Abstract:

In order to verify the applicability of four widely-used critical plane models ( including the maximum shear strain amplitude model,the KBM model,the FS model and the MKBM model) to the multiaxial fatigue life prediction of metallic materials,a comparison of these models were performed according to the statistical data of multiaxial fatigue test of the thin-walled tubular specimens with 8 kinds of metallic materials under 173 straining conditions.Additionally,some major problems existing in the fatigue damage evaluation and the fatigue life prediction based on critical plane parameters are discussed.The results show that both the maximum shear strain amplitude model and the KBM model accurately predict the fatigue life of the specimen under multiaxial proportional loading conditions,while non-conservative fatigue life is obtained when the specimen is under the action of multiaxial non-proportional load.Moreover,it is found that both the FS model and the MKBM model work well for the multiaxial non-proportional fatigue life prediction due to the introduction of the maximum normal stress acting on the critical plane which can reflect the effect of material's non-proportional additional hardening on the multiaxial fatigue damage.

Key words: multiaxial fatigue, fatigue life prediction, critical plane method, non-proportional loading