at 1.5 fold nominal design speed,multiple fan blades were manufactured,and dovetail specimens were sampled at one of weak locations of fan blade to conduct tension-tension fatigue test.The correspodning finite element model was established to simulate the reaction forces in blade root regions,thus the maximum longitudinal forces applied to dovetail elements were determined.By introducing cohesive elements between adjacent layers and considering in-plane damage of laminas,the maximum load in the sinuisoidal spectrum was dynamiclly enlarged so that the actual static reaction forces in simulations caused the propagation of cracks similar to those in the test.The evolution of damage variables in terms of loading cycles were effectively represented,and the multiple damage modes were obtained when fatigue failure occurred under the circumstance that no design curves were currently available to formulate ther relationship.Test results showed that the average loading cycle was 17 207 until the delamination cracks appeared within the dovetail body.There was small dispersity regarding the locations of damage onset and propagation.Numerical results showed that the tensile matrix and the interlaminar debonding were the dominating damage modes that led to the ultimate low cycle fatigue failure.This study will support the establishment of low cycle fatigue test process and fatigue failure criterion.
维普
万方数据